BoP Lab / Classes / P2

P2 vs SMX vs SRF pace at every track

Lap times across years say as much about the weather as the class. % of P2 is each class's best lap as a share of P2'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.

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AS +B-Spec +EP +FA +FC +FE2 +FF +FP +FV +FX +GT1 +GT2 +GTX +HP +P +P2×SM +vsSMX ×vsSRF ×SRF3 +STL +STU +T1 +T2 +T3 +T4 +Show 50 inactive classes

Series Runoffs Super Tour Both

Reference · what % is measured against

Tracks · untick to narrow Auto Club Speedway Barber Motorsports Park Blackhawk Farms Raceway Buttonwillow Raceway Park Circuit of St. Louis (formerly Gateway Motorsports Circuit of the Americas Daytona International Speedway Grattan Raceway Hallett Motor Racing Circuit Homestead-Miami Speedway Indianapolis Motor Speedway Laguna Seca Michelin Raceway Road Atlanta Mid-Ohio Sports Car Course New Jersey Motorsports Park NOLA Motorsports Park Pacific Raceways Pittsburgh International Race Complex Portland International Raceway Pueblo Motorsports Park Road America Sebring International Raceway Sonoma Raceway Summit Point Raceway Thunderhill Raceway Park Virginia International Raceway Watkins Glen International Willow Springs Raceway World Wide Technology Raceway

Closest to the field: P2 100.0% of P2 Jeff Shafer, Daytona International Speedway Runoffs 2015 race · SMX 119.8% of P2 Skyler Cottrell, Road America Runoffs 2026 qualifying · SRF 120.1% of P2 Cliff White, Daytona International Speedway Runoffs 2015 qualifying

% of P2Lap times

P2SMXSRFsolid race · dashed qualifying · slower is lower

P2SMXSRFsolid race · dashed qualifying · each class's best lap as a share of P2's at the same event (the reference class, changeable above); 100% is level, less is quicker, so up the chart is quicker

