Lap times across years say as much about the weather as the class. % of STL is each class's best lap as a share of STL'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.
Quickest here:STL 1:35.439 John Schmitt, Runoffs 2016 qualifying · SM 1:40.514 Justin Hille, Runoffs 2016 qualifying · GT2 1:25.405 Andrew Aquilante, Runoffs 2016 qualifying · AS 1:30.651 Tom Sloe, Runoffs 2016 qualifying
STLSMGT2ASsolid race · dashed qualifying · slower is lower
STLSMGT2ASsolid race · dashed qualifying · each class's best lap as a share of STL's at the same event (the reference class, changeable above); 100% is level, less is quicker, so up the chart is quicker
2:30.537Derek Ketchie · fastest of 16 · top 5 within 2.9s-1.528s (-1.00%)
2:30.657Danny Steyn · fastest of 16 · top 5 within 0.6s-1.470s (-0.97%)
134.8Mike Taylor+2.6 mph (+2.0%)
2:42.173Brett Kowalski · fastest of 34 · top 5 within 0.3s-0.938s (-0.58%)
2:42.725Francisco Barroso · fastest of 35 · top 5 within 0.2s-1.705s (-1.04%)
119.6Wyatt Couch+0.3 mph (+0.3%)
+12.068squal +11.636s
108.0%qual 107.7%
2:09.634John Atwell · fastest of 18 · top 5 within 4.3s-2.173s (-1.65%)
2:10.650John Atwell · fastest of 18 · top 5 within 4.1s-2.797s (-2.10%)
163.0Jack Stanford-0.3 mph (-0.2%)
-20.007squal -20.903s
86.7%qual 86.1%
2:26.911Andrew McDermid · fastest of 8 · top 5 within 3.4s+0.119s (+0.08%)
2:28.471Andrew McDermid · fastest of 8 · top 5 within 2.4s-0.761s (-0.51%)
151.0Andrew McDermid-0.6 mph (-0.4%)
-2.186squal -3.626s
98.5%qual 97.6%
32 rule changes (STL: 4, SM: 2, GT2: 13, AS: 13)11 cars added · 4 weight · 2 engine · 1 induction · 1 suspension & brakes · 1 tyres & wheels · 7 wording · 5 other · AS Camaro 16+ Spec Line: 1LE front splitter kit permitted, belt tensioner and motor mount parts allowed, spark plug position defined. · AS class adds Pirelli P Zero Trofeo Track as permitted tyre option for competition. · AS class rear trailing arms no longer required to maintain stock length, only to locate rear axle. · AS Ford Mustang GT 4.6L 4-valve regains allowance, minimum weight 3200 lbs. · AS Ford Mustang Coupe GT 05-14 Gen3 Coyote minimum weight increases from 3100 to 3400 lbs. · SM/SMX Mazda rear toe link part number revised from 0000-04-5361426 to 0000-04-5361. · STL removes Mazda MX-5 Cup entirely; renames Spec MX5 Challenge to Spec MX5; renames Global Cup to MX-5 Cup (16-18); removes Global Cup (2019). · AS GM LM7 5.3L must use full prep Holley carburetor as described in 9.1.6.D.c.1, not specifically 4776. · STL, STU weight calculation procedure clarified: positive percentages added first, negative subtracted second, then fixed weights applied. · GT2 Panoz Esperante GTS spec simplified to standard GT2 rules unless noted; detailed suspension, brake, aero specs removed. · TA2 shock absorbers rise to $1005, rear calipers to $585, brake pads to $330 per axle; wheels drop to $165. · GT2 Porsche 991.1 GT3 Cup now permits modifications from Grand Am, IMSA Cup, World Challenge rules; factory Lexan windows and ABS allowed. · AS EFI engine build sheets add dry sump, header, camshaft, and timing chain tensioner options for LS, LT1, Ford, and Mopar engines. · AS LT1 Camaro engine build sheet added with full specs; LT1 weight 3200 lbs, GTO tire to 275, Mustang weight to 3525 lbs, oil catch tanks now required. · GT2-ST Corvette C7 L76 minimum weight drops 100 lbs to 3000, restrictor rises to 83 mm FPR. · GT2 Porsche 997.2 GT3 Cup removes permission for Lexan front windows and clarifies ABS allowance status. · SM/SMX part number 0000-10-6900 replaced with 0000-06-5016-KT in GCR 9.1.7.C.1.j.1.c. · STL adds Mazda BP 1.6, 1600cc, minimum weight 2160 lbs. · AS Spec Lines reorganized for 2026; detailed chassis, engine, weight, wheelbase, tire and brake specifications moved to main rules and engine build sheets. · Ginetta G56 GT4 (V8) added to GT2 with GM LS V8, 6.2L, 72mm restrictor, 3300 lbs. · GT3U class removed from GCR; GT3U cars now compete in STU. · GT2 Audi R8 GT4 removes requirement to carry GT4 rules at events, directs to GT2-ST header note. · AS GM LM7 5.3L gains Edelbrock 71187 intake manifold, MSD 6014 ignition box, Holly 4776 carb option under full prep spec line. · GT2 Porsche 911 SC gains 4.0L air-cooled engine option at 2275 or 2350 lbs depending on valve count. · M3 E92 classified in GT2 with 3999cc V8, 35mm restrictor, 3300 lb minimum weight. · AS Ford Mustang and Mercury Capri with Restricted Prep engines get 61 mm restrictor, down from 64 mm. · GT2 adds Cadillac CTS, Chevrolet Impala/Malibu/Monte Carlo/SS, Dodge Intrepid, Ford Fusion/Taurus, Lincoln MKS, Pontiac G8/GTO/Grand Prix, Toyota Camry, and Gen late Model Stock Car bodies Camaro/Mustang/Camry. · GT2 Mazda BP 1839cc DOHC classified with 2250 lbs minimum weight, 46mm restrictor, EFR6258 or EFR7163 turbo allowed. · STL minimum weights increase across all engine sizes, 1300cc to 1850cc up to 195–250 lbs. · AS Ford Mustang GT 94-04 Restricted Prep Engine now permits Ford Motorsport M-6250-F303 camshaft. · AS Cadillac CTS-V 04-07 Restricted Prep minimum weight drops to 3400 lbs.showhide
AS 2016+ Camaro Spec Line Full Prep #39646otheraddedAS Camaro 16+ Spec Line: 1LE front splitter kit permitted, belt tensioner and motor mount parts allowed, spark plug position defined.
AS Consideration of Pirelli P Zero Trofeo Track for AS Competition #40495tyres & wheelsadded · tyres & wheelsAS class adds Pirelli P Zero Trofeo Track as permitted tyre option for competition.
AS Change in 9.1.6.D.4.d.5 in Suspension Mounting Points #40094suspension & brakesfaster · suspension & brakesAS class rear trailing arms no longer required to maintain stock length, only to locate rear axle.
AS Re-Add 4.6L 4v 96-04 Mustang Cobra #40239cars addedaddedAS Ford Mustang GT 4.6L 4-valve regains allowance, minimum weight 3200 lbs.
AS Errors and Omissions #40532weightslower · weightAS Ford Mustang Coupe GT 05-14 Gen3 Coyote minimum weight increases from 3100 to 3400 lbs.
SM Rear Toe Link #40271wordingwordingSM/SMX Mazda rear toe link part number revised from 0000-04-5361426 to 0000-04-5361.
STL Spec Line Clean Up #40344cars addedremoved · cars addedSTL removes Mazda MX-5 Cup entirely; renames Spec MX5 Challenge to Spec MX5; renames Global Cup to MX-5 Cup (16-18); removes Global Cup (2019).
AS Clarification for LM7 Holley Carburetor #40167wordingwordingAS GM LM7 5.3L must use full prep Holley carburetor as described in 9.1.6.D.c.1, not specifically 4776.
STL Calculating Weight #40224wordingwordingSTL, STU weight calculation procedure clarified: positive percentages added first, negative subtracted second, then fixed weights applied.
GT2 Panoz Esperante GTS Letter ID Number: #38494 - Additional Info #38584wordingunclearGT2 Panoz Esperante GTS spec simplified to standard GT2 rules unless noted; detailed suspension, brake, aero specs removed.
GT2 Appendix L Update #39923otherotherTA2 shock absorbers rise to $1005, rear calipers to $585, brake pads to $330 per axle; wheels drop to $165.
GT2 GT2 Porsche 997.2 GT3 Cup EDIT #40125otheraddedGT2 Porsche 991.1 GT3 Cup now permits modifications from Grand Am, IMSA Cup, World Challenge rules; factory Lexan windows and ABS allowed.
AS Header Information Update for EFI Engine Build Sheets #39886engineadded · engineAS EFI engine build sheets add dry sump, header, camshaft, and timing chain tensioner options for LS, LT1, Ford, and Mopar engines.
AS Errors and Omissions #39933otherfasterAS LT1 Camaro engine build sheet added with full specs; LT1 weight 3200 lbs, GTO tire to 275, Mustang weight to 3525 lbs, oil catch tanks now required.
GT2 Corvette C7 (14-19) L76 Specline Errors/Missing Changes #39838weight -100 lbsfaster · weightGT2-ST Corvette C7 L76 minimum weight drops 100 lbs to 3000, restrictor rises to 83 mm FPR.
GT2 GT2 Porsche 997.2 GT3 Cup #39936wordingwordingGT2 Porsche 997.2 GT3 Cup removes permission for Lexan front windows and clarifies ABS allowance status.
SM 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.
AS Re-Organization of AS Spec lines for 2026 #39887wordingwordingAS Spec Lines reorganized for 2026; detailed chassis, engine, weight, wheelbase, tire and brake specifications moved to main rules and engine build sheets.
GT2 Classification Request - Ginetta G56 GT4 (V8) #39625cars addedaddedGinetta G56 GT4 (V8) added to GT2 with GM LS V8, 6.2L, 72mm restrictor, 3300 lbs.
GT2 Remove GT3U from GCR as it is now in STU #39862cars addedremoved · cars addedGT3U class removed from GCR; GT3U cars now compete in STU.
GT2 Audi R8 GT4 remove spec line notes #39864wordingwordingGT2 Audi R8 GT4 removes requirement to carry GT4 rules at events, directs to GT2-ST header note.
AS Edelbrock manifold (& timing kit) to Chevy LS Spec Lines Request #39055cars addedaddedAS GM LM7 5.3L gains Edelbrock 71187 intake manifold, MSD 6014 ignition box, Holly 4776 carb option under full prep spec line.
GT2 Allow Larger Air Cooled Engines in Porsche 911 GT2 #39249cars addedaddedGT2 Porsche 911 SC gains 4.0L air-cooled engine option at 2275 or 2350 lbs depending on valve count.
GT2 Classify T1 BMW in GT2 #39408cars addedaddedM3 E92 classified in GT2 with 3999cc V8, 35mm restrictor, 3300 lb minimum weight.
AS Restrictor Plate Change for Gen 2 Ford Coyote Engine #39501inductionslower · inductionAS Ford Mustang and Mercury Capri with Restricted Prep engines get 61 mm restrictor, down from 64 mm.
GT2 Additional Body Options to Replace Older Stock Car Bodies #39086cars addedaddedGT2 adds Cadillac CTS, Chevrolet Impala/Malibu/Monte Carlo/SS, Dodge Intrepid, Ford Fusion/Taurus, Lincoln MKS, Pontiac G8/GTO/Grand Prix, Toyota Camry, and Gen late Model Stock Car bodies Camaro/Mustang/Camry.
GT2 GT3 Turbo to GT2? #39365cars addedaddedGT2 Mazda BP 1839cc DOHC classified with 2250 lbs minimum weight, 46mm restrictor, EFR6258 or EFR7163 turbo allowed.
GT2 Tech Bulletins for GT2 and GT2-ST #39537cars added -100 lbs
STL Weight adjustment for STL #39579weightslower · weightSTL minimum weights increase across all engine sizes, 1300cc to 1850cc up to 195–250 lbs.
AS 1994 Mustang Spec Line Request #39104engineadded · engineAS Ford Mustang GT 94-04 Restricted Prep Engine now permits Ford Motorsport M-6250-F303 camshaft.
