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BoP Lab / Buttonwillow Raceway Park

F5 + SRF + F6 + STU at Buttonwillow Raceway Park

No mapCal Club 2024, Cal Club 2023

Track map: sectors and speed trap

Track map with timing sectors and speed trap
Shown for: Cal Club 2026 (practice, qualifying, race) · Cal Club 2025 (practice, qualifying, race)
Class · click a class to switch, + to compare alongside
Track configuration
Events

This track has been raced on 4 configurations (The Circuit, 2.57 mi; 19, 2.92 mi; 1.83 mi; 3.02 mi). Laps on different configurations are not comparable, so only events on the 2.57 mile layout are shown; switch above to see the others.

F5 has no laps in the events chosen. It ran at Super Tour Apr 2017: add that event.

SRF has no laps in the events chosen. It ran at Super Tour Apr 2017, Majors Apr 2016: add those events.

F6 has no laps in the events chosen. It ran at Cal Club 2024: add that event.

One session is left out because the timing does not look like full laps: Cal Club 2023 Qualifying #2.

PosCarDriverClass#LapTheoreticalQualRace5-lap stintConsistencyTrapS1S2S3
1Mazda RX-3Tony RiveraSTU091:50.913 A-Q21:50.8701:50.913 A-Q21:52.737 A-R21:54.126 A-R2+2.638 A-R2135.2 A-Q230.415 A-Q232.456 A-Q247.999 A-Q2
2Mazda MiataWhitfield GreggSTU171:51.602 B-P1:51.6022:02.264 B-Q22:01.538 B-R12:02.222 B-R1+1.271 B-R1116.3 A-Q130.652 B-P32.263 B-P48.687 B-P
3BMW M3Wilson PowellSTU771:52.380 B-P1:52.1641:55.401 B-Q11:53.843 B-R11:54.699 B-R1+1.965 B-R1102.6 B-R130.577 B-P32.372 B-P49.215 B-P
4Honda S2000Rylan HazeltonSTU491:53.640 B-R11:53.1401:55.834 B-Q11:53.640 B-R11:54.534 A-R2+0.714 A-R2134.8 A-R230.582 B-R132.779 B-R149.779 A-R2
5BMW 330Sean LovettSTU371:56.492 A-Q21:56.4261:56.492 A-Q21:57.049 A-R21:57.605 A-R2+1.649 A-R2133.7 A-R231.816 A-Q233.669 A-Q150.941 A-Q2
6Nissan 300ZXJames SlechtaSTU751:59.183 A-Q21:59.1831:59.183 A-Q22:00.458 A-R22:01.009 A-R2+0.921 A-R2132.0 A-Q132.882 A-Q234.528 A-Q251.773 A-Q2
7Mazda MX-5Oscar JacksonSTU1611:59.707 B-R21:58.8881:59.707 B-R21:59.952 B-R2+1.112 B-R2103.9 B-R232.339 B-R234.219 B-R252.330 B-R2
8Mazda RX-7Michael LewisSTU322:00.248 A-R12:00.1792:00.248 A-R12:02.190 A-R2+1.431 A-R2130.4 A-R132.729 A-R134.570 A-R152.880 A-R1
9Mazda MX-5Dale ShoemakerSTU522:01.642 B-R22:01.1762:04.115 B-Q12:01.642 B-R22:02.793 B-R2+2.442 B-R2125.9 A-Q232.956 B-R234.983 B-R253.237 B-R2

One row per driver and car (a driver who changed cars has a row for each). Each cell is that driver's best in that car across the selected events, with the session it was set in. Best 5-lap stint is the mean of the driver's quickest five consecutive race laps, and consistency is how far their median race lap sat behind their best in that race (small is a driver who does it every lap); both come from the race with the best stint. The fastest in each column is purple, and a car whose best lap is more than 115% of the fastest in its class is greyed (marked ">115%" beside the driver) and left out of the colour scale. Click a column to sort, a row to highlight it. Theoretical lap is the sum of the best sectors, whichever laps they came from, and never slower than the best lap (where a car's fastest laps were recorded without sector times, its best lap is used). The 115% mark is about the car's best lap only: a car whose best lap is within 115% of the fastest in its class is never marked. Greyed sectors with no theoretical lap mean the sector times on file do not add up to a believable lap. Letters refer to the events above; Q is qualifying, R a race.

