STU vs FE2 vs GTL pace at Buttonwillow Raceway Park
Quickest here:STU 1:50.913 Tony Rivera, Cal Club 2026 qualifying · FE2 1:39.265 Jon McClintock, Cal Club 2026 qualifying
STUFE2GTLsolid race · dashed qualifying · slower is lower
STUFE2GTLsolid 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, higher is quicker
Event
STU
FE2
GTL
Qual best
Race best
Trap
Qual best
Race best
Trap
vs STU
% of STU
Qual best
Race best
Trap
vs STU
% of STU
Cal Club 2026 CALCL262026-02-21
1:50.913Tony Rivera · fastest of 6 · top 5 within 14.1s-4.488s (-3.89%)
1:52.737Tony Rivera · fastest of 7 · top 5 within 7.7s-0.903s (-0.79%)
135.2Tony Rivera+21.8 mph (+19.3%)
1:39.265Jon McClintock · fastest of 3 · top 3 within 1.5s-0.093s (-0.09%)
1:40.253Jon McClintock · fastest of 3 · top 3 within 2.2s+0.541s (+0.54%)
156.6Paul Marino+29.4 mph (+23.1%)
-12.484squal -11.648s
88.9%qual 89.5%
19 rule changes (STU: 17, FE2: 2)7 weight · 3 tyres & wheels · 2 cars added · 2 induction · 1 engine · 4 wording · STU Mazda MZR (LF, L3, L5) Turbo classified; Jack Spania Racing 70 mm intake manifold and Fab9 Tuning bottom-mount turbo kit approved. · STU 36mm restrictor allows 2830 lbs (up 10 lbs from 2820); 37mm allows 2980 lbs (down 5 lbs from 2985). · STU cars over 3150 lbs lose 275-tire option with 2% weight adder. · STU Honda K20 and K24 engines lose 2% minimum weight penalty. · STU Honda K24 engine swap weight increases by 2% effective November 1, 2025. · FE and FE2 Enterprises must use bubble tail P/N WM138014; FE2 allows only this configuration. · STU Lotus Elise SC and Exige SC weight reduced from 2450 to 2250 lbs. · STU-TCR tire width increases to 275 with weight adder raised from 100 to 150 pounds. · STL/STU Lotus weight reduced: Evora GT4 to 2700 lbs, Elise Cup R to 2250 lbs, Elise/Exige SC to 2450-2550 lbs. · STU 2.8-3.2L N/A engines now allow 245 max tire width; over 3150 lbs may run 275 with 2% weight penalty. · STU Mazda MZR may use Goodwin 61-2510 or Gato Performance 31972 intake manifold. · STU Honda JDM H23a added, 2259cc displacement, minimum weight per Chart, must meet ST engine regulations. · STU wheel width rules clarified: cars ≤2,850 lbs max 8 inches, cars >2,850 lbs max 9 inches. · STU Spec Line GT3U minimum weight reduced from plus 250 to plus 225 pounds; wheel and tire options clarified with weight adjustments. · FE2 allows driver safety and comfort modifications for disabled drivers with SCCA approval, not transferable to other drivers. · STU BMW N54/N55 3.0L classified at Chart +3% minimum weight; N54 twin turbo not allowed. · STU Mini Cooper S SC supercharger pulley diameter reduced from 2.285 to 2.185. · STU Honda K20C1 Turbo I4 exempted from 3% DI weight adder in Spec Lines Table A. · STU GT3U minimum weight increases 150 to 250 pounds.showhide
STU Request for Permission on Aftermarket Turbo Kit and Intake #39529cars addedfasterSTU Mazda MZR (LF, L3, L5) Turbo classified; Jack Spania Racing 70 mm intake manifold and Fab9 Tuning bottom-mount turbo kit approved.
STU Turbo Inlet Restrictor Table #38961inductionslowerSTU 36mm restrictor allows 2830 lbs (up 10 lbs from 2820); 37mm allows 2980 lbs (down 5 lbs from 2985).
STU 275 Tire Rule #38983tyres & wheelsslowerSTU cars over 3150 lbs lose 275-tire option with 2% weight adder.
STU STU Honda Engine weight penalty #39375weightfasterSTU Honda K20 and K24 engines lose 2% minimum weight penalty.
STU Non-Homologated Engine Swaps - Specifically K24A2 w/ Honda CRZ #38746weightslowerSTU Honda K24 engine swap weight increases by 2% effective November 1, 2025.
FE2 FE & FE2 Bubble Tail #38978wordingneutralFE and FE2 Enterprises must use bubble tail P/N WM138014; FE2 allows only this configuration.
STU Lotus Weight Reduction E&O #38919weightfasterSTU Lotus Elise SC and Exige SC weight reduced from 2450 to 2250 lbs.
STU STU-TCR Adjustments #38723tyres & wheelsslowerSTU-TCR tire width increases to 275 with weight adder raised from 100 to 150 pounds.
STU Lotus Weight Reduction #38772weight -50 lbsfasterSTL/STU Lotus weight reduced: Evora GT4 to 2700 lbs, Elise Cup R to 2250 lbs, Elise/Exige SC to 2450-2550 lbs.
STU 2.8-3.2L N/A Engine Allowances #38007tyres & wheelsunclearSTU 2.8-3.2L N/A engines now allow 245 max tire width; over 3150 lbs may run 275 with 2% weight penalty.
STU 2006-2015 Mazda Miata Intake Manifold #38422wordingneutralSTU Mazda MZR may use Goodwin 61-2510 or Gato Performance 31972 intake manifold.
STU Requesting Approval of the JDM Honda h23a #38489cars addedneutralSTU Honda JDM H23a added, 2259cc displacement, minimum weight per Chart, must meet ST engine regulations.
STU Wheel Size Inconsistency #38018wordingneutralSTU wheel width rules clarified: cars ≤2,850 lbs max 8 inches, cars >2,850 lbs max 9 inches.
STU Table C: STU-GT3U Clarification #38268weightfasterSTU Spec Line GT3U minimum weight reduced from plus 250 to plus 225 pounds; wheel and tire options clarified with weight adjustments.
FE2 Driver Safety & Comfort #37965wordingneutralFE2 allows driver safety and comfort modifications for disabled drivers with SCCA approval, not transferable to other drivers.