2:32.065Jose Osiris Pena · fastest of 14 · top 5 within 3.4s+2.002s (+1.33%)
2:32.127Jose Osiris Pena · fastest of 13 · top 5 within 2.4s+1.882s (+1.25%)
132.2Jon Sewell-2.1 mph (-1.5%)
2:43.111Bobby Gossett · fastest of 32 · top 5 within 0.3s+2.005s (+1.24%)
2:44.430Kyle Greenhill · fastest of 28 · top 5 within 0.3s+2.944s (+1.82%)
119.3Francisco Barroso-0.6 mph (-0.5%)
+12.303squal +11.046s
108.1%qual 107.3%
2:11.807Brad McAllister · fastest of 16 · top 5 within 3.4s-0.053s (-0.04%)
2:13.447John Atwell · fastest of 13 · top 5 within 3.6s+0.136s (+0.10%)
163.3Charlie Peter-1.0 mph (-0.6%)
-18.680squal -20.258s
87.7%qual 86.7%
2:26.792Andrew McDermid · fastest of 11 · top 5 within 3.9s+0.214s (+0.15%)
2:29.232Gregory Eaton · fastest of 10 · top 5 within 4.0s+2.803s (+1.91%)
151.5Andrew McDermid+1.9 mph (+1.3%)
-2.895squal -5.273s
98.1%qual 96.5%
25 rule changes (STL: 3, SM: 4, GT2: 7, AS: 11)3 cars added · 3 engine · 3 weight · 2 aero · 2 induction · 9 wording · 3 other · GT2 Porsche 911, 963, 994 may use 993 3.8 RSR rear deck lid or faithful aftermarket reproductions. · Lotus Evora GT4 minimum weight drops to 2700 lbs; Elise Cup R to 2250 lbs; Elise SC and Exige SC to 2450–2550 lbs. · AS Ford Mustang GT 5.0 2018- minimum weight reduced to 3525 lbs. · AS Ford Mustang GT 05-14 Restricted Prep Engine gains additional gear ratio option: 3.66, 2.43, 1.69, 1.32, 1.00, .65. · 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. · AS Ford Mustang GT 5.0L 15-17 flat plate restrictor reduces from 67mm to 64mm. · AS LS1/LS6 intakes added for 5.3L truck engine: part numbers 12561269 and 88894095. · SM tire marking rules clarified: one Hoosier SM 7.5 P205/50/ZR17 set per Super Tour weekend, impound after first dry session, damaged tires may be replaced with used tires only. · STL Mazda MX5 Challenge minimum weight now references GCR 9.1.7.1; mandatory component spec list removed, alternative tires only allowed. · AS Flotek head value seat cutting dimensions figure updated for consistency. · AS class notes cleaned: fuel cell and ECM specifications removed from multiple Camaro, Firebird, Challenger and Mustang variants. · AS removes 'Any ECM maybe used' note from five Cadillac and Chevrolet/Pontiac V8 Restricted Prep models. · GT2 Pontiac Fiero drivetrain changed to RWD and hood bulge permitted for front engine relocation. · TA2 OEM wing height rule exemption removed; STO permits factory aero but bans it with aftermarket wings. · GT2 STO aftermarket ABS weight penalty reduced from 100 lbs to 50 lbs. · AS Ford Mustang and Cobra Coyote engine restrictor increases to 80mm from 67mm or 64mm. · AS Mustang GT 05-14 Restricted loses 300 lbs engine; 15-17 and 2018+ models lose 61mm and 60mm restrictors respectively. · AS class: multiple American muscle cars gain additional allowed gear ratio options across model years and prep levels. · AS LS-engine cars gain ECU freedom: CTS-V, Camaro, Firebird (70–02) and Camaro SS may use any ECM. · GT2 Panoz Esperante GTS adds 2013-2016 Ford EcoBoost Twin Turbo V-6, 3496 cc, 2600 lbs, twin turbo induction. · TA2 rear wing height rule clarified: OEM aerodynamic devices exempt from peak-of-roof height limit. · GT2 Sunbeam Tiger gains Holly 650 cfm carburetors PN #80541-1 and PN #80541-2 as alternate options. · 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. · STL STU Mazda Miata alternate front hubs Mazda Motorsports Development Part #0000-04-5HUB-S1 approved.showhide
GT2 Rear Deck Lid for Older Air-Cooled Porsche #38506aeroadded · aeroGT2 Porsche 911, 963, 994 may use 993 3.8 RSR rear deck lid or faithful aftermarket reproductions.
STL Lotus Weight Reduction #38772weight -50 lbsfaster · weightLotus Evora GT4 minimum weight drops to 2700 lbs; Elise Cup R to 2250 lbs; Elise SC and Exige SC to 2450–2550 lbs.
AS RE: Previous Letter 37695 Update #38245weight -75 lbsfaster · weightAS Ford Mustang GT 5.0 2018- minimum weight reduced to 3525 lbs.
AS Errors and Omissions #38234otheraddedAS Ford Mustang GT 05-14 Restricted Prep Engine gains additional gear ratio option: 3.66, 2.43, 1.69, 1.32, 1.00, .65.
SM SMX Data Submission - Penalties #38248otheraddedSMX drivers must submit data acquisition files on time or face suspension and $250 fine.
SM 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.
AS Errors and Omission #38055inductionslower · inductionAS Ford Mustang GT 5.0L 15-17 flat plate restrictor reduces from 67mm to 64mm.
AS Request to Add LS1/LS6 Intakes for 5.3L Truck Engine EnO #38197cars addedaddedAS LS1/LS6 intakes added for 5.3L truck engine: part numbers 12561269 and 88894095.
SM Clarify Tire Marking Regs #38005wordingwordingSM tire marking rules clarified: one Hoosier SM 7.5 P205/50/ZR17 set per Super Tour weekend, impound after first dry session, damaged tires may be replaced with used tires only.
STL E&O: SMX Allowance in STL #37945wordingunclearSTL Mazda MX5 Challenge minimum weight now references GCR 9.1.7.1; mandatory component spec list removed, alternative tires only allowed.
AS Flotek Head Plunge Cut Inconsistencies #37502wordingwordingAS Flotek head value seat cutting dimensions figure updated for consistency.
AS Notes clean up #37693wordingwordingAS class notes cleaned: fuel cell and ECM specifications removed from multiple Camaro, Firebird, Challenger and Mustang variants.
AS Race memo #37902wordingwordingAS removes 'Any ECM maybe used' note from five Cadillac and Chevrolet/Pontiac V8 Restricted Prep models.
GT2 Hood Bulge allowed #37000wordingwordingGT2 Pontiac Fiero drivetrain changed to RWD and hood bulge permitted for front engine relocation.
GT2 OEM Wing Adjustment #37590aeroaeroTA2 OEM wing height rule exemption removed; STO permits factory aero but bans it with aftermarket wings.
GT2 GT2/ST - Remove Aftermarket/Racing ABS penalty #36538weightfaster · weightGT2 STO aftermarket ABS weight penalty reduced from 100 lbs to 50 lbs.
AS Increase Coyote Engine Restrictor to 80mm #36177enginefaster · engineAS Ford Mustang and Cobra Coyote engine restrictor increases to 80mm from 67mm or 64mm.
AS Performance Pack for 2015+ Mustang #36867enginefaster · engineAS Mustang GT 05-14 Restricted loses 300 lbs engine; 15-17 and 2018+ models lose 61mm and 60mm restrictors respectively.
AS Gear Ratios #37131otheraddedAS class: multiple American muscle cars gain additional allowed gear ratio options across model years and prep levels.
AS ECU specs for LS engine #37208engineadded · engineAS LS-engine cars gain ECU freedom: CTS-V, Camaro, Firebird (70–02) and Camaro SS may use any ECM.
SM 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.
STL Request to Remove Miata Hubs from General category #37138cars addedaddedSTL STU Mazda Miata alternate front hubs Mazda Motorsports Development Part #0000-04-5HUB-S1 approved.
2:30.063Joe Moser · fastest of 18 · top 5 within 3.7s-1.357s (-0.90%)
2:30.245Joe Moser · fastest of 16 · top 5 within 4.2s-1.870s (-1.23%)
134.3Joe Moser+1.3 mph (+1.0%)
2:41.106Ethan Goulart · fastest of 49 · top 5 within 0.5s-1.103s (-0.68%)
2:41.486Brett Kowalski · fastest of 43 · top 5 within 0.3s-2.262s (-1.38%)
119.9Alex Bertagnoli-1.4 mph (-1.2%)
+11.241squal +11.043s
107.5%qual 107.4%
2:11.860Charlie Peter · fastest of 23 · top 5 within 1.1s-0.438s (-0.33%)
2:13.311John Atwell · fastest of 23 · top 5 within 0.9s-0.968s (-0.72%)
164.3Jonathan Start+2.1 mph (+1.3%)
-16.934squal -18.203s
88.7%qual 87.9%
2:26.578Gregory Eaton · fastest of 18 · top 5 within 2.6s-0.467s (-0.32%)
2:26.429Gregory Eaton · fastest of 18 · top 5 within 2.5s-1.239s (-0.84%)
149.6Gregory Eaton+0.4 mph (+0.3%)
-3.816squal -3.485s
97.5%qual 97.7%
32 rule changes (STL: 4, SM: 4, GT2: 13, AS: 11)8 cars added · 8 engine · 4 weight · 2 aero · 1 tyres & wheels · 3 wording · 6 other · AS Mustang GT 05-14 Restricted Prep and 2018- gain alternate transmission ratio options. · 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. · GT2-ST: aftermarket replacement differential housings permitted if exact equivalent. · GT4 cars now permitted in GT2-ST with factory power stick or Pro Series restrictor, 100-pound weight penalty for slicks. · AS adds 2018-23 Ford Mustang GT 5.0L at 3600 lbs, 275 tire, 60mm restrictor, optional Brembo front brakes. · AS Chevrolet Camaro 1LE (2016-) added with 3600 lbs minimum weight, 275 tires, 60mm restrictor, 345/338mm brakes. · AS Chevrolet/Pontiac Camaro & Firebird 82–92 5.7L LS1 classified: 3200 lbs, 13.1×1.27 disc brakes, 17 in max wheel, 65 mm restrictor, SLP intake lid permitted. · AS Chevrolet Camaro, Firebird, and Ford Mustang now permit Flo Tek cylinder heads in multiple generations. · GT2-ST Acura NSX minimum weight rises to 3000 lbs, restrictor increases to 45mm TIR. · GT2-ST Spec Corvette (14-19) LS2 restrictor increases from 78mm to 80mm flat plate. · AS Camaro, Firebird 93-02 and GTO 04-06 add approved LS1 connecting rod part numbers to Notes. · AS Cadillac CTS-V, Chevy Camaro SS V8, Dodge Challenger, Ford Mustang GT 5.0L, Pontiac GTO allowed 11" wheels until 3/1/25. · Chevrolet Camaro, Pontiac Firebird 70–81 Full Prep classified in AS at 3400–3600 lbs with 108.0 wheelbase, specific head castings, and suspension modifications permitted. · AS class adds fuel cell location notes to multiple Cadillac, Chevrolet, Dodge and Ford models: cells within 24 inches of standard tank. · Chevrolet Camaro 6th gen Full Prep added to AS class at 3400 lbs base or 3600 lbs with built engine. · AS class: Ford Mustang GT 05-14 Restricted prep added; Cadillac CTS-V 04-07 to 3450 lbs; Camaro/Firebird variants reconfigured with weight and notes changes; Dodge Challenger 08-20 restrictor 76mm to 80mm; Ford Mustang variants updated wei… · Chevrolet Corvette C8 (2020–) classified in GT2-ST: 6162 cc, 3300 lbs minimum, 71 mm restrictor, flat plate. · Mitjet ST 2015 added to GT2, must run per VTS specs with FIA form CdM008. · GT1-GTX rear blade spoiler: angle 50–75°, max 59.0 wide by 5.0 high inches; total area limit removed. · GT1, GT2, GT3, GTL, GTX Direct Injection now permitted if original equipment. · GT2 Chevrolet Corvette 7011 OEM 7-liter minimum weight reduces to 3125 lbs, down 150 lbs. · GT2 Nissan and GT3 Mazda, Mitsubishi 4G93, Nissan QR25DE/DD, QE25DE/DD now permit Direct Injection per 9.1.2.F.7.5.E. · STL and STU now permit electric power steering pumps, OEM electric-assisted steering, or column-mounted electric steering assist systems. · STL normally aspirated minimum weights reduced: 1900cc to 2540 lbs, 1950cc to 2583 lbs, 2000cc to 2625 lbs; short-wheelbase FWD adds 1.25%; Honda B16/B17/B18C1 throttle to 51mm, B18C Type R and Mazda MZR to 50mm. · STL Mazda 12A: 5th and 6th intake port actuators and valves may no longer be removed or disabled. · GT2 Dodge Viper Gen 3 hybrid kit restrictor reduced from 50mm to 45mm flat plates in 8300 class. · STL 79-85 RX7 12A now allows auto-type 2 bbl carburetor with 42mm choke on dual-y manifold, not just stock Nikki. · GTL spec lines moved contiguous with GT2 and GT3; GTA category and specs renumbered behind GTL; P2 engine tables reorganised with restrictor and weight specifications clarified. · GT2-ST Dodge Viper including Comp Coupe, ACR/ACR-X adds VRL front fascia, 100 lbs weight reduction.showhide
AS Mustang transmission ratios #36662otheraddedAS Mustang GT 05-14 Restricted Prep and 2018- gain alternate transmission ratio options.