Sectors

Sectors are numbered in lap order from start/finish, whatever each event's timing called them; the loop names are SCCA timing's.

By car

CarClassDriversLapQualRaceTrapS1S2S3
Mazda RX-3STU11:50.913Tony Rivera1:50.913Tony Rivera1:52.737Tony Rivera135.2Tony Rivera30.415Tony Rivera32.456Tony Rivera47.999Tony Rivera
Mazda MiataSTU11:51.602Whitfield Gregg2:02.264Whitfield Gregg2:01.538Whitfield Gregg116.3Whitfield Gregg30.652Whitfield Gregg32.263Whitfield Gregg48.687Whitfield Gregg
BMW M3STU11:52.380Wilson Powell1:55.401Wilson Powell1:53.843Wilson Powell102.6Wilson Powell30.577Wilson Powell32.372Wilson Powell49.215Wilson Powell
Honda S2000STU11:53.640Rylan Hazelton1:55.834Rylan Hazelton1:53.640Rylan Hazelton134.8Rylan Hazelton30.582Rylan Hazelton32.779Rylan Hazelton49.779Rylan Hazelton
BMW 330STU11:56.492Sean Lovett1:56.492Sean Lovett1:57.049Sean Lovett133.7Sean Lovett31.816Sean Lovett33.669Sean Lovett50.941Sean Lovett
Nissan 300ZXSTU11:59.183James Slechta1:59.183James Slechta2:00.458James Slechta132.0James Slechta32.882James Slechta34.528James Slechta51.773James Slechta
Mazda MX-5STU21:59.707Oscar Jackson2:04.115Dale Shoemaker1:59.707Oscar Jackson125.9Dale Shoemaker32.339Oscar Jackson34.219Oscar Jackson52.330Oscar Jackson
Mazda RX-7STU12:00.248Michael Lewis2:00.248Michael Lewis130.4Michael Lewis32.729Michael Lewis34.570Michael Lewis52.880Michael Lewis

The best any driver of each car managed across the selected events, with who set it. Spellings and model years of the same car are grouped; click a row marked ▸ to see each version. Grouping is worked out from the names, so tell us if two cars are wrongly merged or split.

Rule changes between these events

Cal Club 2023 → Cal Club 2024 2023-02-24 to 2024-02-23

SRF Update SRF Brake Rule

#33469 from Robey Clark · Rule change · TB 23-01 (2023-01 Fastrack)

In SRF, GCR section 9.1.8.D.X.g, change as follows:
"Brakes: Hawk Blue 9012 pads P/N 801993 must be used. Wilwood vented rotor P/N 800065 shall be used as delivered with no
machining of any kind. Minimum thickness 12.20mm (0.481"). The 1985 Renault Alliance solid front rotor (Reference: Bendix
PRT1318 or Centrix 121.11004) may be used on front, rear, or both axles, but each axle must be paired to the same type
rotor. The Renault Alliance solid front rotors may not be used. Rubber caliper bushings may be replaced with bronze bushings P/N
1196185 or P/N 1196185. Original caliper pistons may be replaced with vented caliper piston P/N 1196184; no other
modification allowed. Wilwood caliper with bracket universal fit P/N 800038 may be used as delivered with no modification of
any kind. Wilwood knock back spring (2.63 lbs.) P/N 800045 may be used as delivered with no modification of any kind;

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maximum of one spring per caliper."
P2 Engine Table
Spec
Line Engine Series

A specification table follows in the original; it is not shown here.

STU E&O STU NA Weight Chart.