STU BMW N54/N55 Engine Allowance Follow Up #37447engineneutralSTU BMW N54/N55 3.0L classified at Chart +3% minimum weight; N54 twin turbo not allowed.
STU STU Mini Cooper pulley size clarification re: letter #36980 #37717inductionfasterSTU Mini Cooper S SC supercharger pulley diameter reduced from 2.285 to 2.185.
STU Question About a Weight Modifier #37782weightfasterSTU Honda K20C1 Turbo I4 exempted from 3% DI weight adder in Spec Lines Table A.
STU Increase Minimum Weight #37919weight +100 lbsslowerSTU GT3U minimum weight increases 150 to 250 pounds.
Cal Club 2025 CALCL252025-02-22
1:55.401Wilson Powell · fastest of 4 · top 4 within 8.7s
1:53.640Rylan Hazelton · fastest of 5 · top 5 within 8.0s
113.3Rylan Hazelton
1:39.358Paul Marino · fastest of 4 · top 4 within 1.5s
1:39.712Paul Marino · fastest of 4 · top 4 within 1.7s
127.2Tom Hope
-13.928squal -16.043s
87.7%qual 86.1%
154 earlier rule changes on record, in force before Cal Club 2025 (from 2019)32 cars added · 17 induction · 17 weight · 13 engine · 11 aero · 4 tyres & wheels · 1 removed · 59 wording · TA2 rear wing height rule clarified: OEM aerodynamic devices exempt from peak-of-roof requirement. · STU Audi 1.8T wagon deleted; Porsche 944 1800 weight to Chart, turbo inlet restrictor removed. · STU-GT3 reclassified as STU-GT3U effective January 1, 2026. · STU GT3 TCR gains 275-width tire option with 100 lb weight penalty, but not in A compound. · STL/STU: 90-05 Mazda Miata alternate front wheel hubs moved from General to specific part approval. · STU BMW N54/N55 turbo inlet restrictors now required per GCR definition; turbo swapping prohibited. · GTL Toyota G16E-GTS removes direct injection ban wording, effective 11/1/2024. · GTL Nissan L16 limited prep gains alternate 32mm choke option at 1910 lbs minimum weight. · STU Mini Cooper S SC 1900 restricts to 2.565 diameter pulley; 2100 allows 2.285 diameter pulley. · GTL adds Toyota GR86 2021-2023, 2dr RWD, 101.3 in wheelbase. · GTL adds Spec Miata 1990-2005 with legal Spec Miata engine and intake system. · Mazda MX5 RF 2017- added to GTL with 91.0 inch wheelbase. · STU RWD turbo cars no longer required to reduce restrictor by 1 mm from table. · GTL added to GT3 choke option line for induction control. · GT2-ST Acura NSX minimum weight raised to 3000 lbs, restrictor increased to 45mm TIR. · GTL Datsun 510 L16 Limited Prep allows 34 mm chokes, minimum weight rises to 2000 lbs. · STU Mini Cooper S SC: alternate LEAP OMICRON hood scoop LEP-OMICRON3 permitted. · STU BMW S54 B32 OEM now permits dry sump oiling system. · GT1, GT2, GT3, GTL, GTX rear spoiler maximum surface area limit of 295.0 square inches removed. · GT1/GT2/GT3/GTL/GTX Direct Injection now permitted if OE, using only OE pump, hoses, injectors. · GT2/3 Nissan, Mazda, Mitsubishi 4G93, QR25DE/DD, QE25DE/DD Direct Injection now permitted per 9.1.2.F.7.5.E. · STL and STU power steering rules clarified to permit electric-assisted and hydraulic-assisted steering systems. · GTL Mazda 12A rotary engines may machine and use 13B housing to O.E. 12A specifications. · GTL Toyota GR86 (DR86, 2021-2024, 2-door RWD, 101.3-inch wheelbase) newly classified. · GTL BMW Mini years corrected to 2002-2013. · GTL small unrestricted engines under 1399cc lose 40-50 lbs across Alfa, AMC, Triumph, Mini, Sprite, Fiat, Ford, Honda, Mazda, Nissan, Subaru, Toyota, Volkswagen. · GTL Honda Fit 2009-13 2-door FWD classified with wheelbase options 94.0, 97.0, or 99.0 inches. · GTL spec lines moved to contiguous position with GT2 and GT3; GTA category and spec lines renumbered and moved behind GTL. · GTL Nissan Sentra/200SX A14 engine weight reduced from 1850 lbs to 1800 lbs. · Toyota GR Cup and GR86 Cup (2022-) newly classified in STU at 2700 lbs with 2387 cc engine. · Fields Cardinal V8 classified in GT1 with Ford V8 engine, 4.9L displacement, 2100 lbs minimum weight. · STU Mazda BP5A classified at 1839 cc maximum displacement, 2023-04-01. · STU minimum weight chart updated: 2450cc to 2595lbs, 2600cc to 2710lbs. · GTL Toyota 3K, 4K, 5K engines now permitted to use 4Y block only. · GT2 Toyota 4A-F and 4A-FE 1.6L DOHC 16V engines newly classified in spec line. · GTL Fiat 1500 Limited Prep X1/9 weight increases to 2000 lbs. · GT2 TA2 and GTA throttle body part numbers updated to GM 90mm electronic #12570790 or Edelbrock 90mm mechanical #33869 or #3870. · Ford Festiva 1988-1993 added to GTL with Mazda B3 1324cc engine. · GTL Toyota G16E-GTS 3-cylinder engine added: 1618cc, 1945 lbs, naturally aspirated with SIR fuel induction. · GT taillights may now be original style or a panel graphic with functioning red LED brake lamps; wording change only. · STU Mazda 13B Turbo classified, streetport only, stock turbos prohibited, alternatives allowed. · STU OEM louver vents now exempt from vent count and 200 square inch allowance. · STU 2400cc non-4-valve engines gain 9% base weight reduction; DI turbo prep limits removed. · STU normally-aspirated 2976–3200 cc single-throttle engines lose 10% base engine weight reduction. · ST redundant language removed from balance shaft and pulley modification rules. · STU cars that qualified for 9 inch wheels in 2021 may continue through 2022 only. · STU splitter definition clarified: must be single-plane with no vertical deviations, attached to lowest front point. · STU BMW S52B32 minimum weight drops 90 lbs to 3110; max displacement cut to 3152 cc. · STU BMW S50B32 Euro classified at 3201 cc displacement, 3300 lbs minimum weight. · ST engine swap origin country requirement changes from North America to the United States for case-by-case approval. · STU Honda CRX (84-91) and Civic Del Sol (93-97) ineligible for front wheel drive weight