	Event	P2			SMX					SRF
	Event	Qual best	Race best	Trap	Qual best	Race best	Trap	vs P2	% of P2	Qual best	Race best	Trap	vs P2	% of P2
	Road America Runoffs 20262026-09-28	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%)	2:36.472Skyler Cottrell · fastest of 21 · top 5 within 0.4s+0.240s (+0.15%)	2:36.414Cam Ebben · fastest of 21 · top 5 within 1.1s-0.677s (-0.43%)	128.4Christian Hoagland-0.6 mph (-0.5%)	+26.973squal +25.866s	120.8%qual 119.8%
5 rule changes (SMX: 2, SRF: 3)2 engine · 2 wording · 1 other · SRF rain/brake light part number and GCR section reference corrected for original roll hoop mounting. · SM/SMX Mazda rear toe link part number revised from 0000-04-5361426 to 0000-04-5361. · SM/SMX part number 0000-10-6900 replaced with 0000-06-5016-KT in GCR 9.1.7.C.1.j.1.c. · SRF3 spark plugs limited to NGK LTR7IX-11 P/N G301041 only; washers and sealing rings prohibited. · SRF3 adds HD Oil Cooler P/N G1148500 option alongside standard P/N G480503, no fan permitted.showhide 2026-09-01 SRF GCR Rain/Brake Light Correction #40579wordingwordingSRF rain/brake light part number and GCR section reference corrected for original roll hoop mounting. 2026-07-01 SMX Rear Toe Link #40271wordingwordingSM/SMX Mazda rear toe link part number revised from 0000-04-5361426 to 0000-04-5361. 2026-04-01 SMX Part Number Change Request #39914otherunclearSM/SMX part number 0000-10-6900 replaced with 0000-06-5016-KT in GCR 9.1.7.C.1.j.1.c. 2026-03-01 SRF SRF3 Spark Plugs #39899engineengineSRF3 spark plugs limited to NGK LTR7IX-11 P/N G301041 only; washers and sealing rings prohibited. 2025-10-01 SRF Add HD Oil Cooler #38979engineaddedengineSRF3 adds HD Oil Cooler P/N G1148500 option alongside standard P/N G480503, no fan permitted.
	Road America Runoffs 20252025-09-29				2:36.232Cam Ebben · fastest of 20 · top 5 within 0.2s+0.581s (+0.37%)	2:37.091Michael Tinis · fastest of 19 · top 5 within 0.3s+0.813s (+0.52%)	129.1Camden Gruber-0.4 mph (-0.3%)
8 rule changes (P2: 1, SMX: 5, SRF: 2)1 weight · 5 wording · 2 other · SMX drivers must submit data acquisition files on time or face suspension and $250 fine. · SMX penalty language clarified: level 1 and 3 infractions may carry $1,000 fines, level 2 and 4 may carry $500 fines. · SMX tire marking rules clarified: one set Toyo RR P235/40/ZR17 per weekend, impound after first dry session, damaged tires may be replaced with used only. · SMX competitors must submit AiM data files within 60 minutes instead of 30 after timed sessions. · SRF drivers with disabilities may modify seat and controls for safety and comfort with SCCA approval, noted in logbook, for that driver only. · SRF SADEV-SRF3 6-speed sequential transmission: effective date clarified to 1 April 2025 onward. · P2 2000 cc Pinto engine car minimum weight set to 1335 lbs. · SMX OE instrument cluster must stay unmodified and connected; aftermarket dash allowed if wiring only re-routed; alternate gauges now permitted; foot pedal comfort mods allowed without relocation.showhide 2025-06-01 SMX SMX Data Submission - Penalties #38248otheraddedSMX drivers must submit data acquisition files on time or face suspension and $250 fine. 2025-06-01 SMX Committee) SMX Penaly Clarification updated language #38337wordingwordingSMX penalty language clarified: level 1 and 3 infractions may carry $1,000 fines, level 2 and 4 may carry $500 fines. 2025-05-01 SMX Clarify Tire Marking Regs #38004wordingwordingSMX tire marking rules clarified: one set Toyo RR P235/40/ZR17 per weekend, impound after first dry session, damaged tires may be replaced with used only. 2025-05-01 SMX SMX Data Submission Timeframe #38039wordingwordingSMX competitors must submit AiM data files within 60 minutes instead of 30 after timed sessions. 2025-04-01 SRF Driver Safety & Comfort #37966otheraddedSRF drivers with disabilities may modify seat and controls for safety and comfort with SCCA approval, noted in logbook, for that driver only. 2025-04-01 SRF Update SADEV transmission specs #37992wordingwordingSRF SADEV-SRF3 6-speed sequential transmission: effective date clarified to 1 April 2025 onward. 2024-12-01 P2 2000 cc Pinto Engine Car Weight #37187weightslowerweightP2 2000 cc Pinto engine car minimum weight set to 1335 lbs. 2024-12-01 SMX E&O SMX Regs 9.1.7.1.D.5.u-.w #37070wordingwordingSMX OE instrument cluster must stay unmodified and connected; aftermarket dash allowed if wiring only re-routed; alternate gauges now permitted; foot pedal comfort mods allowed without relocation.