#33737 from Eric Heinrich · Rule change · TB 23-03 (2023-03 Fastrack)

In STU, GCR Section 9.1.4.1.H.1. chart, Factory Engine Displacement (cc) Minimum Weight (lbs), change as follows:
"2450 2596 2595"
"2600 2860 2710"

STU Alternate OEM Miata Intake Manifold

#33827 from Brandon Steinhauer · Rule change · TB 23-04 (2023-04 Fastrack)

In STU Spec lines, classify Mazda BP5A as follows:
STU Maximum Displacement (cc's) Minimum Weight Notes
Mazda BP5A 1839 Chart May use engine in its entirety or specific
components from the engine.

SRF Update SRF Front W2 Rain Tire Part Number

#34118 from Robey Clark · Rule change · TB 23-05 (2023-05 Fastrack)

In SRF, GCR section 9.1.8.D.1.X.f, change as follows:
"Front – Hoosier P/N 46100 1 P185/65R13 W2"

SRF Hoosier SRF Wet Front Tire Rule Update

#34189 from Robey Clark · Rule change · TB 23-06 (2023-06 Fastrack)

In SRF, GCR section 9.1.8.D.1.X.f, change as follows:
"Wet:
Front – Hoosier P/N 46100 P185/60R13 H20 or W2
Rear – Hoosier P/N 46105 P205/60R13 H20 or W2
Ground clearance is 2.5" with driver as raced when P185/60R13 (H20 or W2) tires are used."

STU 2022 Toyota GR Cup for STU

#34449 from Club Racing Board · Rule change · TB 23-06 (2023-05 Fastrack)

In STU Spec Lines, Toyota GR Cup (2022-), classify as follows:

A specification table follows in the original; it is not shown here.

SRF SRF Radiator Rule Update

#34805 from Robey Clark · Rule change · TB 23-10 (2023-10 Fastrack)

In SRF, GCR section 9.1.8.D.1.V.j, change as follows:
"Radiator - Enterprises new style P/N 480465 (requires baffle P/N 480464) or P/N 480466 can be used. P/N 480466, may can be
replaced with Automotive P/N 1R698, CU698 or equivalent OEM manufacturer justified by one cross-reference chart equivalent,
as long as the size, shape, and material are the same as the original P/N. The capacity, core thickness, etc., cannot be changed
even if allowed under the above. The competitor is responsible for providing this documentation of the cross-reference P/N."

SRF Update SRF Rain / Brake Rule

#34706 from Robey Clark · Rule change · TB 23-09 (2023-09 Fastrack)

In SRF, GCR section 9.1.8.D.1.W.l, change as follows:
"A Super Bright LEDs Inc. rain / brake light comprised of a single standard trailer oval lamp, 2-1/4 inches x 6-1/2 inches, with
incandescent or LED illumination, P/N PT-STRB-R24, is required in the original roll hoop mounting location. This rule supersedes
GCR section 9.3.32.B.2 effective 1/1/2024 through 12/31/2024. No changes may be made to the original 3-pin connector on the
wiring harness. The secondary filament of the brake light assembly shall must be connected to a switch enabling its use as a rain
light."

SRF Update SRF Brake Light Rule v1

#34853 from Robey Clark · Rule change · TB 23-10 (2023-10 Fastrack)

In SRF, GCR section 9.1.8.D.1.W.l, change as follows:
"A Super Bright LEDs Inc. P/N PT-STRB-R24 (SCCA Enterprises P/N 180427A) rain / brake light, P/N PT-STRB-R24, is required in the
original roll hoop mounting location. This rule supersedes GCR section 9.3.32.B.2 effective 1/1/2024 through 12/31/2024. No
changes may be made to the original 3-pin connector on the wiring harness. An SCCA Enterprises P/N 1190503 Strobing Brake
Light Pigtail is required. The secondary filament of the brake light assembly must be connected to a switch enabling its use as
a strobing rain light. A Strobing Brake Light Kit P/N 1168003 is available, which includes the brake light and pigtail."