reductions. · STU vehicles at or over 2950 lbs base weight may use 9 inch wide wheels instead of 8.0 inch maximum. · STU minimum weights reduced: 2450cc to 2596 lbs, 2500cc to 2635 lbs, 2550cc to 2675 lbs. · Ginetta G40 classified in GTL with Ford Zetec 1796cc engine at 2050 lbs, plus 51 lbs for IRS or 26 lbs for sequential. · STU normally aspirated engines: minimum weights reduced up to 310 lbs; single throttle body weight reduction removed. · STU Audi A4 1.8T minimum weight fixed at 3050 lbs, VF30 turbo with 35mm restrictor now required only. · STL and STU Improved Touring vehicles must conform to 9.1.4 Tires & Wheels requirements. · STU engines may delete balance shafts and plug openings; alternate pulleys allowed for timing belt or chain operation only. · STU hood vents allowed to include louvers within 200 sq. inch area. · STU adds Honda K23 with 2354cc displacement and minimum weight per chart, K24 block allowed with K23 internals and head. · STU Honda K23 internals rule relaxed to require only K23 crankshaft, allowing other internal modifications. · STL and STU piston engines clarified: intake manifold and cylinder head porting remains free. · GT3 Fun Cup Beetle EVO3 classified with 1984 cc sealed SOHC engine, 2060 lbs minimum weight. · GTA part numbers updated: 0-80541-1 to 0-80541-2 in two sections and 6010 to 6014X in TA2 Appendix. · GTL Honda B18a,b vs B18c: new split classifies B18a,b at 2050 lbs, B18c at 2065 lbs. · GTL Nissan B13 Sentra allowed hood bulge maximum 1.5 inches high, 10.0 inches long, 6.0 inches wide. · GTL BMW E21 added to GT Cars - BMW classification. · STU fender flare wording clarified: exterior contour of any wheel opening may not change opening size, location or shape from side view. · STU Mazda 12A Bridge Port Miata weight reduced from 2550 lbs to 2350 lbs. · STU fender flare rules clarified: maximum 2 inches, must cover tire contact patch from above, cannot alter body configuration or wheel opening geometry. · STU Honda S2000 allows F20/F22 K24 crankshaft with chart weight for achieved displacement. · ST oil coolers and filters now explicitly allowed to be added or substituted; wording clarifies existing permissions. · GTL Mazda 12A SIR increases to 29mm, minimum weight rises to 2000 lbs. · STL/STU 90-05 Mazda Miata gains approval for Mazda Motorsports Development alternate front wheel hubs. · Fiat X-1/9 Bertone 1500 added to GTL with 2000 lbs minimum weight, SOHC, fuel induction options, Level 2 prep. · ST cars may relocate ABS actuation hardware and wiring anywhere in engine compartment. · STU Porsche PDK automatic transmission limited to 8 forward speeds instead of torque converter restriction. · STU Mazda 13B Street Port 2400 removes choke location restriction, allows auto-type 2bbl with dual-Y manifold. · STU driveshaft and half-shaft materials change from OEM-type to steel or aluminum. · GTL Nissan MRA8DE 1797cc engine classified with 2050 lbs minimum weight and 22.5mm restrictor. · GTL Mazda 13B SIR increases from 26mm to 28mm; 27mm plus 175 lbs option removed. · STU Mazda 13B Street Port classified at 2400 lbs minimum weight, replacing peripheral and bridge port variants. · ST aero devices and reference areas now include end plates but exclude fasteners protruding over 1/2 inch. · FE2 oil cooler wording clarified: optional air-to-oil cooler allowed, Setrab 50-625-7612 or equivalent max 13 inches wide by 6.5 inches high. · GT1, GT2, GT3, GTL, GTX now permit turbocharging/supercharging if listed on spec line. · STU fender flare rules reworded: up to 2" per corner allowed with 1% weight penalty total. · GTL Mazda 13B restrictor increases to 26mm SIR, minimum weight rises to 2125 lbs. · STL and STU clarify weight adjustment calculation order: engine adjustments first, then chassis adjustments. · STL and STU rear wing rules clarify that wicker is a Gurney flap; no performance change. · GTL Toyota MR2 Spyder 1999-2007 newly classified. · TA2 Gurney flap wording clarified: terminology standardized to 'Gurney flap', height limits and thickness specifications remain 0.50 inch / 0.625 inch or 0.375 inch / 0.0625 inch depending on configuration. · STO rear wing wording clarified: 'wicker' changed to 'Gurney flap' in maximum chord and mounting height rules. · GT classes clarify Gurney flap wording, replacing wickerbill/tab terminology with flap; specifications unchanged. · GTL Mazda 13B restrictor size clarification issued; refer to letter 28518 for details. · STU request for alternate intake manifold denied; no rule change issued. · GT3 and STU add Borg-Warner EFR6258 to approved turbocharger list. · STU large displacement turbo engines limited by GCR turbo list; non-turbo trim suggested as more competitive. · STU sequential shifters referred to Board of Directors for approval; no change implemented yet. · GTL stall test procedure clarified: intake system must pass SIR test as raced, no air bypass allowed. · STU Mazda 13B Bridge Port and Street Port engines added with 2550 and 2250 lbs minimum weights respectively. · GTL wing mount openings excluded from square inch limit. · STU Honda S2000 adds HKS Supercharger kits 12001-AH006 and 12001-AH010 as allowed. · STU Lotus Elise Cup R and SC models, plus Exige SC, gain 100–200 lbs minimum weight. · STU Volkswagen GTI/GLI MK5 and Jetta Mk4 may install turbo inlet restrictor in OEM turbo inlet housing. · STU Honda K20C1 Turbo I4 restrictor reduces from 36mm to 35mm. · STU GM Ecotech LNF now allowed with turbo removed or 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. · GTL wing mounting posts limited to 85 square inches exposed area each, measured flat from side view. · GTL wing mounting posts limited to 85 square inches