	Road America Runoffs 20242024-10-01	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%)	2:35.651Ethan Lampe · fastest of 23 · top 5 within 0.7s	2:36.278Ethan Jacobs · fastest of 22 · top 5 within 0.7s	129.5Michael Borden	+27.956squal +28.246s	121.8%qual 122.2%
19 rule changes (P2: 5, SMX: 4, SRF: 10)2 engine · 2 suspension & brakes · 1 tyres & wheels · 10 wording · 4 other · SRF3 air filter rule removes K&N RC-9160 option, specifies Weems P/N WM301020 only. · SRF Wilwood vented rotor minimum thickness increases to 13.25mm, 0.522 inches. · SRF3 Hoosier decal placement changed from four logos on nose and tail to three logos on sides and center front. · SMX Spec MX-5 camera requirement: non-functioning recorder now will instead of may warrant penalty or disqualification. · SM and SMX must run latest AIM Data Logger Spec MX-5 ECU Protocol, effective 2024-09-01. · SMX Mazda MX-5 OE versus OEM definitions clarified in GCR section 9.1.7.1; wording change only. · SM and SMX now allow an alternate shifter bushing at the bottom of the shift lever. · FE and SRF protest fee rules redirected to GCR section 8.3.1.D for fees and procedure. · SRF Hoosier contingency decal requirement reduced from four decals in specific locations to three decals with simplified placement. · SRF wet tyres: front P185/60R13 H20 or W2 and rear P205/60R13 H20 or W2 removed; front P185/65R13 W2 and rear P205/60R13 W2 now required. Hoosier decal placement specified. · 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. · 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. · SRF rain/brake light must be Super Bright LEDs Inc. P/N PT-STRB-R24; secondary filament must connect to rain light switch. · SRF brake light must be Super Bright LEDs Inc. P/N PT-STRB-R24, with SCCA Enterprises P/N 180427A pigtail and strobing rain light kit. · SRF adds mandatory front brake ducts 12–36 inches, throttle pedal heel-toe extension, braided stainless flex lines, camber limit 5.0 degrees, radiator opening height 3½ ± ½ inches, rear shift cable clamp P/N WM302007A. · P2 Table 1 engine date ranges clarified: Stock Engine replaced with specific marques Suzuki, Yamaha, Honda, BMW for 2009-newer and 2008-older rows. · SRF radiator options expanded: Enterprises P/N 480465 with baffle 480464, 480466, or Automotive 1R698 and CU698 allowed if cross-reference equivalent.showhide 2024-10-01 SRF Update SRF3 Air Filter Rule #36681wordingremovedSRF3 air filter rule removes K&N RC-9160 option, specifies Weems P/N WM301020 only. 2024-10-01 SRF Update SRF Brake Rotor Thickness #36687suspension & brakessuspension & brakesSRF Wilwood vented rotor minimum thickness increases to 13.25mm, 0.522 inches. 2024-10-01 SRF Hoosier Tire Decal Placement #36739wordingwordingSRF3 Hoosier decal placement changed from four logos on nose and tail to three logos on sides and center front. 2024-09-01 SMX SMX Camera Rule Correction #36496wordingwordingSMX Spec MX-5 camera requirement: non-functioning recorder now will instead of may warrant penalty or disqualification. 2024-09-01 SMX Committee) AIM ECU Protocol #36556engineaddedengineSM and SMX must run latest AIM Data Logger Spec MX-5 ECU Protocol, effective 2024-09-01. 2024-09-01 SMX Committee) OE versus OEM Definitons #36608wordingwordingSMX Mazda MX-5 OE versus OEM definitions clarified in GCR section 9.1.7.1; wording change only. 2024-09-01 SMX Committee) Shifter Bushing #36611otheraddedSM and SMX now allow an alternate shifter bushing at the bottom of the shift lever. 2024-09-01 SRF Protest Fee Clarification #36540wordingwordingFE and SRF protest fee rules redirected to GCR section 8.3.1.D for fees and procedure. 2024-09-01 SRF Update to Letter 36619 with new Hoosier Contingency Decal Info #36624wordingwordingSRF Hoosier contingency decal requirement reduced from four decals in specific locations to three decals with simplified placement. 