SM SMX Camera Rule Correction #36496wordingwordingSMX Spec MX-5 camera requirement: non-functioning recorder now will instead of may warrant penalty or disqualification.
SM Committee) AIM ECU Protocol #36556engineadded · engineSM and SMX must run latest AIM Data Logger Spec MX-5 ECU Protocol, effective 2024-09-01.
SM Committee) OE versus OEM Definitons #36608wordingwordingSMX Mazda MX-5 OE versus OEM definitions clarified in GCR section 9.1.7.1; wording change only.
SM Committee) Shifter Bushing #36611otheraddedSM and SMX now allow an alternate shifter bushing at the bottom of the shift lever.
GT2 GT4 cars may run in GT2-ST #36235cars addedaddedGT4 cars now permitted in GT2-ST with factory power stick or Pro Series restrictor, 100-pound weight penalty for slicks.
AS Request for Classification of 2018-2023 mustang In #35764cars addedaddedAS adds 2018-23 Ford Mustang GT 5.0L at 3600 lbs, 275 tire, 60mm restrictor, optional Brembo front brakes.
AS 6th gen Camaro limited prep #35733cars addedaddedAS Chevrolet Camaro 1LE (2016-) added with 3600 lbs minimum weight, 275 tires, 60mm restrictor, 345/338mm brakes.
AS Chevrolet/Pontiac Camaro & Firebird (82-92) 5.7L V8 LS1 Alum BLK #35825cars addedaddedAS Chevrolet/Pontiac Camaro & Firebird 82–92 5.7L LS1 classified: 3200 lbs, 13.1×1.27 disc brakes, 17 in max wheel, 65 mm restrictor, SLP intake lid permitted.
AS Full Prep Head #35891engineadded · engineAS Chevrolet Camaro, Firebird, and Ford Mustang now permit Flo Tek cylinder heads in multiple generations.
GT2 Request for Spec Line 1010 Reconsideration #35009weight +300 lbsslower · weightGT2-ST Acura NSX minimum weight rises to 3000 lbs, restrictor increases to 45mm TIR.
GT2 Request to Eliminate the FPR from the Corvette (-2013) with LS2 #35878enginefaster · engineGT2-ST Spec Corvette (14-19) LS2 restrictor increases from 78mm to 80mm flat plate.
AS Restricted Prep Aftermarket Parts Request #35682otheraddedAS Camaro, Firebird 93-02 and GTO 04-06 add approved LS1 connecting rod part numbers to Notes.
AS Allowance of 11 #35824tyres & wheelsfaster · tyres & wheelsAS Cadillac CTS-V, Chevy Camaro SS V8, Dodge Challenger, Ford Mustang GT 5.0L, Pontiac GTO allowed 11" wheels until 3/1/25.
AS Request to Classify 1970-1981 Camaro and Firebird in AS #33659cars addedaddedChevrolet Camaro, Pontiac Firebird 70–81 Full Prep classified in AS at 3400–3600 lbs with 108.0 wheelbase, specific head castings, and suspension modifications permitted.
AS Fuel Cell 12 #34194otheraddedAS class adds fuel cell location notes to multiple Cadillac, Chevrolet, Dodge and Ford models: cells within 24 inches of standard tank.
AS Please Classify the 6th Gen Into AS. #35448cars addedaddedChevrolet Camaro 6th gen Full Prep added to AS class at 3400 lbs base or 3600 lbs with built engine.
AS spec lines #35713otherunclearAS class: Ford Mustang GT 05-14 Restricted prep added; Cadillac CTS-V 04-07 to 3450 lbs; Camaro/Firebird variants reconfigured with weight and notes changes; Dodge Challenger 08-20 restrictor 76mm to 80mm; Ford Mustang variants updated wei…
GT2 Classify Corvette C8 (2020- ) into GT2/ST #33759cars addedaddedChevrolet Corvette C8 (2020–) classified in GT2-ST: 6162 cc, 3300 lbs minimum, 71 mm restrictor, flat plate.
GT2 Requesting classification for a 2015 Mitjet ST in GT2 #35408cars addedaddedMitjet ST 2015 added to GT2, must run per VTS specs with FIA form CdM008.
GT2 Rear Blade Spoiler Clarification #35261aeroaeroGT1-GTX rear blade spoiler: angle 50–75°, max 59.0 wide by 5.0 high inches; total area limit removed.
GT2 GT Direct Injection allowance and rules #35437engineadded · engineGT1, GT2, GT3, GTL, GTX Direct Injection now permitted if original equipment.
GT2 REDUCE C6 CORVETTE WEIGHT WITH OEM 7 LITER ENGINE REDUCE BY 150LB #35385weight -150 lbsfaster · weightGT2 Chevrolet Corvette 7011 OEM 7-liter minimum weight reduces to 3125 lbs, down 150 lbs.
GT2 GT2/3 remove Direction Injection not allowed in Spec line notes #35439engineadded · engineGT2 Nissan and GT3 Mazda, Mitsubishi 4G93, Nissan QR25DE/DD, QE25DE/DD now permit Direct Injection per 9.1.2.F.7.5.E.
STL ST Electric-Assisted Steering Systems #35066aeroadded · aeroSTL and STU now permit electric power steering pumps, OEM electric-assisted steering, or column-mounted electric steering assist systems.
STL BOP Adjustments #35112weightfaster · weightSTL normally aspirated minimum weights reduced: 1900cc to 2540 lbs, 1950cc to 2583 lbs, 2000cc to 2625 lbs; short-wheelbase FWD adds 1.25%; Honda B16/B17/B18C1 throttle to 51mm, B18C Type R and Mazda MZR to 50mm.
STL Mazda 12A #35320engineremoved · engineSTL Mazda 12A: 5th and 6th intake port actuators and valves may no longer be removed or disabled.
GT2 Dodge Viper Gen 3 hybrid Kit Update Request #35200engineslower · engineGT2 Dodge Viper Gen 3 hybrid kit restrictor reduced from 50mm to 45mm flat plates in 8300 class.
STL Alternate Carburetor Request for 79-85 RX7 12a #35181engineadded · engineSTL 79-85 RX7 12A now allows auto-type 2 bbl carburetor with 42mm choke on dual-y manifold, not just stock Nikki.
GT2 Errors in GTCS Headings and Use of the Terms Category and ClassChange existing GTL and GTA Rules #34453wordingwordingGTL spec lines moved contiguous with GT2 and GT3; GTA category and specs renumbered behind GTL; P2 engine tables reorganised with restrictor and weight specifications clarified.
GT2 Late E & O #34966weightfaster · weightGT2-ST Dodge Viper including Comp Coupe, ACR/ACR-X adds VRL front fascia, 100 lbs weight reduction.
2:05.779Danny Steyn · fastest of 22 · top 5 within 3.4s+0.305s (+0.24%)
2:06.682Joe Moser · fastest of 20 · top 5 within 1.5s-1.150s (-0.90%)
131.8Danny Steyn+0.1 mph (+0.1%)
2:14.986Danny Steyn · fastest of 52 · top 5 within 0.1s+0.322s (+0.24%)
2:16.229Julian DaCosta · fastest of 46 · top 5 within 0.3s-2.878s (-2.07%)
120.3Jim Drago+1.1 mph (+0.9%)
+9.547squal +9.207s
107.5%qual 107.3%
1:52.004Barry Boes · fastest of 15 · top 5 within 1.6s+0.918s (+0.83%)
1:52.865Jared Odrick · fastest of 15 · top 5 within 1.0s-0.183s (-0.16%)
164.0Tom Patton-0.2 mph (-0.1%)
-13.817squal -13.775s
89.1%qual 89.0%
2:03.082Daniel Richardson · fastest of 11 · top 5 within 2.2s+0.920s (+0.75%)
2:04.120Gregory Eaton · fastest of 9 · top 5 within 3.0s-0.458s (-0.37%)
154.6James Jost+3.7 mph (+2.5%)
-2.562squal -2.697s
98.0%qual 97.9%
26 rule changes (STL: 2, SM: 1, GT2: 19, AS: 4)7 engine · 5 cars added · 2 induction · 2 tyres & wheels · 2 weight · 1 aero · 4 wording · 3 other · GT2 Mazda 20B rotary minimum weight reduced to 2280 lbs, with 100-lb penalty for Grand Am transaxle and independent rear suspension. · AS crate motor part number specification clarified; both CT400 P/N-19370604 and 19370604 engine assemblies permitted for GM vehicles. · AS Ford Mustang GT 5.0L (15-17) Restricted maximum wheel diameter increases to 19.0 inches. · AS Dodge Challenger 5.7L/6.1L/6.4L V8 allows alternate front upper control arms; SPC-66045 spec part removed. · AS Dodge Challenger 5.7L/6.1L/6.4L V8 now allows alternate front brake calipers with adaptor brackets for component compatibility. · GT2 BMW E46 M3, E36, Z3, 5000cc V8: 3.4L at 2575 lbs, 4.0L at 2900 lbs, 4.5L at 2950 lbs, 5.0L at 3000 lbs; S54 97mm stroke permitted at 2800 lbs. · GT2 Corvette C7 restrictor increases from 73mm to 77mm flat plate. · STL ITA and ITS RX7, and ITS/ITA/ITB/ITC 1985+ models clarified to require tires per 9.1.4.2. · GT2 adds 2009-2012 Porsche Cayman S, 3.4L, RWD, no PDK transmission. · Fields Cardinal V8 added to GT1 with Ford V8 engine, 4.9L, 2100 lbs, fuel injection. · GT2 Ginetta G56 GTA may use Factory installed ProMap ECU Map. · GT2 Mazda 13B Street Port turbo changes from EFR 76/70 to BW7670 or Garrett G30-660 with 46mm TIR at 2280 lbs. · GT2 Porsche SOHC 2478/2681/2992 turbos: EFR 76/70 compressor 42mm to 44mm, SIR to TIR designation. · GT2-ST Chevrolet Corvette 14-19 restrictor increases from 70 to 73 mm. · GT2 and GTL add Toyota 4A-F and 4A-FE 1.6L DOHC 16V engines as permitted options. · GT2 Mazda 13B turbocharger part number changed from EFR 70/76 to 76/70, compressor 42mm to 46mm. · GT2-ST BMW E36/46 spec line adds MA Shaw carbon/composite door and body kit options to notes. · GT3 normally aspirated cars may now use chokes instead of SIRs, same size as listed SIR, one per carburetor barrel. · GT3 2.0L 4-valve non-turbo engines may run unrestricted at 2060 lbs minimum weight. · GT2 Porsche 991.1 TBR 70–72mm, 991.2 weight 3100–3000lbs TBR 65–67mm, all 991/997 models ABS now free; GT2-ST Corvette and others flat plate 75–78mm, 74–77mm, 71–74mm, 68–71mm, 65–68mm per engine; Viper weight 3275–3125lbs all displacement… · SM Mazda MX-5 Miata 01-05 minimum weight rises to 2450 lbs, or 2465 with alternate bore. · Spec MX5 in STL allows ACT clutch 0000-02-5004-G6, wheels 17x8, Toyo RR and RA1 235-40-17 tyres, or alternatives on 17x7 per rules. · GT2 TA2 and GTA throttle body part numbers updated to GM 12570790 or Edelbrock 33869/3870. · GT2 Ginetta G56 GTA may now use optional 18" x 9" and 18" x 10" wheels. · GT2/ST BMW E36/E46 Z3 5000cc V8 now permits MAShaw body kit: wide body, M3 front bumper with splitter, fenders, rockers, flairs, rear bumper. · GT2 Chevrolet Corvette L76 5967 restrictor increases from 73 mm to 74 mm.showhide
GT2 GT2 Mazda 20B 3 rotor ENO #34765weight -220 lbsfaster · weightGT2 Mazda 20B rotary minimum weight reduced to 2280 lbs, with 100-lb penalty for Grand Am transaxle and independent rear suspension.