exposed area each, measured flat from side. · GTL wing endplates change from 8.5×3.0 inch rectangle to maximum 64 square inches. · GTL Mazda 12A Street Port minimum weight reduced to 1950 lbs from 2000 lbs. · STU vehicles over 2951 lbs base weight may use 9 inch wide wheels, up from 2950 lbs. · STU turbocharged engines now use base weight instead of minimum weight, with 3% DI increase applied to base weight. · GT1, GT2, GT3, GTL, GTX may omit windshield clips if factory glass is bonded per original specifications. · Factory Five Type 65 Coupe R with Ford 302/351 or 5.0/5.2L NA added to GTX-MISC at 2600 lbs. · GTL adds Jetta Mk1 two door classification effective 2020-01-01. · FE and FE2 minimum weight increased to 1270 lbs including driver; spring options and tire warmer ban added. · GTL Honda CRX 84-87 and 88-91 remove IRS option with 2.5% weight penalty. · STU cars with manual OEM throttle bodies may convert to OEM electronic throttle body of same inner diameter. · GTL Fun Cup Beetle engine weight specified at 1850 lbs with sealed SOHC 1780cc specification. · STU wing assembly wording corrected: no part higher than roof height. · GTL Fun Cup Beetle removes reference to VW engine table; Fun Cup engine spec remains 1.8L at 2040 lbs. · GTL Honda CRZ 10-14, CRZ 15-16, and Insight 00-06 gain alternate wheelbase option of 90.6 in. · STU Nissan SR20DET removes -2mm penalty in Table B. · STU alternate intake manifolds now allowed case-by-case instead of prohibited. · STU aftermarket side skirts must meet 3-inch ride height, no openings except jacks or side exhaust, no wider than fascias, not higher than door bottom, no chassis reinforcement. · STU fender flare wording clarified: each fender may be flared up to 2" for tire clearance with 1% weight penalty. · GTL adds VW Fun Cup Beetle, all model years, 2-door RWD, 94.5-inch wheelbase. · GTX tube frame cars gain fuel injection with 90mm maximum throttle body size. · Ligier JS2 R classified in GTX, no performance parameters specified in filing. · GTL Mazda 13B may use 25mm SIR with 175 lbs weight penalty added. · STL and STU ride height measurement clarified: without driver, at rocker panel lowest point, excluding pinch weld. · GT1 and GT2/GT3/LITE ride height requirements removed from GCR sections 9.1.2.D.5.a.1 and 9.1.2.F.7.b. · STU Mazda 13B Bridge Port may use ELITE ROTARY SHOP FD V2.0 intake manifold instead of stock. · STU Mazda MZR LF/L3/L5 may use Goodwin Part #61-2510 intake manifold with stock or Acura throttle body. · STU suspension rules clarified: alternate components from same manufacturer moved from section E to section D. · STU Honda/Acura B20 classified at 1973 cc, now permits VTEC B16 or B18 cylinder head and intake manifold. · STU flared fenders up to 2" with 1% weight penalty moved from base to Advanced Aero rules. · TCA Honda Civic Si (2017-) must run 37mm TIR maximum as of June 1, 2019. · STU BMW S54B32 OEM reclassified from E46 designation, 3246 cc, 3300 lbs minimum weight. · GTL Mazda 12A may use 28mm SIR plus 175 lbs. · GTL Mustang 94-04 newly classified in GTL. · Honda Civic Si 2017- classified STU at 1500cc, 2800 lbs minimum with OEM engine and bodywork. · STU BMW E46 S54 OEM 3246cc added at 3300 lbs minimum weight, no Super Touring allowances. · STU Mazda 13B and 13B Bridge Port may use RE or REW housings and intake with turbo removed. · STU Honda K24 may use intake part #s 17100-RRB-A00 or 17100-PRB-A10. · STU Mazda 12A Bridge Port engine classified at 2550 lbs minimum weight with specified carburetor induction options. · STU World Challenge car weight calculation method removed; new basis unclear from text provided. · STU AWD cars no longer required to reduce restrictor 1 mm from table. · STU rear wing maximum cord length set to 12 inches, end plates to 72.0 square inches each. · GTL Mini 1275-1399 Iron and Aluminum Crossflow gain 75 lbs weight reduction to 125 lbs with OE common sump gearbox. · GTL BMC thru Rover Group removes long inactive Mini engines: 948, 970, 1071, 1098. · GTX FIA GT3: Audi R8 40mm restrictor 2900 lbs, BMW Z4 70mm 2800 lbs, Ferrari 488 35mm restrictor 3025 lbs classified. · STU Honda K20C1 Turbo I4 1996cc added at 3025 lbs minimum weight with 36mm TIR.showhide
GTL Correct language regarding OEM Areo Devices #37137wordingneutralTA2 rear wing height rule clarified: OEM aerodynamic devices exempt from peak-of-roof requirement.
STU Audi 1.8t Wagon STU Table B #36685cars addedfasterSTU Audi 1.8T wagon deleted; Porsche 944 1800 weight to Chart, turbo inlet restrictor removed.
STU Merger GT3 to STU #37486wordingneutralSTU-GT3 reclassified as STU-GT3U effective January 1, 2026.
STU GT3 TCR Tire allowance #37494tyres & wheelsslowerSTU GT3 TCR gains 275-width tire option with 100 lb weight penalty, but not in A compound.
STU Request to Remove Miata Hubs from General category #37138wordingneutralSTL/STU: 90-05 Mazda Miata alternate front wheel hubs moved from General to specific part approval.
STU BMW N54/N55 Engine Allowance #37146inductionslowerSTU BMW N54/N55 turbo inlet restrictors now required per GCR definition; turbo swapping prohibited.
GTL G16E-GTS Fuel Injection Spec Line Change #36588wordingunclearGTL Toyota G16E-GTS removes direct injection ban wording, effective 11/1/2024.
GTL GTL Alternate Weight and Choke Option for L16 engine #36653inductionfasterGTL Nissan L16 limited prep gains alternate 32mm choke option at 1910 lbs minimum weight.
STU R53 15% Pulley Request #36980inductionslowerSTU Mini Cooper S SC 1900 restricts to 2.565 diameter pulley; 2100 allows 2.285 diameter pulley.
GTL Request to Include Toyota GR86 in GTL #36324cars addedneutralGTL adds Toyota GR86 2021-2023, 2dr RWD, 101.3 in wheelbase.