2024-08-01 SRF Update Rain Tire Rule and Hoosier Decal Placement #36436tyres & wheelstyres & wheelsSRF wet tyres: front P185/60R13 H20 or W2 and rear P205/60R13 H20 or W2 removed; front P185/65R13 W2 and rear P205/60R13 W2 now required. Hoosier decal placement specified. 2024-05-01 P2 CN Spec ECU #35835wordingwordingP2 Spec Line E engine notes clarify oil system, ECU, and exhaust remain unrestricted; wording only. 2024-05-01 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. 2024-01-01 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. 2024-01-01 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. 2024-01-01 SRF Update SRF Rain / Brake Rule #34706otherotherSRF rain/brake light must be Super Bright LEDs Inc. P/N PT-STRB-R24; secondary filament must connect to rain light switch. 2024-01-01 SRF Update SRF Brake Light Rule v1 #34853otherotherSRF brake light must be Super Bright LEDs Inc. P/N PT-STRB-R24, with SCCA Enterprises P/N 180427A pigtail and strobing rain light kit. 2024-01-01 SRF SRF / SRF3 Rule Updates #35268suspension & brakessuspension & brakesSRF adds mandatory front brake ducts 12–36 inches, throttle pedal heel-toe extension, braided stainless flex lines, camber limit 5.0 degrees, radiator opening height 3½ ± ½ inches, rear shift cable clamp P/N WM302007A. 2023-12-01 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. 2023-10-01 SRF SRF Radiator Rule Update #34805otheraddedSRF radiator options expanded: Enterprises P/N 480465 with baffle 480464, 480466, or Automotive 1R698 and CU698 allowed if cross-reference equivalent.
	Virginia International Raceway Runoffs 20232023-09-23	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%)	2:11.435Nathan Nicholson · fastest of 18 · top 5 within 0.6s	2:12.616Noah Harmon · fastest of 16 · top 5 within 0.1s	127.8Noah Harmon	+23.787squal +22.845s	121.9%qual 121.0%
11 rule changes (P2: 8, SRF: 3)3 engine · 2 tyres & wheels · 1 cars added · 5 wording · SRF wet front tyre changes to Hoosier P/N 46100 P185/60R13 H20 or W2 with 2.5" ground clearance. · 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. · SRF front W2 rain tyre Hoosier part number changes from 46100 to 46101 P185/65R13. · 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. · SRF removes 1985 Renault Alliance solid front rotor option; restrictor sizes decrease 1mm for newer Kawasaki and multi-brand engines; minimum weights increase to 1100 lbs. · 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 2023-06-01 SRF Hoosier SRF Wet Front Tire Rule Update #34189tyres & wheelstyres & wheelsSRF wet front tyre changes to Hoosier P/N 46100 P185/60R13 H20 or W2 with 2.5" ground clearance. 2023-05-01 P2 Clarify minimum side body height requirement #34143wordingwordingP2 minimum side body height must equal front axle centerline height, viewed from side. 2023-05-01 P2 Clarify closed cockpit single seat car allowance #34144wordingwordingP2 closed cockpit single seat cars now prohibited unless Table 1 spec line permits. 2023-05-01 SRF Update SRF Front W2 Rain Tire Part Number #34118tyres & wheelstyres & wheelsSRF front W2 rain tyre Hoosier part number changes from 46100 to 46101 P185/65R13. 2023-04-01 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. 2023-04-01 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. 2023-03-01 SRF Update SRF Brake Rule #33469enginefasterengineSRF removes 1985 Renault Alliance solid front rotor option; restrictor sizes decrease 1mm for newer Kawasaki and multi-brand engines; minimum weights increase to 1100 lbs. 2023-01-01 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. 2023-01-01 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. 2023-01-01 P2 E&O original class intent #33519wordingwordingP2 chassis now allows composite materials partially installed; anti-intrusion panels attachment simplified; Stohr and converted models clarified. 2023-01-01 P2 Update Engine Table Spec Line B.1 #33608engine
	Virginia International Raceway Runoffs 20222022-09-24	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%)
