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BoP Lab / Buttonwillow Raceway Park

GT1 vs P2 pace at Buttonwillow Raceway Park

Class · click a class to switch, + to compare alongside (up to 4)
Reference class · the others' laps as a share of this one's at the same event, so years compare despite weather; + a class above to measure against it
Track configuration

Quickest here: GT1 1:39.857 Michael McAleenan, Cal Club 2026 qualifying · P2 1:09.928 Tim Day Jr, Cal Club 2023 qualifying

1:101:151:201:251:301:351:401:4525 rule changes between Cal Club 2023 and Cal Club 202525 ▾5 rule changes between Cal Club 2025 and Cal Club 20265 ▾GT1 race best at Cal Club 2025: 1:42.305 (Michael Lewis)GT1 race best at Cal Club 2026: 1:41.045 (Michael McAleenan)GT1 qualifying best at Cal Club 2025: 1:43.967 (Michael Lewis)GT1 qualifying best at Cal Club 2026: 1:39.857 (Michael McAleenan)P2 race best at Cal Club 2026: 1:39.758 (Tim Day Jr)P2 qualifying best at Cal Club 2023: 1:09.928 (Tim Day Jr)P2 qualifying best at Cal Club 2026: 1:37.278 (Tim Day Jr)Cal Club 20232023Cal Club 20252025Cal Club 20262026
GT1P2solid race · dashed qualifying · slower is lower
97.5%98%98.5%99%99.5%100%25 rule changes between Cal Club 2023 and Cal Club 202525 ▾5 rule changes between Cal Club 2025 and Cal Club 20265 ▾GT1 race best at Cal Club 2025: 100.0% of GT1's (Michael Lewis)GT1 race best at Cal Club 2026: 100.0% of GT1's (Michael McAleenan)GT1 qualifying best at Cal Club 2025: 100.0% of GT1's (Michael Lewis)GT1 qualifying best at Cal Club 2026: 100.0% of GT1's (Michael McAleenan)P2 race best at Cal Club 2026: 98.7% of GT1's (Tim Day Jr)P2 qualifying best at Cal Club 2026: 97.4% of GT1's (Tim Day Jr)Cal Club 20232023Cal Club 20252025Cal Club 20262026
GT1P2solid race · dashed qualifying · each class's best lap as a share of GT1's at the same event (the reference class, changeable above); 100% is level, higher is quicker
EventGT1P2
Qual bestRace bestTrapQual bestRace bestTrapvs GT1% of GT1
Cal Club 2026 CALCL262026-02-211:39.857Michael McAleenan · fastest of 2-4.110s (-3.95%)1:41.045Michael McAleenan · fastest of 2-1.260s (-1.23%)167.6Michael McAleenan+53.8 mph (+47.3%)1:37.278Tim Day Jr · only car+27.350s (+39.11%)1:39.758Tim Day Jr · only car155.4Tim Day Jr-1.287squal -2.579s98.7%qual 97.4%
5 rule changes (GT1: 5)4 cars added · 1 weight · GT1 adds Porsche 992.1 GT3 Cup (2022-2025) with OEM ABS, traction control, RSR bumper, canards, and any exhaust allowed. · GT1-ST Acura NSX GT3 EVO 22 weight drops 100 lbs to 3000 lbs. · Acura NSX GT3 EVO 22 reclassified from GT1 to GT1-ST with 3100 lbs minimum weight. · GT1 LS Limited Prep Engine expands to include LS1, LS2, LS3, LS6 with 11:1 max compression. · Acura NSX GT3 EVO 22 classified in GT1 with 3500cc twin turbo V-6, 3100 lbs, max RPM 7500.showhide
  • GT1 Request for Addition of Porsche 992.1 GT3 Cup into GT1 #39322cars addedcars addedGT1 adds Porsche 992.1 GT3 Cup (2022-2025) with OEM ABS, traction control, RSR bumper, canards, and any exhaust allowed.
  • GT1 NSX Parity With Other GT3s Let Alone a GT1 Car #39311weight -100 lbsfasterGT1-ST Acura NSX GT3 EVO 22 weight drops 100 lbs to 3000 lbs.
  • GT1 RM 25-06 GT1 reclassify the Acura NSX GT3 EVO 22 to GT1-ST #39101cars addedcars addedAcura NSX GT3 EVO 22 reclassified from GT1 to GT1-ST with 3100 lbs minimum weight.
  • GT1 Correction to Limited prep LS Chevy engine for GT1 #38902cars addedcars addedGT1 LS Limited Prep Engine expands to include LS1, LS2, LS3, LS6 with 11:1 max compression.