SRF SRF / SRF3 Rule Updates

#35268 from Robey Clark · Rule change · TB 24-01 (2024-01 Fastrack)

In SRF, GCR section 9.1.8.D.1.H, add the following:
"NO MODIFICATIONS ALLOWED. Front brake ducts are required, attached to the openings in the lower radiator baffles, any
flexible 4" duct material allowed, installed length minimum 12" maximum 36" in length. Must be securely fastened, Bracket Part
# P/N 800368 can be used. Shall Must serve no other purpose. An extension may be welded to the side of the throttle pedal to
improve heel-and-toe braking. Master cylinder casting / location must be used as delivered on P/N 180110 Pedal Mounting
support. Aeroquip style -3 braided stainless flex lines only, must attach to all brake components without modification. Brake pad
"anti-rattle" clips must be removed."
In SRF, GCR section 9.1.8.D.1.V, add the following:

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"ii. Rear SADEV shift cable aluminum two-piece style clamp may be used. The P/N WM302007A clamp must serve no other
purpose."
In SRF, GCR section 9.1.8.D.1.X.k, add the following:
"Negative camber shall must not exceed 5.0 degrees absolute maximum front and rear."
In SRF, GCR section 9.1.8.D.1.AA.b, add the following:
"2. Height of the radiator opening vertical surface 3 1/2“ +/- 1/2"."
P2 Engine Table B.1
2008 and older Stock
Suzuki, Yamaha,
Honda, BMW
38.5mm
P2 Engine Table B.2 Not required
P2 Engine Table B.3 38.5mm
Modified
Engine
950 lbs.
1005cc max
P2 Engine Table B.1
2008 and older 37mm
P2 Engine Table B.2 Not required
P2 Engine Table B.3 39mm
Stock Engine
1050 lbs.

STU ST Electric-Assisted Steering Systems

#35066 from Jose Osiris Pena · Rule change · TB 24-02 (2024-01 Fastrack)

In GCR, Section 9.1.4.M.16., change as follows:
"Power steering may be modified in any of the following ways:
a. disconnected , pump, belt, pulley, and hoses may be removed. Hoses may also be looped. Steering rack or box may be
modified internally to work without pump.
b. an OEM manual steering rack for that model may be fitted
c. an electric power steering pump may be fitted
d. an OEM electric-assisted steering system may be used or any column mounted electric steering assist may be used
e. an OEM hydraulic-assisted steering system may be used"

Cal Club 2024 → Cal Club 2025 2024-02-23 to 2025-02-22

STU Letter #35397 addendum

#35453 from Aaron Fitzsimmons · Rule change · TB 24-03 (2024-03 Fastrack)

In STU Spec Lines, Mini Cooper S SC with Minimum Weight 1900 and 2100, add to Notes:
"Alternate LEAP OMICRON hood scoop part # LEP-OMICRON3 is permitted."

STU S54 Drysump

#35464 from Macey Urso · Rule change · TB 24-03 (2024-03 Fastrack)

In STU Spec Lines, BMW S54 B32 OEM, add to Notes as follows:
"Dry Sump oiling system permitted."

STU RWD Turbo Disadvantage

#36255 from David Fiorelli · Rule change · TB 24-08 (2024-08 Fastrack)

In GCR, Section 9.1.4.1.H.3 - Inlet Restrictor (mm) Minimum Weight (lbs) table, change as follows:
"RWD cars must reduce restrictor 1 mm from this table"

SRF Update Rain Tire Rule and Hoosier Decal Placement

#36436 from Robey Clark · Rule change · TB 24-08 (2024-08 Fastrack)

In SRF, GCR section 9.1.8.D.1.X.f, change as follows:
"Wet:
Front – Hoosier P/N 46100 P185/60R13 H20 or W2
Rear – Hoosier P/N 46105 P205/60R13 H20 or W2
Ground clearance is 2.5” with driver as raced when P185/60R13 (H20 or W2) tires are used.
OR
Front – Hoosier P/N 46101 P185/65R13 W2
Rear – Hoosier P/N 46105 P205/60R13 W2

