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BoP Lab / Classes / STU

STU vs FP vs P2 pace at every track

Lap times across years say as much about the weather as the class. % of STU is each class's best lap as a share of STU's on the same day, so the conditions drop out: 100% is level, less is quicker, and a move in it is the class getting faster or slower against the field.

Class · click a class to switch, + to compare alongside (up to 4)
Series
Reference · what % is measured against
Tracks · untick to narrow

Closest to the field: STU 100.0% of STU Eric Heinrich, Daytona International Speedway Runoffs 2015 race · FP 90.3% of STU Mason Workman, Virginia International Raceway Runoffs 2022 race · P2 84.3% of STU Jeff Shafer, Indianapolis Motor Speedway Runoffs 2017 qualifying

1:201:402:002:202:4040 rule changes between Runoffs 2018 and Runoffs 201940 ▾42 rule changes between Runoffs 2019 and Runoffs 202042 ▾41 rule changes between Runoffs 2020 and Runoffs 202141 ▾56 rule changes between Runoffs 2021 and Runoffs 202256 ▾17 rule changes between Runoffs 2022 and Runoffs 202317 ▾30 rule changes between Runoffs 2023 and Runoffs 202430 ▾36 rule changes between Runoffs 2024 and Runoffs 202536 ▾49 rule changes between Runoffs 2025 and Runoffs 202649 ▾STU race best at Runoffs 2015: 2:06.756 (Eric Heinrich)STU race best at Runoffs 2016: 1:34.597 (Cameron Maugeri)STU race best at Runoffs 2017: 1:49.387 (Rob Huffmaster)STU race best at Runoffs 2018: 1:46.514 (Kevin Boehm)STU race best at Runoffs 2019: 2:00.483 (Kevin Boehm)STU race best at Runoffs 2020: 2:28.410 (Anthony Geraci)STU race best at Runoffs 2021: 1:47.441 (Joe Moser)STU race best at Runoffs 2022: 2:32.357 (Mark Liller)STU race best at Runoffs 2023: 2:02.302 (Mark Liller)STU race best at Runoffs 2024: 2:25.824 (Thomas Noble)STU race best at Runoffs 2025: 2:24.497 (Chip Herr)STU race best at Runoffs 2026: 2:26.416 (Richard Astacio)STU qualifying best at Runoffs 2015: 2:05.494 (Eric Heinrich)STU qualifying best at Runoffs 2016: 1:32.738 (Joe Moser)STU qualifying best at Runoffs 2017: 1:48.921 (Rob Huffmaster)STU qualifying best at Runoffs 2018: 1:19.234 (Franklin Church)STU qualifying best at Runoffs 2019: 1:59.948 (Kevin Boehm)STU qualifying best at Runoffs 2020: 2:27.883 (David Fiorelli)STU qualifying best at Runoffs 2021: 1:47.078 (Joe Moser)STU qualifying best at Runoffs 2022: 2:00.615 (Johan Schwartz)STU qualifying best at Runoffs 2023: 2:00.389 (Johan Schwartz)STU qualifying best at Runoffs 2024: 2:26.227 (Thomas Noble)STU qualifying best at Runoffs 2025: 2:23.083 (Peter Cunningham)STU qualifying best at Runoffs 2026: 2:24.912 (Richard Astacio)FP race best at Runoffs 2015: 2:12.419 (Kevin Ruck)FP race best at Runoffs 2016: 1:36.399 (John Walker)FP race best at Runoffs 2017: 1:53.007 (Eric Prill)FP race best at Runoffs 2018: 1:48.481 (Joe Huffaker)FP race best at Runoffs 2019: 2:08.076 (Eric Prill)FP race best at Runoffs 2020: 2:34.033 (Kevin Ruck)FP race best at Runoffs 2021: 1:59.933 (Cliff Ira)FP race best at Runoffs 2022: 2:17.641 (Mason Workman)FP race best at Runoffs 2023: 2:07.787 (Cliff Ira)FP race best at Runoffs 2024: 2:33.246 (Kevin Ruck)FP race best at Runoffs 2025: 2:34.271 (Chris Bovis)FP race best at Runoffs 2026: 2:33.240 (David Strittmatter)FP qualifying best at Runoffs 2015: 2:11.009 (Kevin Ruck)FP qualifying best at Runoffs 2016: 1:35.938 (John Walker)FP qualifying best at Runoffs 2017: 1:52.091 (Eric Prill)FP qualifying best at Runoffs 2018: 1:47.588 (Joe Huffaker)FP qualifying best at Runoffs 2019: 2:07.436 (Eric Prill)FP qualifying best at Runoffs 2020: 2:31.414 (Ethan Shippert)FP qualifying best at Runoffs 2021: 1:51.082 (Craig Chima)FP qualifying best at Runoffs 2022: 2:06.217 (Eric Prill)FP qualifying best at Runoffs 2023: 2:08.248 (Cliff Ira)FP qualifying best at Runoffs 2024: 2:32.327 (Cliff Ira)FP qualifying best at Runoffs 2025: 2:32.395 (David Strittmatter)FP qualifying best at Runoffs 2026: 2:33.275 (Stephen Simonds)P2 race best at Runoffs 2015: 1:52.355 (Jeff Shafer)P2 race best at Runoffs 2016: 1:20.904 (Jeff Shafer)P2 race best at Runoffs 2017: 1:32.481 (Jeff Shafer)P2 race best at Runoffs 2018: 1:32.071 (Chuck Bona)P2 race best at Runoffs 2019: 1:50.258 (Greg Gyann)P2 race best at Runoffs 2020: 2:09.793 (Robert Iversen)P2 race best at Runoffs 2021: 1:35.322 (Tim Day Jr)P2 race best at Runoffs 2022: 2:15.834 (Greg Gyann)P2 race best at Runoffs 2023: 1:48.829 (Lucian Pancea)P2 race best at Runoffs 2024: 2:08.322 (Bart Wolf)P2 race best at Runoffs 2026: 2:09.441 (Mike Reupert)P2 qualifying best at Runoffs 2015: 1:51.825 (Chris Farrell)P2 qualifying best at Runoffs 2016: 1:20.188 (Jeff Shafer)P2 qualifying best at Runoffs 2017: 1:31.826 (Jeff Shafer)P2 qualifying best at Runoffs 2018: 1:28.784 (Tim Day Jr)P2 qualifying best at Runoffs 2019: 1:49.111 (Robert Iversen)P2 qualifying best at Runoffs 2020: 2:08.514 (Robert Iversen)P2 qualifying best at Runoffs 2021: 1:33.235 (Tim Day Jr)P2 qualifying best at Runoffs 2022: 1:47.566 (Tim Day Jr)P2 qualifying best at Runoffs 2023: 1:48.590 (Greg Gyann)P2 qualifying best at Runoffs 2024: 2:07.405 (Bart Wolf)P2 qualifying best at Runoffs 2026: 2:10.606 (Greg Gyann)Daytona International Speedway · Runoffs 2015R2015Mid-Ohio Sports Car Course · Runoffs 2016R2016Indianapolis Motor Speedway · Runoffs 2017R2017Sonoma Raceway · Runoffs 2018R2018Virginia International Raceway · Runoffs 2019R2019Road America · Runoffs 2020R2020Indianapolis Motor Speedway · Runoffs 2021R2021Virginia International Raceway · Runoffs 2022R2022Virginia International Raceway · Runoffs 2023R2023Road America · Runoffs 2024R2024Road America · Runoffs 2025R2025Road America · Runoffs 2026R2026
STUFPP2solid race · dashed qualifying · slower is lower
90%100%110%40 rule changes between Runoffs 2018 and Runoffs 201940 ▾42 rule changes between Runoffs 2019 and Runoffs 202042 ▾41 rule changes between Runoffs 2020 and Runoffs 202141 ▾56 rule changes between Runoffs 2021 and Runoffs 202256 ▾17 rule changes between Runoffs 2022 and Runoffs 202317 ▾30 rule changes between Runoffs 2023 and Runoffs 202430 ▾36 rule changes between Runoffs 2024 and Runoffs 202536 ▾49 rule changes between Runoffs 2025 and Runoffs 202649 ▾STU race best at Runoffs 2015: 100.0% of STU's (Eric Heinrich)STU race best at Runoffs 2016: 100.0% of STU's (Cameron Maugeri)STU race best at Runoffs 2017: 100.0% of STU's (Rob Huffmaster)STU race best at Runoffs 2018: 100.0% of STU's (Kevin Boehm)STU race best at Runoffs 2019: 100.0% of STU's (Kevin Boehm)STU race best at Runoffs 2020: 100.0% of STU's (Anthony Geraci)STU race best at Runoffs 2021: 100.0% of STU's (Joe Moser)STU race best at Runoffs 2022: 100.0% of STU's (Mark Liller)STU race best at Runoffs 2023: 100.0% of STU's (Mark Liller)STU race best at Runoffs 2024: 100.0% of STU's (Thomas Noble)STU race best at Runoffs 2025: 100.0% of STU's (Chip Herr)STU race best at Runoffs 2026: 100.0% of STU's (Richard Astacio)STU qualifying best at Runoffs 2015: 100.0% of STU's (Eric Heinrich)STU qualifying best at Runoffs 2016: 100.0% of STU's (Joe Moser)STU qualifying best at Runoffs 2017: 100.0% of STU's (Rob Huffmaster)STU qualifying best at Runoffs 2018: 100.0% of STU's (Franklin Church)STU qualifying best at Runoffs 2019: 100.0% of STU's (Kevin Boehm)STU qualifying best at Runoffs 2020: 100.0% of STU's (David Fiorelli)STU qualifying best at Runoffs 2021: 100.0% of STU's (Joe Moser)STU qualifying best at Runoffs 2022: 100.0% of STU's (Johan Schwartz)STU qualifying best at Runoffs 2023: 100.0% of STU's (Johan Schwartz)STU qualifying best at Runoffs 2024: 100.0% of STU's (Thomas Noble)STU qualifying best at Runoffs 2025: 100.0% of STU's (Peter Cunningham)STU qualifying best at Runoffs 2026: 100.0% of STU's (Richard Astacio)FP race best at Runoffs 2015: 104.5% of STU's (Kevin Ruck)FP race best at Runoffs 2016: 101.9% of STU's (John Walker)FP race best at Runoffs 2017: 103.3% of STU's (Eric Prill)FP race best at Runoffs 2018: 101.8% of STU's (Joe Huffaker)FP race best at Runoffs 2019: 106.3% of STU's (Eric Prill)FP race best at Runoffs 2020: 103.8% of STU's (Kevin Ruck)FP race best at Runoffs 2021: 111.6% of STU's (Cliff Ira)FP race best at Runoffs 2022: 90.3% of STU's (Mason Workman)FP race best at Runoffs 2023: 104.5% of STU's (Cliff Ira)FP race best at Runoffs 2024: 105.1% of STU's (Kevin Ruck)FP race best at Runoffs 2025: 106.8% of STU's (Chris Bovis)FP race best at Runoffs 2026: 104.7% of STU's (David Strittmatter)FP qualifying best at Runoffs 2015: 104.4% of STU's (Kevin Ruck)FP qualifying best at Runoffs 2016: 103.5% of STU's (John Walker)FP qualifying best at Runoffs 2017: 102.9% of STU's (Eric Prill)Off the chart: FP qualifying best at Runoffs 2018: 135.8% of STU's (Joe Huffaker)FP qualifying best at Runoffs 2019: 106.2% of STU's (Eric Prill)FP qualifying best at Runoffs 2020: 102.4% of STU's (Ethan Shippert)FP qualifying best at Runoffs 2021: 103.7% of STU's (Craig Chima)FP qualifying best at Runoffs 2022: 104.6% of STU's (Eric Prill)FP qualifying best at Runoffs 2023: 106.5% of STU's (Cliff Ira)FP qualifying best at Runoffs 2024: 104.2% of STU's (Cliff Ira)FP qualifying best at Runoffs 2025: 106.5% of STU's (David Strittmatter)FP qualifying best at Runoffs 2026: 105.8% of STU's (Stephen Simonds)P2 race best at Runoffs 2015: 88.6% of STU's (Jeff Shafer)P2 race best at Runoffs 2016: 85.5% of STU's (Jeff Shafer)P2 race best at Runoffs 2017: 84.5% of STU's (Jeff Shafer)P2 race best at Runoffs 2018: 86.4% of STU's (Chuck Bona)P2 race best at Runoffs 2019: 91.5% of STU's (Greg Gyann)P2 race best at Runoffs 2020: 87.5% of STU's (Robert Iversen)P2 race best at Runoffs 2021: 88.7% of STU's (Tim Day Jr)P2 race best at Runoffs 2022: 89.2% of STU's (Greg Gyann)P2 race best at Runoffs 2023: 89.0% of STU's (Lucian Pancea)P2 race best at Runoffs 2024: 88.0% of STU's (Bart Wolf)P2 race best at Runoffs 2026: 88.4% of STU's (Mike Reupert)P2 qualifying best at Runoffs 2015: 89.1% of STU's (Chris Farrell)P2 qualifying best at Runoffs 2016: 86.5% of STU's (Jeff Shafer)P2 qualifying best at Runoffs 2017: 84.3% of STU's (Jeff Shafer)P2 qualifying best at Runoffs 2018: 112.1% of STU's (Tim Day Jr)P2 qualifying best at Runoffs 2019: 91.0% of STU's (Robert Iversen)P2 qualifying best at Runoffs 2020: 86.9% of STU's (Robert Iversen)P2 qualifying best at Runoffs 2021: 87.1% of STU's (Tim Day Jr)P2 qualifying best at Runoffs 2022: 89.2% of STU's (Tim Day Jr)P2 qualifying best at Runoffs 2023: 90.2% of STU's (Greg Gyann)P2 qualifying best at Runoffs 2024: 87.1% of STU's (Bart Wolf)P2 qualifying best at Runoffs 2026: 90.1% of STU's (Greg Gyann)Daytona International Speedway · Runoffs 2015R2015Mid-Ohio Sports Car Course · Runoffs 2016R2016Indianapolis Motor Speedway · Runoffs 2017R2017Sonoma Raceway · Runoffs 2018R2018Virginia International Raceway · Runoffs 2019R2019Road America · Runoffs 2020R2020Indianapolis Motor Speedway · Runoffs 2021R2021Virginia International Raceway · Runoffs 2022R2022Virginia International Raceway · Runoffs 2023R2023Road America · Runoffs 2024R2024Road America · Runoffs 2025R2025Road America · Runoffs 2026R2026
STUFPP2solid race · dashed qualifying · each class's best lap as a share of STU's at the same event (the reference class, changeable above); 100% is level, less is quicker, so up the chart is quicker
EventSTUFPP2
Qual best Race best Trap Qual best Race best Trap vs STU % of STU Qual best Race best Trap vs STU % of STU 
Road America Runoffs 20262026-09-282:24.912Richard Astacio · fastest of 17 · top 5 within 2.6s+1.829s (+1.28%)2:26.416Richard Astacio · fastest of 16 · top 5 within 1.5s+1.919s (+1.33%)145.1Hugh Stewart+0.8 mph (+0.5%)2:33.275Stephen Simonds · fastest of 26 · top 5 within 1.0s+0.880s (+0.58%)2:33.240David Strittmatter · fastest of 25 · top 5 within 1.7s-1.031s (-0.67%)132.4David Strittmatter±0.0 mph (±0.0%)+6.824squal +8.363s104.7%qual 105.8%2:10.606Greg Gyann · fastest of 11 · top 5 within 5.3s+3.201s (+2.51%)2:09.441Mike Reupert · fastest of 11 · top 5 within 4.2s+1.119s (+0.87%)155.0Matt Strand+2.4 mph (+1.6%)-16.975squal -14.306s88.4%qual 90.1%