13 rule changes (P2: 10, SRF: 3)1 cars added · 1 weight · 8 wording · 3 other · SRF tire rule wording clarified: tires must be run as delivered. · SRF brake rotor minimum thickness reduced from 13.25 mm to 12.20 mm; seals and air filter specs clarified. · 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. · P2 Oldsmobile cam rules correct spelling from 'after market' to 'aftermarket' in two sections. · 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. · 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. · P2 Control Area definition clarified: rectangular zone from rear edge of front tires to front edge of rear tires, full car width. · 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. · SRF wet tyres front P185/65R13 W2 option added; air box clarified as-delivered; SRF3 restrictor plate G301048 mandatory Jan 1 2022; P2 motorcycle engines up to 1005cc with 35mm restrictor, 2009+ stock 1075 lbs, 2008 stock 1025 lbs, modifie…showhide 2022-06-01 SRF SRF Tire Rule Update #32614wordingwordingSRF tire rule wording clarified: tires must be run as delivered. 2022-06-01 SRF Brake, seal, and air filter clarifications #32670otherfasterSRF brake rotor minimum thickness reduced from 13.25 mm to 12.20 mm; seals and air filter specs clarified. 2022-05-01 P2 E&O Clarification of Chassis Construction Requirements #32469wordingwordingP2 chassis construction clarified: full composite allowed; partial composite must roll without composite parts installed. 2022-05-01 P2 Clean up P2 wording #32525wordingwordingP2 classification wording cleaned up in GCR section 9.1.8.C and GCR contents. 2022-04-01 P2 After Market to Aftermarket #32373wordingwordingP2 Oldsmobile cam rules correct spelling from 'after market' to 'aftermarket' in two sections. 2022-03-01 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. 2022-03-01 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. 2022-03-01 P2 E&O class name #32196wordingwordingP2 Converted F5 cars renamed F500, must retain F500 suspension, minimum width 55 inches. 2022-02-01 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. 2022-01-01 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. 2021-12-01 P2 BoP adjustment effective 1-1-22 #31538otherunclearP2 specification line B.1 engine table entry amended; details of change not provided in excerpt. 2021-12-01 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. 2021-12-01 SRF Three Updates to SRF Rules #31523otherotherSRF wet tyres front P185/65R13 W2 option added; air box clarified as-delivered; SRF3 restrictor plate G301048 mandatory Jan 1 2022; P2 motorcycle engines up to 1005cc with 35mm restrictor, 2009+ stock 1075 lbs, 2008 stock 1025 lbs, modifie…
	Indianapolis Motor Speedway Runoffs 20212021-09-25	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
14 rule changes (P2: 8, SRF: 6)3 engine · 2 cars added · 1 tyres & wheels · 7 wording · 1 other · P2 CN Honda K20A-FD2 engine rebuild clarified: balancing, porting, polishing prohibited; valve jobs and honing must follow factory procedures. · 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. · SRF wet tyres add Hoosier W2 option alongside existing H20 from October 4, 2021. · SRF adds SADEV-SRF3 6-speed sequential transmission option with ratios 3.0–0.92:1 and 3.20 final drive. · SRF seal requirements clarified: seals now must be on driveline components in designated locations; unsealed components removed and inspected by CSR or Enterprises rather than engine shipped for testing. · SRF3 alternator pulley specified as P/N G902130 or G902130A, minimum 12oz. · 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. · P2 adds new spec line for 2-cycle 3-cylinder engine up to 820cc with 10 front, 14–15 rear wheel width. · SRF and SRF3 mandatory identification revised: removed Ford Performance and Blue Oval decals, added Hoosier logo placement. · 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. · SRF rear springs limited to P/N 280390 only, previous part numbers no longer allowed; ground clearance wording clarified.showhide 2021-09-01 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. 2021-08-01 P2 F5 P2 Conversion #30856wordingwordingP2 Converted F5 cars must retain F5 suspension and meet P2 non-spec requirements except minimum width is 55 inches. 2021-08-01 P2 Clarify minimum body width requirement #30859wordingwordingP2 minimum body width clarified: cannot extend inward beyond vertical plane through tire centerlines. 