GTL Inclusion of Modified Spec Miata for GTL competition #36325cars addedneutralGTL adds Spec Miata 1990-2005 with legal Spec Miata engine and intake system.
GTL Include Mazda MX5 RF 2017- in GTL #36428cars addedneutralMazda MX5 RF 2017- added to GTL with 91.0 inch wheelbase.
STU RWD Turbo Disadvantage #36255inductionfasterSTU RWD turbo cars no longer required to reduce restrictor by 1 mm from table.
GTL Add GTL to GT3 choke option line. #36236wordingunclearGTL added to GT3 choke option line for induction control.
GTL Request for Spec Line 1010 Reconsideration #35009weight +300 lbsslowerGT2-ST Acura NSX minimum weight raised to 3000 lbs, restrictor increased to 45mm TIR.
GTL Allow 34 mm chokes for the Datsun 510 #35661weight +50 lbsslowerGTL Datsun 510 L16 Limited Prep allows 34 mm chokes, minimum weight rises to 2000 lbs.
STU Letter #35397 addendum #35453wordingneutralSTU Mini Cooper S SC: alternate LEAP OMICRON hood scoop LEP-OMICRON3 permitted.
STU S54 Drysump #35464wordingneutralSTU BMW S54 B32 OEM now permits dry sump oiling system.
GTL Rear Blade Spoiler Clarification #35261aerofasterGT1, GT2, GT3, GTL, GTX rear spoiler maximum surface area limit of 295.0 square inches removed.
GTL GT Direct Injection allowance and rules #35437enginefasterGT1/GT2/GT3/GTL/GTX Direct Injection now permitted if OE, using only OE pump, hoses, injectors.
GTL GT2/3 remove Direction Injection not allowed in Spec line notes #35439inductionfasterGT2/3 Nissan, Mazda, Mitsubishi 4G93, QR25DE/DD, QE25DE/DD Direct Injection now permitted per 9.1.2.F.7.5.E.
STU ST Electric-Assisted Steering Systems #35066wordingneutralSTL and STU power steering rules clarified to permit electric-assisted and hydraulic-assisted steering systems.
GTL Rotary Engine 12A Rotor Housings #35131wordingneutralGTL Mazda 12A rotary engines may machine and use 13B housing to O.E. 12A specifications.
GTL Request to Include Toyota GR86 in GTL #35198cars addedneutralGTL Toyota GR86 (DR86, 2021-2024, 2-door RWD, 101.3-inch wheelbase) newly classified.
GTL Errors and Omissions, GTL engines & Cars #35226wordingneutralGTL BMW Mini years corrected to 2002-2013.
GTL Small Engines in GT Lite #34842weightfasterGTL small unrestricted engines under 1399cc lose 40-50 lbs across Alfa, AMC, Triumph, Mini, Sprite, Fiat, Ford, Honda, Mazda, Nissan, Subaru, Toyota, Volkswagen.
GTL Request to Classify Honda Fit body in GTL #35020cars addedneutralGTL Honda Fit 2009-13 2-door FWD classified with wheelbase options 94.0, 97.0, or 99.0 inches.
GTL Errors in GTCS Headings and Use of the Terms Category and ClassChange existing GTL and GTA Rules #34453wordingneutralGTL spec lines moved to contiguous position with GT2 and GT3; GTA category and spec lines renumbered and moved behind GTL.
GTL Weight for Nissan Sentra/200SX A 1400's #34918weight -50 lbsfasterGTL Nissan Sentra/200SX A14 engine weight reduced from 1850 lbs to 1800 lbs.
STU 2022 Toyota GR Cup for STU #34449cars addedneutralToyota GR Cup and GR86 Cup (2022-) newly classified in STU at 2700 lbs with 2387 cc engine.
GTL Please classify Fields Cardinal V8 #33784cars addedneutralFields Cardinal V8 classified in GT1 with Ford V8 engine, 4.9L displacement, 2100 lbs minimum weight.
STU Alternate OEM Miata Intake Manifold #33827wordingneutralSTU Mazda BP5A classified at 1839 cc maximum displacement, 2023-04-01.
STU E&O STU NA Weight Chart. #33737weightfasterSTU minimum weight chart updated: 2450cc to 2595lbs, 2600cc to 2710lbs.
GTL Toyota 4Y Engine Classification Request #33562engineneutralGTL Toyota 3K, 4K, 5K engines now permitted to use 4Y block only.
GTL Toyota 4A-F and 4A-FE 1.6L DOHC 16V Engine Request #33415cars addedneutralGT2 Toyota 4A-F and 4A-FE 1.6L DOHC 16V engines newly classified in spec line.
GTL Fiat HP Limited Prep X1/9 Weight in GTL #33297weightslowerGTL Fiat 1500 Limited Prep X1/9 weight increases to 2000 lbs.
GTL GT2 (TA2)/GTA Part Number Update #33315wordingneutralGT2 TA2 and GTA throttle body part numbers updated to GM 90mm electronic #12570790 or Edelbrock 90mm mechanical #33869 or #3870.
GTL Request to add Ford Festiva to GTL #33335cars addedneutralFord Festiva 1988-1993 added to GTL with Mazda B3 1324cc engine.
GTL Engine Request #33064cars addedneutralGTL Toyota G16E-GTS 3-cylinder engine added: 1618cc, 1945 lbs, naturally aspirated with SIR fuel induction.
GTL Tail lights on all GT category race cars. #32799wordingneutralGT taillights may now be original style or a panel graphic with functioning red LED brake lamps; wording change only.
STU Request Mazda 13 B turbo #32668cars addedneutralSTU Mazda 13B Turbo classified, streetport only, stock turbos prohibited, alternatives allowed.
STU Hood Vents and Intercooler Scoops #32733aerofasterSTU OEM louver vents now exempt from vent count and 200 square inch allowance.
STU Non 4 valve weight reduction removed #32808enginefasterSTU 2400cc non-4-valve engines gain 9% base weight reduction; DI turbo prep limits removed.
STU Error in new minimum weight table when combined with other text #32711engineslowerSTU normally-aspirated 2976–3200 cc single-throttle engines lose 10% base engine weight reduction.
STU Redundant Language in May GCR #32713wordingneutralST redundant language removed from balance shaft and pulley modification rules.