49 rule changes (STU: 15, FP: 34)10 cars added · 10 weight · 7 induction · 4 engine · 2 tyres & wheels · 1 aero · 12 wording · 3 other · GT3U wheel and tyre options clarified: 15x7 with 225 section at +275 lbs; 15x9 with 245 section at +275 lbs plus 1.5%; 16–18x9 with 245 section at +275 lbs plus 3.0%. · HP Mini Cooper 02-06 compression ratio increases from 10.6 to 11.0:1. · 1996-2000 Honda Civic CX/DX/LX with D16Y7 engine newly classified in HP. · HP 1275 Midget/Sprite alternate intake manifold from MG-B now permitted; balance tube shortening and flange modification allowed. · HP Honda Civic DX/LX 92–95 wheels 13x7 to 15x7, weight 2420 to 2350 lbs. · STU cars at or under 2,825 lbs minimum weight limited to 8-inch wheels; over 2,825 lbs limited to 9-inch wheels. · STU GT3U minimum weight increases from GT3 race weight plus 225 to plus 275 pounds; 2.0L unrestricted engines add 75 lbs. · STU adds BMW M50B20TU engine, 1991 cc, minimum weight per chart, must meet all STU engine regulations. · STL, STU weight calculation procedure clarified: positive percentages added first, negative subtracted second, then fixed weights applied. · EP Mazda MX-5 94-97 front track widens to 1516 mm, rear to 1534 mm. · FP Volkswagen Jetta 82-84 carburation option 2 comma removed; all five models' carb specs clarified or confirmed. · FP Spec Line Volkswagen Rabbit and Scirocco 1789cc base weight corrected to 1803 lbs. · EP Triumph GT6 auto-type drivetrain choke size increases from 44mm to 45mm. · BMW E21 320i/is (80–83) newly classified in HP Spec Lines effective 2026-05-01. · HP BMW 318is 84-85 displacement corrected to 1767 cc, 89.0 x 71.0 mm bore and stroke. · STU Honda K20C1 Turbo I4 turbo restrictor increases from 35mm to 36mm TIR. · STU GT86 Cup car must meet 2022 Toyota GR Cup rules, tires maximum 245 section width. · STU Mazda Renesis Street Port added to Table B with 2450 lbs minimum weight and 70mm throttle body options. · STU eliminates 33 and 34 mm inlet restrictor options, removing minimum weights of 2380 and 2525 lbs. · FP Fiat X-1/9 1300 and 1500 intake and exhaust valve sizes corrected to 36.3/(1.43) and 31.2-33.3/(1.23-1.31). · FP Fiat X-1/9 & Bertone dual carburetors choke size increases from 28mm to 30mm on intake runner manifold. · STU Mazda MZR engines may now use Fab 9 Elite NC MX5 Performance Intake manifold as alternative option. · FP adds Toyota 5E 1497cc DOHC engine, 1900 lbs, 23mm restrictor, SIR fuel induction. · FP class adds Toyota 4E DOHC 1331 cc engine, 1900 lbs minimum weight, unrestricted fuel induction. · FP Fiat X1/9 fuel injection carburetors simplified to one 36 or 40 DCNF option; exhaust valve enlarged to 33.0/1.30. · STU Mazda MZR (LF, L3, L5) Turbo added; Goodwin intake removed, Jack Spania Racing 70 mm intake and Fab9 Tuning bottom-mount turbo kit approved. · EP Triumph TR2–TR4A may use 5-speed gearbox without overdrive; Weber carburetors and weight reference deleted. · EP BMW Z3 2.5L and other models get smaller restrictors, 50mm to 55mm, and Z3 2.5L weight rises 50 to 78 lbs. · FP Lancia Scorpion minimum weight cut to 1950 lbs from 2030 lbs. · FP VW Rabbit Convertible no longer required to remove factory roll bar. · FP Acura Integra and Honda Civic models gain 50–79 lbs minimum weight; Mazda Miata and Mercury Capri compression ratio to 11.0:1 and valve lift to .425". · FP Honda D15, D16, B16A, B18 engines gain 105–120 lbs minimum weight across seven configurations. · STU 36mm restrictor revised to 2830 cc, 37mm to 2980 cc. · STU removes 275 tire option and 2% weight adder for cars over 3150 lbs; maximum section width now 245. · STU Honda K20 and K24 engines lose 2% weight penalty; minimum weight now per chart only. · EP Nissan 280Z minimum weight lowered to 2400 lbs, 2460 lbs with *, 2520 lbs with **. · EP Mazda MX-5 1.8L 90-97 minimum weight reduced to 2125 lbs. · HP Spec Lines Austin-Healey Sprite/Midget 1098cc minimum weight drops to 1550 lbs. · HP Volvo 142 P-1800 engine gains compression ratio limit 12.0:1 and valve lift limit .425 inch. · HP Mini DOHC 1.6 valve lift limit drops to .390" from .450". · FP Scirocco 83–88 classified Prep Level 1: 1733–1803 lbs, 1715–1780 cc, iron block, aluminium head, carburetted or fuel injected. · FP and HP Volkswagen Rabbit descriptions updated to clarify Cabriolet body style inclusion. · EP, FP, HP: rear drum-to-disc brake conversion clarified; rotors solid, diameter limited to largest front rotor permitted. · EP Ford Mustang 94-98 fuel injected throttle body inside diameter set to 60. · FP Volkswagen Scirocco: remove two weight tiers at 1733 and 1803 lbs, two engine options, and 13-inch wheel option; allow 15-inch wheels. · STU Honda K24 engine swap weight increases by 2 percent, effective November 1, 2025. · HP Plymouth Arrow gains 4 or 5 speed transmission option specification. · Appendix G.2.3 clarifies rim width and diameter are absolute maximums; wording corrected from 'is' to 'are'. · EP, FP, HP throttle body inside dimensions and butterfly now allow +/-.25mm tolerance from stock.showhide
  • STU Wheel and tire requirements for GT3U #40679wordingwordingGT3U wheel and tyre options clarified: 15x7 with 225 section at +275 lbs; 15x9 with 245 section at +275 lbs plus 1.5%; 16–18x9 with 245 section at +275 lbs plus 3.0%.
  • FP Mini Cooper Compression Ratio #40517enginefasterengineHP Mini Cooper 02-06 compression ratio increases from 10.6 to 11.0:1.
  • FP 1996-2000 Honda Civic (CX, DX, VP, LX) with Engine Code D16Y7 #40322cars addedadded1996-2000 Honda Civic CX/DX/LX with D16Y7 engine newly classified in HP.
  • FP 1275 Midget/Sprit Alternate intake manifold E/O #40370inductionaddedinductionHP 1275 Midget/Sprite alternate intake manifold from MG-B now permitted; balance tube shortening and flange modification allowed.
  • FP HP Honda Civic (92-95) #40464weight -70 lbsfasterweightHP Honda Civic DX/LX 92–95 wheels 13x7 to 15x7, weight 2420 to 2350 lbs.
  • STU 9” Wheels #40433tyres & wheelsslowertyres & wheelsSTU cars at or under 2,825 lbs minimum weight limited to 8-inch wheels; over 2,825 lbs limited to 9-inch wheels.
  • STU Weight adjustment to former GT3U cars #40474weightslowerweightSTU GT3U minimum weight increases from GT3 race weight plus 225 to plus 275 pounds; 2.0L unrestricted engines add 75 lbs.
  • STU Request to allow BMW M50B20TU engine in STU #40202cars addedaddedSTU adds BMW M50B20TU engine, 1991 cc, minimum weight per chart, must meet all STU engine regulations.
  • STU Calculating Weight #40224wordingwordingSTL, STU weight calculation procedure clarified: positive percentages added first, negative subtracted second, then fixed weights applied.
  • FP Miata track width - errors and omissions #39976aerofasteraeroEP Mazda MX-5 94-97 front track widens to 1516 mm, rear to 1534 mm.
  • FP GCR Spec Line Correction #39977wordingwordingFP Volkswagen Jetta 82-84 carburation option 2 comma removed; all five models' carb specs clarified or confirmed.
  • FP CGR Spec Line Weight Correction #39978wordingwordingFP Spec Line Volkswagen Rabbit and Scirocco 1789cc base weight corrected to 1803 lbs.
  • FP Triumph GT6 Spec Change. #40098inductionfasterinductionEP Triumph GT6 auto-type drivetrain choke size increases from 44mm to 45mm.
  • FP Request to Classify BMW E21 320i #40110cars addedaddedBMW E21 320i/is (80–83) newly classified in HP Spec Lines effective 2026-05-01.
  • FP BMW 318is 84-85 engine displacement correction #40116wordingwordingHP BMW 318is 84-85 displacement corrected to 1767 cc, 89.0 x 71.0 mm bore and stroke.
  • STU Turbo Restrictor Size Increase Request #40008inductionfasterinductionSTU Honda K20C1 Turbo I4 turbo restrictor increases from 35mm to 36mm TIR.
  • STU GT86 Cups Car in STU #40028wordingwordingSTU GT86 Cup car must meet 2022 Toyota GR Cup rules, tires maximum 245 section width.
  • STU Mazda Rx-8 Renesis - Streetported Variant & Added Weight #39785cars addedaddedSTU Mazda Renesis Street Port added to Table B with 2450 lbs minimum weight and 70mm throttle body options.
  • STU Eliminate 33 and 34 mm TIRs #39872inductionremovedinductionSTU eliminates 33 and 34 mm inlet restrictor options, removing minimum weights of 2380 and 2525 lbs.
  • FP Correct Valve Sizes on FP Fiat x19 1300 and 1500 #39850otherotherFP Fiat X-1/9 1300 and 1500 intake and exhaust valve sizes corrected to 36.3/(1.43) and 31.2-33.3/(1.23-1.31).
  • FP Dual Carburetor Adjustments #39851inductionfasterinductionFP Fiat X-1/9 & Bertone dual carburetors choke size increases from 28mm to 30mm on intake runner manifold.
  • STU Fab 9 Racing Intake Manifold in STU #39767cars addedaddedSTU Mazda MZR engines may now use Fab 9 Elite NC MX5 Performance Intake manifold as alternative option.
  • FP Request Toyota 5E Series Engines #38208otheraddedFP adds Toyota 5E 1497cc DOHC engine, 1900 lbs, 23mm restrictor, SIR fuel induction.
  • FP Request for Toyota 4E Series Engines #38209cars addedaddedFP class adds Toyota 4E DOHC 1331 cc engine, 1900 lbs minimum weight, unrestricted fuel induction.
  • FP Dual Carbs for the Fiat X1/9 #39593enginefasterengineFP Fiat X1/9 fuel injection carburetors simplified to one 36 or 40 DCNF option; exhaust valve enlarged to 33.0/1.30.
  • STU Request for Permission on Aftermarket Turbo Kit and Intake #39529cars addedaddedSTU Mazda MZR (LF, L3, L5) Turbo added; Goodwin intake removed, Jack Spania Racing 70 mm intake and Fab9 Tuning bottom-mount turbo kit approved.
  • FP TR2 Notes E&O #39180wordingwordingEP Triumph TR2–TR4A may use 5-speed gearbox without overdrive; Weber carburetors and weight reference deleted.
  • FP Balance of Power #39187induction +50 lbsslowerinductionEP BMW Z3 2.5L and other models get smaller restrictors, 50mm to 55mm, and Z3 2.5L weight rises 50 to 78 lbs.
  • FP Competition Adjustment Request #39259weight -80 lbsfasterweightFP Lancia Scorpion minimum weight cut to 1950 lbs from 2030 lbs.
  • FP Factory Roll Bar Removal on VW Convertible #39268wordingwordingFP VW Rabbit Convertible no longer required to remove factory roll bar.
  • FP FP Parity Request #39325weight +50 lbsslowerweightFP Acura Integra and Honda Civic models gain 50–79 lbs minimum weight; Mazda Miata and Mercury Capri compression ratio to 11.0:1 and valve lift to .425".
  • FP Adjust former-GTL Honda's with B/D-Series Engines #39374weightslowerweightFP Honda D15, D16, B16A, B18 engines gain 105–120 lbs minimum weight across seven configurations.
  • STU Turbo Inlet Restrictor Table #38961wordingwordingSTU 36mm restrictor revised to 2830 cc, 37mm to 2980 cc.
  • STU 275 Tire Rule #38983tyres & wheelsslowertyres & wheelsSTU removes 275 tire option and 2% weight adder for cars over 3150 lbs; maximum section width now 245.
  • STU STU Honda Engine weight penalty #39375weightfasterweightSTU Honda K20 and K24 engines lose 2% weight penalty; minimum weight now per chart only.
  • FP Please Lower Weight of 280Z #38871weight -160 lbsfasterweightEP Nissan 280Z minimum weight lowered to 2400 lbs, 2460 lbs with *, 2520 lbs with **.
  • FP Miata Weight Adjustment Follow Up #38949weight -25 lbsfasterweightEP Mazda MX-5 1.8L 90-97 minimum weight reduced to 2125 lbs.
  • FP Weight Break for 1098 Midget / Sprite #38970weight -80 lbsfasterweightHP Spec Lines Austin-Healey Sprite/Midget 1098cc minimum weight drops to 1550 lbs.
  • FP HP Volvo 142 spec omission #38994engineslowerengineHP Volvo 142 P-1800 engine gains compression ratio limit 12.0:1 and valve lift limit .425 inch.
  • FP HP Mini DOHC 1.6 #38996engineslowerengineHP Mini DOHC 1.6 valve lift limit drops to .390" from .450".
  • FP 83-88 FP Scirocco Spec Line Creation #38997cars addedaddedFP Scirocco 83–88 classified Prep Level 1: 1733–1803 lbs, 1715–1780 cc, iron block, aluminium head, carburetted or fuel injected.
  • FP Add to Rabbit description #39019wordingwordingFP and HP Volkswagen Rabbit descriptions updated to clarify Cabriolet body style inclusion.
  • FP Clean-up 9.1.5.E.7e #39025otherotherEP, FP, HP: rear drum-to-disc brake conversion clarified; rotors solid, diameter limited to largest front rotor permitted.
  • FP Add TB size to Ford Mustang (94-98) Spec Line #39130inductionaddedinductionEP Ford Mustang 94-98 fuel injected throttle body inside diameter set to 60.
  • FP Correct Existing VW Scirocco Spec Line #39140cars addedremovedcars addedFP Volkswagen Scirocco: remove two weight tiers at 1733 and 1803 lbs, two engine options, and 13-inch wheel option; allow 15-inch wheels.
  • STU Non-Homologated Engine Swaps - Specifically K24A2 w/ Honda CRZ #38746weightslowerweightSTU Honda K24 engine swap weight increases by 2 percent, effective November 1, 2025.
  • FP HP Plymouth Arrow spec omission #38995cars addedaddedHP Plymouth Arrow gains 4 or 5 speed transmission option specification.
  • FP Add Wheel Diameter to Appendix G #39008wordingwordingAppendix G.2.3 clarifies rim width and diameter are absolute maximums; wording corrected from 'is' to 'are'.
  • FP Add TB ID tolerance to general Prod rules #39009wordingaddedEP, FP, HP throttle body inside dimensions and butterfly now allow +/-.25mm tolerance from stock.