2021-08-01 SRF SRF Wet Tires #30849tyres & wheelsaddedtyres & wheelsSRF wet tyres add Hoosier W2 option alongside existing H20 from October 4, 2021. 2021-08-01 SRF SADEV-SRF3 Transmission #30926cars addedaddedSRF adds SADEV-SRF3 6-speed sequential transmission option with ratios 3.0–0.92:1 and 3.20 final drive. 2021-08-01 SRF SRF Update Maintenance, Repairs and Seals #30961wordingwordingSRF seal requirements clarified: seals now must be on driveline components in designated locations; unsealed components removed and inspected by CSR or Enterprises rather than engine shipped for testing. 2021-06-01 SRF SRF3 Alternator Pulley #30684engineaddedengineSRF3 alternator pulley specified as P/N G902130 or G902130A, minimum 12oz. 2021-05-01 P2 E&O tonneau cover provision in cockpit opening section #30459wordingwordingP2 tonneau covers now allowed to meet minimum dimensions; cockpit equipment attachment wording clarified. 2021-05-01 P2 Remove effective dates in Table 1 #30468wordingwordingP2 removes effective date 01/01/2021 from six car spec lines in Table 1. 2021-05-01 P2 E&O Maximum Valves Per Cylinder #30560engineengineP2 engine specs B.1, B.2, B.3 limited to maximum 4 valves per cylinder. 2021-03-01 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. 2021-03-01 SRF Mandatory identification: #30223wordingwordingSRF and SRF3 mandatory identification revised: removed Ford Performance and Blue Oval decals, added Hoosier logo placement. 2020-12-01 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. 2020-12-01 SRF SRF Shocks, Springs and Ride Height. #29688otherotherSRF rear springs limited to P/N 280390 only, previous part numbers no longer allowed; ground clearance wording clarified.
	Road America Runoffs 20202020-10-02	2:08.514Robert Iversen · fastest of 12 · top 5 within 3.0s	2:09.793Robert Iversen · fastest of 12 · top 5 within 3.9s	153.1Robert Iversen
11 rule changes (P2: 6, SRF: 5)1 aero · 1 cars added · 1 engine · 1 induction · 1 tyres & wheels · 1 weight · 4 wording · 1 other · 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. · Elan NP01 added to P2 Table 1 as Spec Line car with 2000cc displacement and 42mm restrictor. · P2 Enterprises Sports Racer now permits 55mm flat plate intake restrictor Part # WM303013 as alternative to SIR. · SRF Penske shock P/N 280396 bump stop P/N 280407 becomes mandatory, maximum one per shock, effective 05/01/2020. · P2 Enterprise Sports Racer 2.3L engine must use SIR or Flat Plate restrictor meeting peak horsepower, sized in whole or 0.5mm increments. · P2 electronic throttle control wording clarified: ETC permitted if stock ECU throttle pedal activates original throttle shaft mechanism. · P2 adds BMW to permitted motorcycle-based engines alongside Kawasaki, Suzuki, Yamaha, Honda. · SRF rain and brake rule supersedes GCR 9.3.32.B.2 effective 1/1/2024 through 12/31/2024. · SRF adds tire warmer prohibition and specifies Hoosier dry and wet tire part numbers. · SRF front nose weight minimum reduced from 35 to 32 lbs. · SRF2 becomes Regional Only; SRF3 nomenclature changed from GEN3 to Ford 1.6L conversion; SRF and SRF3 no longer compete together for points.showhide 2020-09-01 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. 2020-06-01 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. 2020-05-01 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. 2020-05-01 SRF SRF Bump Stop Correction #27019wordingwordingSRF Penske shock P/N 280396 bump stop P/N 280407 becomes mandatory, maximum one per shock, effective 05/01/2020. 2020-04-01 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. 2020-03-01 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. 2020-01-01 P2 Request for addition of BMW Engine in P2 Engine Table #27821engineaddedengineP2 adds BMW to permitted motorcycle-based engines alongside Kawasaki, Suzuki, Yamaha, Honda. 202-01-01 SRF SRF Rain / Brake Rule - BoD approved as follows #34958wordingwordingSRF rain and brake rule supersedes GCR 9.3.32.B.2 effective 1/1/2024 through 12/31/2024. 2019-12-01 SRF SRF Tire Warmer Rule #27622tyres & wheelstyres & wheelsSRF adds tire warmer prohibition and specifies Hoosier dry and wet tire part numbers. 2019-12-01 SRF SRF / SRF3 Nose Weight Reduction #27706weightfasterweightSRF front nose weight minimum reduced from 35 to 32 lbs. 2019-12-01 SRF SRF / SRF3 Majors & Regional Class Updates #27723wordingwordingSRF2 becomes Regional Only; SRF3 nomenclature changed from GEN3 to Ford 1.6L conversion; SRF and SRF3 no longer compete together for points.