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1. It is forbidden to regroove tires.
2. The use of tire warmers or cooling methods other than natural air convection or conduction is prohibited. The penalty for
violation will be the loss of qualifying times and/or the disqualification of race results.
3. Hoosier SRF/SRF3 Decal Placement:
Four (4) "Hoosier" decals are required in the following locations: Two (2) 11" X 3" decals on the vertical plane of the front nose to
the outside of the cooling opening on each side and two (2) 18" X 5" decals, one on each side of the engine cover or above the
rear wheel openings on the vertical plane. Hoosier decals are available, free of charge, from all Hoosier tire distributors including
SCCA Enterprises."

SRF Protest Fee Clarification

#36540 from SCCA Staff · Rule change · TB 24-09 (2024-09 Fastrack)

In FE, GCR section 9.1.1.I.2.U.b.3, change as follows:
"Protest Fee: Regional -$25.00, National -$50.00. See GCR section 8.3.1.D for fees and payment procedure."
In SRF, GCR section 9.1.8.D.1.U.b.3, change as follows:
"Protest Fee: Regional -$25.00, National -$50.00. See GCR section 8.3.1.D for fees and payment procedure. Item 1 will be done by
the CSR or other shop that is equipped for this type of work and will be paid directly."

SRF Update to Letter 36619 with new Hoosier Contingency Decal Info

#36624 from Robey Clark · Rule change · TB 24-09 (2024-09 Fastrack)

In SRF, GCR section 9.1.8.D.1.X.f.3, change as follows:
"Four (4) "Hoosier" decals are required in the following locations: Two (2) 11" X 3" decals on the vertical plane of the front nose
to the outside of the cooling opening on each side and two (2) 18" X 5" decals, one on each side of the engine cover or above the
rear wheel openings on the vertical plane. Hoosier decals are available, free of charge, from all Hoosier tire distributors including
SCCA Enterprises Per Hoosier's contingency program, three (3) decals are required to qualify for contingency awards. One (1)
decal must be located on each side of the car and one (1) decal must be visible on the front."

SRF Update SRF3 Air Filter Rule

#36681 from Robey Clark · Rule change · TB 24-10 (2024-10 Fastrack)

In SRF, GCR section 9.1.8.D.2.H.23, change as follows:
"Air Filter: P/N WM301020 or K&N RC-9160"

SRF Update SRF Brake Rotor Thickness

#36687 from Robey Clark · Rule change · TB 24-10 (2024-10 Fastrack)

In SRF, GCR section 9.1.8.D.1.X.g, change as follows:
"Brakes: Hawk Blue 9012 pads P/N 801993 must be used. Wilwood vented rotor P/N 800065 shall must be used as delivered with
no machining of any kind. Minimum thickness 12.20mm (0.481”) 13.25mm (0.522”)."

SRF Hoosier Tire Decal Placement

#36739 from Robey Clark · Rule change · TB 24-10 (2024-10 Fastrack)

In SRF, GCR section 9.1.8.D.2.B, change as follows:
"Mandatory identification: "SRF3" near the side car numbers. "Hoosier" logo (4) on both sides front lower outer corners of the
nose and each side of the tail. Three (3) "Hoosier" logos, one (1) on each side of the car and one (1) on the center front of the car."

STU R53 15% Pulley Request

#36980 from Aaron Fitzsimmons · Rule change · TB 24-11 (2024-11 Fastrack)

In STU Spec Lines, Mini Cooper S SC, add to notes:
1900: "Stock supercharger pulley. 2.565 diameter."
2100: "JCW Pulley permitted. May run a 2.285 diameter pulley."