Road America Runoffs 20252025-09-292:23.083Peter Cunningham · fastest of 16 · top 5 within 2.6s-3.144s (-2.15%)2:24.497Chip Herr · fastest of 15 · top 5 within 3.8s-1.327s (-0.91%)144.3Chip Herr-1.0 mph (-0.7%)2:32.395David Strittmatter · fastest of 20 · top 5 within 2.9s+0.068s (+0.04%)2:34.271Chris Bovis · fastest of 19 · top 5 within 1.8s+1.025s (+0.67%)132.4David Strittmatter-1.1 mph (-0.8%)+9.774squal +9.312s106.8%qual 106.5%
36 rule changes (STU: 18, FP: 17, P2: 1)13 weight · 7 cars added · 6 induction · 3 engine · 3 tyres & wheels · 4 wording · STU Lotus Elise SC and Exige SC weight reduced from 2450 to 2250 lbs. · STU-TCR gains GT3 TCR spec lines; 275 tyre option now costs 150 lb adder, up from 100 lb. · Lotus Evora GT4 minimum weight drops to 2700 lbs; Elise Cup R to 2250 lbs; Elise SC and Exige SC to 2450–2550 lbs. · EP BMW Z4 03-05 gains 52mm flat plate intake restrictor. · EP Fiat 124 Spider Competition 1600 and 2000 minimum weight drops 50 lbs to 2000; carburetors now allow 36mm chokes instead of 34mm. · STU 2.8–3.2L N/A engines now permit 245 max tyre width; over 3150 lbs cars may run 275 with 2% weight penalty. · STU Mazda MZR intake manifold now allows Goodwin 61-2510 or Gato Performance 31972. · STU Honda JDM H23a added, 2259 cc, minimum weight per chart, must meet ST engine regulations. · HP Fiat X-1/9 and Bertone 1500 minimum weights reduced to 1740 lbs, 1784 lbs, 1827 lbs; 1300 models to 1600, 1640, 1680 lbs; additional 1300 and 1500 specs to 2010, 1900 lbs. · STU wheels capped at 18 inches diameter; under 2,850 lbs max 8 inches wide, over 2,850 lbs max 9 inches wide. · STU-GT3U minimum weight reduced from plus 250 to plus 225 pounds; wheel and tyre options clarified with weight adjustments. · Chevrolet Spark 16-22 classified in HP Pre at 1850 lbs base, 1896 lbs modified, 1943 lbs. · HP Ford Festiva 88-93 minimum weight lowered to 1600 lbs, competition weight to 1640, prepared weight to 1680; compression ratio raised to 11.0:1. · EP BMW Z3 2.5L, Z3 2.8L, 328i E36/E46, 325i E36/E46 intake restrictors reduced 4mm each, to 52–58mm. · FP Acura Integra and Honda Civic models restricted from 55mm to 51mm intake; Del Sol VTEC weight raised to 2290, 2347, 2405 lbs. · EP, FP, HP may use any interior or exterior mirror meeting rule 9.3.36. · EP Honda S2000 1997cc minimum weight drops 75 lbs to 2375; 2157cc drops 60 lbs to 2450. · EP Mazda MX-5 Miata 99-05 minimum weight reduced to 2100 lbs, 2153 lbs with power, 2205 lbs modified. · FP Volkswagen Jetta Mark IV 4dr FWD added to GTL-FP Cars classification with 98.2 in wheelbase. · FP adds optional induction chokes as alternative to SIR, same size as listed restrictor. · STU BMW N54/N55 3.0 classified at chart plus 3% minimum weight; N54 twin turbo not allowed. · STU Mini Cooper S SC pulley diameter reduced to 2.185 inches. · STU Honda K20C1 Turbo I4 exempted from 3% direct injection weight adder. · STU GT3U minimum weight increases 150 pounds to 250 pounds. · EP BMW models now require flat plate intake restrictors: Z3 2.5L 52mm, Z3 2.8L 55mm, 328i E36 58mm, 328i/ci E46 58mm, 325i E46 56mm, 325i E36 56mm, 325is M-Technic 56mm. · EP BMW 325i/is E30 84-91 weight reduced to 2150 lbs base, 2204 lbs with turbo, 2258 lbs supercharged. · FP Sprite and Midget 1275cc and 1500cc bore, stroke, displacement, and valve specifications corrected to factory dimensions. · F Production now permits GT-Lite cars meeting Appendix N specs to compete, governed by Appendix N not PCS 9.1.5. · STU Audi 1.8T Wagon removed; Porsche 944 1800cc weight to Chart, turbo inlet restrictor deleted. · STU-GT3 reclassified as STU-GT3U, effective 1 January 2026. · STU GT3 TCR may run 275-wide DOT tires with 100 lb weight penalty; A compound prohibited at 275. · P2 2000 cc Pinto engine car minimum weight set to 1335 lbs. · STL STU Mazda Miata alternate front hubs Mazda Motorsports Development Part #0000-04-5HUB-S1 approved. · STU BMW N54/N55 turbo inlet restrictors now required per GCR definition; twin turbo conversion to single turbo clarified. · HP 1275 Spridget compression ratio raised to 12.0:1; 1098cc also raised to 12.0:1. · STU Mini Cooper S SC: 1900 stock pulley spec to 2.565 diameter; 2100 now permits 2.285 diameter pulley.showhide
  • STU Lotus Weight Reduction E&O #38919weightfasterweightSTU Lotus Elise SC and Exige SC weight reduced from 2450 to 2250 lbs.
  • STU STU-TCR Adjustments #38723weightslowerweightSTU-TCR gains GT3 TCR spec lines; 275 tyre option now costs 150 lb adder, up from 100 lb.
  • STU Lotus Weight Reduction #38772weight -50 lbsfasterweightLotus Evora GT4 minimum weight drops to 2700 lbs; Elise Cup R to 2250 lbs; Elise SC and Exige SC to 2450–2550 lbs.
  • FP BMW Z4 update #38490inductionslowerinductionEP BMW Z4 03-05 gains 52mm flat plate intake restrictor.
  • FP EP Fiat 124 Spider Competition Adjustment Request #38498weight -50 lbsfasterweightEP Fiat 124 Spider Competition 1600 and 2000 minimum weight drops 50 lbs to 2000; carburetors now allow 36mm chokes instead of 34mm.
  • STU 2.8-3.2L N/A Engine Allowances #38007tyres & wheelsfastertyres & wheelsSTU 2.8–3.2L N/A engines now permit 245 max tyre width; over 3150 lbs cars may run 275 with 2% weight penalty.
  • STU 2006-2015 Mazda Miata Intake Manifold #38422engineaddedengineSTU Mazda MZR intake manifold now allows Goodwin 61-2510 or Gato Performance 31972.
  • STU Requesting Approval of the JDM Honda h23a #38489cars addedaddedSTU Honda JDM H23a added, 2259 cc, minimum weight per chart, must meet ST engine regulations.
  • FP Base Weight Adjustment for H-Production X1/9 Spec Lines #38255weight -50 lbsfasterweightHP Fiat X-1/9 and Bertone 1500 minimum weights reduced to 1740 lbs, 1784 lbs, 1827 lbs; 1300 models to 1600, 1640, 1680 lbs; additional 1300 and 1500 specs to 2010, 1900 lbs.
  • STU Wheel Size Inconsistency #38018tyres & wheelstyres & wheelsSTU wheels capped at 18 inches diameter; under 2,850 lbs max 8 inches wide, over 2,850 lbs max 9 inches wide.
  • STU Table C: STU-GT3U Clarification #38268weightfasterweightSTU-GT3U minimum weight reduced from plus 250 to plus 225 pounds; wheel and tyre options clarified with weight adjustments.
  • FP Request for Classification of Chevrolet Spark #37755cars addedaddedChevrolet Spark 16-22 classified in HP Pre at 1850 lbs base, 1896 lbs modified, 1943 lbs.
  • FP Request to Lower Ford Festiva Minimum Weight to 1600 LBS #37939weight -100 lbsfasterweightHP Ford Festiva 88-93 minimum weight lowered to 1600 lbs, competition weight to 1640, prepared weight to 1680; compression ratio raised to 11.0:1.
  • FP Request Competition Adjustment to BMW Z3 2.5L #37120inductionslowerinductionEP BMW Z3 2.5L, Z3 2.8L, 328i E36/E46, 325i E36/E46 intake restrictors reduced 4mm each, to 52–58mm.
  • FP FP Class Adjustments #37458inductionslowerinductionFP Acura Integra and Honda Civic models restricted from 55mm to 51mm intake; Del Sol VTEC weight raised to 2290, 2347, 2405 lbs.
  • FP Interpretation of Production Rules on Mirrors #37235wordingaddedEP, FP, HP may use any interior or exterior mirror meeting rule 9.3.36.
  • FP Weight Reduction for Honda S2000 #37466weightfasterweightEP Honda S2000 1997cc minimum weight drops 75 lbs to 2375; 2157cc drops 60 lbs to 2450.
  • FP Mazda 1999 Miata 1.8L #37488weight -50 lbsfasterweightEP Mazda MX-5 Miata 99-05 minimum weight reduced to 2100 lbs, 2153 lbs with power, 2205 lbs modified.
  • FP Errors & Omissions #37648cars addedaddedFP Volkswagen Jetta Mark IV 4dr FWD added to GTL-FP Cars classification with 98.2 in wheelbase.
  • FP GTL/FP consolidation 2025 Rules #37659inductionaddedinductionFP adds optional induction chokes as alternative to SIR, same size as listed restrictor.
  • STU BMW N54/N55 Engine Allowance Follow Up #37447cars addedaddedSTU BMW N54/N55 3.0 classified at chart plus 3% minimum weight; N54 twin turbo not allowed.
  • STU STU Mini Cooper pulley size clarification re: letter #36980 #37717inductionfasterinductionSTU Mini Cooper S SC pulley diameter reduced to 2.185 inches.
  • STU Question About a Weight Modifier #37782weightfasterweightSTU Honda K20C1 Turbo I4 exempted from 3% direct injection weight adder.
  • STU Increase Minimum Weight #37919weight +100 lbsslowerweightSTU GT3U minimum weight increases 150 pounds to 250 pounds.
  • FP Effective date for Jan 2025 GCR updates #37654inductionslowerinductionEP BMW models now require flat plate intake restrictors: Z3 2.5L 52mm, Z3 2.8L 55mm, 328i E36 58mm, 328i/ci E46 58mm, 325i E46 56mm, 325i E36 56mm, 325is M-Technic 56mm.
  • FP Request to Reduce Weight of BMW 325i/is E30 (84-91) Spec Line #37119weight -50 lbsfasterweightEP BMW 325i/is E30 84-91 weight reduced to 2150 lbs base, 2204 lbs with turbo, 2258 lbs supercharged.
  • FP Fix Error in Spridget Spec Line #37437wordingwordingFP Sprite and Midget 1275cc and 1500cc bore, stroke, displacement, and valve specifications corrected to factory dimensions.
  • FP Create ruleset that allows GTL cars to run in FP #37485cars addedaddedF Production now permits GT-Lite cars meeting Appendix N specs to compete, governed by Appendix N not PCS 9.1.5.
  • STU Audi 1.8t Wagon STU Table B #36685cars addedremovedcars addedSTU Audi 1.8T Wagon removed; Porsche 944 1800cc weight to Chart, turbo inlet restrictor deleted.
  • STU Merger GT3 to STU #37486wordingunclearSTU-GT3 reclassified as STU-GT3U, effective 1 January 2026.
  • STU GT3 TCR Tire allowance #37494tyres & wheelsaddedtyres & wheelsSTU GT3 TCR may run 275-wide DOT tires with 100 lb weight penalty; A compound prohibited at 275.
  • P2 2000 cc Pinto Engine Car Weight #37187weightslowerweightP2 2000 cc Pinto engine car minimum weight set to 1335 lbs.
  • STU Request to Remove Miata Hubs from General category #37138cars addedaddedSTL STU Mazda Miata alternate front hubs Mazda Motorsports Development Part #0000-04-5HUB-S1 approved.
  • STU BMW N54/N55 Engine Allowance #37146wordingwordingSTU BMW N54/N55 turbo inlet restrictors now required per GCR definition; twin turbo conversion to single turbo clarified.
  • FP 1275 HP Spridget Level 2 Only #36518enginefasterengineHP 1275 Spridget compression ratio raised to 12.0:1; 1098cc also raised to 12.0:1.
  • STU R53 15% Pulley Request #36980enginefasterengineSTU Mini Cooper S SC: 1900 stock pulley spec to 2.565 diameter; 2100 now permits 2.285 diameter pulley.
Road America Runoffs 20242024-10-012:26.227Thomas Noble · fastest of 18 · top 5 within 2.3s-1.656s (-1.12%)2:25.824Thomas Noble · fastest of 17 · top 5 within 2.4s-2.586s (-1.74%)145.3Thomas Noble+1.1 mph (+0.8%)2:32.327Cliff Ira · fastest of 26 · top 5 within 2.1s+0.913s (+0.60%)2:33.246Kevin Ruck · fastest of 24 · top 5 within 1.4s-0.787s (-0.51%)133.5David Strittmatter+0.3 mph (+0.2%)+7.422squal +6.100s105.1%qual 104.2%2:07.405Bart Wolf · fastest of 14 · top 5 within 3.0s-1.109s (-0.86%)2:08.322Bart Wolf · fastest of 13 · top 5 within 0.6s-1.471s (-1.13%)152.5Lucian Pancea-0.6 mph (-0.4%)-17.502squal -18.822s88.0%qual 87.1%
30 rule changes (STU: 4, FP: 21, P2: 5)9 weight · 4 cars added · 3 induction · 2 aero · 2 engine · 1 removed · 8 wording · 1 other · FP Honda CRX/CRX Si 84-87 block material changes from iron to aluminium. · HP Volkswagen Golf and Jetta 85-92 track correction: front 1537 mm (60.5 in.), rear 1529 mm (60.2 in.). · STU RWD turbo cars no longer required to reduce inlet restrictor by 1 mm from table minimum. · Nissan 300ZX 84–89 added to EP, 2550–2678 lbs, 2960 cc SOHC, fuel injection, 12.0:1 compression, 0.500" valve lift limit. · Mazda RX-7 92-97 added to EP Prep as Level 2 rotary 13B 6-port, 2200–2310 lbs, carb or fuel injection, 42 mm choke. · EP Mazda RX-8 (04-11) alternate spec line removed; single spec line retained. · FP Honda CRX 84-87 plastic front header nose panel, rocker skirts, door caps can now be replica alternate material stock appearance. · FP Acura Integra 90-01 and Honda Civic Del Sol VTEC, Civic Si 99-00 require 55mm flat plate intake restrictor. · P2 Spec Line E engine notes clarify oil system, ECU, and exhaust remain unrestricted; wording only. · P2 FIA Group CN notes clarify V de V European Proto Endurance Challenge bodywork, rear diffuser, wing, wheels, assisted shifting allowed; regulations link provided. · HP removes four redundant VW spec lines: Rabbit Cabriolet 1780, Scirocco 1588, Scirocco 1780 8-valve 83-88, Scirocco 1588. · FP Mazda Protégé ES (01-03) renamed to Mazda Protégé ES/5 (01-03). · STU Mini Cooper S SC gains alternate LEAP OMICRON hood scoop part LEP-OMICRON3 as permitted option. · STU BMW S54 B32 OEM dry sump oiling system now permitted. · HP Honda Civic 1.5 1988-91 minimum weight drops 70 lbs to 2175; also 2-speed and 3-speed minimums cut 72 and 73 lbs. · STL and STU now permit electric power steering pumps, OEM electric-assisted steering, or column-mounted electric steering assist systems. · EP BMW Z3 2.5L minimum weight increased to 2500 lbs, 2563 lbs with power adder, 2625 lbs with two power adders. · FP Honda throttle body inside diameters corrected across seven models: Civic 1.5 to 42", Civic Si to 55", CRX 1.5 to 42", CRX 84-87 to 33/42", CRX Si 88-91 to 55". · EP Mazda MX-5 1.8L (90-97) minimum weight cut to 2150 lbs; (94-97) variants to 2000, 2050, 2100 lbs. · EP Triumph GT6 dual 1.75-inch carburetors weight rises to 1940 lbs; triple Weber 40 DCOE option added at 1990 lbs. · EP Honda S2000 fuel injected throttle body inside diameter increases from 62mm to 64mm. · EP Triumph TR8 dry sump allowance moved from Carburetor line to Notes. · EP Porsche 944/924S 2.5L and 2.7L minimum weights corrected: 2479cc to 2306–2363 lbs, 2681cc to 2358–2415 lbs. · P2 AMAC and related cars: clarified B.1 modified engine range to 2008 and older stock engines only, with 38mm restrictor and 1025 lbs minimum weight. · P2 Suzuki GSX-R1000 engine: 2007–2008 crankcase 11300-21860 may be replaced with 2016–2019 GSX-S1000 part 11301-04840. · EP Porsche 944/924S combines 2.5L and 2.7L variants (83-89), raises weight to 2250–2415 lbs, allows 2681cc displacement. · FP Toyota Corolla 2TC loses 43 lbs to 1810; HP Corolla loses 50–52 lbs to 1910–2006. · EP Triumph GT6 minimum weight drops to 1800 lbs. · P2 Table 1 engine date ranges clarified: Stock Engine replaced with specific marques Suzuki, Yamaha, Honda, BMW for 2009-newer and 2008-older rows.showhide
  • FP Errors/emissions Honda Civic/CRX #36700enginefasterengineFP Honda CRX/CRX Si 84-87 block material changes from iron to aluminium.