STU Opposed to the Proposed STU Weight Chart #32381wordingneutralSTU cars that qualified for 9 inch wheels in 2021 may continue through 2022 only.
STU Clarification request for GCR 9.1.4.D.3.a Splitter Definition #32414wordingneutralSTU splitter definition clarified: must be single-plane with no vertical deviations, attached to lowest front point.
STU Request Adjustment to Min Weight for STU BMW E36 M3 (95-99) #31535weight -90 lbsfasterSTU BMW S52B32 minimum weight drops 90 lbs to 3110; max displacement cut to 3152 cc.
STU BMW E36 M3 Canadian (North American) S50B32 engine #31866cars addedneutralSTU BMW S50B32 Euro classified at 3201 cc displacement, 3300 lbs minimum weight.
STU Engine Swap Origin Country #32209wordingneutralST engine swap origin country requirement changes from North America to the United States for case-by-case approval.
STU CRX/Civic Del Sol #32214weightslowerSTU Honda CRX (84-91) and Civic Del Sol (93-97) ineligible for front wheel drive weight reductions.
STU Error correction #32383tyres & wheelsfasterSTU vehicles at or over 2950 lbs base weight may use 9 inch wide wheels instead of 8.0 inch maximum.
STU Single TB Weight Modifiers Add to Chart #32393weightfasterSTU minimum weights reduced: 2450cc to 2596 lbs, 2500cc to 2635 lbs, 2550cc to 2675 lbs.
GTL Request to Classify Ginetta G40 in GTL #31599cars addedneutralGinetta G40 classified in GTL with Ford Zetec 1796cc engine at 2050 lbs, plus 51 lbs for IRS or 26 lbs for sequential.
STU Single TB Weight Modifiers #31449weightfasterSTU normally aspirated engines: minimum weights reduced up to 310 lbs; single throttle body weight reduction removed.
STU Request to Remove A4 1.8t from STU Spec Line Tables #31465weightslowerSTU Audi A4 1.8T minimum weight fixed at 3050 lbs, VF30 turbo with 35mm restrictor now required only.
STU Improved Touring Tires #32063tyres & wheelsneutralSTL and STU Improved Touring vehicles must conform to 9.1.4 Tires & Wheels requirements.
STU Request Allowance for Balance Shaft Delete in STU #31434enginefasterSTU engines may delete balance shafts and plug openings; alternate pulleys allowed for timing belt or chain operation only.
STU Request Louvers in hood vents #31916aeroneutralSTU hood vents allowed to include louvers within 200 sq. inch area.
STU Request to Add Honda K23 Spec Line #30682cars addedneutralSTU adds Honda K23 with 2354cc displacement and minimum weight per chart, K24 block allowed with K23 internals and head.
STU RE: Aug FT letter 30682 #31060enginefasterSTU Honda K23 internals rule relaxed to require only K23 crankshaft, allowing other internal modifications.
STU Throttling Device Clarification #31323wordingneutralSTL and STU piston engines clarified: intake manifold and cylinder head porting remains free.
GTL Request car classification #31032cars addedneutralGT3 Fun Cup Beetle EVO3 classified with 1984 cc sealed SOHC engine, 2060 lbs minimum weight.
GTL Request to Update GTA Obsolete Part Numbers #30615wordingneutralGTA part numbers updated: 0-80541-1 to 0-80541-2 in two sections and 6010 to 6014X in TA2 Appendix.
GTL Request clarification for the Honda B18a,bVS B18c #30482wordingneutralGTL Honda B18a,b vs B18c: new split classifies B18a,b at 2050 lbs, B18c at 2065 lbs.
GTL Request to Allow Hood Bulge on Nissan B13 Sentra #30504aeroneutralGTL Nissan B13 Sentra allowed hood bulge maximum 1.5 inches high, 10.0 inches long, 6.0 inches wide.
GTL Request BMW E21 Classing #30582cars addedneutralGTL BMW E21 added to GT Cars - BMW classification.
STU STU Fender flares #30696wordingneutralSTU fender flare wording clarified: exterior contour of any wheel opening may not change opening size, location or shape from side view.
STU Request weight reduction for 12A bridgeport motor in Miata #30751weight -200 lbsfasterSTU Mazda 12A Bridge Port Miata weight reduced from 2550 lbs to 2350 lbs.
STU Request for Fender Flare Clarification #30375wordingneutralSTU fender flare rules clarified: maximum 2 inches, must cover tire contact patch from above, cannot alter body configuration or wheel opening geometry.
STU Provision for Interchangeable Engine Components Already Allowed #30342engineunclearSTU Honda S2000 allows F20/F22 K24 crankshaft with chart weight for achieved displacement.
STU ST Oil Coolers E&O Correction to 9.1.4.2.H #30388wordingneutralST oil coolers and filters now explicitly allowed to be added or substituted; wording clarifies existing permissions.
GTL Request for Help for Mazda 12A #29754induction +50 lbsslowerGTL Mazda 12A SIR increases to 29mm, minimum weight rises to 2000 lbs.
STU Super Touring Alternate Miata Hubs #30345wordingneutralSTL/STU 90-05 Mazda Miata gains approval for Mazda Motorsports Development alternate front wheel hubs.
GTL Request LP HP Fiat X1/9 & Bertone 1500 to GTL #30058cars addedneutralFiat X-1/9 Bertone 1500 added to GTL with 2000 lbs minimum weight, SOHC, fuel induction options, Level 2 prep.
STU Brake Component Relocation #29990wordingneutralST cars may relocate ABS actuation hardware and wiring anywhere in engine compartment.
STU Porsche PDK #30081wordingneutralSTU Porsche PDK automatic transmission limited to 8 forward speeds instead of torque converter restriction.
STU Reference Letter #29333 Proposed STU 13B Spec Line Changes #30086inductionfasterSTU Mazda 13B Street Port 2400 removes choke location restriction, allows auto-type 2bbl with dual-Y manifold.
STU Drive Shaft Request #30087wordingneutralSTU driveshaft and half-shaft materials change from OEM-type to steel or aluminum.
GTL Increase 13b SIR size #29867inductionfasterGTL Mazda 13B SIR increases from 26mm to 28mm; 27mm plus 175 lbs option removed.
STU 13B Rules Adjustment #29333cars addedslowerSTU Mazda 13B Street Port classified at 2400 lbs minimum weight, replacing peripheral and bridge port variants.