AS Crate Motor Part Numbers #32944wordingwordingAS crate motor part number specification clarified; both CT400 P/N-19370604 and 19370604 engine assemblies permitted for GM vehicles.
AS Request wheel size change #33007tyres & wheelsfaster · tyres & wheelsAS Ford Mustang GT 5.0L (15-17) Restricted maximum wheel diameter increases to 19.0 inches.
AS Alternative Upper Front Control Arms for Dodge Challenger #33352wordingwordingAS Dodge Challenger 5.7L/6.1L/6.4L V8 allows alternate front upper control arms; SPC-66045 spec part removed.
AS Front Brake Caliper Adapters for Dodge Challenger #33353otherotherAS Dodge Challenger 5.7L/6.1L/6.4L V8 now allows alternate front brake calipers with adaptor brackets for component compatibility.
GT2 appendix letter #33635 #34206cars addedaddedGT2 BMW E46 M3, E36, Z3, 5000cc V8: 3.4L at 2575 lbs, 4.0L at 2900 lbs, 4.5L at 2950 lbs, 5.0L at 3000 lbs; S54 97mm stroke permitted at 2800 lbs.
GT2 Remove Weight and Restrictor Penalty for Corvette C7 Body #34342enginefaster · engineGT2 Corvette C7 restrictor increases from 73mm to 77mm flat plate.
STL Clarify STL table B - IT spec notes on Tires #34187wordingwordingSTL ITA and ITS RX7, and ITS/ITA/ITB/ITC 1985+ models clarified to require tires per 9.1.4.2.
GT2 Request to class 2011 Porsche Cayman S #33771cars addedaddedGT2 adds 2009-2012 Porsche Cayman S, 3.4L, RWD, no PDK transmission.
GT2 Please classify Fields Cardinal V8 #33784cars addedaddedFields Cardinal V8 added to GT1 with Ford V8 engine, 4.9L, 2100 lbs, fuel injection.
GT2 Adding Ginetta G56 GTA Factory ProTune for GT2 Class #33825engineadded · engineGT2 Ginetta G56 GTA may use Factory installed ProMap ECU Map.
GT2 GT2 Mazda 13B Turbo #33729engineengineGT2 Mazda 13B Street Port turbo changes from EFR 76/70 to BW7670 or Garrett G30-660 with 46mm TIR at 2280 lbs.
GT2 Request Permission to Use a Substitute Turbo #33337engineengineGT2 Porsche SOHC 2478/2681/2992 turbos: EFR 76/70 compressor 42mm to 44mm, SIR to TIR designation.
GT2 Request to Reduce Restriction on C7 GT2 Corvette #33342enginefaster · engineGT2-ST Chevrolet Corvette 14-19 restrictor increases from 70 to 73 mm.
GT2 Toyota 4A-F and 4A-FE 1.6L DOHC 16V Engine Request #33415cars addedaddedGT2 and GTL add Toyota 4A-F and 4A-FE 1.6L DOHC 16V engines as permitted options.
GT2 GT2 Mazda 13b turbocharger part # update #33437enginefaster · engineGT2 Mazda 13B turbocharger part number changed from EFR 70/76 to 76/70, compressor 42mm to 46mm.
GT2 GT2-ST BMW E36/46 spec line remove #33610otheraddedGT2-ST BMW E36/46 spec line adds MA Shaw carbon/composite door and body kit options to notes.
GT2 GT3 Choke option effective 1-01-2023 #33669inductionadded · inductionGT3 normally aspirated cars may now use chokes instead of SIRs, same size as listed SIR, one per carburetor barrel.
GT2 GT3 2.0L choke/weight option #33670otheraddedGT3 2.0L 4-valve non-turbo engines may run unrestricted at 2060 lbs minimum weight.
GT2 BOP adjustment for GT2 & GT2-ST #33681inductionfaster · inductionGT2 Porsche 991.1 TBR 70–72mm, 991.2 weight 3100–3000lbs TBR 65–67mm, all 991/997 models ABS now free; GT2-ST Corvette and others flat plate 75–78mm, 74–77mm, 71–74mm, 68–71mm, 65–68mm per engine; Viper weight 3275–3125lbs all displacement…
SM BOP for NB1 and NB2 #32309weightslower · weightSM Mazda MX-5 Miata 01-05 minimum weight rises to 2450 lbs, or 2465 with alternate bore.
STL Spec MX5 in STL #33473cars addedaddedSpec MX5 in STL allows ACT clutch 0000-02-5004-G6, wheels 17x8, Toyo RR and RA1 235-40-17 tyres, or alternatives on 17x7 per rules.
GT2 GT2 (TA2)/GTA Part Number Update #33315wordingwordingGT2 TA2 and GTA throttle body part numbers updated to GM 12570790 or Edelbrock 33869/3870.
GT2 Ginetta G56 GTA - Optional Wheels #33357tyres & wheelsadded · tyres & wheelsGT2 Ginetta G56 GTA may now use optional 18" x 9" and 18" x 10" wheels.
GT2 Allow the MAShaw Body Kit on the GT2/ST Spec Line for BMW E36/E46 #32447aeroadded · aeroGT2/ST BMW E36/E46 Z3 5000cc V8 now permits MAShaw body kit: wide body, M3 front bumper with splitter, fenders, rockers, flairs, rear bumper.
GT2 Request for C5/C6 Corvette Restrictor Size Review #32982enginefaster · engineGT2 Chevrolet Corvette L76 5967 restrictor increases from 73 mm to 74 mm.
2:05.474Danny Steyn · fastest of 24 · top 5 within 2.3s-1.729s (-1.36%)
2:07.832Danny Steyn · fastest of 22 · top 5 within 1.9s+0.559s (+0.44%)
131.7Trever Degioanni-3.2 mph (-2.3%)
2:14.664Danny Steyn · fastest of 60 · top 5 within 0.2s+0.112s (+0.08%)
2:19.107Travis Wiley · fastest of 58 · top 5 within 0.9s+2.648s (+1.94%)
119.2Jonathan Neudorf-0.6 mph (-0.5%)
+11.275squal +9.190s
108.8%qual 107.3%
1:51.086Andrew Aquilante · fastest of 23 · top 5 within 1.1s+0.904s (+0.82%)
1:53.048Daniel Bender · fastest of 17 · top 5 within 3.1s+0.573s (+0.51%)
164.2Scotty B White+1.4 mph (+0.9%)
-14.784squal -14.388s
88.4%qual 88.5%
2:02.162Kurt Rezzetano · fastest of 13 · top 5 within 2.3s-0.776s (-0.63%)
2:04.578Gregory Eaton · fastest of 11 · top 5 within 2.9s+0.678s (+0.55%)
150.9James Jost-3.0 mph (-2.0%)
-3.254squal -3.312s
97.5%qual 97.4%
29 rule changes (STL: 5, SM: 1, GT2: 14, AS: 9)8 cars added · 6 engine · 3 weight · 2 tyres & wheels · 7 wording · 3 other · AS adds Hoosier W2 wet tyre option alongside R7, R6, WET/H20. · AS Dodge Challenger 08-20 gains two transmission ratio options: 2.97–0.50 or 2.26–0.63. · GT1, GT2, GT3, GTL, GTX tail lights may now be original style or custom panel graphic with functioning red LED brake lamps. · Ginetta GTA G56 added to GT2 as spec car, 2600 lbs, 3.7L Ford V6 sealed, 6-speed Quaife sequential. · GT2 adds approved carbon roof suppliers and part numbers for BMW E36 and E46 models to Notes. · GT2 BMW E46 M3, E36, Z3, and 5000cc V8 may use 95mm S54 crankshaft at +150 lbs. · Audi R8 GT4 added to GT2 at 5.2L, 3000 lbs minimum weight, factory restrictor. · AS Cadillac CTS-V 6.0L V8 Restricted Prep removes 295 tire size 50 lb penalty. · GT2 shock absorber attachment points clarified as movable; wording correction only. · GT2 Porsche 104.0 x 88.0 SOHC minimum weight increases to 2090 lbs; EFR 76/70 turbo allowances added for three Porsche engines at specific weights. · SM Majors must run authorized Penske shock and mount; Regional competitors not required until further evaluation. · Ginetta G40 added to GT2 with Mazda MZR/L5-VE engine, 2488cc or 2399cc, 1950 lbs base weight. · Toyota Supra GT4 added to GT2-ST with 3000cc displacement, 3000 lb minimum weight, factory restrictor. · GT2 Porsche 944/924 may use ERC 76/70 Turbo instead of Jayco super 50. · STU single throttle body weight reduction removed; minimum weights revised down to 2990 lbs at 3000cc from 3300 lbs. · STL and STU Improved Touring vehicles must now conform to section 9.1.4 Tires & Wheels. · GT2-ST Porsche Cayman 05-15 throttle body restrictor increased from 70mm to 75mm. · SMG Long Tube Headers: Borla PN 17237 discontinued, approved alternatives American Racing MT3-05134300LSNC or Kooks PN 11312000. · AS Mercury Capri 79-86 removed as separate spec line, merged into Ford Mustang 79-93 spec line. · AS Spec Mustang SMG Restricted Prep removes 3.73 gear ratio and 355/300 brake disc sizes. · AS Camaro, Firebird, Mustang full prep engines: alternate GM and Ford Performance cylinder heads permitted regionally with Allstar restrictor ALL26180. · GT2 Porsche Cayman 05-15 4.0L and 4.2L swap flat plate restrictor for throttle body restrictor at 2700 lbs. · STL/STU intake manifold and cylinder head porting clarified as free; intake and exhaust porting wording removed. · STL Mazda Renesis flat plate restrictor increases from 55mm to 60mm. · STL 79-85 RX7 12A allows emissions removal and jet correction on stock Nikki carb. · AS Chevrolet/Pontiac Camaro & Firebird 93-02 gains BMR AA004 or UMI 2310 adjustable front upper control arms. · AS Pontiac GTO 04-06 Restricted Prep minimum weight rises: LS1 to 3300 lbs, LS2 to 3350 lbs on 295 tires. · GT2 Mazda 13B street port gains EFR 70/76 turbocharger with 42mm inlet restrictor at 2280 lbs minimum. · GT3 Volkswagen Fun Cup Beetle EVO3 classified, sealed SOHC 1984cc engine, 2060 lbs minimum weight.showhide
AS Request to add Hoosier W2 #33031tyres & wheelsadded · tyres & wheelsAS adds Hoosier W2 wet tyre option alongside R7, R6, WET/H20.
AS correction of Dodge Challenger specification line #33151cars addedaddedAS Dodge Challenger 08-20 gains two transmission ratio options: 2.97–0.50 or 2.26–0.63.
GT2 Tail lights on all GT category race cars. #32799wordingwordingGT1, GT2, GT3, GTL, GTX tail lights may now be original style or custom panel graphic with functioning red LED brake lamps.
GT2 Addendum to letter #32514 Ginetta GTA G56 #33076cars addedaddedGinetta GTA G56 added to GT2 as spec car, 2600 lbs, 3.7L Ford V6 sealed, 6-speed Quaife sequential.