  • FP Errant entry in HP production line item #36231wordingwordingHP Volkswagen Golf and Jetta 85-92 track correction: front 1537 mm (60.5 in.), rear 1529 mm (60.2 in.).
  • STU RWD Turbo Disadvantage #36255inductionfasterinductionSTU RWD turbo cars no longer required to reduce inlet restrictor by 1 mm from table minimum.
  • FP NIssan 300ZX Z31 to EP #35830cars addedaddedNissan 300ZX 84–89 added to EP, 2550–2678 lbs, 2960 cc SOHC, fuel injection, 12.0:1 compression, 0.500" valve lift limit.
  • FP RX7 1993 and Up Request In EP Spec Lines, classify #36031cars addedaddedMazda RX-7 92-97 added to EP Prep as Level 2 rotary 13B 6-port, 2200–2310 lbs, carb or fuel injection, 42 mm choke.
  • FP Clean-up Multiple EP RX-8 Spec Lines In EP #36156cars addedremovedcars addedEP Mazda RX-8 (04-11) alternate spec line removed; single spec line retained.
  • FP Request to Replace CRX Plastic Panels #35876cars addedaddedFP Honda CRX 84-87 plastic front header nose panel, rocker skirts, door caps can now be replica alternate material stock appearance.
  • FP FP data and parity #35896inductionaddedinductionFP Acura Integra 90-01 and Honda Civic Del Sol VTEC, Civic Si 99-00 require 55mm flat plate intake restrictor.
  • P2 CN Spec ECU #35835wordingwordingP2 Spec Line E engine notes clarify oil system, ECU, and exhaust remain unrestricted; wording only.
  • P2 E&O - Correct FIA Group CN spec line notes #35900wordingwordingP2 FIA Group CN notes clarify V de V European Proto Endurance Challenge bodywork, rear diffuser, wing, wheels, assisted shifting allowed; regulations link provided.
  • FP GCR Correction - Redundant HP Spec Lines #35623removedremovedHP removes four redundant VW spec lines: Rabbit Cabriolet 1780, Scirocco 1588, Scirocco 1780 8-valve 83-88, Scirocco 1588.
  • FP Update FP Protege (01-03) Model Info #35715wordingwordingFP Mazda Protégé ES (01-03) renamed to Mazda Protégé ES/5 (01-03).
  • STU Letter #35397 addendum #35453aeroaddedaeroSTU Mini Cooper S SC gains alternate LEAP OMICRON hood scoop part LEP-OMICRON3 as permitted option.
  • STU S54 Drysump #35464otheraddedSTU BMW S54 B32 OEM dry sump oiling system now permitted.
  • FP Update 1988-1991 Civic to Match 1988-1991 CRX #35399weightfasterweightHP Honda Civic 1.5 1988-91 minimum weight drops 70 lbs to 2175; also 2-speed and 3-speed minimums cut 72 and 73 lbs.
  • STU ST Electric-Assisted Steering Systems #35066aeroaddedaeroSTL and STU now permit electric power steering pumps, OEM electric-assisted steering, or column-mounted electric steering assist systems.
  • FP FP data #35060weight +25 lbs
  • FP Request to Review Z3 2.5 Spec Line #35073weight +50 lbsslowerweightEP BMW Z3 2.5L minimum weight increased to 2500 lbs, 2563 lbs with power adder, 2625 lbs with two power adders.
  • FP Corrections to Honda Spec Lines in FP #35250wordingunclearFP Honda throttle body inside diameters corrected across seven models: Civic 1.5 to 42", Civic Si to 55", CRX 1.5 to 42", CRX 84-87 to 33/42", CRX Si 88-91 to 55".
  • FP Miata Alternate Head #35253weight -50 lbsfasterweightEP Mazda MX-5 1.8L (90-97) minimum weight cut to 2150 lbs; (94-97) variants to 2000, 2050, 2100 lbs.
  • FP Triumph GT6 Adjustments #35255weightslowerweightEP Triumph GT6 dual 1.75-inch carburetors weight rises to 1940 lbs; triple Weber 40 DCOE option added at 1990 lbs.
  • FP Honda S2000 throttle body #35272inductionfasterinductionEP Honda S2000 fuel injected throttle body inside diameter increases from 62mm to 64mm.
  • FP Correction within Triumph TR8 Spec Line #35315wordingwordingEP Triumph TR8 dry sump allowance moved from Carburetor line to Notes.
  • FP Correction to EP 924S/944 Spec Line #35317weightweightEP Porsche 944/924S 2.5L and 2.7L minimum weights corrected: 2479cc to 2306–2363 lbs, 2681cc to 2358–2415 lbs.
  • P2 E&O - Clarify B.1 modified engine range in AMAC spec lines #35225wordingwordingP2 AMAC and related cars: clarified B.1 modified engine range to 2008 and older stock engines only, with 38mm restrictor and 1025 lbs minimum weight.
  • P2 Replacement Engine Crankcase for 07/08 Suzuki GSX-R1000 Engines #35340engineaddedengineP2 Suzuki GSX-R1000 engine: 2007–2008 crankcase 11300-21860 may be replaced with 2016–2019 GSX-S1000 part 11301-04840.
  • FP Porsche 944/924S Rule Change Request #35002weightslowerweightEP Porsche 944/924S combines 2.5L and 2.7L variants (83-89), raises weight to 2250–2415 lbs, allows 2681cc displacement.
  • FP FP and HP Toyota Corolla #35030weight -43 lbsfasterweightFP Toyota Corolla 2TC loses 43 lbs to 1810; HP Corolla loses 50–52 lbs to 1910–2006.
  • FP Triumph GT6 Adjustments #35054weight -30 lbsfasterweightEP Triumph GT6 minimum weight drops to 1800 lbs.
  • P2 Correct Table 1 for Engine Date Range Specifications #35182wordingwordingP2 Table 1 engine date ranges clarified: Stock Engine replaced with specific marques Suzuki, Yamaha, Honda, BMW for 2009-newer and 2008-older rows.
Virginia International Raceway Runoffs 20232023-09-232:00.389Johan Schwartz · fastest of 13 · top 5 within 2.3s-0.226s (-0.19%)2:02.302Mark Liller · fastest of 14 · top 5 within 1.6s-30.055s (-19.73%)144.0Mark Liller+0.1 mph (+0.1%)2:08.248Cliff Ira · fastest of 21 · top 5 within 1.0s+2.031s (+1.61%)2:07.787Cliff Ira · fastest of 20 · top 5 within 0.8s-9.854s (-7.16%)133.7Cliff Ira+1.1 mph (+0.9%)+5.485squal +7.859s104.5%qual 106.5%1:48.590Greg Gyann · fastest of 12 · top 5 within 1.7s+1.024s (+0.95%)1:48.829Lucian Pancea · fastest of 11 · top 5 within 0.9s-27.005s (-19.88%)150.9Lucian Pancea-0.2 mph (-0.2%)-13.473squal -11.799s89.0%qual 90.2%
17 rule changes (STU: 3, FP: 6, P2: 8)6 cars added · 3 engine · 1 weight · 7 wording · FP and HP Sprite and Spitfire 1500 intake valve size corrected to 36.6 mm, removing prior decimal specifications. · HP Volkswagen Rabbit Cabriolet 1780 removed; Rabbit 1588 and 1715 reclassified with year and body-type clarifications. · STU adds 2022 Toyota GR Cup and GR86 Cup, both 2387cc, 2700 lbs, 18-inch wheels, 245/620R18 slicks. · Ford Fiesta HP model years change to 11-19; Chevrolet Sonic FP model years change to 12-19. · Toyota Celica 78-80 classified FP Prep level 2, 2100–2205 lbs, 2190 cc SOHC four-cylinder, stock carburetion, 11.0:1 compression limit, .450" valve lift limit. · P2 minimum side body height must equal front axle centerline height, viewed from side. · P2 closed cockpit single seat cars now prohibited unless Table 1 spec line permits. · P2 engine table spec line B.1 redundant effective date language removed and table updated. · P2 motorcycle restrictor reduced 35mm to 34mm for 2011+ Kawasaki; minimum weights increased to 1100 lbs for 2009+ engines; cockpit length corrected to 23.622 inches. · STU Mazda BP5A now classified at 1839 cc displacement, 2510 lbs minimum weight, alternate intake manifold permitted. · STU minimum weights adjusted: 2450 cc to 2595 lbs, 2600 cc to 2710 lbs. · FP Mazda Protégé ES (01-03) renamed to Protégé ES/5 (01-03) to include P5 model variant. · EP, FP, HP port matching limited to 1 inch depth from mating surface. · Sebeco NP01-EVO and Elan NP01 added to P2 with Mazda 2.0L MZR, no restrictor required, 1600 lb minimum weight. · P2 Radical SR3/SR4, Cup, Club Sport, Pro-Sport, PR6: assisted shifting clarified from A-assisted to Aassisted; Cup engine restrictor changed from Unrestricted to Not required. · P2 chassis now allows composite materials partially installed; anti-intrusion panels attachment simplified; Stohr and converted models clarified.showhide
  • FP Correct Intake Valve Size on 1500cc Midget/Spitfire #34419wordingwordingFP and HP Sprite and Spitfire 1500 intake valve size corrected to 36.6 mm, removing prior decimal specifications.
  • FP ITC to FP? #34286cars addedremovedcars addedHP Volkswagen Rabbit Cabriolet 1780 removed; Rabbit 1588 and 1715 reclassified with year and body-type clarifications.
  • STU 2022 Toyota GR Cup for STU #34449cars addedaddedSTU adds 2022 Toyota GR Cup and GR86 Cup, both 2387cc, 2700 lbs, 18-inch wheels, 245/620R18 slicks.
  • FP Request to Classify Sonic and Fiesta in HP #34264cars addedaddedFord Fiesta HP model years change to 11-19; Chevrolet Sonic FP model years change to 12-19.
  • FP Classification Request for 1978 Toyota Celica #34097cars addedaddedToyota Celica 78-80 classified FP Prep level 2, 2100–2205 lbs, 2190 cc SOHC four-cylinder, stock carburetion, 11.0:1 compression limit, .450" valve lift limit.
  • P2 Clarify minimum side body height requirement #34143wordingwordingP2 minimum side body height must equal front axle centerline height, viewed from side.
  • P2 Clarify closed cockpit single seat car allowance #34144wordingwordingP2 closed cockpit single seat cars now prohibited unless Table 1 spec line permits.
  • P2 Remove redundant effective date language and update engine table #34012wordingwordingP2 engine table spec line B.1 redundant effective date language removed and table updated.
  • P2 E&O - Correct dimensional equivalents #34038enginefasterengineP2 motorcycle restrictor reduced 35mm to 34mm for 2011+ Kawasaki; minimum weights increased to 1100 lbs for 2009+ engines; cockpit length corrected to 23.622 inches.
  • STU Alternate OEM Miata Intake Manifold #33827engineaddedengineSTU Mazda BP5A now classified at 1839 cc displacement, 2510 lbs minimum weight, alternate intake manifold permitted.
  • STU E&O STU NA Weight Chart. #33737weightfasterweightSTU minimum weights adjusted: 2450 cc to 2595 lbs, 2600 cc to 2710 lbs.
  • FP Request to Add Mazda Protege P5 to FP #33664cars addedaddedFP Mazda Protégé ES (01-03) renamed to Protégé ES/5 (01-03) to include P5 model variant.
  • FP Review Limited Prep Port Matching Rules #33600wordingwordingEP, FP, HP port matching limited to 1 inch depth from mating surface.
  • P2 Request to Classify Sebeco NP01 #33378cars addedaddedSebeco NP01-EVO and Elan NP01 added to P2 with Mazda 2.0L MZR, no restrictor required, 1600 lb minimum weight.
  • P2 Radical spec line clarifications #33485wordingwordingP2 Radical SR3/SR4, Cup, Club Sport, Pro-Sport, PR6: assisted shifting clarified from A-assisted to Aassisted; Cup engine restrictor changed from Unrestricted to Not required.
  • P2 E&O original class intent #33519wordingwordingP2 chassis now allows composite materials partially installed; anti-intrusion panels attachment simplified; Stohr and converted models clarified.