	Virginia International Raceway Runoffs 20192019-10-05	1:49.111Robert Iversen · fastest of 14 · top 5 within 0.8s	1:50.258Greg Gyann · fastest of 13 · top 5 within 0.4s	149.4Robert Iversen
10 rule changes (P2: 9, SRF: 1)4 engine · 1 aero · 1 cars added · 1 induction · 1 weight · 2 wording · P2 Honda K20A-FD2 non-composite chassis intake restrictor note clarified; restrictor implementation date removed. · 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. · P2 cars limited to power application on maximum two wheels. · SRF drivers may now use Dash Windscreen Kit P/N 1180103 or P/N 180102. · P2 Enterprise minimum weight increased to 1375 lbs.; peak horsepower of sealed ESR engine reduced per CRB specification. · 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. · 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.showhide 2019-10-01 P2 Update Engine Table Line E notes #27414wordingwordingP2 Honda K20A-FD2 non-composite chassis intake restrictor note clarified; restrictor implementation date removed. 2019-08-31 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. 2019-07-01 P2 E&O Transmissions #27006engineslowerengineP2 cars limited to power application on maximum two wheels. 2019-07-01 SRF SRF Dash Windscreen Kit #27028aeroaddedaeroSRF drivers may now use Dash Windscreen Kit P/N 1180103 or P/N 180102. 2019-06-01 P2 Request to restrict all cars #26246weightslowerweightP2 Enterprise minimum weight increased to 1375 lbs.; peak horsepower of sealed ESR engine reduced per CRB specification. 2019-03-01 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). 2019-03-01 P2 Change Line A.1 restrictor size #26429engineslowerengineP2 Line A.1 restrictor reduced from 40mm to 38mm. 2019-01-01 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. 2019-01-01 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. 2019-01-01 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.
	Sonoma Raceway Runoffs 20182018-10-10	1:28.784Tim Day Jr · fastest of 17 · top 5 within 5.0s	1:32.071Chuck Bona · fastest of 18 · top 5 within 0.9s	144.4Tim Day Jr
No rule changes on record between these events
	Indianapolis Motor Speedway Runoffs 20172017-09-25	1:31.826Jeff Shafer · fastest of 26 · top 5 within 4.9s	1:32.481Jeff Shafer · fastest of 24 · top 5 within 3.8s							1:51.573Thomas Kirchman · fastest of 50 · top 5 within 2.8s	1:53.769Todd Harris · fastest of 45 · top 5 within 0.2s		+21.288squal +19.747s	123.0%qual 121.5%
No rule changes on record between these events
	Mid-Ohio Sports Car Course Runoffs 20162016-09-19	1:20.188Jeff Shafer · fastest of 18 · top 5 within 4.0s	1:20.904Jeff Shafer · fastest of 16 · top 5 within 2.2s							1:37.344Mike Miserendino · fastest of 27 · top 5 within 0.8s	1:37.621Todd Harris · fastest of 27 · top 5 within 0.6s		+16.717squal +17.156s	120.7%qual 121.4%
No rule changes on record between these events
	Daytona International Speedway Runoffs 20152015-09-21	1:51.825Chris Farrell · fastest of 17 · top 5 within 3.6s	1:52.355Jeff Shafer · fastest of 17 · top 5 within 2.8s							2:14.306Cliff White · fastest of 39 · top 5 within 1.2s	2:16.700Cliff White · fastest of 38 · top 5 within 0.5s		+24.345squal +22.481s	121.7%qual 120.1%

By track

Track	Events	Typical % of P2	Best	Latest
Road America	4	100.0%3 of 4 with P2	100.0%Runoffs 2020	100.0%Runoffs 2026
Virginia International Raceway	3	100.0%	100.0%Runoffs 2019	100.0%Runoffs 2023
Indianapolis Motor Speedway	2	100.0%	100.0%Runoffs 2017	100.0%Runoffs 2021
Daytona International Speedway	1	100.0%	100.0%Runoffs 2015	100.0%Runoffs 2015
Mid-Ohio Sports Car Course	1	100.0%	100.0%Runoffs 2016	100.0%Runoffs 2016
Sonoma Raceway	1	100.0%	100.0%Runoffs 2018	100.0%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 P2'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.