GT2 Information requested for carbon roofs on BMW E36/E46 cars in GT2 #32682cars addedaddedGT2 adds approved carbon roof suppliers and part numbers for BMW E36 and E46 models to Notes.
GT2 Request to Allow the 95mm S54 BMW Crankshaft in GT2-ST #32698engineadded · engineGT2 BMW E46 M3, E36, Z3, and 5000cc V8 may use 95mm S54 crankshaft at +150 lbs.
GT2 Request to classify Audi R8 FIA GT4 to GT2 #32805cars addedaddedAudi R8 GT4 added to GT2 at 5.2L, 3000 lbs minimum weight, factory restrictor.
GT2 Typo in rules for shocks #32308wordingwordingGT2 shock absorber attachment points clarified as movable; wording correction only.
GT2 additional response to letters #31898 & 32083 #32424engine +140 lbsslower · engineGT2 Porsche 104.0 x 88.0 SOHC minimum weight increases to 2090 lbs; EFR 76/70 turbo allowances added for three Porsche engines at specific weights.
SM Update GCR Section 9.1.7.3.A.1. #32217wordingwordingSM Majors must run authorized Penske shock and mount; Regional competitors not required until further evaluation.
GT2 Request to Classify Ginetta G40 in GT2 #31597cars addedaddedGinetta G40 added to GT2 with Mazda MZR/L5-VE engine, 2488cc or 2399cc, 1950 lbs base weight.
GT2 2021 Supra GR GT4 #31737cars addedaddedToyota Supra GT4 added to GT2-ST with 3000cc displacement, 3000 lb minimum weight, factory restrictor.
GT2 Proposed Technical Bulletin #31900otherunclearGT2 Porsche 944/924 may use ERC 76/70 Turbo instead of Jayco super 50.
STL Single TB Weight Modifiers #31449weightfaster · weightSTU single throttle body weight reduction removed; minimum weights revised down to 2990 lbs at 3000cc from 3300 lbs.
STL Improved Touring Tires #32063tyres & wheelstyres & wheelsSTL and STU Improved Touring vehicles must now conform to section 9.1.4 Tires & Wheels.
GT2 GT2/ST Porsche Cayman #31451 correct TBR size error #31991enginefaster · engineGT2-ST Porsche Cayman 05-15 throttle body restrictor increased from 70mm to 75mm.
AS Proposed Revisions to SCCA GCR 2021 Appendix M, Part 3 #30295wordingwordingSMG Long Tube Headers: Borla PN 17237 discontinued, approved alternatives American Racing MT3-05134300LSNC or Kooks PN 11312000.
AS specification line consolidation and correction #31846cars addedremoved · cars addedAS Mercury Capri 79-86 removed as separate spec line, merged into Ford Mustang 79-93 spec line.
AS correction of SMG specification line #31847wordingremovedAS Spec Mustang SMG Restricted Prep removes 3.73 gear ratio and 355/300 brake disc sizes.
AS Alternate cylinder heads for full prep engine builds - Evaluation #31851engineadded · engineAS Camaro, Firebird, Mustang full prep engines: alternate GM and Ford Performance cylinder heads permitted regionally with Allstar restrictor ALL26180.
GT2 Restrictor Clarification for 2015 Cayman #31451otherunclearGT2 Porsche Cayman 05-15 4.0L and 4.2L swap flat plate restrictor for throttle body restrictor at 2700 lbs.
STL Throttling Device Clarification #31323wordingwordingSTL/STU intake manifold and cylinder head porting clarified as free; intake and exhaust porting wording removed.
STL Mazda Renesis Restriction #31467enginefaster · engineSTL Mazda Renesis flat plate restrictor increases from 55mm to 60mm.
STL Clarification of 79-85 RX7 Spec line #31621wordingwordingSTL 79-85 RX7 12A allows emissions removal and jet correction on stock Nikki carb.
AS Request for adjustable Front Upper Control Arms on 4th Gen F-Body #30457otheraddedAS Chevrolet/Pontiac Camaro & Firebird 93-02 gains BMR AA004 or UMI 2310 adjustable front upper control arms.
AS Request Pontiac GTO tire size change #30881weightslower · weightAS Pontiac GTO 04-06 Restricted Prep minimum weight rises: LS1 to 3300 lbs, LS2 to 3350 lbs on 295 tires.
GT2 Turbo Request for 13B Engine #30656engineadded · engineGT2 Mazda 13B street port gains EFR 70/76 turbocharger with 42mm inlet restrictor at 2280 lbs minimum.
GT2 Request car classification #31032cars addedaddedGT3 Volkswagen Fun Cup Beetle EVO3 classified, sealed SOHC 1984cc engine, 2060 lbs minimum weight.
1:51.665Danny Steyn · fastest of 42 · top 5 within 1.7s-0.982s (-0.87%)
2:02.711Joe Moser · fastest of 37 · top 5 within 3.2s+10.122s (+8.99%)
131.8Max Gee
1:57.695Brian Henderson · fastest of 90 · top 5 within 0.5s-0.611s (-0.52%)
1:58.837Brian Henderson · fastest of 88 · top 5 within 0.3s-0.263s (-0.22%)
119.8Kyle Greenhill
-3.874squal +6.030s
96.8%qual 105.4%
1:39.665Andrew Aquilante · fastest of 22 · top 5 within 1.8s-0.254s (-0.25%)
2:03.513Tim Kezman · fastest of 18 · top 5 within 9.6s+22.537s (+22.32%)
163.7Jonathan Start
+0.802squal -12.000s
100.7%qual 89.3%
1:50.427Drew Cattell · fastest of 31 · top 5 within 1.9s+5.207s (+4.95%)
1:50.606Gregory Eaton · fastest of 28 · top 5 within 1.7s-0.901s (-0.81%)
153.8James Jost
-12.105squal -1.238s
90.1%qual 98.9%
46 rule changes (STL: 15, SM: 1, GT2: 16, AS: 14)11 cars added · 10 weight · 7 engine · 3 aero · 1 induction · 1 suspension & brakes · 9 wording · 4 other · GT2 Dodge Viper ACR/ACR-X8300 front fascia loses 100 lbs, to 3175 VRL. · STL Mazda Spec MX-5 removes redundant specification line referencing 2014 regulations. · GT2 adds 04-06 World Challenge Pontiac GTO, 6062 cc, 3000 lbs minimum, World Challenge rules. · GTA part numbers updated: 0-80541-1 to 0-80541-2 in two locations and 6010 to 6014X in TA2 Appendix. · Grullon GT 2.0L Acura K20 moved from GTX to GT2-ST class at 2350 lbs unrestricted. · GT2-ST Porsche Cayman restrictor increases from 65mm to 75mm flat plate at 2700 lbs. · GT2 Dodge Viper VRL Spec minimum weight reduced 100 lbs to 3275. · TA2 cars may run prior generation rules or current Trans Am rules at 2930 lbs minimum weight with free tire make and size. · AS Cadillac CTS-V 6.0L LS6 removes 295-tire 50 lb penalty. · AS consolidates seven SN95 Mustang '94-'04 spec lines into three unified lines by model year and engine. · AS Camaro/Firebird LT1 and LS1 transmission changed to TUET1 6362; Mustang GT 4.6L/5spd to TUKT16901, loses 300 lbs. · AS Camaro & Firebird and Mustang GT gear ratio specifications restored with alternate sets permitted. · AS Camaro, Firebird, Mustang, and Capri all gain 50 lbs minimum weight across seven model year variants. · STL Volkswagen 2.0L TFSI 1984 cc engine permitted without turbocharger, meeting all other STL specs. · STL Pontiac Solstice/Saturn Sky allowed 4 inch ride height. · STL Mazda B5 DOHC added to class; must meet all STL regulations. · STL Honda B16A (JDM) restrictor reduced from 54mm to 53mm. · GT2 Sunbeam SBF engine firing order 1,3,7,2,6,5,4,8 now available for Boss 302 variants. · SM adds procedure for CRB-approved obsolete parts and BOP testing in sanctioned events with point forfeiture. · ST oil coolers and filters now explicitly listed as addable or substitutable parts in vents and breathers section. · AS Mustang 4.6L 5spd gains cold air intake freedom; 5.0L 6spd now requires 56mm flat plate restrictor. · AS CTS-V 5.7L LS6 and 6.0L LS2 may use Driveshaft Shop P/N GMCTSV2-C carbon fiber driveshaft. · AS Chevrolet Camaro SS V8 6.2L Restricted Prep model years extended from 10–13 to 10–15. · GT2-ST Corvette (-2019) LS2 and L76 5967 gain 100 lbs minimum weight to 3100; 6162 and 7011 variants gain 50–100 lbs; L76 restrictor opens 70 to 73 mm. · GT2 rear engine opening position requirement removed. · GT2 Ford Mustang/Thunderbird Boss 302 firing order changes from unrestricted to optional later SBF 302 order 1,3,7,2,6,5,4,8. · STL GM Ecotec LNF now permits any Ecotec engine family with 55mm flat plate restrictor. · ST 90-05 Mazda Miata allowed alternate front wheel hub Mazda Motorsports Development Part #0000-04-5HUB-S1. · GT2 allows ABS braking systems if shown on the individual Spec Line. · GT2 Corvette C6 and C7 spec lines split for clarification; C7 LS2, L76, LS3, LT1, LS7 weights raised 100–150 lbs effective 3/1/2021. · ST cars may now relocate ABS actuation hardware and wiring anywhere in the engine compartment. · STL rear wing trailing edge may be mounted no further rearward than the center of the rearmost part approved bodywork. · STL alternate transmissions now allow OEM gear sets and input shaft modifications for fitment. · AS Ford Mustang GT 5.0L 15-17 Restricted added to Spec Line with 3600 lbs minimum weight, 55mm restrictor, 18×10 wheels, 295 tires. · AS underhood bracing on stock hoods, trunks, and rear decks may be modified or removed. · AS Cadillac CTS-V 04-07 with 295 tire drops to 3450 lbs; Camaro SS V8 10-13 and Challenger 08-20 specs removed. · AS Camaro & Firebird (93-02) and Mustang GT (05-14) specifications restored with weight minimums 3250–3500 and 3350–3600 lbs respectively. · GT2 Ford Mustang/Thunderbird Boss 302 firing order becomes unrestricted. · GT2 BMW E46 M3 and E36, Z3, and 5000cc V8 minimum weight reduced to 2500 lbs. · STL RWD strut-front cars lose 2.5% weight penalty, others lose 3% penalty for FWD parity. · STL Honda F20C drops 2% weight penalty, minimum weight reduced. · STL Honda B16/B17/B18C1 restrictor reduced to 53mm, B18C variants and Mazda MZR to 52mm. · AS Dodge Challenger gains 6.1L and 6.4L V8 options; 5.7L weight rises to 3500 lbs on 295 tyres, 3600 on 315 tyres; compression to 10.9:1 max. · AS Camaro & Firebird (93-02) and Ford Mustang Coupe GT (05-14) spec lines consolidated; Camaro/Firebird now allows both LT1 and LS1 engines; Mustang now allows both 4.6L 3-valve and 5.0L 4-valve engines with restrictor. · GT2 Chrysler/Dodge/Plymouth DOHC 2429cc engine classified, 1950 lbs minimum weight. · ST aero devices and reference areas must include end plates, exclude fasteners under 1/2" protrusion.showhide
GT2 Correct letter 30565 GT2/ST #31088weightfaster · weightGT2 Dodge Viper ACR/ACR-X8300 front fascia loses 100 lbs, to 3175 VRL.
STL Request to clean up Spec MX-5 Redundancy #31069wordingwordingSTL Mazda Spec MX-5 removes redundant specification line referencing 2014 regulations.
GT2 Request the 04-06 Pontiac GTO WC Car Be Added to the GT2/ST Chart #30339cars addedaddedGT2 adds 04-06 World Challenge Pontiac GTO, 6062 cc, 3000 lbs minimum, World Challenge rules.
GT2 Request to Update GTA Obsolete Part Numbers #30615wordingwordingGTA part numbers updated: 0-80541-1 to 0-80541-2 in two locations and 6010 to 6014X in TA2 Appendix.