  • P2 Update Engine Table Spec Line B.1 #33608engine
Virginia International Raceway Runoffs 20222022-09-242:00.615Johan Schwartz · fastest of 21 · top 5 within 2.6s+0.667s (+0.56%)2:32.357Mark Liller · fastest of 19 · top 5 within 4.3s+31.874s (+26.46%)143.9Johan Schwartz+0.1 mph (+0.1%)2:06.217Eric Prill · fastest of 18 · top 5 within 1.5s-1.219s (-0.96%)2:17.641Mason Workman · fastest of 15 · top 5 within 3.2s+9.565s (+7.47%)132.5Cliff Ira+1.2 mph (+0.9%)-14.716squal +5.602s90.3%qual 104.6%1:47.566Tim Day Jr · fastest of 12 · top 5 within 3.0s-1.545s (-1.42%)2:15.834Greg Gyann · fastest of 12 · top 5 within 10.1s+25.576s (+23.20%)151.1Robert Iversen+1.8 mph (+1.2%)-16.523squal -13.049s89.2%qual 89.2%
56 rule changes (STU: 21, FP: 25, P2: 10)10 weight · 9 engine · 7 cars added · 3 aero · 3 induction · 3 tyres & wheels · 1 suspension & brakes · 18 wording · 2 other · Volkswagen New Beetle 2.5L 5-cyl DOHC classified in EP at 2400–2520 lbs with fuel injection. · EP Mazda RX-7 12A/13B and 13B now permit 2 bbl fuel injected throttle body with 42mm chokes on dual-y manifold. · EP VW Corrado 92-95 stroke corrected to 90.3 mm and displacement to 2792 cc. · STU Mazda 13B Turbo added as Chart Limited displacement, streetport only, alternative turbos only. · STU OEM louver vents no longer count against vent allowance or 200 square inch limit. · STU non-4-valve engines gain 9% base engine weight reduction allowance; 2400cc minimum weight drops 1 lb to 2595. · STU normally-aspirated engines 2976cc–3200cc with single throttle body lose 10% base engine weight reduction allowance. · ST removes redundant language about engine balance shaft removal and alternate pulley installation. · EP Subaru BRZ title updated to include model years 13–20; Toyota 86/Scion FR-S title likewise updated to 13–20. · FP Lotus Super Seven 91.7 ci minimum weight increases 50 lbs, to 1580. · EP Mazda MX-5 Global Cup 16-22 minimum weight set to 2400 lbs; sequential gearbox allowed with 150 lbs penalty. · BMW 128i (08-13) classified in EP at 2700 lbs minimum with 2996 cc engine, stock throttle body, 11.0:1 compression and 0.400" valve lift limits. · EP, FP, HP open cars now allow carbon fiber hardtops if they retain OEM exterior profiles. · Mazda Protégé ES 99-00 classified FP, 2150–2258 lbs, 1839 cc DOHC, fuel injection, 11.0:1 compression, 0.450" valve lift. · P2 chassis construction clarified: full composite allowed; partial composite must roll without composite parts installed. · P2 classification wording cleaned up in GCR section 9.1.8.C and GCR contents. · STU cars that qualified for 9 inch wheels in 2021 may continue running them through 2022 only. · STU splitter definition clarified: must attach to lowest point of front, have no vertical deviations. · EP Mazda RX-8 13B carburetor option replaced with fuel-injected throttle body or stock fuel injection. · EP, FP, HP Production clarify idle control valve options: stock original allowed, removable with blocked ports, or mechanical replaced with electronic stock type. · FP BMW 325e/es displacement corrected to 2693 cc. · P2 Oldsmobile cam rules correct spelling from 'after market' to 'aftermarket' in two sections. · STU BMW E36 M3 (95-99) S52B32 minimum weight cut to 3110 lbs from 3200, displacement to 3152 cc. · STU BMW S50B32 Euro maximum displacement 3201 cc, minimum weight 3300 lbs, permits 0.040 overbore and 0.5 compression increase. · ST engine swap origin rule narrowed: North America changed to United States only for case-by-case approval. · STU Honda CRX 84-91 and Civic Del Sol 93-97 both ineligible for front-wheel-drive weight reductions. · STU wheel width rule clarified: under 2950 lbs uses max 8.0 inches, 2950 lbs and over uses max 9.0 inches. · STU single-throttle body cars get lower minimum weights: 2450cc to 2596 lbs, 2500cc to 2635 lbs, 2550cc to 2675 lbs. · EP BMW Z3 2.5L intake restrictor reduced from 59mm to 58mm flat plate. · Ford Mustang 94-98 weight reduced to 2550/2614/2678 lbs; 99-03 3.8L classified EP at 2700/2768/2835 lbs. · EP, FP, HP Improved Touring cars may use any DOT-approved tyre as defined by 9.3.45. · FP VW Golf III/Jetta III 93-98 intake valve shrinks to 39.5 mm (1.56 in), exhaust to 32.9 mm (1.30 in). · P2 adds Beasley B2 at 1350 lbs with Mazda 12A, 40.5mm venturi, and up to 16.5in wing chord. · P2 wings: terminology change from 'cord' to 'chord', and 'only' removed from Bobsy and Jondal notes. · P2 Converted F5 cars renamed F500, must retain F500 suspension, minimum width 55 inches. · STU single throttle body weight reduction removed; minimum weights revised down to 2990 lbs at 3000cc from 3300 lbs. · STU Audi A4 1.8T minimum weight fixed to 3050 lbs, K04 turbo removed, VF30 with 35mm restrictor required; Porsche 944 1800 weight fixed to 3050 lbs, VW/Audi 1.8L engine removed, 35mm inlet restrictor required. · STL and STU Improved Touring vehicles must now conform to section 9.1.4 Tires & Wheels. · EP, FP, HP: stock/original idle control devices permitted unmodified or completely removed with openings blocked. · P2 motorcycle engines gain 5cc to 1505cc max, two-stroke gains 5cc to 1205cc max, automotive engines add 50 lbs minimum weight to 1350 lbs. · STU engines may delete balance shafts and plug openings; alternate pulleys or gears allowed only for timing belt or chain operation. · STU hood vents now allow louvers within 200 square inches. · EP Porsche 968 intake valve size changes to 39.0 mm, 1.54 mm seat width. · EP, FP, HP front-wheel-drive cars may alter body and subframes to install alternate axle shaft, matching RWD freedom. · EP BMW Z3 2.5L adds alternate throttle body option with Turner adapter and permits head casting 1738400. · FP Honda Civic Del Sol VTEC compression ratio limited to 11.0:1, valve lift to .425", removes dry sump and internal engine prep allowances. · FP Honda Prelude 84-87 and Mazda GLC/323 86-88 valve lift measurement method clarified, Level 1 parts list removed. · P2 Control Area definition clarified: rectangular zone from rear edge of front tires to front edge of rear tires, full car width. · STU adds Honda K23 with 2354 cc displacement and chart minimum weight, K24 block allowed with K23 internals and head. · STU Honda K23 relaxes internal engine requirement, now needs only K23 crankshaft. · STL/STU intake manifold and cylinder head porting clarified as free; intake and exhaust porting wording removed. · EP Porsche 944S2 89-91 requires 56mm flat plate intake restrictor; compression ratio 12.0:1 max, valve lift 0.500" max, dry sump allowed. · Toyota Corolla GTS RWD (84-87) and FX16 FWD (87-88) added to HP; old Corolla (84-87) removed. · P2 specification line B.1 engine table entry amended; details of change not provided in excerpt. · P2 Control Area definition clarified: rear tire edge and front tire edge bounds, car's lower surface width, floor extensions and aerodynamic attachments included, vertical structures prohibited. · Toyota MR-2 1.6L 85-89 HP track width corrected to 15×47 / 15×47 inches; stock track baseline now 103% plus 2.5 inches.showhide
  • FP Request to classify VW New Beetle 2.5L in EP #32725cars addedaddedVolkswagen New Beetle 2.5L 5-cyl DOHC classified in EP at 2400–2520 lbs with fuel injection.
  • FP Request Rotary Injection on Dual Y manifold #32775inductionaddedinductionEP Mazda RX-7 12A/13B and 13B now permit 2 bbl fuel injected throttle body with 42mm chokes on dual-y manifold.
  • FP Request for Corrado Stroke & Displacement Correction #32985wordingwordingEP VW Corrado 92-95 stroke corrected to 90.3 mm and displacement to 2792 cc.
  • STU Request Mazda 13 B turbo #32668cars addedaddedSTU Mazda 13B Turbo added as Chart Limited displacement, streetport only, alternative turbos only.
  • STU Hood Vents and Intercooler Scoops #32733aeroaddedaeroSTU OEM louver vents no longer count against vent allowance or 200 square inch limit.
  • STU Non 4 valve weight reduction removed #32808weightfasterweightSTU non-4-valve engines gain 9% base engine weight reduction allowance; 2400cc minimum weight drops 1 lb to 2595.
  • STU Error in new minimum weight table when combined with other text #32711engineslowerengineSTU normally-aspirated engines 2976cc–3200cc with single throttle body lose 10% base engine weight reduction allowance.
  • STU Redundant Language in May GCR #32713wordingwordingST removes redundant language about engine balance shaft removal and alternate pulley installation.
  • FP Subaru BRZ Model Years #32500wordingwordingEP Subaru BRZ title updated to include model years 13–20; Toyota 86/Scion FR-S title likewise updated to 13–20.
  • FP Weight Adjustment of Lotus 7 #32213weight +50 lbsslowerweightFP Lotus Super Seven 91.7 ci minimum weight increases 50 lbs, to 1580.
  • FP EP MX-5 Global Cup Car #32218weightweightEP Mazda MX-5 Global Cup 16-22 minimum weight set to 2400 lbs; sequential gearbox allowed with 150 lbs penalty.
  • FP Please Class BMW 128i in EP #32370cars addedaddedBMW 128i (08-13) classified in EP at 2700 lbs minimum with 2996 cc engine, stock throttle body, 11.0:1 compression and 0.400" valve lift limits.
  • FP Inconsistency in Body Work Descriptions #32396aeroaddedaeroEP, FP, HP open cars now allow carbon fiber hardtops if they retain OEM exterior profiles.
  • FP Request to classify the 1999-2000 Mazda Protege in FP #32398cars addedaddedMazda Protégé ES 99-00 classified FP, 2150–2258 lbs, 1839 cc DOHC, fuel injection, 11.0:1 compression, 0.450" valve lift.
  • P2 E&O Clarification of Chassis Construction Requirements #32469wordingwordingP2 chassis construction clarified: full composite allowed; partial composite must roll without composite parts installed.
  • P2 Clean up P2 wording #32525wordingwordingP2 classification wording cleaned up in GCR section 9.1.8.C and GCR contents.
  • STU Opposed to the Proposed STU Weight Chart #32381tyres & wheelsaddedtyres & wheelsSTU cars that qualified for 9 inch wheels in 2021 may continue running them through 2022 only.
  • STU Clarification request for GCR 9.1.4.D.3.a Splitter Definition #32414wordingwordingSTU splitter definition clarified: must attach to lowest point of front, have no vertical deviations.
  • FP Mazda RX8 with 13b Rotary #32170engineengineEP Mazda RX-8 13B carburetor option replaced with fuel-injected throttle body or stock fuel injection.
  • FP Request Idle control valve clarification #32178wordingwordingEP, FP, HP Production clarify idle control valve options: stock original allowed, removable with blocked ports, or mechanical replaced with electronic stock type.
  • FP Correct FP BMW 325e/es Displacement #32394wordingunclearFP BMW 325e/es displacement corrected to 2693 cc.
  • P2 After Market to Aftermarket #32373wordingwordingP2 Oldsmobile cam rules correct spelling from 'after market' to 'aftermarket' in two sections.
  • STU Request Adjustment to Min Weight for STU BMW E36 M3 (95-99) #31535weight -90 lbsfasterweightSTU BMW E36 M3 (95-99) S52B32 minimum weight cut to 3110 lbs from 3200, displacement to 3152 cc.
  • STU BMW E36 M3 Canadian (North American) S50B32 engine #31866engineaddedengineSTU BMW S50B32 Euro maximum displacement 3201 cc, minimum weight 3300 lbs, permits 0.040 overbore and 0.5 compression increase.
  • STU Engine Swap Origin Country #32209wordingwordingST engine swap origin rule narrowed: North America changed to United States only for case-by-case approval.
  • STU CRX/Civic Del Sol #32214weightslowerweightSTU Honda CRX 84-91 and Civic Del Sol 93-97 both ineligible for front-wheel-drive weight reductions.
  • STU Error correction #32383wordingwordingSTU wheel width rule clarified: under 2950 lbs uses max 8.0 inches, 2950 lbs and over uses max 9.0 inches.
  • STU Single TB Weight Modifiers Add to Chart #32393weightfasterweightSTU single-throttle body cars get lower minimum weights: 2450cc to 2596 lbs, 2500cc to 2635 lbs, 2550cc to 2675 lbs.
  • FP EP Adjustments #31858inductionslowerinductionEP BMW Z3 2.5L intake restrictor reduced from 59mm to 58mm flat plate.
  • FP 1999 3.8L Ford Mustang to EP? #31635weightfasterweightFord Mustang 94-98 weight reduced to 2550/2614/2678 lbs; 99-03 3.8L classified EP at 2700/2768/2835 lbs.
  • FP Improved Touring Tires #32064tyres & wheelsaddedtyres & wheelsEP, FP, HP Improved Touring cars may use any DOT-approved tyre as defined by 9.3.45.
  • FP VW Golf Jetta 2.0L intake and exhaust size correction. #32173engineslowerengineFP VW Golf III/Jetta III 93-98 intake valve shrinks to 39.5 mm (1.56 in), exhaust to 32.9 mm (1.30 in).
  • P2 Add spec line for Beasley B2 #32147cars addedaddedP2 adds Beasley B2 at 1350 lbs with Mazda 12A, 40.5mm venturi, and up to 16.5in wing chord.
  • P2 E&O Table 1 spec line wing terminology #32148wordingwordingP2 wings: terminology change from 'cord' to 'chord', and 'only' removed from Bobsy and Jondal notes.
  • P2 E&O class name #32196wordingwordingP2 Converted F5 cars renamed F500, must retain F500 suspension, minimum width 55 inches.
  • STU Single TB Weight Modifiers #31449weightfasterweightSTU single throttle body weight reduction removed; minimum weights revised down to 2990 lbs at 3000cc from 3300 lbs.
  • STU Request to Remove A4 1.8t from STU Spec Line Tables #31465weightslowerweightSTU Audi A4 1.8T minimum weight fixed to 3050 lbs, K04 turbo removed, VF30 with 35mm restrictor required; Porsche 944 1800 weight fixed to 3050 lbs, VW/Audi 1.8L engine removed, 35mm inlet restrictor required.
  • STU Improved Touring Tires #32063tyres & wheelstyres & wheelsSTL and STU Improved Touring vehicles must now conform to section 9.1.4 Tires & Wheels.
  • FP Throttle Body and Idle Air #31800wordingwordingEP, FP, HP: stock/original idle control devices permitted unmodified or completely removed with openings blocked.
  • P2 E&O Engine section #31969weightslowerweightP2 motorcycle engines gain 5cc to 1505cc max, two-stroke gains 5cc to 1205cc max, automotive engines add 50 lbs minimum weight to 1350 lbs.
  • STU Request Allowance for Balance Shaft Delete in STU #31434enginefasterengineSTU engines may delete balance shafts and plug openings; alternate pulleys or gears allowed only for timing belt or chain operation.
  • STU Request Louvers in hood vents #31916aeroaddedaeroSTU hood vents now allow louvers within 200 square inches.
  • FP Porsche 968 Engine Questions #31478engineengineEP Porsche 968 intake valve size changes to 39.0 mm, 1.54 mm seat width.
  • FP PCS E. 2. n. 4. Add Axle Shaft to Allow FWD the Same Freedom #31592otheraddedEP, FP, HP front-wheel-drive cars may alter body and subframes to install alternate axle shaft, matching RWD freedom.
  • FP BMW Z3 2.5L Spec Line #31724engineaddedengineEP BMW Z3 2.5L adds alternate throttle body option with Turner adapter and permits head casting 1738400.
  • FP FP Del Sol VTEC #31859engineslowerengineFP Honda Civic Del Sol VTEC compression ratio limited to 11.0:1, valve lift to .425", removes dry sump and internal engine prep allowances.
  • FP Standardize Level 2 Classifications in FP #31868wordingwordingFP Honda Prelude 84-87 and Mazda GLC/323 86-88 valve lift measurement method clarified, Level 1 parts list removed.
  • P2 E&O letter #31539 – Control Area definition #31783wordingwordingP2 Control Area definition clarified: rectangular zone from rear edge of front tires to front edge of rear tires, full car width.
  • STU Request to Add Honda K23 Spec Line #30682cars addedaddedSTU adds Honda K23 with 2354 cc displacement and chart minimum weight, K24 block allowed with K23 internals and head.