STU Request to Remove Miata Hubs from General category

#37138 from Christopher Childs · Rule change · TB 24-12 (2024-12 Fastrack)

In GCR, Section 9.1.4.M.18., change as follows:
"18. Allow alternate front wheel front hubs, Mazda Motorsports Development Part #0000-04-5HUB-S1, for the 90-05 Mazda
Miata: Mazda Motorsports Development Part #0000-04-5HUB-S1."

STU BMW N54/N55 Engine Allowance

#37146 from Martin Sarukhanyan · Rule change · TB 24-12 (2024-12 Fastrack)

"Turbo inlet restrictors designed per GCR Appendix F Technical Glossary definition of “Turbo Inlet Restrictor” may be required;
see table 9.1.4.1.H.h.2 3. Swapping of turbochargers between engine makes and models is prohibited. Supercharged cars may be
approved on a case-by-case basis; twin turbo engines are allowed on a case-by-case basis only. Contact the Road Racing
Technical Office for details. Twin turbo engines may be converted to single turbo using one of the allowed alternate turbos (see
9.1.4.1.H.3 2). Aftermarket turbocharger and supercharger kits will be allowed on a case-by-case basis.

STU Audi 1.8t Wagon STU Table B

#36685 from Mike McLaughlin · Rule change · TB 25-01 (2025-01 Fastrack)

In STU Spec Lines, Table B: Alternate Vehicle and Engine Requirements, delete Audi/VW 1.8 Turbo in its entirety.
In STU Spec Lines, Table B: Alternate Vehicle and Engine Requirements, Porsche 944 w/Max Displacement 1800, change as
follows:
Weight: "3050 Chart"
Notes: "VW/Audi 1.8L 35mm turbo engine permittedinlet restrictor required."

STU Merger GT3 to STU

#37486 from Club Racing Board · Rule change · TB 25-01 (2025-01 Fastrack)

In STU, Table C, change STU-GT3 charge as follows:
"(Effective January 1, 2026) TABLE C: STU-GT3U"

STU GT3 TCR Tire allowance

#37494 from Club Racing Board · Rule change · TB 25-01 (2025-01 Fastrack)

In STU, Table C, GT3 TCR, add to Notes the following:
"May run DOT approved tire with maximum section width of 275 with 100 pound weight adder. May not run A compound with
275."

Cal Club 2025 → Cal Club 2026 2025-02-22 to 2026-02-21

STU BMW N54/N55 Engine Allowance Follow Up

#37447 from Martin Sarukhanyan · Rule change · TB 25-03 (2025-03 Fastrack)

In STU Spec Lines, Table A, classify BMW N54/N55 as follows:
STU Maximum Displacement
(cc's) Minimum Weight Notes
BMW N54/N55 3.0 Chart +3% (DI) Short blocks, heads, and intakes may be
freely swapped within these engine
designations. N54 twin turbo not allowed

STU STU Mini Cooper pulley size clarification re: letter #36980

#37717 from Aaron Fitzsimmons · Rule change · TB 25-03 (2025-03 Fastrack)

In STU Spec Lines, Mini Cooper S SC, add to notes:
2100: "May run a 2.285 2.185 diameter pulley."

STU Question About a Weight Modifier

#37782 from Peter St Pierre · Rule change · TB 25-03 (2025-03 Fastrack)

In STU Spec Lines, Table A, Honda K20C1 Turbo I4, add to Notes the following:
"The 3% DI weight adder does not need to be applied."

STU Increase Minimum Weight

#37919 from Club Racing Board · Rule change · TB 25-03 (2025-03 Fastrack)

In STU Spec Lines, Table C: STU-GT3U, change Minimum Weight as follows:
"150 250 pounds"

SRF Driver Safety & Comfort

#37966 from Robey Clark · Rule change · TB 25-04 (2025-04 Fastrack)

In SRF, GCR section 9.1.8.D.1.D, add the following:
"f. Driver Safety and Comfort modifications to seat and controls for drivers with disabilities may be made only by approval. These
modifications must be reported to SCCA Enterprises and noted in the car logbook. The modifications are approved only for the
noted driver with disabilities. If the car is used by or sold to another driver, it must be returned to the previous standard
configuration."