  • GT1 Request to Classify Acura NSX GT3 Evo 22 #37367cars addedcars addedAcura NSX GT3 EVO 22 classified in GT1 with 3500cc twin turbo V-6, 3100 lbs, max RPM 7500.
Cal Club 2025 CALCL252025-02-221:43.967Michael Lewis · only car1:42.305Michael Lewis · only car113.8Michael Lewis
25 rule changes (GT1: 15, P2: 10)4 cars added · 3 engine · 3 induction · 2 weight · 1 aero · 12 wording · GT1 LS1 Limited Prep engine added, 2600 lbs with driver, 383 cubic inches max, hydraulic roller cam, 750 cfm carb. · TA2 rear wing height rule clarified: OEM aerodynamic devices exempt from peak-of-roof requirement. · GT1-ST restrictor sizes removed for 13 cars; new specs not printed in letter. · GT1-ST Lamborghini Huracan GT3 Evo and 2019+ GT3 both shift to Unrestricted from 39mm and 52mm restrictors. · P2 2000cc Pinto engine car minimum weight set to 1335 lbs. · GT1 Mazda 26B engine classified at 2850 lbs minimum weight. · GT2-ST Acura NSX minimum weight raised to 3000 lbs, restrictor increased to 45mm TIR. · GT1 Camaro 1993-2002 classification updated; 2010- model separately classified. · P2 Spec ECU engine modifications clarified: oil system, ECU, and exhaust unrestricted only. · P2 FIA Group CN spec notes clarified: Series changed to Challenge, documentation requirement moved to online link. · 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. · Lamborghini Huracan GT3 EVO(1) and GT3 added to GT1-ST at 3000 and 3100 lbs minimum weight respectively. · GT1 Trick Flow Specialties Ultra 18 Degree GM Cylinder Head Part #TFS-3181T001-CO1 allowed. · P2 AMAC modified engine range clarified to 2008 and older stock engines only, restrictor 38mm, weight 1025 lbs. · P2 Suzuki GSX-R1000 07/08 engine crankcase may swap to GSX-S1000 16/19 part #11301-04840. · GTL spec lines moved to contiguous position with GT2 and GT3; GTA category and spec lines renumbered and moved behind GTL. · P2 Table 1 corrects engine date ranges and brand specifications for Stock and Modified engines across multiple car models. · Fields Cardinal V8 classified in GT1 with Ford V8 engine, 4.9L displacement, 2100 lbs minimum weight. · P2 side body height requirement clarified: outermost surface between wheel openings must equal front axle centerline height. · P2 closed cockpit single seat cars now prohibited unless specifically allowed in Table 1. · GT1 Mercedes AMG GT3 16-19 preparation wording changed to per FIA GT3 homologation. · P2 engine table wording updated; redundant effective date language removed. · P2 motorcycle engines: 2011+ Kawasaki restrictor reduced to 34mm, minimum weight raised to 1100 lbs; 2009+ other brands weight raised to 1100 lbs.showhide
  • GT1 Addition of a limited prep LS Chevy engine for GT1 #37045cars addedcars addedGT1 LS1 Limited Prep engine added, 2600 lbs with driver, 383 cubic inches max, hydraulic roller cam, 750 cfm carb.
  • GT1 Correct language regarding OEM Areo Devices #37137wordingwordingTA2 rear wing height rule clarified: OEM aerodynamic devices exempt from peak-of-roof requirement.
  • GT1 GT1-ST Adjustments #37481inductionunclearGT1-ST restrictor sizes removed for 13 cars; new specs not printed in letter.
  • GT1 Lamborghini Huracan GT3 Evo Restrictor Help #36254inductionfasterGT1-ST Lamborghini Huracan GT3 Evo and 2019+ GT3 both shift to Unrestricted from 39mm and 52mm restrictors.
  • P2 2000 cc Pinto Engine Car Weight #37187weightslowerP2 2000cc Pinto engine car minimum weight set to 1335 lbs.
  • GT1 Request to Classify Mazda 26B Engine #36230cars addedcars addedGT1 Mazda 26B engine classified at 2850 lbs minimum weight.
  • GT1 Request for Spec Line 1010 Reconsideration #35009weight +300 lbsslowerGT2-ST Acura NSX minimum weight raised to 3000 lbs, restrictor increased to 45mm TIR.
  • GT1 Camaro 1993- and 2010- #35652wordingwordingGT1 Camaro 1993-2002 classification updated; 2010- model separately classified.
  • P2 CN Spec ECU #35835wordingwordingP2 Spec ECU engine modifications clarified: oil system, ECU, and exhaust unrestricted only.