  • STU RE: Aug FT letter 30682 #31060enginefasterengineSTU Honda K23 relaxes internal engine requirement, now needs only K23 crankshaft.
  • STU Throttling Device Clarification #31323wordingwordingSTL/STU intake manifold and cylinder head porting clarified as free; intake and exhaust porting wording removed.
  • FP 944S2 Restrictor #31396inductionslowerinductionEP Porsche 944S2 89-91 requires 56mm flat plate intake restrictor; compression ratio 12.0:1 max, valve lift 0.500" max, dry sump allowed.
  • FP Classing Clarification for 1986 Toyota Corolla FX16 #31527cars addedaddedToyota Corolla GTS RWD (84-87) and FX16 FWD (87-88) added to HP; old Corolla (84-87) removed.
  • P2 BoP adjustment effective 1-1-22 #31538otherunclearP2 specification line B.1 engine table entry amended; details of change not provided in excerpt.
  • P2 E&O clarification of "Control Area" definition #31539wordingwordingP2 Control Area definition clarified: rear tire edge and front tire edge bounds, car's lower surface width, floor extensions and aerodynamic attachments included, vertical structures prohibited.
  • FP E&O; MR2 Track #31120suspension & brakessuspension & brakesToyota MR-2 1.6L 85-89 HP track width corrected to 15×47 / 15×47 inches; stock track baseline now 103% plus 2.5 inches.
Indianapolis Motor Speedway Runoffs 20212021-09-251:47.078Joe Moser · fastest of 30 · top 5 within 2.0s-1.843s (-1.69%)1:47.441Joe Moser · fastest of 28 · top 5 within 1.8s-1.946s (-1.78%)146.9Kip VanSteenburg1:51.082Craig Chima · fastest of 39 · top 5 within 1.2s-1.009s (-0.90%)1:59.933Cliff Ira · fastest of 33 · top 5 within 5.4s+6.926s (+6.13%)131.8Cliff Ira+12.492squal +4.004s111.6%qual 103.7%1:33.235Tim Day Jr · fastest of 16 · top 5 within 3.3s+1.409s (+1.53%)1:35.322Tim Day Jr · fastest of 10 · top 5 within 4.8s+2.841s (+3.07%)150.3Robert Iversen-12.119squal -13.843s88.7%qual 87.1%
41 rule changes (STU: 12, FP: 21, P2: 8)12 cars added · 7 weight · 4 engine · 1 aero · 1 induction · 1 suspension & brakes · 12 wording · 3 other · P2 CN Honda K20A-FD2 engine rebuild clarified: balancing, porting, polishing prohibited; valve jobs and honing must follow factory procedures. · EP Honda S2000 now allows F22c engine in 1997cc and 2157cc displacements with revised weight brackets and specifications. · EP Nissan 240-SX S13/S14 weight drops to 2400 lbs base, 2460 turbo, 2520 supercharged; comp ratio raised to 12.0:1, valve lift to 0.500 inch. · P2 Converted F5 cars must retain F5 suspension and meet P2 non-spec requirements except minimum width is 55 inches. · P2 minimum body width clarified: cannot extend inward beyond vertical plane through tire centerlines. · EP Lotus/Caterham 7 America fuel injection permitted; IT preparation engine limitation removed. · Plymouth Arrow 76–80 classified in HP Prep at 1800–1890 lbs with 1598 cc iron-block OHV four-cylinder. · BMW 318i/is E30 (84-85) reclassified from FP to HP at 2200–2310 lbs, SOHC 1797cc, fuel injection, 11.0:1 compression, .425" valve lift limit. · FP Fiat X1/9 1300 loses 50 lbs to 1665; X1/9 Bertone loses 50 lbs to 1765. · Daimler SP 250 classified in EP with 2165 lbs minimum weight, 2548 cc eight-cylinder OHV engine, SU or Stromberg carburetors. · STU fender flare wording clarified: flare of exterior contour may not change wheel opening size, location or shape from side view. · STU Mazda 12A Bridgeport weight reduced from 2550 lbs to 2350 lbs. · Porsche 924 Level 1 Prep moved from EP to FP classification. · EP, FP, HP clarify percentage weight penalties sum before applying to base weight, round to nearest pound. · 84-87 Mazda 626 reclassified from FP to HP with 2300–2415 lb weight, 1998cc SOHC engine, two 32mm carburetors. · FP Fiat X1/9 and Bertone 1300 brake rotors now 257 x 12 mm, 10.1 inch diameter, 0.407 inch thickness. · P2 tonneau covers now allowed to meet minimum dimensions; cockpit equipment attachment wording clarified. · P2 removes effective date 01/01/2021 from six car spec lines in Table 1. · P2 engine specs B.1, B.2, B.3 limited to maximum 4 valves per cylinder. · STU fender flare rules clarified: maximum 2 inches total, must cover tire contact patch from above, cannot alter body configuration or wheel opening geometry. · Mazda 3 S 04-08 classified in EP at 2350 lbs minimum, 2.26L DOHC four-cylinder, fuel injected with 55mm throttle body, comp ratio 12.0:1 max, valve lift 0.500" max. · FP Volkswagen Golf and Jetta III and IV intake valves increase to 40.0 mm, exhaust to 33.0 mm. · STU Honda S2000 now allows F20/F22 K24 crankshaft with chart weight for achieved displacement. · ST oil coolers and filters now explicitly listed as addable or substitutable parts in vents and breathers section. · P2 adds new spec line for 2-cycle 3-cylinder engine up to 820cc with 10 front, 14–15 rear wheel width. · ST 90-05 Mazda Miata allowed alternate front wheel hub Mazda Motorsports Development Part #0000-04-5HUB-S1. · ST cars may now relocate ABS actuation hardware and wiring anywhere in the engine compartment. · STU Porsche PDK automatic transmission limited to 8 forward speeds; sequential DCT systems require 3.5% minimum weight increase. · STU Mazda 13B Street Port 2400 removes choke location rule, allows auto-type 2bbl with any dual-Y manifold. · STU driveshaft and half-shafts now explicitly permitted in steel or aluminum, removing OEM material requirement. · EP Austin-Healey 3000 gains option to use TR-6 front calipers and discs as alternate. · FP Volkswagen Golf 1.8, Jetta, Rabbit and Scirocco gain 50 lb weight breaks, minimum weights to 1900–1733 lbs. · STU Mazda 13B Spec and Bridge Port removed; Street Port added at 2400 lbs minimum weight. · FP Mk2 Golf and Jetta 1.8 lose 50 lbs to 1900; HP Jetta GLI engine code removed. · EP, FP, HP Level 1 and Level 2 induction systems: carburettor jets, needles, metering rods allowed; throttle body porting permitted; wording clarified. · EP Nissan Datsun SRL 311U Roadster minimum weight reduced 75 lbs to 1925. · EP Triumph TR8 78-81 minimum weight drops to 2500 lbs. · Honda Civic EX 96-00 classified FP2 at 1975 lbs, SOHC 1590cc, fuel injection, 56mm throttle body, comp ratio 12.0:1 max, valve lift 0.450" max. · FP adds FAJS to permitted Weber-type and auto-type carburetor substitutes in two sections. · P2 motorcycle-engine cars: 2009+ stock 37mm restrictor, 2008- stock 35mm, modified 1075 lbs. Honda K20A 50mm restrictor. Various spec cars: restrictors increased or decreased 0.5–3mm. · ST aero devices and reference areas must include end plates, exclude fasteners under 1/2" protrusion.showhide
  • P2 P2 CN Engine Rebuild Clarification #31000wordingwordingP2 CN Honda K20A-FD2 engine rebuild clarified: balancing, porting, polishing prohibited; valve jobs and honing must follow factory procedures.
  • FP Request to Allow F22c Engine for 2000-2003 Honda S2000 #30548cars addedaddedEP Honda S2000 now allows F22c engine in 1997cc and 2157cc displacements with revised weight brackets and specifications.
  • FP Request a review of the S14 240SX in EP. #30873weight -200 lbsfasterweightEP Nissan 240-SX S13/S14 weight drops to 2400 lbs base, 2460 turbo, 2520 supercharged; comp ratio raised to 12.0:1, valve lift to 0.500 inch.
  • P2 F5 P2 Conversion #30856wordingwordingP2 Converted F5 cars must retain F5 suspension and meet P2 non-spec requirements except minimum width is 55 inches.
  • P2 Clarify minimum body width requirement #30859wordingwordingP2 minimum body width clarified: cannot extend inward beyond vertical plane through tire centerlines.
  • FP Lotus/Caterham 7 America Request #30392wordingwordingEP Lotus/Caterham 7 America fuel injection permitted; IT preparation engine limitation removed.
  • FP Request to classify ITC Plymouth Arrow #30588cars addedaddedPlymouth Arrow 76–80 classified in HP Prep at 1800–1890 lbs with 1598 cc iron-block OHV four-cylinder.
  • FP Reclassification of the 1984/85 BMW 318i from FP to HP #30661cars addedaddedBMW 318i/is E30 (84-85) reclassified from FP to HP at 2200–2310 lbs, SOHC 1797cc, fuel injection, 11.0:1 compression, .425" valve lift limit.
  • FP Fiat x1/9 Competition Adjustments #30711weight -50 lbsfasterweightFP Fiat X1/9 1300 loses 50 lbs to 1665; X1/9 Bertone loses 50 lbs to 1765.
  • FP Reclassify Daimler SP 250 #30721cars addedaddedDaimler SP 250 classified in EP with 2165 lbs minimum weight, 2548 cc eight-cylinder OHV engine, SU or Stromberg carburetors.
  • STU STU Fender flares #30696wordingwordingSTU fender flare wording clarified: flare of exterior contour may not change wheel opening size, location or shape from side view.
  • STU Request weight reduction for 12A bridgeport motor in Miata #30751weight -200 lbsfasterweightSTU Mazda 12A Bridgeport weight reduced from 2550 lbs to 2350 lbs.
  • FP Move Porsche 924 in Level 1 Prep From EP to FP #30135cars addedaddedPorsche 924 Level 1 Prep moved from EP to FP classification.
  • FP Clarify Application of Percentage Based Weight Penalties #30669wordingwordingEP, FP, HP clarify percentage weight penalties sum before applying to base weight, round to nearest pound.
  • FP Change Classification of 84-87 Mazda 626 from FP to HP #30350cars addedadded84-87 Mazda 626 reclassified from FP to HP with 2300–2415 lb weight, 1998cc SOHC engine, two 32mm carburetors.
  • FP Fiat X1/9 brake rotors #30423otherotherFP Fiat X1/9 and Bertone 1300 brake rotors now 257 x 12 mm, 10.1 inch diameter, 0.407 inch thickness.
  • P2 E&O tonneau cover provision in cockpit opening section #30459wordingwordingP2 tonneau covers now allowed to meet minimum dimensions; cockpit equipment attachment wording clarified.
  • P2 Remove effective dates in Table 1 #30468wordingwordingP2 removes effective date 01/01/2021 from six car spec lines in Table 1.
  • P2 E&O Maximum Valves Per Cylinder #30560engineengineP2 engine specs B.1, B.2, B.3 limited to maximum 4 valves per cylinder.
  • STU Request for Fender Flare Clarification #30375wordingwordingSTU fender flare rules clarified: maximum 2 inches total, must cover tire contact patch from above, cannot alter body configuration or wheel opening geometry.
  • FP Please Classify Mazda3 in FP #30165cars addedaddedMazda 3 S 04-08 classified in EP at 2350 lbs minimum, 2.26L DOHC four-cylinder, fuel injected with 55mm throttle body, comp ratio 12.0:1 max, valve lift 0.500" max.
  • FP Golf MkIII Valve Size Request #30268enginefasterengineFP Volkswagen Golf and Jetta III and IV intake valves increase to 40.0 mm, exhaust to 33.0 mm.
  • STU Provision for Interchangeable Engine Components Already Allowed #30342engineaddedengineSTU Honda S2000 now allows F20/F22 K24 crankshaft with chart weight for achieved displacement.
  • STU ST Oil Coolers E&O Correction to 9.1.4.2.H #30388wordingwordingST oil coolers and filters now explicitly listed as addable or substitutable parts in vents and breathers section.
  • P2 Add a new spec line for a 2-cycle, 3-cylinder engine up to 820cc #30272cars addedaddedP2 adds new spec line for 2-cycle 3-cylinder engine up to 820cc with 10 front, 14–15 rear wheel width.
  • STU Super Touring Alternate Miata Hubs #30345cars addedaddedST 90-05 Mazda Miata allowed alternate front wheel hub Mazda Motorsports Development Part #0000-04-5HUB-S1.
  • STU Brake Component Relocation #29990suspension & brakessuspension & brakesST cars may now relocate ABS actuation hardware and wiring anywhere in the engine compartment.
  • STU Porsche PDK #30081wordingwordingSTU Porsche PDK automatic transmission limited to 8 forward speeds; sequential DCT systems require 3.5% minimum weight increase.
  • STU Reference Letter #29333 Proposed STU 13B Spec Line Changes #30086wordingwordingSTU Mazda 13B Street Port 2400 removes choke location rule, allows auto-type 2bbl with any dual-Y manifold.
  • STU Drive Shaft Request #30087otherotherSTU driveshaft and half-shafts now explicitly permitted in steel or aluminum, removing OEM material requirement.
  • FP Alternate Front Brake Rotors and Calipers for EP AH 3000 #29893otherotherEP Austin-Healey 3000 gains option to use TR-6 front calipers and discs as alternate.
  • FP Request VW weight break #29963weight -50 lbsfasterweightFP Volkswagen Golf 1.8, Jetta, Rabbit and Scirocco gain 50 lb weight breaks, minimum weights to 1900–1733 lbs.
  • STU 13B Rules Adjustment #29333cars addedremovedcars addedSTU Mazda 13B Spec and Bridge Port removed; Street Port added at 2400 lbs minimum weight.
  • FP Mk2 VW Consistency and Cleanup of FP and HP Spec Lines #29195weight -50 lbsfasterweightFP Mk2 Golf and Jetta 1.8 lose 50 lbs to 1900; HP Jetta GLI engine code removed.
  • FP Correct Wording for Level 1 and Level 2 Induction Systems #29406inductionfasterinductionEP, FP, HP Level 1 and Level 2 induction systems: carburettor jets, needles, metering rods allowed; throttle body porting permitted; wording clarified.
  • FP Weight Reduction for Datsun Roadster #29409weight -75 lbsfasterweightEP Nissan Datsun SRL 311U Roadster minimum weight reduced 75 lbs to 1925.
  • FP EP TR8 Adjustment #29512weight -100 lbsfasterweightEP Triumph TR8 78-81 minimum weight drops to 2500 lbs.
  • FP Request to Classify 1996-2000 Honda Civic EX #29515cars addedaddedHonda Civic EX 96-00 classified FP2 at 1975 lbs, SOHC 1590cc, fuel injection, 56mm throttle body, comp ratio 12.0:1 max, valve lift 0.450" max.
  • FP FAJS Carburetor #29576cars addedaddedFP adds FAJS to permitted Weber-type and auto-type carburetor substitutes in two sections.
  • P2 Balance of Performance adjustments effective 01-01-2021 #29822engineunclearP2 motorcycle-engine cars: 2009+ stock 37mm restrictor, 2008- stock 35mm, modified 1075 lbs. Honda K20A 50mm restrictor. Various spec cars: restrictors increased or decreased 0.5–3mm.
  • STU Request clarification on wing measurement #29640aeroaeroST aero devices and reference areas must include end plates, exclude fasteners under 1/2" protrusion.