SRF Update SADEV transmission specs

#37992 from Club Racing Board · Rule change · TB 25-04 (2025-04 Fastrack)

In SRF, GCR section 9.1.8.D.2.K, change as follows:
"OR
SADEV-SRF3 6-Speed Sequential (beginning from Oct. 4, 2021 onward):
1st 12-36 3.0000 : 1
2nd 15-31 2.0667 : 1
3rd 18-28 1.5556 : 1
4th 22-28 1.2727 : 1
5th 24-26 1.0833 : 1

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6th 25-23 0.9200 : 1
Final Drive Ratio: 15-48 3.20"

STU Wheel Size Inconsistency

#38018 from David Fiorelli · Rule change · TB 25-05 (2025-05 Fastrack)

In GCR, Section 9.1.4.1.F.1., change as follows:
"Wheels may not exceed 18 inches in diameter. or 8.0 inches in width for vehicles 2950 lbs. and under minimum allowed race
weight. Vehicles over 2850 minimum allowed race weight may use a 9 inch wide wheel. Cars equal to or less than 2,850 lbs.
minimum allowed race weight may not use wheels wider than 8 inches. Cars greater than 2,850 lbs. minimum allowed race
weight may not use wheels wider than 9 inches."

STU Table C: STU-GT3U Clarification

#38268 from Club Racing Board · Rule change · TB 25-05 (2025-05 Fastrack)

In STU Spec Line, Table C: STU-GT3U, change as follows:
Minimum Weight: “Current GT3 race weight plus 250 225 pounds”
Notes: "DOT approved tire with maximum section width of 245. GT3 cars base wheel is a maximum of 15”x9”. 18”x9” wheels
allowd with a 3% weight addition. GT3 cars utilizing 15”x7” wheels are limited to a maximum section width of 225 with a 25
pound weight reduction"
"All GT3U (Majors and Runoffs) cars using up to 15"x7" wheels limited to 225 section width tires shall run at current GT3 race
weight plus 225lbs. All Gt3U cars shall run a DOT approved tire with a maximum section width of 245. GT3U cars are allowed
optional 15"x9" wheels with a 1.5% weight addition or up to 18"x9" wheels with a 3.0% weight addition to the total weight

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including the 225 lbs."

STU 2.8-3.2L N/A Engine Allowances

#38007 from Ben Slechta · Rule change · TB 25-07 (2025-07 Fastrack)

In GCR, Section 9.1.4.G.1, add the following:
"A maximum section width of 245 is permitted. Cars over 3150 lbs. may run a 275 tire with a 2% weight adder."

STU 2006-2015 Mazda Miata Intake Manifold

#38422 from German Candelario Candelario · Rule change · TB 25-07 (2025-07 Fastrack)

In STU, Table A, Mazda MZR (LF, L3, L5), change Notes as follows:
"May use Goodwin Part # 61-2510 or Gato Performance Part #31972 Intake manifold . "

STU Requesting Approval of the JDM Honda h23a

#38489 from Eric Fiest · Rule change · TB 25-07 (2025-07 Fastrack)

In STU, Table B, classify Honda JDM H23a as follows:
STU Maximum Displacement (cc's) Minimum Weight Notes
Honda JDM H23a 2259 Chart Must meet all ST engine regulations.

STU STU-TCR Adjustments

#38723 from Club Racing Board · Rule change · TB 25-08 (2025-08 Fastrack)

In STU Spec Lines, Table C: STU-GT3U, GT3-TCR, change as follows: Remove the current TCR spec line and add the TCR spec lines
from GT3 that are being removed, adding the below to the notes.
"DOT approved tire with maximum section width of 245. May run DOT approved tire with maximum section width of 275 with
100 150 pound weight adder. May not run A-compound with 275. STU-TCR spitters and side valance must comply with
9.1.4.D.3.f. STU-TCR chassis ride height must comply with 9.1.4.1.A.1."