  • P2 E&O - Correct FIA Group CN spec line notes #35900wordingwordingP2 FIA Group CN spec notes clarified: Series changed to Challenge, documentation requirement moved to online link.
  • GT1 Rear Blade Spoiler Clarification #35261aerofasterGT1, GT2, GT3, GTL, GTX rear spoiler maximum surface area limit of 295.0 square inches removed.
  • GT1 GT Direct Injection allowance and rules #35437enginefasterGT1/GT2/GT3/GTL/GTX Direct Injection now permitted if OE, using only OE pump, hoses, injectors.
  • GT1 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.
  • GT1 Request for Acceptance of Lamborghini Huracan GT3 in GT1-ST #34929cars addedcars addedLamborghini Huracan GT3 EVO(1) and GT3 added to GT1-ST at 3000 and 3100 lbs minimum weight respectively.
  • GT1 Cylinder heads #35040wordingwordingGT1 Trick Flow Specialties Ultra 18 Degree GM Cylinder Head Part #TFS-3181T001-CO1 allowed.
  • P2 E&O - Clarify B.1 modified engine range in AMAC spec lines #35225wordingwordingP2 AMAC modified engine range clarified to 2008 and older stock engines only, restrictor 38mm, weight 1025 lbs.
  • P2 Replacement Engine Crankcase for 07/08 Suzuki GSX-R1000 Engines #35340engineunclearP2 Suzuki GSX-R1000 07/08 engine crankcase may swap to GSX-S1000 16/19 part #11301-04840.
  • GT1 Errors in GTCS Headings and Use of the Terms Category and ClassChange existing GTL and GTA Rules #34453wordingwordingGTL spec lines moved to contiguous position with GT2 and GT3; GTA category and spec lines renumbered and moved behind GTL.
  • P2 Correct Table 1 for Engine Date Range Specifications #35182wordingwordingP2 Table 1 corrects engine date ranges and brand specifications for Stock and Modified engines across multiple car models.
  • GT1 Please classify Fields Cardinal V8 #33784cars addedcars addedFields Cardinal V8 classified in GT1 with Ford V8 engine, 4.9L displacement, 2100 lbs minimum weight.
  • P2 Clarify minimum side body height requirement #34143wordingwordingP2 side body height requirement clarified: outermost surface between wheel openings must equal front axle centerline height.
  • P2 Clarify closed cockpit single seat car allowance #34144wordingwordingP2 closed cockpit single seat cars now prohibited unless specifically allowed in Table 1.
  • GT1 Mercedes AMG GT3 Notes #33804wordingwordingGT1 Mercedes AMG GT3 16-19 preparation wording changed to per FIA GT3 homologation.
  • P2 Remove redundant effective date language and update engine table #34012wordingwordingP2 engine table wording updated; redundant effective date language removed.
  • P2 E&O - Correct dimensional equivalents #34038engineslowerP2 motorcycle engines: 2011+ Kawasaki restrictor reduced to 34mm, minimum weight raised to 1100 lbs; 2009+ other brands weight raised to 1100 lbs.
Cal Club 2023 CALCL232023-02-241:09.928Tim Day Jr · fastest of 2
67 earlier rule changes on record, in force before Cal Club 2023 (from 2019)14 cars added · 8 induction · 7 weight · 6 engine · 4 aero · 2 tyres & wheels · 25 wording · 1 other · GT1 sequential transmission weight penalty reduced from 50 to 25 lbs. · GT1-ST Porsche 992 GT3 Cup classified with 3997cc displacement, 2950 lbs minimum weight. · Sebeco NP01-EVO and Elan NP01 Mazda 2.0L MZR added to P2, 1600 lb minimum, no restrictor required. · P2 Radical SR3/SR4/Cup/Club Sport/Pro-Sport/PR6 removes assisted shifting requirement across all spec lines. · P2 chassis rules clarified to allow composite materials in non-fully-composite construction; anti-intrusion panel attachment standardized; Stohr and converted F600 cars added with specific allowances. · Unable to summarize: the change to P2 Engine Table Spec Line B.1 is not detailed in the provided text. · GT2 TA2 and GTA throttle body part numbers updated to GM 90mm electronic #12570790 or Edelbrock 90mm mechanical #33869 or #3870. · GT1 Trans Am bodywork weight penalty reduced from 100 lbs to 75 lbs. · GT1 Chevrolet RO7, Ford FR9, and Dodge R7 weight penalties reduced from 50 to 25 lbs. · GT taillights may now be original style or a panel graphic with functioning red LED brake lamps; wording change only. · GT1 TransAm bodywork allowed with 100 lb. weight penalty. · P2 