Road America Runoffs 20202020-10-022:27.883David Fiorelli · fastest of 14 · top 5 within 4.1s2:28.410Anthony Geraci · fastest of 14 · top 5 within 3.1s144.2David Fiorelli2:31.414Ethan Shippert · fastest of 23 · top 5 within 2.2s2:34.033Kevin Ruck · fastest of 21 · top 5 within 2.3s133.2Sam Henry+5.623squal +3.531s103.8%qual 102.4%2:08.514Robert Iversen · fastest of 12 · top 5 within 3.0s2:09.793Robert Iversen · fastest of 12 · top 5 within 3.9s153.1Robert Iversen-18.617squal -19.369s87.5%qual 86.9%
42 rule changes (STU: 17, FP: 19, P2: 6)9 cars added · 7 engine · 3 weight · 2 induction · 1 aero · 15 wording · 5 other · HP 84-87 Toyota Corolla wheel diameter increases from 13 to 15 inches. · P2 rear wing rules clarified: standard wing 6×12 inches, end plates 14-inch square; alternate 1-meter formula wing 110cm wide, 9×18 inches, end plates 14×18 inches. · STU fender flare rule reworded: now per-corner up to 2" total, 1% weight penalty applies to entire modification. · EP BMW Z3 2.5L cylinder head casting 1738400 permitted with iron block castings 1748933 or 1738566. · STL and STU clarify weight adjustment calculation order: engine adjustments first, then chassis percentage additions, subtractions, and fixed pounds. · STL STU rear wing Gurney flap terminology clarified from wicker to Gurney flap in mounting and chord rules. · Porsche 911 S 67-68 classified in EP at 1800–1890 lbs, 1991cc opposed 6-cylinder SOHC with 36mm carburetors. · FP Mazda 626 84-87 carburetor spec clarified to two auto-type sidedraft 32mm choke or fuel injection. · STU request for alternate intake manifold denied; no change to rules. · GT3 and STU add Borg-Warner EFR6258 turbocharger to approved turbo lists. · STU large displacement turbo engines limited by GCR turbo list; no BoP change granted. · STU sequential shifters referred to Board of Directors for approval; no rule change effective. · EP BMW 2.8L, 328i E36/E46, and 325i E36 now require iron blocks only; 325i E46 aluminum block removed. · FP Volkswagen Scirocco E&O adds four engine variants with weights 1520–1853 lbs and displacements 1471–1780 cc. · Elan NP01 added to P2 Table 1 as Spec Line car with 2000cc displacement and 42mm restrictor. · STU Mazda 13B Bridge Port and Street Port added with 2550 lbs and 2250 lbs minimum weight respectively. · FP Pre: 1990–1994 Mazda Protégé classified at 2150–2258 lbs, 1839cc DOHC, fuel injection, 11.0:1 compression, .450" valve lift limit. · HP Mini Cooper 02-06 and 07-13 convertible model years corrected to 05-08 and 09-15 respectively. · P2 Enterprises Sports Racer now permits 55mm flat plate intake restrictor Part # WM303013 as alternative to SIR. · EP Caterham 7 America engine limited to IT prep with specific sections, comp ratio 10.0:1, valve lift .380 inch. · 1989-90 Nissan 240-SX SOHC added to FP Pre L2 at 2400–2520 lbs, 2389 cc, fuel injection, 11.0:1 compression, .450" valve lift limit. · P2 Enterprise Sports Racer 2.3L engine must use SIR or Flat Plate restrictor meeting peak horsepower, sized in whole or 0.5mm increments. · STU Honda S2000 gains HKS Supercharger kits 12001-AH006 and 12001-AH010 as allowed options. · STU Lotus Elise Cup R and SC Exige SC gain 100 lbs minimum weight to 2300, 2500. · STU Volkswagen GTI/GLI MK5 and Jetta Mk4 may now install turbo inlet restrictor in OEM housing, per TIR spec. · STU Honda K20C1 Turbo I4 restrictor reduces from 36mm to 35mm. · STU GM Ecotech LNF now permitted without turbo, with LE5 head and intake manifold, meeting STL specs. · STU Porsche 944 now permits VW/Audi 1.8L and 2.0L turbo engines as alternates to original. · FP Volkswagen Jetta, Rabbit, Scirocco reclassified with weights 1520–1853 lbs, intake valves 40.0 mm, exhaust 33.0 mm, throttle 35/52 mm. · HP Datsun 510 allows 40 DCOE carburetor option alongside existing 40 DCNF and 36mm DCNVH; auto side drafts moved to penalty structure. · Porsche 914-4 2.0L classified in FP Prep 2 at 2030–2132 lbs with 1968cc OHV engine, Solex/Weber/Dellorto carbs or fuel injection, 11.0:1 compression limit, .450" valve lift limit. · FP Ford Fiesta 78-80 minimum weight reduced 130 lbs, to 1660. · P2 electronic throttle control wording clarified: ETC permitted if stock ECU throttle pedal activates original throttle shaft mechanism. · STU vehicles over 2951 lbs base weight may use 9 inch wide wheels, changed from 2950 lbs. · STU turbocharged engines now use base weight instead of minimum weight; DFI cars add 3% to base weight. · HP Datsun 1200 carburetor option changes from 26mm to 30mm choke(s) in 40 DCN, DCNF, IDF. · Mazda Miata models EP and FP throttle body specified 55mm, brake rotor thickness figures removed. · FP Mazda Protégé ES 2001–2003 newly classified at 2350–2468 lbs with 1991 cc DOHC four-cylinder, fuel injection, 11.0:1 compression, .450 in. valve lift limit. · P2 adds BMW to permitted motorcycle-based engines alongside Kawasaki, Suzuki, Yamaha, Honda. · FP and HP: 1988–91 Honda Civic and CRX track widths corrected to 61.3 / 61.7 inches across multiple levels. · EP, FP, HP cylinder head rules reorganized for clarity; no performance change. · STU allows OEM electronic throttle bodies, manual conversion, cam changes, and manual-to-electronic conversion with same inner diameter.showhide
  • FP 84-87 Toyota Corolla HP Wheel Diameter Allowance Proposal E&O #29458otherfasterHP 84-87 Toyota Corolla wheel diameter increases from 13 to 15 inches.
  • P2 E&O clarification of P2 rear wing requirements #29205aeroaeroP2 rear wing rules clarified: standard wing 6×12 inches, end plates 14-inch square; alternate 1-meter formula wing 110cm wide, 9×18 inches, end plates 14×18 inches.
  • STU Request for Advanced Aero Rule Wording Clarification. #29124wordingwordingSTU fender flare rule reworded: now per-corner up to 2" total, 1% weight penalty applies to entire modification.
  • FP EP BMW Z3 Rule Clarification #28998wordingwordingEP BMW Z3 2.5L cylinder head casting 1738400 permitted with iron block castings 1748933 or 1738566.
  • STU Minimum Weight Determination #27695wordingwordingSTL and STU clarify weight adjustment calculation order: engine adjustments first, then chassis percentage additions, subtractions, and fixed pounds.
  • STU ST Gurney flap Wicker clarification #29012wordingwordingSTL STU rear wing Gurney flap terminology clarified from wicker to Gurney flap in mounting and chord rules.
  • FP Request to Classify Porsche 911 2.0L #28456cars addedaddedPorsche 911 S 67-68 classified in EP at 1800–1890 lbs, 1991cc opposed 6-cylinder SOHC with 36mm carburetors.
  • FP Request to change to Carburetor Spec Line 84-87 Mazda 626 #28926wordingwordingFP Mazda 626 84-87 carburetor spec clarified to two auto-type sidedraft 32mm choke or fuel injection.
  • STU Request for Alternate Intake Manifold #26514wordingunclearSTU request for alternate intake manifold denied; no change to rules.
  • STU Request for Addition to GT3 Approved Turbo List #27576cars addedaddedGT3 and STU add Borg-Warner EFR6258 turbocharger to approved turbo lists.
  • STU Request BoP for my Car #29004wordingunclearSTU large displacement turbo engines limited by GCR turbo list; no BoP change granted.
  • STU Sequential Shifters in STU #29031wordingunclearSTU sequential shifters referred to Board of Directors for approval; no rule change effective.
  • FP BMW Cylinder Head Casting and Part Numbers #28708engineslowerengineEP BMW 2.8L, 328i E36/E46, and 325i E36 now require iron blocks only; 325i E46 aluminum block removed.
  • FP Correct Scirocco Spec line E&O #28892cars addedaddedFP Volkswagen Scirocco E&O adds four engine variants with weights 1520–1853 lbs and displacements 1471–1780 cc.
  • P2 Classify Elan NP01 in P2 Table 1 #28812cars addedaddedElan NP01 added to P2 Table 1 as Spec Line car with 2000cc displacement and 42mm restrictor.
  • STU Rotary Help #27833cars addedaddedSTU Mazda 13B Bridge Port and Street Port added with 2550 lbs and 2250 lbs minimum weight respectively.
  • FP Request to Classify 1990-1994 Mazda Protege #28381cars addedaddedFP Pre: 1990–1994 Mazda Protégé classified at 2150–2258 lbs, 1839cc DOHC, fuel injection, 11.0:1 compression, .450" valve lift limit.
  • FP Error in Mini Cooper Spec Line #28713wordingwordingHP Mini Cooper 02-06 and 07-13 convertible model years corrected to 05-08 and 09-15 respectively.
  • P2 SCCA Enterprises ESR / P2 engine restrictor testing #28669otheraddedP2 Enterprises Sports Racer now permits 55mm flat plate intake restrictor Part # WM303013 as alternative to SIR.
  • FP Caterham 7 Spec Line #28498wordingwordingEP Caterham 7 America engine limited to IT prep with specific sections, comp ratio 10.0:1, valve lift .380 inch.
  • FP Request to classify SOHC 1989-90 240SX in F prod L2 #28553cars addedadded1989-90 Nissan 240-SX SOHC added to FP Pre L2 at 2400–2520 lbs, 2389 cc, fuel injection, 11.0:1 compression, .450" valve lift limit.
  • P2 Add ESR inlet restrictor #27869inductionaddedinductionP2 Enterprise Sports Racer 2.3L engine must use SIR or Flat Plate restrictor meeting peak horsepower, sized in whole or 0.5mm increments.
  • STU Request to approve Honda S2000 HKS supercharger #27281otheraddedSTU Honda S2000 gains HKS Supercharger kits 12001-AH006 and 12001-AH010 as allowed options.
  • STU Request BoP on the Lotus #27637weight +100 lbsslowerweightSTU Lotus Elise Cup R and SC Exige SC gain 100 lbs minimum weight to 2300, 2500.
  • STU Turbo Inlet Restrictor On MK5 Volkswagen #27704otherslowerSTU Volkswagen GTI/GLI MK5 and Jetta Mk4 may now install turbo inlet restrictor in OEM housing, per TIR spec.
  • STU Honda K20C1 removal #27732engineslowerengineSTU Honda K20C1 Turbo I4 restrictor reduces from 36mm to 35mm.
  • STU Change GM LNF 2.0 Allowance to LSJ Engine for Viable STL 2.0 #27884engineaddedengineSTU GM Ecotech LNF now permitted without turbo, with LE5 head and intake manifold, meeting STL specs.
  • STU Alternate Engine for Porsche 944 #28259engineaddedengineSTU Porsche 944 now permits VW/Audi 1.8L and 2.0L turbo engines as alternates to original.
  • FP VW Weight and Valve Size Request #27886wordingwordingFP Volkswagen Jetta, Rabbit, Scirocco reclassified with weights 1520–1853 lbs, intake valves 40.0 mm, exhaust 33.0 mm, throttle 35/52 mm.
  • FP Request to allow 40 DCOE carb for the Datsun 510 #28195engineaddedengineHP Datsun 510 allows 40 DCOE carburetor option alongside existing 40 DCNF and 36mm DCNVH; auto side drafts moved to penalty structure.
  • FP Request to classify Porsche 914 2L in LPrep FProd #28231cars addedaddedPorsche 914-4 2.0L classified in FP Prep 2 at 2030–2132 lbs with 1968cc OHV engine, Solex/Weber/Dellorto carbs or fuel injection, 11.0:1 compression limit, .450" valve lift limit.
  • FP Request Ford Fiesta Weight Adjustment #28336weightfasterweightFP Ford Fiesta 78-80 minimum weight reduced 130 lbs, to 1660.
  • P2 Request for Fly by Wire Rule Wording Change #28247wordingwordingP2 electronic throttle control wording clarified: ETC permitted if stock ECU throttle pedal activates original throttle shaft mechanism.
  • STU Please Modify the STU Wheel Size Rule for Clarity #27694weightfasterweightSTU vehicles over 2951 lbs base weight may use 9 inch wide wheels, changed from 2950 lbs.
  • STU Turbo Engine Cars Base Weight #28032wordingwordingSTU turbocharged engines now use base weight instead of minimum weight; DFI cars add 3% to base weight.
  • FP Request for Help for Datsun 1200 #27934inductionfasterinductionHP Datsun 1200 carburetor option changes from 26mm to 30mm choke(s) in 40 DCN, DCNF, IDF.
  • FP Request to List Mazda Miata Throttle Body Size #27907wordingwordingMazda Miata models EP and FP throttle body specified 55mm, brake rotor thickness figures removed.
  • FP Request to Classify 2001-2003 Mazda Protege ES in FP #27922cars addedaddedFP Mazda Protégé ES 2001–2003 newly classified at 2350–2468 lbs with 1991 cc DOHC four-cylinder, fuel injection, 11.0:1 compression, .450 in. valve lift limit.
  • P2 Request for addition of BMW Engine in P2 Engine Table #27821engineaddedengineP2 adds BMW to permitted motorcycle-based engines alongside Kawasaki, Suzuki, Yamaha, Honda.
  • FP Request to Correct Track of 1988-91 Honda Civic #27487otherotherFP and HP: 1988–91 Honda Civic and CRX track widths corrected to 61.3 / 61.7 inches across multiple levels.
  • FP Re-organize Prep2 Cylinder Head Rules for Clarity & Consistency #27661wordingwordingEP, FP, HP cylinder head rules reorganized for clarity; no performance change.
  • STU Request for an electronic throttle body #27342engineaddedengineSTU allows OEM electronic throttle bodies, manual conversion, cam changes, and manual-to-electronic conversion with same inner diameter.
