STU + GT2 at Buttonwillow Raceway Park

2024-03-01 GT2 Classify Corvette C8 (2020- ) into GT2/ST

#33759 from Andrew Aquilante · Rule change · TB 24-03 (2024-03 Fastrack)

In GT2 Spec Lines, classify Chevrolet Corvette C8 (20-) as follows:
GT2-ST Maximum Displacement Minimum Weight Restrictor Notes
Chevrolet Corvette C8
(20-)
6162 3300 71mm -
Flat Plate
LT2 engine.

Applies to Chevrolet Corvette on this page: Igor Lyustin

2024-03-01 GT2 Requesting classification for a 2015 Mitjet ST in GT2

#35408 from Jim Froula · Rule change · TB 24-03 (2024-03 Fastrack)

In GT2 Spec Lines, GT Cars - MITJET ST, classify MITJET ST as follows:
GT Cars – MITJET ST
Model Years Body Style Drive-
line
Wheel-
base (in)
Notes
MITJET ST 2015 RWD 94.5 Must run per VTS specifications. Must have

2024-03-01 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."

2024-03-01 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."

2024-05-01 GT2 Request for Spec Line 1010 Reconsideration

#35009 from Kristofer Olson · Rule change · TB 24-05 (2024-05 Fastrack)

In GT2-ST Spec Lines, Acura NSX, change as follows:
Minimum Weight: "2700 3000"
Restrictor: "43 45mm TIR"

2024-05-01 GT2 Request to Eliminate the FPR from the Corvette (-2013) with LS2

#35878 from Michael Quattlebaum · Rule change · TB 24-05 (2024-05 Fastrack)

In GT2-ST Spec Lines, Chevrolet Corvette (14-19), change Restrictor as follows:
"78 80mm flat plate"

2024-07-01 GT2 GT2-ST Rule Clarification

#36093 from Dominic Starkweather · Rule change · TB 24-07 (2024-07 Fastrack)

In GCR Section, Appendix K. 2012.M2, add the following:
"After market replacement differential housings are permitted as long as they are an exact equivalent."

2024-07-01 GT2 GT4 cars may run in GT2-ST

#36235 from Grand Touring Committee · Rule change · TB 24-07 (2024-07 Fastrack)

In 9.1.2. GT2 Spec Lines, GT3 Cars, change Note as follows:
"Note: All GT4 cars are permitted to compete in GT2-ST provided they use a factory supplied power stick or Pro Series
required restrictor. Must have GT4 rules in possession at all race events. Cars must comply with 2012 STO rules as
stated in Appendix K of the GCR. Engine Displacements in this table are nominal. Each competitor shall have available
definitive documentation (e.g., factory manual) of the original displacement for the engine used. Slicks allowed on all
GT2/ST cars with a 100-pound weight penalty."

2024-08-01 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"

2024-11-01 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."

2024-12-01 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."

2024-12-01 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.

2025-01-01 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."

2025-01-01 GT2 Panoz Esperante GTS BOP

#36686 from Brian Goldburg · Rule change · TB 25-01 (2025-01 Fastrack)

In GT2 SPEC LINES, GT Engines - PANOZ, classify 2013-2016 Ford EcoBoost Twin Turbo as follows:
GT Engines – PANOZ
Engine
Family
Engine Type Bore x
Stroke
(in.)
Disp.

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

2025-01-01 GT2 Correct language regarding OEM Areo Devices

#37137 from Christopher Childs · Rule change · TB 25-01 (2025-01 Fastrack)

In GCR, Section APPENDIX L. 2013 TA2 TECHNICAL REGULATIONS, B.2.c., change as follows:
"B. Aerodynamic Devices
2. Rear wing
c. The entire rear wing assembly, including the end plates and any Gurney flap, shall be mounted level
with, or below, the peak of the roof. OEM aerodynamic devices do not need to adhere to the height rule."

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

2025-01-01 GT2 GT2 Sunbeam Tiger Alternate Carburetor

#37198 from Tom Patton · Rule change · TB 25-01 (2025-01 Fastrack)

In GT2 Spec Lines, GT Engines - SUNBEAM, add to Fuel Induction as follows:
"Carburetors(s) Holly 650 cfm PN #80541-1 and PN #80541-2"

2025-01-01 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"

2025-01-01 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."

2025-02-01 GT2 GT2/ST - Remove Aftermarket/Racing ABS penalty

#36538 from Jorge A Nazario · Rule change · TB 25-02 (2025-02 Fastrack)

In GCR, Appendix K. 2012 STO Rules, O.9., change as follows:
"May run OEM ABS or convert to an aftermarket ABS controller with 100 50 lb. weight penalty."