chassis construction rules clarified: fully composite or partially composite requiring composite for mobility allowed; partial composite must roll without composite parts. · P2 classification wording cleaned up in GCR section 9.1.8.C and Contents. · P2 Oldsmobile cam rules clarify aftermarket manufacturer requirements; wording only. · Mercedes Benz AMG GT3 classified in GT1 at 3050 lbs with 40mm restrictors, prepared per FIA GT3 homologation. · GT1 wheels: 18-inch tyres get wider rear allowance, from 13 to 14 MAX inches. · P2 adds Beasley B2 spec line with 1350 lbs, Mazda 12A, 40.5mm venturi, 16.5in wing. · P2 wing specs correct terminology from 'cord' to 'chord' for 16.5in single or dual element wings. · P2 Converted F5 cars reclassified as Converted F500 cars; suspension must comply with F500 requirements, minimum width 55 inches. · GT1 allows 17-inch wheels newly; 18-inch wheels require 50 lb penalty; maximum widths 12 front/13 rear, or 13/14 for 18-inch. · P2 motorcycle engines increase to 1505cc max, two-stroke to 1205cc max; automotive engines gain 50 lbs minimum weight to 1350. · P2 Control Area definition narrowed; aerodynamic attachments and vertical structures like turning vanes now prohibited. · P2 Engine Table Spec Line B.1 changed effective 1-1-22, details not provided in excerpt. · P2 Control Area definition clarified: floor extensions and aerodynamic attachments on bottom or top side now explicitly included. · GT3 Fun Cup Beetle EVO3 classified with 1984 cc sealed SOHC engine, 2060 lbs minimum weight. · P2 CN Honda K20A-FD2 engine rebuild rules clarified: machining prohibition replaced with specific restrictions on balancing, porting, polishing, valve jobs, cylinder honing. · GTA part numbers updated: 0-80541-1 to 0-80541-2 in two sections and 6010 to 6014X in TA2 Appendix. · Converted F5 cars in P2 minimum width reduced to 55 inches from F5 spec. · P2 clarifies minimum body width requirement between front and rear wheels for Ralt RT40, RT41, Swift 008, 014. · P2 tonneau covers now allowed to meet minimum dimensions; equipment attachment requirements clarified. · P2 multiple chassis models remove effective dates from Table 1 specifications. · P2 engines limited to 4 valves per cylinder maximum across all three spec lines. · P2 adds new spec line for 2-cycle 3-cylinder engine up to 820cc with 10 front and 14-15 rear wheel width. · P2 Honda K20A-FD2 intake restrictor reduced from 55mm to 50mm, making cars faster. · GT1, GT2, GT3, GTL, GTX now permit turbocharging/supercharging if listed on spec line. · P2 rear wing requirements clarified: standard wing 6×12 inches, end plates 14-inch square; alternate 110cm width wing 9×18 inches, end plates 14×18 inches. · GT1 adds Trans Am spec engines: Chevrolet R07, Ford FR9, Dodge R7, each with 50 lbs. weight penalty. · 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. · GT1 Gurney flap wicker clarification: terminology standardized from lips/tabs/wicker to flaps throughout specifications. · GT classes clarify Gurney flap wording, replacing wickerbill/tab terminology with flap; specifications unchanged. · Elan NP01 classified in P2 Table 1 as Spec Line car with 2000cc displacement and P2 Engine Table restrictor. · P2 Enterprises Sports Racer adds 55mm flat plate intake restrictor Part # WM303013 as alternative to SIR. · P2 Enterprise Sports Racer 2.3L engine now requires SIR or Flat Plate restrictor sized in 0.5mm increments. · P2 fly-by-wire throttle control wording clarified: stock ECUs with drive-by-wire must activate original throttle shaft mechanism. · GT1, GT2, GT3, GTL, GTX may omit windshield clips if factory glass is bonded per original specifications. · GT2/ST Ford 5.0L Coyote 3rd Gen OEM added at 3200 lbs with Boss intake manifold permitted. · Factory Five Type 65 Coupe R with Ford 302/351 or 5.0/5.2L NA added to GTX-MISC at 2600 lbs. · GT1 sequential shifting transmission weight penalty reduced from 75 to 50 lbs. · GT1 non-18-inch-wheel cars now get 18-inch wheels with 50 lb penalty, down from 100 lb. · GT1 Spec Lines allows 5 Star NASCAR Camaro 2018+ body for General Motors Corporation. · P2 adds BMW to motorcycle-based