STU Request clarification on wing measurement #29640aeroneutralST aero devices and reference areas now include end plates but exclude fasteners protruding over 1/2 inch.
FE2 FE/FE2 Oil Cooler #29293wordingneutralFE2 oil cooler wording clarified: optional air-to-oil cooler allowed, Setrab 50-625-7612 or equivalent max 13 inches wide by 6.5 inches high.
GTL GT Category Wording #29193wordingunclearGT1, GT2, GT3, GTL, GTX now permit turbocharging/supercharging if listed on spec line.
STU Request for Advanced Aero Rule Wording Clarification. #29124wordingneutralSTU fender flare rules reworded: up to 2" per corner allowed with 1% weight penalty total.
GTL Request to change the Mazda 13b restrictor size #28518induction +175 lbsfasterGTL Mazda 13B restrictor increases to 26mm SIR, minimum weight rises to 2125 lbs.
STU Minimum Weight Determination #27695wordingneutralSTL and STU clarify weight adjustment calculation order: engine adjustments first, then chassis adjustments.
STU ST Gurney flap Wicker clarification #29012wordingneutralSTL and STU rear wing rules clarify that wicker is a Gurney flap; no performance change.
GTL Request to classify 1999-2007 Toyota MR2 Spyder body #28870cars addedneutralGTL Toyota MR2 Spyder 1999-2007 newly classified.
GTL TA2 Gurney flap wicker clarification #28874wordingneutralTA2 Gurney flap wording clarified: terminology standardized to 'Gurney flap', height limits and thickness specifications remain 0.50 inch / 0.625 inch or 0.375 inch / 0.0625 inch depending on configuration.
GTL STO Gurney flap wicker clarification #28883wordingneutralSTO rear wing wording clarified: 'wicker' changed to 'Gurney flap' in maximum chord and mounting height rules.
GTL Mazda 13b Restrictor Size Follow up to Letter 28518 #29015wordingunclearGTL Mazda 13B restrictor size clarification issued; refer to letter 28518 for details.
STU Request for Alternate Intake Manifold #26514wordingneutralSTU request for alternate intake manifold denied; no rule change issued.
STU Request for Addition to GT3 Approved Turbo List #27576wordingneutralGT3 and STU add Borg-Warner EFR6258 to approved turbocharger list.
STU Request BoP for my Car #29004wordingneutralSTU large displacement turbo engines limited by GCR turbo list; non-turbo trim suggested as more competitive.
STU Sequential Shifters in STU #29031wordingneutralSTU sequential shifters referred to Board of Directors for approval; no change implemented yet.
GTL Stall Test #28709wordingneutralGTL stall test procedure clarified: intake system must pass SIR test as raced, no air bypass allowed.
STU Rotary Help #27833cars addedneutralSTU Mazda 13B Bridge Port and Street Port engines added with 2550 and 2250 lbs minimum weights respectively.
GTL GTL Wing Rule #28754aeroneutralGTL wing mount openings excluded from square inch limit.
STU Request to approve Honda S2000 HKS supercharger #27281enginefasterSTU Honda S2000 adds HKS Supercharger kits 12001-AH006 and 12001-AH010 as allowed.
STU Request BoP on the Lotus #27637weight +100 lbsslowerSTU Lotus Elise Cup R and SC models, plus Exige SC, gain 100–200 lbs minimum weight.
STU Turbo Inlet Restrictor On MK5 Volkswagen #27704inductionslowerSTU Volkswagen GTI/GLI MK5 and Jetta Mk4 may install turbo inlet restrictor in OEM turbo inlet housing.
STU Honda K20C1 removal #27732inductionslowerSTU 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 #27884engineslowerSTU GM Ecotech LNF now allowed with turbo removed or with LE5 head and intake manifold, meeting STL specs.
STU Alternate Engine for Porsche 944 #28259engineunclearSTU Porsche 944 now permits VW/Audi 1.8L and 2.0L turbo engines as alternates.
GTL Wing Mounting Upright Size #27641aeroneutralGTL wing mounting posts limited to 85 square inches exposed area each, measured flat from side view.
GTL Wing Mounting Upright Size #27641aeroneutralGTL wing mounting posts limited to 85 square inches exposed area each, measured flat from side.
GTL GTL wing end plates addition #28243aerofasterGTL wing endplates change from 8.5×3.0 inch rectangle to maximum 64 square inches.
GTL Clarification to letter #27406 #28309weight -50 lbsfasterGTL Mazda 12A Street Port minimum weight reduced to 1950 lbs from 2000 lbs.
STU Please Modify the STU Wheel Size Rule for Clarity #27694weightfasterSTU vehicles over 2951 lbs base weight may use 9 inch wide wheels, up from 2950 lbs.
STU Turbo Engine Cars Base Weight #28032wordingneutralSTU turbocharged engines now use base weight instead of minimum weight, with 3% DI increase applied to base weight.
GTL Windshield Clips #27323wordingneutralGT1, GT2, GT3, GTL, GTX may omit windshield clips if factory glass is bonded per original specifications.
GTL Request Factory Five Daytona coupe classification #26308cars addedneutralFactory Five Type 65 Coupe R with Ford 302/351 or 5.0/5.2L NA added to GTX-MISC at 2600 lbs.
GTL Request to Classify the MK1 two door Jetta #27648cars addedneutralGTL adds Jetta Mk1 two door classification effective 2020-01-01.
FE2 FE / FE2 Update Rules #27624weightslowerFE and FE2 minimum weight increased to 1270 lbs including driver; spring options and tire warmer ban added.
GTL 88-91 Honda CRX Spec Line Correction #27233wordingneutralGTL Honda CRX 84-87 and 88-91 remove IRS option with 2.5% weight penalty.
STU Request for an electronic throttle body #27342wordingneutralSTU cars with manual OEM throttle bodies may convert to OEM electronic throttle body of same inner diameter.
GTL Fun Cup Beetle #27334wordingneutralGTL Fun Cup Beetle engine weight specified at 1850 lbs with sealed SOHC 1780cc specification.
STU Request to correct E&O advanced aerodynamics #27290wordingneutralSTU wing assembly wording corrected: no part higher than roof height.