GT2 GTX class correction to GT2/ST #30973cars addedaddedGrullon GT 2.0L Acura K20 moved from GTX to GT2-ST class at 2350 lbs unrestricted.
GT2 Porsche Cayman Engine Modification and Engine Request #30472enginefaster · engineGT2-ST Porsche Cayman restrictor increases from 65mm to 75mm flat plate at 2700 lbs.
GT2 Request weight clarification Viper CC #30565weightfaster · weightGT2 Dodge Viper VRL Spec minimum weight reduced 100 lbs to 3275.
GT2 Variance, 2021 TA2 Rules vs GCR Appendix L #30641cars addedaddedTA2 cars may run prior generation rules or current Trans Am rules at 2930 lbs minimum weight with free tire make and size.
AS Request CTS-V Spec Line Error Correction #30242weightfaster · weightAS Cadillac CTS-V 6.0L LS6 removes 295-tire 50 lb penalty.
AS Request to consolidate SN95 Mustang '94-'04 Mustang spec lines #30428wordingwordingAS consolidates seven SN95 Mustang '94-'04 spec lines into three unified lines by model year and engine.
AS American Sedan Transmission Rule Change Request #30595enginefaster · engineAS Camaro/Firebird LT1 and LS1 transmission changed to TUET1 6362; Mustang GT 4.6L/5spd to TUKT16901, loses 300 lbs.
AS Correction to specifications inadvertently deleted #30691wordingwordingAS Camaro & Firebird and Mustang GT gear ratio specifications restored with alternate sets permitted.
AS weight adjustments #30700weight +50 lbsslower · weightAS Camaro, Firebird, Mustang, and Capri all gain 50 lbs minimum weight across seven model year variants.
STL VW Engine Request #30625engineadded · engineSTL Volkswagen 2.0L TFSI 1984 cc engine permitted without turbocharger, meeting all other STL specs.
STL Request Mazda B5 DOHC #30420cars addedaddedSTL Mazda B5 DOHC added to class; must meet all STL regulations.
STL Honda B16A (JDM) Restrictor change #30531engineslower · engineSTL Honda B16A (JDM) restrictor reduced from 54mm to 53mm.
GT2 GT2 tiger firing order #30421wordingwordingGT2 Sunbeam SBF engine firing order 1,3,7,2,6,5,4,8 now available for Boss 302 variants.
SM Updates - Obsolete Parts & BOP Parts #30438wordingaddedSM adds procedure for CRB-approved obsolete parts and BOP testing in sanctioned events with point forfeiture.
STL ST Oil Coolers E&O Correction to 9.1.4.2.H #30388wordingwordingST oil coolers and filters now explicitly listed as addable or substitutable parts in vents and breathers section.
AS AS Mustang LP 4.6 3V Classification Transmission Request #29886enginefaster · engineAS Mustang 4.6L 5spd gains cold air intake freedom; 5.0L 6spd now requires 56mm flat plate restrictor.
AS Request CF driveshaft on CTS-V for durability improvement #30117otheraddedAS CTS-V 5.7L LS6 and 6.0L LS2 may use Driveshaft Shop P/N GMCTSV2-C carbon fiber driveshaft.
AS Adjustment to model years of 5th generation RP Camaro #30348cars addedaddedAS Chevrolet Camaro SS V8 6.2L Restricted Prep model years extended from 10–13 to 10–15.
GT2 GT2-ST CORVETTE CHANGES #30029weight +100 lbsslower · weightGT2-ST Corvette (-2019) LS2 and L76 5967 gain 100 lbs minimum weight to 3100; 6162 and 7011 variants gain 50–100 lbs; L76 restrictor opens 70 to 73 mm.
GT2 29742 Change new wording to read as: #30329wordingwordingGT2 Ford Mustang/Thunderbird Boss 302 firing order changes from unrestricted to optional later SBF 302 order 1,3,7,2,6,5,4,8.
STL GM Ecotec engines in STL #30247engineadded · engineSTL GM Ecotec LNF now permits any Ecotec engine family with 55mm flat plate restrictor.
STL Super Touring Alternate Miata Hubs #30345cars addedaddedST 90-05 Mazda Miata allowed alternate front wheel hub Mazda Motorsports Development Part #0000-04-5HUB-S1.
GT2 ABS Restrictions #30064otheraddedGT2 allows ABS braking systems if shown on the individual Spec Line.
STL Brake Component Relocation #29990suspension & brakessuspension & brakesST cars may now relocate ABS actuation hardware and wiring anywhere in the engine compartment.
STL Super Touring Wing Clarification #30111aeroaeroSTL rear wing trailing edge may be mounted no further rearward than the center of the rearmost part approved bodywork.
STL Transmission Options #30118otheraddedSTL alternate transmissions now allow OEM gear sets and input shaft modifications for fitment.
AS Request for 2015 -2017 Ford Mustang Spec Line #29514cars addedaddedAS Ford Mustang GT 5.0L 15-17 Restricted added to Spec Line with 3600 lbs minimum weight, 55mm restrictor, 18×10 wheels, 295 tires.
AS Request Trunk lid / Rear Hatch clarification #29591wordingwordingAS underhood bracing on stock hoods, trunks, and rear decks may be modified or removed.
AS Common Weight for CTS-V Tire #29759weightfaster · weightAS Cadillac CTS-V 04-07 with 295 tire drops to 3450 lbs; Camaro SS V8 10-13 and Challenger 08-20 specs removed.
AS Correction to specifications inadvertently deleted #30041cars addedaddedAS Camaro & Firebird (93-02) and Mustang GT (05-14) specifications restored with weight minimums 3250–3500 and 3350–3600 lbs respectively.
GT2 Request change to engine firing order rule #29742engineadded · engineGT2 Ford Mustang/Thunderbird Boss 302 firing order becomes unrestricted.
GT2 Request E-46 BMW M3 balance of performance #29833weight -100 lbsfaster · weightGT2 BMW E46 M3 and E36, Z3, and 5000cc V8 minimum weight reduced to 2500 lbs.
STL Request for FWD and RWD Parity #29728weightfaster · weightSTL RWD strut-front cars lose 2.5% weight penalty, others lose 3% penalty for FWD parity.
STL Request for FWD and RWD Parity #30023inductionslower · inductionSTL Honda B16/B17/B18C1 restrictor reduced to 53mm, B18C variants and Mazda MZR to 52mm.
AS Request Additional Engine Options for Dodge Challenger Spec Line #29543cars addedaddedAS Dodge Challenger gains 6.1L and 6.4L V8 options; 5.7L weight rises to 3500 lbs on 295 tyres, 3600 on 315 tyres; compression to 10.9:1 max.
AS Rule simplification spec line communization #29824cars addedcars addedAS Camaro & Firebird (93-02) and Ford Mustang Coupe GT (05-14) spec lines consolidated; Camaro/Firebird now allows both LT1 and LS1 engines; Mustang now allows both 4.6L 3-valve and 5.0L 4-valve engines with restrictor.
GT2 Request for Bigger Engine in Plymouth Breeze #29380cars addedaddedGT2 Chrysler/Dodge/Plymouth DOHC 2429cc engine classified, 1950 lbs minimum weight.
STL Request clarification on wing measurement #29640aeroaeroST aero devices and reference areas must include end plates, exclude fasteners under 1/2" protrusion.
2:31.420Danny Steyn · fastest of 33 · top 5 within 3.1s
2:32.115Joe Moser · fastest of 30 · top 5 within 1.5s
132.9Darin Treakle
2:42.209Kyle Greenhill · fastest of 77 · top 5 within 0.5s
2:43.748Preston Pardus · fastest of 75 · top 5 within 1.0s
121.3Kyle Greenhill
+11.633squal +10.789s
107.6%qual 107.1%
2:12.298Andrew Aquilante · fastest of 20 · top 5 within 2.9s
2:14.279Andrew Aquilante · fastest of 19 · top 5 within 2.4s
162.2Scotty B White
-17.836squal -19.122s
88.3%qual 87.4%
2:27.045Gregory Eaton · fastest of 18 · top 5 within 0.6s
2:27.668Gregory Eaton · fastest of 15 · top 5 within 1.5s
149.2Gregory Eaton
-4.447squal -4.375s
97.1%qual 97.1%
55 rule changes (STL: 11, SM: 2, GT2: 26, AS: 16)13 cars added · 12 engine · 8 weight · 2 aero · 2 suspension & brakes · 16 wording · 2 other · GT2 stock car bodies removal rescinded; 1997-current year commercially available stock car bodywork allowed. · GT2 Appendix L section 4.8.4.2.10.3.6 renumbered, eliminating subsections .17–.19. · GT2 TA2 wing width maximum clarified to 65 -5/16 inches, including end plates. · SM allows aftermarket radiators in original location with stock OEM cooling fan, and permits 1990-1997 cars to install upper radiator seal NA75-50-OK7A. · GT1/GT2/GT3/GTL/GTX turbocharging and supercharging now permitted if listed on spec line. · Chevrolet Corvette (-2019) GT2-ST permitted LS1/LS6 alternate intake manifold, DORMAN part # 615-900. · GT2 997.2 GT3 Cup minimum weight reduced from 3000 to 2900 lbs. · AS Dodge Challenger 5.7L V8 now requires iron block instead of aluminum, compression to 10.5:1 max, intake valve 12.7 mm, exhaust 12.3 mm, intake timing 188 degrees, exhaust timing 205 degrees. · AS Dodge Challenger 08-14 rear spoiler: 1GL20RXF replaced with 1GL20TZZAB; 82211606 still permitted. · GT2 BMW E46 M3, E36, Z3, and 5000cc V8 gain Trans Am SGT option: regular shifter 3000 lbs., paddle shifter plus 150 lbs. · GT2 allows up to four hood/fender louvered panels, max 600 sq inches total, min five slots each, ahead of windscreen. · SM rear brake caliper may use single bracket under upper retaining bolt head to prevent pin failure. · STL and STU clarify weight adjustment calculation order: engine adjustments first, then chassis percentage additions, subtractions, and fixed pounds. · STL STU rear wing Gurney flap terminology clarified from wicker to Gurney flap in mounting and chord rules. · AS class pursuing specified list of eligible tires; list details unclear from text provided. · AS class tire eligibility list under development; no specifications changed yet. · AS Coyote Mustang restrictor plate under review for 2021; no change effective yet. · AS Restricted Prep 4.6 3V now permits conversion to 2 valve configuration. · AS Ford Mustang Coupe GT 4.6L 3V Restricted Prep now permits Ford Performance camshaft kit P/N M-6550-3V. · 2010-2014 Camaro remains classified in AS; no specification changes. · AS class cylinder head supplier discontinuation; replacement option pending for 2021 season. · AS Mustang, Capri, Camaro, and Firebird maximum brake rotor diameter increased from 12.2 to 13.1 inches. · unclear · TA2 Gurney flap wording clarified: replace 'wicker bill' and 'wicker' with 'Gurney flap' throughout wing specifications. · STO rear wing rules clarify that wicker is called Gurney flap in two places; no performance change. · GT Gurney flap wording clarified: wickerbill and tab terminology replaced with Gurney flap throughout sections 9.1.2.F.7.b. · GT3 and STU add Borg-Warner EFR6258 turbocharger to approved turbo lists. · GT2 Dodge Viper 8.4 OEM minimum weight reduced to 3275 lbs. · GT2 Chevrolet Corvette -2019 OEM minimum weight reduced to 3275 lbs. · STL adds Mazda MX-5 Global Cup 16-18 at 2450 lbs minimum and 2019 at 2550 lbs minimum. · STL Mazda MX-5 Club 06-15 allowed header part number 0000-06-5407-NC. · STL Acura/Honda B18 and B18C engines: restrictor sizes swapped, B18C1 removed from allowed variants. · GT2 Corvette -2019 LS6 allowed to reduce weight by 50 lbs. · STL Honda B18 loses 53mm restrictor requirement; B18C1 added with 54mm restrictor, B18C1 removed from other variants. · GT2 Panoz GT-S may use TA2 Choice Engine with any 5-speed H-shift transmission. · GT2-ST Corvette LS2 restrictor increases from 70mm to 75mm flat plate; LSX block option added. · GT2-ST Corvette L76 added: 5967cc displacement, 3000 lb minimum weight, 70mm flat plate restrictor. · STU GM Ecotech LNF now permitted without turbo, with LE5 head and intake manifold, meeting STL specs. · STL Mazda MZR restrictor reduced from 54 mm to 53 mm. · STL Mazda MZR restrictor reduces from 55 mm to 53 mm. · GT2 Porsche 991.2 GT3 Cup Car engine displacement corrected to 4.0L from 3.8L. · STL Mazda Spec MX5 Challenge adds approved wheel part numbers 0000-04-5706-GM, 0000-04-5706-SL to notes. · AS rear trailing arms may be replaced with tubular arms maintaining stock length and axle location purpose only. · AS Ford and GM full prep cars get increased weight reduction from 150 to 200 lbs. · 05-10 Ford Mustang Coupe GT 4.6L OHC classified AS with 3200 lbs minimum weight, HR cam permitted. · 10-15 Camaro Full Prep classified AS with 3400 lbs base weight, 3700 lbs over 313 CID, specific head castings and Edelbrock heads permitted. · GT1, GT2, GT3, GTL, GTX may use bonded-glass factory windshields without clips or straps if attached per original specifications. · GT2 Chevrolet SS replaces Dodge Charger; all stock car bodies removed from GT2 in 2021. · GTX Misc. adds Factory Five Type 65 Coupe R Ford 302/351 and 5.0/5.2L NA at 2600 lbs, plus Ferrari 458/488 Challenge, Ford FP350S, Chevrolet C6, Lamborghini Super Trofeo. · 991.2 GT3 Cup Car added to GT2 at 3100 lbs with 63mm throttle body restrictor. · GT2 Acura NSX minimum weight cut from 3000 lbs to 2700 lbs. · GT2 Porsche 991.1 GT3 Cup restrictor size increases from 67 mm to 70 mm. · GT2 Porsche 996/997.1 GT3 Cup minimum weight drops to 2800 lbs. · GT2 Corvette -2019 restrictor reduced from 75 mm to 70 mm.showhide
GT2 rescind GT2 stock car bodies removal #29219cars addedaddedGT2 stock car bodies removal rescinded; 1997-current year commercially available stock car bodywork allowed.