Virginia International Raceway Runoffs 20192019-10-051:59.948Kevin Boehm · fastest of 25 · top 5 within 3.5s2:00.483Kevin Boehm · fastest of 25 · top 5 within 2.5s143.8Kevin Boehm2:07.436Eric Prill · fastest of 19 · top 5 within 0.6s2:08.076Eric Prill · fastest of 18 · top 5 within 0.8s131.4Ken Kannard+7.593squal +7.488s106.3%qual 106.2%1:49.111Robert Iversen · fastest of 14 · top 5 within 0.8s1:50.258Greg Gyann · fastest of 13 · top 5 within 0.4s149.4Robert Iversen-10.225squal -10.837s91.5%qual 91.0%
40 rule changes (STU: 22, FP: 9, P2: 9)8 cars added · 8 engine · 5 aero · 5 induction · 2 weight · 11 wording · 1 other · P2 Honda K20A-FD2 non-composite chassis intake restrictor note clarified; restrictor implementation date removed. · FP and HP Austin-Healey Sprite Mk I / MG Midget may replace rear bodywork aft of cockpit with alternate material stock-appearing components. · EP Mazda MX-5 Global Cup classification updated to include 2019 model year. · Production classes: suspension rule clarified to specify spindles, hubs, bushings, bearings, and ball joints unrestricted. · Production carburetor and fuel injection rules clarified: permitted optional carburetors listed, Weber and auto-type substitutions specified, fuel injection throttle body and butterfly dimensions detailed, intake manifold port extension pr… · EP, FP, HP carburetors: jets, needles, metering rods, needle valves unrestricted; choke parts removable; stock or optional Weber 40 DCN permitted; Weber types, auto types listed. · P2 motorcycle engines: Stock restrictor to 35mm, Modified to 34mm; weights up to 1025 and 1125 lbs respectively. B.5 restrictor to 33mm, weight to 1185 lbs. · STU wing assembly wording corrected: no part may be higher than roof height. · EP Mazda MX-5/Miata model years expand from 1999-2002 to 1999-2005. · P2 cars limited to power application on maximum two wheels. · STU Nissan SR20DET removes -2mm penalty from Table B. · STU allows alternate intake manifolds on case-by-case basis; stock throttle device and manifold otherwise required. · P2 Enterprise minimum weight increased to 1375 lbs.; peak horsepower of sealed ESR engine reduced per CRB specification. · STU aftermarket side skirts now allowed if they meet 3-inch ride height, lack ducts except jacks or exhaust, don't exceed fascia width, stay below door bottom, and don't reinforce chassis. · STU wheel flare wording clarified: each fender may be flared to 2" with 1% weight penalty, maintaining OEM profile. · STL and STU ride height measurement clarified: lowest rocker panel point without driver, excluding pinch weld. · EP, FP, HP: clarified that tapered holes in ball joints can be reamed for bolt conversion, and wheel bearings and hubs unrestricted on all axles. · EP open cars may now use aftermarket hardtops if OEM-appearance and non-carbon-fiber; specific model allowances removed as redundant. · STU Mazda 13B Bridge Port now permits ELITE ROTARY SHOP FD V2.0 intake manifold; stock throttle body requirement removed. · STU Mazda MZR gains alternate Goodwin intake manifold option with stock or Acura throttle body. · STU alternate suspension components rule moved from section E to section D. · STU Honda/Acura B20 now permits B16 or B18 VTEC cylinder head and matching intake manifold. · STU flared fenders up to 2" with 1% weight penalty moved from base to Advanced Aero. · STU Honda Civic Si TCA 2017- requires 37mm TIR throttle as of June 1, 2019. · STU BMW S54B32 OEM classified separately from E46, displacement 3246 cc, minimum weight 3300 lbs, OEM engine mandatory. · FP Dodge Daytona/Chrysler Laser 84-85 added at 2100 lbs; Shelby Charger/Omni 024 83-84 weight cut to 2100 lbs. · P2 stock and modified engines get smaller restrictors (35.0mm, 34.0mm, 33.0mm) and heavier minimums (1025, 1125, 1185 lbs). · P2 Line A.1 restrictor reduced from 40mm to 38mm. · Honda Civic Si 2017- added to STU with 1500cc displacement, 2800 lbs minimum weight, OEM engine and bodywork, specific HPD parts allowed. · STU BMW E46 S54 OEM 3246cc added at 3300 lbs minimum; no Super Touring allowances, OEM intake and cams, 1mm overbore, compression +0.5 permitted. · STU Mazda 13B and 13B Bridge Port may use 13B RE or REW housings and intake with turbo removed. · STU Honda K24 may use intake part numbers 17100-RRB-A00 or 17100-PRB-A10. · STU Mazda 12A Bridge Port added, minimum weight 2550 lbs, Nikki or Auto-type carburettor with specified modifications. · STU World Challenge car weight rule deleted; no replacement specified. · STU AWD/RWD cars no longer must reduce restrictor 1 mm from table. · STU rear wing maximum 12" cord, 72 sq in end plates each, roof height max, body width limit. · P2 Spec Line cars now allow 1345cc Hayabusa stock engines at 1050 lb minimum with 30mm restrictor. · P2 Group CN Honda K20A-FD2 55mm intake restrictor implementation delayed from 1 January to 3 March 2019. · P2 Honda K20A-FD2 Group CN must use stock intake manifold, 64mm throttle, 55mm restrictor at 1500 lbs minimum. · STU adds Honda K20C1 Turbo I4, 1996 cc, 3025 lbs minimum weight, 36mm TIR required.showhide
  • P2 Update Engine Table Line E notes #27414wordingwordingP2 Honda K20A-FD2 non-composite chassis intake restrictor note clarified; restrictor implementation date removed.
  • FP Request bodywork for Austin Healey Bugeye Sprite MK1 #27106aeroaddedaeroFP and HP Austin-Healey Sprite Mk I / MG Midget may replace rear bodywork aft of cockpit with alternate material stock-appearing components.
  • FP Request to classify the GMX5 2019 #27263cars addedaddedEP Mazda MX-5 Global Cup classification updated to include 2019 model year.
  • FP level one susp. component rule #27270wordingwordingProduction classes: suspension rule clarified to specify spindles, hubs, bushings, bearings, and ball joints unrestricted.
  • FP Clarification of Carb Rules - Prep 1 #27300wordingwordingProduction carburetor and fuel injection rules clarified: permitted optional carburetors listed, Weber and auto-type substitutions specified, fuel injection throttle body and butterfly dimensions detailed, intake manifold port extension pr…
  • FP Clarification of Carb Rules - Prep 2 #27301inductioninductionEP, FP, HP carburetors: jets, needles, metering rods, needle valves unrestricted; choke parts removable; stock or optional Weber 40 DCN permitted; Weber types, auto types listed.
  • P2 Update P2 Engine Table spec lines to reflect 3/1/2019 #27254engineslowerengineP2 motorcycle engines: Stock restrictor to 35mm, Modified to 34mm; weights up to 1025 and 1125 lbs respectively. B.5 restrictor to 33mm, weight to 1185 lbs.
  • STU Request to correct E&O advanced aerodynamics #27290wordingwordingSTU wing assembly wording corrected: no part may be higher than roof height.
  • FP Request Miata Eligibility - 2003 #27121cars addedaddedEP Mazda MX-5/Miata model years expand from 1999-2002 to 1999-2005.
  • P2 E&O Transmissions #27006engineslowerengineP2 cars limited to power application on maximum two wheels.
  • STU Remove -2mm penalty from SR20DET Nissan #26982enginefasterengineSTU Nissan SR20DET removes -2mm penalty from Table B.
  • STU Request clarification for manifold and throttle in STU #27004wordingwordingSTU allows alternate intake manifolds on case-by-case basis; stock throttle device and manifold otherwise required.
  • P2 Request to restrict all cars #26246weightslowerweightP2 Enterprise minimum weight increased to 1375 lbs.; peak horsepower of sealed ESR engine reduced per CRB specification.
  • STU Request to clarify afterrmarket side skirts exhaust exit #26814aeroaddedaeroSTU aftermarket side skirts now allowed if they meet 3-inch ride height, lack ducts except jacks or exhaust, don't exceed fascia width, stay below door bottom, and don't reinforce chassis.
  • STU Wheel Flare wording #26872wordingwordingSTU wheel flare wording clarified: each fender may be flared to 2" with 1% weight penalty, maintaining OEM profile.
  • STU Request Ride Height Clarification #26597wordingwordingSTL and STU ride height measurement clarified: lowest rocker panel point without driver, excluding pinch weld.
  • FP Rollcenter Correction Clarification #25873wordingaddedEP, FP, HP: clarified that tapered holes in ball joints can be reamed for bolt conversion, and wheel bearings and hubs unrestricted on all axles.
  • FP Hardtops #26476aeroaddedaeroEP open cars may now use aftermarket hardtops if OEM-appearance and non-carbon-fiber; specific model allowances removed as redundant.
  • STU Request to Use Japanese Mazda 13b Intake Manifold #25790engineaddedengineSTU Mazda 13B Bridge Port now permits ELITE ROTARY SHOP FD V2.0 intake manifold; stock throttle body requirement removed.
  • STU Request Alternate Intake for Mazda MZR In a Rear Wheel Drive App. #26352inductionaddedinductionSTU Mazda MZR gains alternate Goodwin intake manifold option with stock or Acura throttle body.
  • STU E&O Suspension #26424wordingwordingSTU alternate suspension components rule moved from section E to section D.
  • STU Revisit B20 VTEC #26530engineaddedengineSTU Honda/Acura B20 now permits B16 or B18 VTEC cylinder head and matching intake manifold.
  • STU Move Flared Fenders to STU Advanced Aero #26564aeroaeroSTU flared fenders up to 2" with 1% weight penalty moved from base to Advanced Aero.
  • STU TCA Civic SI E&O #26606inductionslowerinductionSTU Honda Civic Si TCA 2017- requires 37mm TIR throttle as of June 1, 2019.
  • STU S54 Spec line #26620cars addedcars addedSTU BMW S54B32 OEM classified separately from E46, displacement 3246 cc, minimum weight 3300 lbs, OEM engine mandatory.
  • FP Request Classification of Dodge Daytona in F Production #26259weight -150 lbsfasterweightFP Dodge Daytona/Chrysler Laser 84-85 added at 2100 lbs; Shelby Charger/Omni 024 83-84 weight cut to 2100 lbs.
  • P2 Change Engine Table Lines B.1 & B.5 #25777inductionslowerinductionP2 stock and modified engines get smaller restrictors (35.0mm, 34.0mm, 33.0mm) and heavier minimums (1025, 1125, 1185 lbs).
  • P2 Change Line A.1 restrictor size #26429engineslowerengineP2 Line A.1 restrictor reduced from 40mm to 38mm.
  • STU Request to Class Assignment for 2017 Civic #24287cars addedaddedHonda Civic Si 2017- added to STU with 1500cc displacement, 2800 lbs minimum weight, OEM engine and bodywork, specific HPD parts allowed.
  • STU Request to run E46 3246cc in STU #25126cars addedaddedSTU BMW E46 S54 OEM 3246cc added at 3300 lbs minimum; no Super Touring allowances, OEM intake and cams, 1mm overbore, compression +0.5 permitted.
  • STU Engine Classification for Rotary #25564engineaddedengineSTU Mazda 13B and 13B Bridge Port may use 13B RE or REW housings and intake with turbo removed.
  • STU K24/K20 Head Swap Clarification/Amendment #25899otheraddedSTU Honda K24 may use intake part numbers 17100-RRB-A00 or 17100-PRB-A10.
  • STU Request to Classify 12a Bridge Ported Rotary Engine #25985cars addedaddedSTU Mazda 12A Bridge Port added, minimum weight 2550 lbs, Nikki or Auto-type carburettor with specified modifications.
  • STU World Challenge Car Eligibility #26387wordingunclearSTU World Challenge car weight rule deleted; no replacement specified.
  • STU Request a phone call for discussion regarding weight #26398inductionfasterinductionSTU AWD/RWD cars no longer must reduce restrictor 1 mm from table.
  • STU Advanced Aero E&O #26413aeroaddedaeroSTU rear wing maximum 12" cord, 72 sq in end plates each, roof height max, body width limit.
  • P2 Request to Allow 1345cc Hayabusa Engines for Spec Line P2 Cars #25595cars addedaddedP2 Spec Line cars now allow 1345cc Hayabusa stock engines at 1050 lb minimum with 30mm restrictor.
  • P2 Change CN inlet restrictor implementation date #25816wordingwordingP2 Group CN Honda K20A-FD2 55mm intake restrictor implementation delayed from 1 January to 3 March 2019.
  • P2 Clarify Honda K20A-FD2 parts requirement #25950engineslowerengineP2 Honda K20A-FD2 Group CN must use stock intake manifold, 64mm throttle, 55mm restrictor at 1500 lbs minimum.
  • STU Request to Equalize Direct Injected Turbo Cars #24890cars addedaddedSTU adds Honda K20C1 Turbo I4, 1996 cc, 3025 lbs minimum weight, 36mm TIR required.
Sonoma Raceway Runoffs 20182018-10-101:19.234Franklin Church · fastest of 10 · top 5 within 21.5s1:46.514Kevin Boehm · fastest of 9 · top 5 within 7.4s103.0Franklin Church1:47.588Joe Huffaker · fastest of 15 · top 5 within 3.0s1:48.481Joe Huffaker · fastest of 14 · top 5 within 2.2s109.1Joe Huffaker+1.967squal +28.354s101.8%qual 135.8%1:28.784Tim Day Jr · fastest of 17 · top 5 within 5.0s1:32.071Chuck Bona · fastest of 18 · top 5 within 0.9s144.4Tim Day Jr-14.443squal +9.550s86.4%qual 112.1%
No rule changes on record between these events
Indianapolis Motor Speedway Runoffs 20172017-09-251:48.921Rob Huffmaster · fastest of 34 · top 5 within 2.0s1:49.387Rob Huffmaster · fastest of 31 · top 5 within 2.4s1:52.091Eric Prill · fastest of 42 · top 5 within 1.2s1:53.007Eric Prill · fastest of 40 · top 5 within 0.7s+3.620squal +3.170s103.3%qual 102.9%1:31.826Jeff Shafer · fastest of 26 · top 5 within 4.9s1:32.481Jeff Shafer · fastest of 24 · top 5 within 3.8s-16.906squal -17.095s84.5%qual 84.3%
No rule changes on record between these events
Mid-Ohio Sports Car Course Runoffs 20162016-09-191:32.738Joe Moser · fastest of 16 · top 5 within 2.5s1:34.597Cameron Maugeri · fastest of 16 · top 5 within 0.8s1:35.938John Walker · fastest of 33 · top 5 within 0.4s1:36.399John Walker · fastest of 27 · top 5 within 0.3s+1.802squal +3.200s101.9%qual 103.5%1:20.188Jeff Shafer · fastest of 18 · top 5 within 4.0s1:20.904Jeff Shafer · fastest of 16 · top 5 within 2.2s-13.693squal -12.550s85.5%qual 86.5%
No rule changes on record between these events
Daytona International Speedway Runoffs 20152015-09-212:05.494Eric Heinrich · fastest of 18 · top 5 within 4.6s2:06.756Eric Heinrich · fastest of 17 · top 5 within 3.5s2:11.009Kevin Ruck · fastest of 20 · top 5 within 1.6s2:12.419Kevin Ruck · fastest of 18 · top 5 within 1.1s+5.663squal +5.515s104.5%qual 104.4%1:51.825Chris Farrell · fastest of 17 · top 5 within 3.6s1:52.355Jeff Shafer · fastest of 17 · top 5 within 2.8s-14.401squal -13.669s88.6%qual 89.1%

By track

TrackEvents Typical % of STU Best Latest 
Road America4100.0%100.0%Runoffs 2020100.0%Runoffs 2026
Virginia International Raceway3100.0%100.0%Runoffs 2019100.0%Runoffs 2023
Indianapolis Motor Speedway2100.0%100.0%Runoffs 2017100.0%Runoffs 2021
Daytona International Speedway1100.0%100.0%Runoffs 2015100.0%Runoffs 2015
Mid-Ohio Sports Car Course1100.0%100.0%Runoffs 2016100.0%Runoffs 2016
Sonoma Raceway1100.0%100.0%Runoffs 2018100.0%Runoffs 2018
About this data
Every event the class ran, at any track, oldest to newest on the chart and newest first in the table. Each point is the class's best lap as a share of STU's best on the same day: the weather and the day cancel out, so one figure compares across years where lap times cannot; a class that suits one track more than another still reads differently there. It still moves when the yardstick's own balance changes or its field thins, and an event the yardstick did not run has no point. A best from fewer than three cars is greyed. The rule changes that took effect between two events are folded between their rows.