GTL GTL #26960wordingneutralGTL Fun Cup Beetle removes reference to VW engine table; Fun Cup engine spec remains 1.8L at 2040 lbs.
GTL Request CRZ wheelbase change #26896wordingunclearGTL Honda CRZ 10-14, CRZ 15-16, and Insight 00-06 gain alternate wheelbase option of 90.6 in.
STU Remove -2mm penalty from SR20DET Nissan #26982enginefasterSTU Nissan SR20DET removes -2mm penalty in Table B.
STU Request clarification for manifold and throttle in STU #27004inductionfasterSTU alternate intake manifolds now allowed case-by-case instead of prohibited.
STU Request to clarify afterrmarket side skirts exhaust exit #26814wordingneutralSTU aftermarket side skirts must meet 3-inch ride height, no openings except jacks or side exhaust, no wider than fascias, not higher than door bottom, no chassis reinforcement.
STU Wheel Flare wording #26872wordingneutralSTU fender flare wording clarified: each fender may be flared up to 2" for tire clearance with 1% weight penalty.
GTL Request to Classify VW Fun Cup Beetle #25986cars addedneutralGTL adds VW Fun Cup Beetle, all model years, 2-door RWD, 94.5-inch wheelbase.
GTL Request GTX Fuel injection for previous GT-1 tube frame cars #26141inductionfasterGTX tube frame cars gain fuel injection with 90mm maximum throttle body size.
GTL Request to Classify Ligier JS2 R #26535cars addedneutralLigier JS2 R classified in GTX, no performance parameters specified in filing.
GTL Request for GTL Mazda 13B SIR Increase with Penalty #26572engineslowerGTL Mazda 13B may use 25mm SIR with 175 lbs weight penalty added.
STU Request Ride Height Clarification #26597wordingneutralSTL and STU ride height measurement clarified: without driver, at rocker panel lowest point, excluding pinch weld.
GTL Request Ride Height Clarification #26600wordingneutralGT1 and GT2/GT3/LITE ride height requirements removed from GCR sections 9.1.2.D.5.a.1 and 9.1.2.F.7.b.
STU Request to Use Japanese Mazda 13b Intake Manifold #25790inductionfasterSTU Mazda 13B Bridge Port may use ELITE ROTARY SHOP FD V2.0 intake manifold instead of stock.
STU Request Alternate Intake for Mazda MZR In a Rear Wheel Drive App. #26352inductionunclearSTU Mazda MZR LF/L3/L5 may use Goodwin Part #61-2510 intake manifold with stock or Acura throttle body.
STU E&O Suspension #26424wordingneutralSTU suspension rules clarified: alternate components from same manufacturer moved from section E to section D.
STU Revisit B20 VTEC #26530enginefasterSTU Honda/Acura B20 classified at 1973 cc, now permits VTEC B16 or B18 cylinder head and intake manifold.
STU Move Flared Fenders to STU Advanced Aero #26564aeroneutralSTU flared fenders up to 2" with 1% weight penalty moved from base to Advanced Aero rules.
STU TCA Civic SI E&O #26606tyres & wheelsslowerTCA Honda Civic Si (2017-) must run 37mm TIR maximum as of June 1, 2019.
STU S54 Spec line #26620wordingneutralSTU BMW S54B32 OEM reclassified from E46 designation, 3246 cc, 3300 lbs minimum weight.
GTL Request Mazda 12a Rotary SIR Increase #26081inductionfasterGTL Mazda 12A may use 28mm SIR plus 175 lbs.
GTL Request to Classify Mustang 2 Body in GTL #26222cars addedneutralGTL Mustang 94-04 newly classified in GTL.
STU Request to Class Assignment for 2017 Civic #24287cars addedneutralHonda Civic Si 2017- classified STU at 1500cc, 2800 lbs minimum with OEM engine and bodywork.
STU Request to run E46 3246cc in STU #25126cars addedneutralSTU BMW E46 S54 OEM 3246cc added at 3300 lbs minimum weight, no Super Touring allowances.
STU Engine Classification for Rotary #25564wordingunclearSTU Mazda 13B and 13B Bridge Port may use RE or REW housings and intake with turbo removed.
STU K24/K20 Head Swap Clarification/Amendment #25899wordingneutralSTU Honda K24 may use intake part #s 17100-RRB-A00 or 17100-PRB-A10.
STU Request to Classify 12a Bridge Ported Rotary Engine #25985cars addedneutralSTU Mazda 12A Bridge Port engine classified at 2550 lbs minimum weight with specified carburetor induction options.
STU World Challenge Car Eligibility #26387wordingunclearSTU World Challenge car weight calculation method removed; new basis unclear from text provided.
STU Request a phone call for discussion regarding weight #26398inductionfasterSTU AWD cars no longer required to reduce restrictor 1 mm from table.
STU Advanced Aero E&O #26413aeroneutralSTU rear wing maximum cord length set to 12 inches, end plates to 72.0 square inches each.
GTL Request for GTL Mini Adjustments #25754weightfasterGTL Mini 1275-1399 Iron and Aluminum Crossflow gain 75 lbs weight reduction to 125 lbs with OE common sump gearbox.
GTL BMC thru Rover Group remove long inactive mini #25771removedneutralGTL BMC thru Rover Group removes long inactive Mini engines: 948, 970, 1071, 1098.
GTL GTX Homologation table update #26034cars addedneutralGTX FIA GT3: Audi R8 40mm restrictor 2900 lbs, BMW Z4 70mm 2800 lbs, Ferrari 488 35mm restrictor 3025 lbs classified.
STU Request to Equalize Direct Injected Turbo Cars #24890cars addedneutralSTU Honda K20C1 Turbo I4 1996cc added at 3025 lbs minimum weight with 36mm TIR.
Best is the class's fastest lap in that event's qualifying or race sessions, with the driver who set it, how many cars set a time that session and how close the top five were; a best from fewer than three cars is greyed. With two or more classes, "vs" is the gap of each class's best to the first class's at the same event. "% of STU" is the class's best as a share of STU's best at the same event (100% is level, less is quicker): weather and track condition move every class together, so this compares across years where the raw times do not. It still breaks when STU's own field changes or one session was wet and another dry. Newest event first. The coloured figure under each value is the change from the previous event that has one (green is quicker, red slower). Whole laps only, so events with different sector layouts still compare. Weather and track condition are not accounted for.