GT2 E&O Typos in Appendix L #29447wordingwordingGT2 Appendix L section 4.8.4.2.10.3.6 renumbered, eliminating subsections .17–.19.
GT2 GT2 wing width wording correction #29469wordingwordingGT2 TA2 wing width maximum clarified to 65 -5/16 inches, including end plates.
SM Radiator E&O Clarifications #29294wordingwordingSM allows aftermarket radiators in original location with stock OEM cooling fan, and permits 1990-1997 cars to install upper radiator seal NA75-50-OK7A.
GT2 GT Category Wording #29193wordingaddedGT1/GT2/GT3/GTL/GTX turbocharging and supercharging now permitted if listed on spec line.
GT2 997.2 E&O link to 27915 #29373weightfaster · weightGT2 997.2 GT3 Cup minimum weight reduced from 3000 to 2900 lbs.
AS Dodge Challenger AS Spec Line Clarification #28698engineslower · engineAS Dodge Challenger 5.7L V8 now requires iron block instead of aluminum, compression to 10.5:1 max, intake valve 12.7 mm, exhaust 12.3 mm, intake timing 188 degrees, exhaust timing 205 degrees.
AS Dodge Challenger AS Spec Line Clarification #2 #28699aeroaeroAS Dodge Challenger 08-14 rear spoiler: 1GL20RXF replaced with 1GL20TZZAB; 82211606 still permitted.
GT2 Request for allowance Trans Am SGT #28951cars addedaddedGT2 BMW E46 M3, E36, Z3, and 5000cc V8 gain Trans Am SGT option: regular shifter 3000 lbs., paddle shifter plus 150 lbs.
GT2 Omitted GT2 fender/hood openings #29171aeroadded · aeroGT2 allows up to four hood/fender louvered panels, max 600 sq inches total, min five slots each, ahead of windscreen.
SM Modifications to prevent failures of Rear Brake Caliper Pin #28953suspension & brakessuspension & brakesSM rear brake caliper may use single bracket under upper retaining bolt head to prevent pin failure.
STL Minimum Weight Determination #27695wordingwordingSTL and STU clarify weight adjustment calculation order: engine adjustments first, then chassis percentage additions, subtractions, and fixed pounds.
STL ST Gurney flap Wicker clarification #29012wordingwordingSTL STU rear wing Gurney flap terminology clarified from wicker to Gurney flap in mounting and chord rules.
AS Support for R-Type Specification Tires #27450wordingunclearAS class pursuing specified list of eligible tires; list details unclear from text provided.
AS Spec Tire Request #27519wordingunclearAS class tire eligibility list under development; no specifications changed yet.
AS Restrictor Plate Change for RP 2011+ Mustang with Coyote Engine #27675wordingunclearAS Coyote Mustang restrictor plate under review for 2021; no change effective yet.
AS 2005-2009 Restricted Prep 4.6 3V #27908engineadded · engineAS Restricted Prep 4.6 3V now permits conversion to 2 valve configuration.
AS Request for 2005-2009 Restricted Prep 4.6 3V Parts #27909engineadded · engineAS Ford Mustang Coupe GT 4.6L 3V Restricted Prep now permits Ford Performance camshaft kit P/N M-6550-3V.
AS Request for Full Preparation Classification for 2010-2014 Camaro #28030wordingunclear2010-2014 Camaro remains classified in AS; no specification changes.
AS Cylinder Heads #28696wordingunclearAS class cylinder head supplier discontinuation; replacement option pending for 2021 season.
AS Request for Max Rotor Diameter Change #28748otherfasterAS Mustang, Capri, Camaro, and Firebird maximum brake rotor diameter increased from 12.2 to 13.1 inches.
AS Request increase rotor diameter #28797wordingunclearunclear
GT2 TA2 Gurney flap wicker clarification #28874wordingwordingTA2 Gurney flap wording clarified: replace 'wicker bill' and 'wicker' with 'Gurney flap' throughout wing specifications.
GT2 STO Gurney flap wicker clarification #28883wordingwordingSTO rear wing rules clarify that wicker is called Gurney flap in two places; no performance change.
GT2 GT Gurney flap wicker clarification #28909wordingwordingGT Gurney flap wording clarified: wickerbill and tab terminology replaced with Gurney flap throughout sections 9.1.2.F.7.b.
STL Request for Addition to GT3 Approved Turbo List #27576cars addedaddedGT3 and STU add Borg-Warner EFR6258 turbocharger to approved turbo lists.
GT2 Request to Adjust Weight of OEM 8.4 Viper #28739weight -50 lbsfaster · weightGT2 Dodge Viper 8.4 OEM minimum weight reduced to 3275 lbs.
GT2 Request to Adjust Weight of OEM Chevrolet Corvette #28896weight -50 lbsfaster · weightGT2 Chevrolet Corvette -2019 OEM minimum weight reduced to 3275 lbs.
STL Request to add 2016-2019 GMX-5 Spec line #28604cars addedaddedSTL adds Mazda MX-5 Global Cup 16-18 at 2450 lbs minimum and 2019 at 2550 lbs minimum.
STL Request to update PN for MX-5 #28622cars addedaddedSTL Mazda MX-5 Club 06-15 allowed header part number 0000-06-5407-NC.
STL Correction - Clarification Honda/Acura B18B engine Letter # 26209 #28873wordingwordingSTL Acura/Honda B18 and B18C engines: restrictor sizes swapped, B18C1 removed from allowed variants.
AS weight adjustments for 2020 season #28785weight -50 lbs
GT2 Request Corvette engine parity #28576weightfaster · weightGT2 Corvette -2019 LS6 allowed to reduce weight by 50 lbs.
STL STL Honda B18 restrictor changes #28794enginefaster · engineSTL Honda B18 loses 53mm restrictor requirement; B18C1 added with 54mm restrictor, B18C1 removed from other variants.
GT2 Request to revisit Panoz GT-S BoP #28280cars addedaddedGT2 Panoz GT-S may use TA2 Choice Engine with any 5-speed H-shift transmission.
STL Change GM LNF 2.0 Allowance to LSJ Engine for Viable STL 2.0 #27884engineadded · engineSTU GM Ecotech LNF now permitted without turbo, with LE5 head and intake manifold, meeting STL specs.
STL Acura/Honda B18C engine chart. Reduce the current 54 mm flat plat #28663engineslower · engineSTL Mazda MZR restrictor reduced from 54 mm to 53 mm.
STL Mazda MZR engine chart. Reduce the current 55 mm flat plate to 53 #28664engineslower · engineSTL Mazda MZR restrictor reduces from 55 mm to 53 mm.
GT2 Request 991.2 Porsche engine displacement verify typo #28194enginefaster · engineGT2 Porsche 991.2 GT3 Cup Car engine displacement corrected to 4.0L from 3.8L.
STL Request to add wheel part numbers #28342cars addedaddedSTL Mazda Spec MX5 Challenge adds approved wheel part numbers 0000-04-5706-GM, 0000-04-5706-SL to notes.
AS Rear Trailing Arms #28007suspension & brakesadded · suspension & brakesAS rear trailing arms may be replaced with tubular arms maintaining stock length and axle location purpose only.
AS Weight reduction for cars running iron heads #28010weightfaster · weightAS Ford and GM full prep cars get increased weight reduction from 150 to 200 lbs.
AS 05-10 Mustang with HR cam classification #28226cars addedadded05-10 Ford Mustang Coupe GT 4.6L OHC classified AS with 3200 lbs minimum weight, HR cam permitted.
AS 10-15 Camaro Full Prep classification #28227cars addedadded10-15 Camaro Full Prep classified AS with 3400 lbs base weight, 3700 lbs over 313 CID, specific head castings and Edelbrock heads permitted.
GT2 Windshield Clips #27323otheraddedGT1, GT2, GT3, GTL, GTX may use bonded-glass factory windshields without clips or straps if attached per original specifications.
GT2 Request to Add Chevrolet SS Body to Appendix L #27898cars addedremoved · cars addedGT2 Chevrolet SS replaces Dodge Charger; all stock car bodies removed from GT2 in 2021.
GT2 Request Factory Five Daytona coupe classification #26308cars addedaddedGTX Misc. adds Factory Five Type 65 Coupe R Ford 302/351 and 5.0/5.2L NA at 2600 lbs, plus Ferrari 458/488 Challenge, Ford FP350S, Chevrolet C6, Lamborghini Super Trofeo.
GT2 Porsche 991.2 GT3 Cup GT2 Classification #27701cars addedadded991.2 GT3 Cup Car added to GT2 at 3100 lbs with 63mm throttle body restrictor.
GT2 Request for Acura NSX Spec Line Changes #27755weightfaster · weightGT2 Acura NSX minimum weight cut from 3000 lbs to 2700 lbs.
GT2 GT2 991.1 restrictor size change #27914enginefaster · engineGT2 Porsche 991.1 GT3 Cup restrictor size increases from 67 mm to 70 mm.
GT2 GT2 996/997.1 weight change #27915weight -100 lbsfaster · weightGT2 Porsche 996/997.1 GT3 Cup minimum weight drops to 2800 lbs.
GT2 GT2/ST Corvette comp adjustment #27920engineslower · engineGT2 Corvette -2019 restrictor reduced from 75 mm to 70 mm.