2025-03-01 GT2 Hood Bulge allowed

#37000 from Gordon Leslie · Rule change · TB 25-03 (2025-03 Fastrack)

In GT2 Spec Lines, GT2 Cars - PONTIAC, Fiero, change as follows:
Drive-line: "FWD RWD"
Add to Notes: "Hood bulge permitted as requested for front engine relocation only."

2025-03-01 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

2025-03-01 GT2 OEM Wing Adjustment

#37590 from Christopher Childs · Rule change · TB 25-03 (2025-03 Fastrack)

In GCR, Section APPENDIX L. 2013 TA2 TECHNICAL REGULATIONS, B.2.c., change as follows:
"The entire rear wing assembly, including the end plates and any Gurney flap, shall be mounted level with, or below, the peak of
the roof. OEM aerodynamic devices do not need to adhere to the height rule."
In GCR, Section APPENDIX K. 2012 STO GENERAL TECHNICAL REGULATIONS, D.4.b., add the following:
"Factory wings, and spoilers, and roof vortex generators are permitted, but must be removed if an approved aftermarket wing is
installed. OEM aerodynamic devices do not need to adhere to the height rule."

2025-03-01 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."

2025-03-01 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."

2025-03-01 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"

2025-05-01 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."

2025-05-01 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

2025-07-01 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."

2025-07-01 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 . "

2025-07-01 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.

2025-08-01 GT2 Rear Deck Lid for Older Air-Cooled Porsche

#38506 from Justin Erion · Rule change · TB 25-08 (2025-08 Fastrack)

In GT2 Spec Lines, GT2 Cars-Porsche, 911 Coupe & Targa., add to Notes the following:
"Porsche 911-based race cars (911,963,994), the use of the 993 3.8 RSR rear deck lid/spoiler is permitted. Aftermarket
reproductions of the original Porsche Motorsports deck lid provided they faithfully replicate OEM dimensions and functionality,
are acceptable for use."

2025-08-01 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."

2025-08-01 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"

2025-09-01 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"

2025-11-01 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%"

2025-12-01 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.

2025-12-01 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."

2025-12-01 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%"

2026-01-01 GT2 Additional Body Options to Replace Older Stock Car Bodies

#39086 from Samuel Daniels · Rule change · TB 26-01 (2026-01 Fastrack)

In GCR, Section 4.8.4.2.1., add the following:
"Cars in the class must use 1997, through current year, commercially available stock car bodywork. The following make/model
bodies are allowed:
1. Cadillac CTS
2. Chevrolet Impala
3. Chevrolet Malibu
4. Chevrolet Monte Carlo
5. Chevrolet SS

2026-01-01 GT2 GT3 Turbo to GT2?

#39365 from Chris Edens · Rule change · TB 26-01 (2026-01 Fastrack)

In GT2 Spec Lines, Engines - MAZDA, classify Engine Family BP as follows:
GT2 Engines - MAZDA
Engine
Family
Engine Type Bore x Stroke
(mm)
Disp.
(CC)

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

2026-01-01 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

2026-01-01 GT2 Tech Bulletins for GT2 and GT2-ST

#39537 from Grand Touring Committee · Rule change · TB 26-01 (2026-01 Fastrack)

In GT2 Spec Lines, GT2 Cars – Porsche, classify 992.1 GT3 Cup as follows:
GT2 Cars – Porsche
Model Year Body
Style Driveline Wheel Base Notes
992.1
GT3 Cup
(22-25) 2 Dr RWD 4.0L flat six. 3250lbs. w/60mm Throttle Body Restrictor (TBR).
Cars must be prepared in accordance with the appropriate

2026-02-01 GT2 Allow Larger Air Cooled Engines in Porsche 911 GT2

#39249 from Justin Erion · Rule change · TB 26-02 (2026-02 Fastrack)

In GT Spec Lines, create GT Cars - PORSCHE and classify SC as follows:
GT Cars - PORSCHE
Model Years Body Style Drive- line Wheel- base
(in)
Notes
SC 1978 2 Dr. Rear engine/RWD 89.45 May use alternate engine bore.
4.0L 2V @2275 lbs. 4.0L 4V @ 2350 lbs.

2026-02-01 GT2 Classify T1 BMW in GT2

#39408 from Jared Lendrum · Rule change · TB 26-02 (2026-02 Fastrack)

In GT Spec Lines, classify M3 E92 in GT Cars - BMW as follows:
GT Cars - BMW
Model Years Body Style Drive-
line
Wheel-
base (in)
Notes
M3 E92 (08-13) 2 Dr. RWD 108.7 Cannot be built to any other rule set.

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