STU Lotus Weight Reduction

#38772 from Club Racing Board · Rule change · TB 25-08 (2025-08 Fastrack)

In 9.1.2. GT2/ST Spec Lines, Lotus Evora GT4, change Weight as follows:
"2750 2700"
In STU Table B: Alternate Vehicle and Engine Allowances, change Weight as follows:
Lotus Elise Cup R: "2300 2250"
Lotus Elise SC/ Lotus Exige SC: "2300 2550
2500 2450"

STU Lotus Weight Reduction E&O

#38919 from Club Racing Board · Rule change · TB 25-09 (2025-09 Fastrack)

In STU Table B: Alternate Vehicle and Engine Allowances, change Weight as follows:
Lotus Elise SC/ Lotus Exige SC: "2450 2250"

SRF Add HD Oil Cooler

#38979 from Robey Clark · Rule change · TB 25-10 (2025-10 Fastrack)

In SRF, GCR section 9.1.8.D.1.V.ff, change as follows:
"SRF3 Oil Cooler, P/N G480503 or HD Oil Cooler P/N G1148500 may be used as mounted per the GEN3 Assembly Manual. No fan
permitted for SRF. HD Oil Cooler kit P/N G1148500 may be used as mounted per the GEN3 Conversion Manual."

STU Non-Homologated Engine Swaps - Specifically K24A2 w/ Honda CRZ

#38746 from William Rori · Rule change · TB 25-09 (2025-09 Fastrack)

In STU Spec Lines, Table B: Alternate Vehicle and Engine Allowances, Honda K24, change Weight as follows:
"(Effective 11/1/2025) Chart + 2%"

STU Turbo Inlet Restrictor Table

#38961 from John Weisberg · Rule change · TB 25-12 (2025-12 Fastrack)

In GCR, Section 9.1.4.H.3, change chart as follows:

A specification table follows in the original; it is not shown here.

STU 275 Tire Rule

#38983 from Peter Federlin · Rule change · TB 25-12 (2025-12 Fastrack)

In GCR, Section 9.1.4.G.1., change as follows:
"A maximum section width of 245 is permitted. Cars over 3150 lbs. may run a 275 tire with a 2% weight adder."

STU STU Honda Engine weight penalty

#39375 from Super Touring Committee · Rule change · TB 25-12 (2025-12 Fastrack)

In STU Spec Lines, Table B: Alternate Vehicle and Engine Allowances, change Minimum Weight as follows:
Honda K20: "Chart + 2%"
Honda K24: "Chart + 2%"

STU Request for Permission on Aftermarket Turbo Kit and Intake

#39529 from John Grim · Rule change · TB 26-01 (2026-01 Fastrack)

In STU Spec Lines, Table A: Alternate Vehicle and Engine Allowances, Mazda MZR (LF, L3, L5), change Notes as follows:
"Short blocks, heads, and intakes may be freely swapped within these engine designations. May use Goodwin Part # 61-
2510 or, Gato Performance Part #31972 or Jack Spania Racing 70 mm sheet-metal aluminum Intake manifold. Must use stock
throttle body or Acura part number 16400-PND-A17."
In STU Spec Lines, Table A: Alternate Vehicle and Engine Allowances, classify Mazda MZR (LF, L3, L5) Turbo as follows:
STU Maximum Displacement (cc's) Minimum Weight Notes
Mazda MZR (LF, L3,
L5) Turbo

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Varies Chart Short blocks, heads, and intakes may be freely
swapped within these engine designations. May
use Jack Spania Racing 70 mm sheet-metal
aluminum Intake manifold. Must use stock
throttle body or Acura part number 16400-PND-
A17. Fab9 Tuning bottom-mount turbo kit
approved with one of the STU approved Turbos.

What the rules allowed changed as listed; this does not say what any particular car ran.