2:07.203Danny Steyn · fastest of 36 · top 5 within 1.8s
2:07.273Cliff Ira · fastest of 35 · top 5 within 1.4s
134.8Cliff Ira
2:14.552Todd Buras · fastest of 60 · top 5 within 0.2s
2:16.459Elivan Goulart · fastest of 56 · top 5 within 0.4s
119.8Jim Drago
+9.186squal +7.349s
107.2%qual 105.8%
1:50.182Andrew Aquilante · fastest of 24 · top 5 within 4.5s
1:52.475Andrew Aquilante · fastest of 19 · top 5 within 3.3s
162.8Tom Patton
-14.798squal -17.021s
88.4%qual 86.6%
2:02.938Gregory Eaton · fastest of 17 · top 5 within 0.8s
2:03.900James Jost · fastest of 16 · top 5 within 2.1s
153.9James Jost
-3.373squal -4.265s
97.3%qual 96.6%
40 rule changes (STL: 11, SM: 4, GT2: 21, AS: 4)15 cars added · 7 weight · 4 engine · 1 aero · 8 wording · 5 other · AS Spec Mustang (SMG) added as Restricted Prep class. · STL adds Mazda Spec MX-5 Challenge, 2000cc displacement, 2500 lb minimum weight, with mandatory Roush, Penske, Eibach, and other specified components. · AS class ride height minimum clarified: five inches measured at rocker panel, excluding seams and stock effects. · GT2 TA2 cars must meet 2930 lbs minimum weight per current Trans Am rules or Appendix L. · STU allows alternate intake manifolds on case-by-case basis; stock throttle device and manifold otherwise required. · AS Ford Mustang 79-93 non-Cobra drops 100 lbs to 3150; over 313 CID Cobra drops 100 lbs to 3450. · GT2-ST Toyota Supra 3SGTE added: 2.0L, 2900 lbs minimum weight, 43mm restrictor. · Acura NSX all years classified to GT2-ST: 3.5L turbocharged, 3000 lbs minimum, 43mm restrictor, specific aero and turbo required. · GT2 TA2 minimum weight increases 100 lbs to 2930 pounds. · STL Acura/Honda B18 except C engine restrictor increased from 53mm to 54mm flat plate. · GT2 BMW E36/E46 M3 and Z3: 4.5L V8 permitted at 2950 lbs, 5.0L V8 at 3000 lbs, plus Flossman body kit allowed. · GTX tube frame cars now allowed fuel injection with maximum 90mm throttle body. · GTX adds Ligier JS2 R classification with restrictor and minimum weight. · STL and STU ride height measurement clarified: lowest rocker panel point without driver, excluding pinch weld. · GT2 Ford Mustang 5.2L classified at 3300 lbs minimum weight, 82mm single throttle body, carbon fiber body parts allowed. · GT1 and GT2/3/Lite remove ride height ground clearance rules; cars may now touch ground when tires deflate. · GT2/ST Porsche Cayman eligible model years extended from 2005–2011 to 2005–2015. · GT2 Porsche Cayman adds 4.0L with 65mm flat plate restrictor at 2700 lbs minimum weight. · SM fuel pump and filter now permitted as Mazda or OEM equivalent part. · STL adds VW 1.8L R4 20VT 1781 cc, 1781 minimum weight, naturally aspirated only. · STL Mazda Renesis minimum weight reduced to 2700 lbs. · STL Mazda MX-5 Cup brake pad compound now open. · STL adds Acura/Honda B18C1 GSR with 1797cc displacement, 54mm flat plate restrictor required, porting outside 1" allowance prohibited. · STL Mazda 12 and 13B now permit port matching; porting ban removed. · AS adds Spec Mustang SMG classification with 107.1 wheelbase, 3.73 gears, 355mm front and 300mm rear brakes. · SM allows factory Mazda ECU and injector harnesses (P/N 0000-10-020E-99, 0000-10-080D-99) on 1999–2000 model year cars, unmodified. · SM electrical rules reorganized and clarified; alternator now externally regulated only by OEM ECU or master kill switch; harness repair by splicing permitted. · SM tire tread protrusion language removed from GCR 9.1.7.C.5. · GT2 BMW E46 M3, E36, Z3, and 5000cc V8 may now use Flossman body kit. · GT2 TA2 clarifies rules; shock caps to $850, brake calipers to $550, pads to $250/axle, wheels to $175 each; allows carbon fiber rear wing; engine setback 21.75 inches max (A–F) or 24 inches (G); carbureted engine displacement 366 cubic in… · GT2 adds BMW 1 Series E82 2008–2012 with N52B30 engine, 2996 cc, 2140 lbs minimum weight. · GT2 Porsche Cayman 05-11 minimum weight drops to 2800 lbs; STO and X51 motor variants noted at 2950 and 2850 lbs. · GT2 Ford Mustang 05- with Ford Racing 5.2l Aluminator engine classified: 5200cc displacement, 3400 lbs minimum weight, 2×41mm flat plate restrictor. · GT2 Porsche 996/997.1 GT3 Cup: add 3.6L displacement and 2900 lbs minimum weight; remove aftermarket exhaust header allowance for 996. · GT2 Ford Mustang FP350S minimum weight reduced 100 lbs to 3400. · GT2 Ford Mustang 05- EcoBoost added: 3500 cc, 3200 lbs minimum, 41 mm restrictor. · GT2 Mazda RX7 Downing GTS body kit allowed without 75 lbs. weight penalty. · GTX FIA GT3: Audi R8 now 40 mm restrictor and 2900 lbs; BMW Z4 now 70 mm restrictor and 2800 lbs; Ferrari 488 now 35 mm restrictor, TIR, and 3025 lbs. · STL B17 now requires 54mm flat plate restrictor; B18C Type R variants move to 54mm restrictor, weight chart baseline. · STL Mazda Miata removes maximum displacement limit; minimum weight corrected to unspecified figure.showhide
AS Request to add SMG to 9.1.6.B.1 AS Intent #27140cars addedaddedAS Spec Mustang (SMG) added as Restricted Prep class.
STL Request to Classify Spec MX-5 Challenge in STL #27399cars addedaddedSTL adds Mazda Spec MX-5 Challenge, 2000cc displacement, 2500 lb minimum weight, with mandatory Roush, Penske, Eibach, and other specified components.
AS Request Ride Height Clarification #26598wordingwordingAS class ride height minimum clarified: five inches measured at rocker panel, excluding seams and stock effects.
GT2 TA2 Weight Clarification #27077weightslower · weightGT2 TA2 cars must meet 2930 lbs minimum weight per current Trans Am rules or Appendix L.
STL Request clarification for manifold and throttle in STU #27004wordingwordingSTU allows alternate intake manifolds on case-by-case basis; stock throttle device and manifold otherwise required.
AS Request to Revert to 2017 Weights #25885weightfaster · weightAS Ford Mustang 79-93 non-Cobra drops 100 lbs to 3150; over 313 CID Cobra drops 100 lbs to 3450.
GT2 Request to classify Toyota Supra with 3SGTE engine #25185cars addedaddedGT2-ST Toyota Supra 3SGTE added: 2.0L, 2900 lbs minimum weight, 43mm restrictor.
GT2 Request to Classify Acura NSX from T1 to GT2? #26121cars addedaddedAcura NSX all years classified to GT2-ST: 3.5L turbocharged, 3000 lbs minimum, 43mm restrictor, specific aero and turbo required.
GT2 Request for TA2 BOP in GT2 #26509weightslower · weightGT2 TA2 minimum weight increases 100 lbs to 2930 pounds.
STL Request Restrictor Plate correction #26779enginefaster · engineSTL Acura/Honda B18 except C engine restrictor increased from 53mm to 54mm flat plate.
GT2 Request for e36/e46 bmw 4500 cc v8 at 2950lbs in GT2/ST #26106cars addedaddedGT2 BMW E36/E46 M3 and Z3: 4.5L V8 permitted at 2950 lbs, 5.0L V8 at 3000 lbs, plus Flossman body kit allowed.
GT2 Request GTX Fuel injection for previous GT-1 tube frame cars #26141engineadded · engineGTX tube frame cars now allowed fuel injection with maximum 90mm throttle body.
GT2 Request to Classify Ligier JS2 R #26535cars addedaddedGTX adds Ligier JS2 R classification with restrictor and minimum weight.
STL Request Ride Height Clarification #26597wordingwordingSTL and STU ride height measurement clarified: lowest rocker panel point without driver, excluding pinch weld.
GT2 Request Ford Perfomance 5.2L crate engine FPR clarification #26159cars addedaddedGT2 Ford Mustang 5.2L classified at 3300 lbs minimum weight, 82mm single throttle body, carbon fiber body parts allowed.
GT2 Request Ride Height Clarification #26600wordingfasterGT1 and GT2/3/Lite remove ride height ground clearance rules; cars may now touch ground when tires deflate.
GT2 Request Porsche Cayman year classification #26241cars addedaddedGT2/ST Porsche Cayman eligible model years extended from 2005–2011 to 2005–2015.
STL Request to reduce weight of RX8 with Renesis rotary #25781weight -100 lbsfaster · weightSTL Mazda Renesis minimum weight reduced to 2700 lbs.
STL Request for Open Brake Pads On Mazda MX-5 Cup NC #25821otheraddedSTL Mazda MX-5 Cup brake pad compound now open.
STL Request to clarify B18C1 GSR Honda B motor table #26209cars addedaddedSTL adds Acura/Honda B18C1 GSR with 1797cc displacement, 54mm flat plate restrictor required, porting outside 1" allowance prohibited.
STL Port Matching #26415enginefaster · engineSTL Mazda 12 and 13B now permit port matching; porting ban removed.
AS SMG Mustang eligibility in American sedan #26224cars addedaddedAS adds Spec Mustang SMG classification with 107.1 wheelbase, 3.73 gears, 355mm front and 300mm rear brakes.
SM Request 99-00 replacement Wire harnesses #25602otheraddedSM allows factory Mazda ECU and injector harnesses (P/N 0000-10-020E-99, 0000-10-080D-99) on 1999–2000 model year cars, unmodified.
SM Organize and Clarify 9.1.7.C.1.o. #25913wordingwordingSM electrical rules reorganized and clarified; alternator now externally regulated only by OEM ECU or master kill switch; harness repair by splicing permitted.
SM Strike Tire Tread Language #26123wordingremovedSM tire tread protrusion language removed from GCR 9.1.7.C.5.
GT2 ST/GT2 BMW Flossman Kit Clarification #22138aeroadded · aeroGT2 BMW E46 M3, E36, Z3, and 5000cc V8 may now use Flossman body kit.
GT2 Request Clarification/Revision of Appendix L (2013 TA2 Rules) #25110wordingwordingGT2 TA2 clarifies rules; shock caps to $850, brake calipers to $550, pads to $250/axle, wheels to $175 each; allows carbon fiber rear wing; engine setback 21.75 inches max (A–F) or 24 inches (G); carbureted engine displacement 366 cubic in…
GT2 Request to classify BMW E82 (1 series) into GT2 #25539cars addedaddedGT2 adds BMW 1 Series E82 2008–2012 with N52B30 engine, 2996 cc, 2140 lbs minimum weight.
GT2 2010 Cayman Street Tuner Into an STO Car,Addendum #25545weightfaster · weightGT2 Porsche Cayman 05-11 minimum weight drops to 2800 lbs; STO and X51 motor variants noted at 2950 and 2850 lbs.
GT2 Request - Classify Ford Performance 5.2l #25716cars addedaddedGT2 Ford Mustang 05- with Ford Racing 5.2l Aluminator engine classified: 5200cc displacement, 3400 lbs minimum weight, 2×41mm flat plate restrictor.
GT2 Request for Ford FP 350s Weight Reduction #25806weightfaster · weightGT2 Ford Mustang FP350S minimum weight reduced 100 lbs to 3400.
GT2 Request to Classify EcoBoost Mustang #25842cars addedaddedGT2 Ford Mustang 05- EcoBoost added: 3500 cc, 3200 lbs minimum, 41 mm restrictor.
GT2 Request to Remove Mazda RX 7 Body Work Penalty #26024weightfaster · weightGT2 Mazda RX7 Downing GTS body kit allowed without 75 lbs. weight penalty.
GT2 GTX Homologation table update #26034otherunclearGTX FIA GT3: Audi R8 now 40 mm restrictor and 2900 lbs; BMW Z4 now 70 mm restrictor and 2800 lbs; Ferrari 488 now 35 mm restrictor, TIR, and 3025 lbs.
STL Request to equalize FPR Reduction on all B-Series Vtec Engines #24746enginefaster · engineSTL B17 now requires 54mm flat plate restrictor; B18C Type R variants move to 54mm restrictor, weight chart baseline.
STL Request E&O for Mazda Miata Spec Line #25955otherunclearSTL Mazda Miata removes maximum displacement limit; minimum weight corrected to unspecified figure.
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 STL's best on the same day: the weather, the track and its configuration cancel out, so one figure compares across tracks and years where lap times cannot. 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.