engine options in 4-cycle line alongside Kawasaki, Suzuki, Yamaha, Honda. · P2 Honda K20A-FD2 non-composite chassis must use 55mm flat plate intake restrictor at 1500 lbs minimum weight. · GT1 Porsche 944/968 classified: 2981cc twin turbo, 2585 lbs minimum weight. · P2 motorcycle engines: Stock restrictor 36.5mm to 35mm, modified 37.5mm to 34mm; B.5 restrictor 37.5mm to 33mm. All weights increase 25 lbs. · GT1 allows Trans Am rear wing, 12" chord, 72" span, 1/2" wicker, 100 sq in endplates, no weight penalty. · P2 cars limited to power application on maximum two wheels, effective 2019-07-01. · P2 Enterprise minimum weight increases to 1375 lbs; peak horsepower of sealed ESR engine reduced per CRB specification. · 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. · 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. · P2 stock engine restrictor shrinks to 35.0mm and weight rises to 1025 lbs; modified engine restrictor to 34.0mm, weight to 1125 lbs; line B.5 restrictor to 33.0mm, weight to 1185 lbs. · P2 Line A.1 restrictor reduced from 40mm to 38mm. · GTX FIA GT3: Audi R8 40mm restrictor 2900 lbs, BMW Z4 70mm 2800 lbs, Ferrari 488 35mm restrictor 3025 lbs classified. · P2 Spec Line cars now allow 1345cc Hayabusa stock engines at 1050 lbs with 30mm restrictor. · P2 Group CN Honda K20A-FD2 55mm restrictor implementation delayed from 1/1/2019 to 3/1/2019. · P2 Honda K20A-FD2 in CN chassis must use stock intake manifold with 64mm throttle body and 55mm restrictor at 1500 lbs minimum weight.showhide
  • GT1 Sequential Transmission Weight Penalty #33503weightfasterGT1 sequential transmission weight penalty reduced from 50 to 25 lbs.
  • GT1 GT1 Porsche 992 #33730cars addedcars addedGT1-ST Porsche 992 GT3 Cup classified with 3997cc displacement, 2950 lbs minimum weight.
  • P2 Request to Classify Sebeco NP01 #33378cars addedcars addedSebeco NP01-EVO and Elan NP01 Mazda 2.0L MZR added to P2, 1600 lb minimum, no restrictor required.
  • P2 Radical spec line clarifications #33485wordingwordingP2 Radical SR3/SR4/Cup/Club Sport/Pro-Sport/PR6 removes assisted shifting requirement across all spec lines.
  • P2 E&O original class intent #33519wordingwordingP2 chassis rules clarified to allow composite materials in non-fully-composite construction; anti-intrusion panel attachment standardized; Stohr and converted F600 cars added with specific allowances.
  • P2 Update Engine Table Spec Line B.1 #33608engineunclearUnable to summarize: the change to P2 Engine Table Spec Line B.1 is not detailed in the provided text.
  • GT1 GT2 (TA2)/GTA Part Number Update #33315wordingwordingGT2 TA2 and GTA throttle body part numbers updated to GM 90mm electronic #12570790 or Edelbrock 90mm mechanical #33869 or #3870.
  • GT1 Request to Reduce Trans Am Bodywork Weight Penalty #33331weightfasterGT1 Trans Am bodywork weight penalty reduced from 100 lbs to 75 lbs.
  • GT1 Request for Reduction in FR9 Weight Penalty #33332weightfasterGT1 Chevrolet RO7, Ford FR9, and Dodge R7 weight penalties reduced from 50 to 25 lbs.
  • GT1 Tail lights on all GT category race cars. #32799wordingwordingGT taillights may now be original style or a panel graphic with functioning red LED brake lamps; wording change only.
  • GT1 GT-1/TransAm rules simplification/modernizing #32763weightslowerGT1 TransAm bodywork allowed with 100 lb. weight penalty.
  • P2 E&O Clarification of Chassis Construction Requirements #32469wordingwordingP2 chassis construction rules clarified: fully composite or partially composite requiring composite for mobility allowed; partial composite must roll without composite parts.
  • P2 Clean up P2 wording #32525wordingwordingP2 classification wording cleaned up in GCR section 9.1.8.C and Contents.
  • P2 After Market to Aftermarket #32373wordingwordingP2 Oldsmobile cam rules clarify aftermarket manufacturer requirements; wording only.
  • GT1 Mercedes Benz AMG GT3 in GT1 #31883cars addedcars addedMercedes Benz AMG GT3 classified in GT1 at 3050 lbs with 40mm restrictors, prepared per FIA GT3 homologation.
  • GT1 Wheel Widths #32205tyres & wheelsfasterGT1 wheels: 18-inch tyres get wider rear allowance, from 13 to 14 MAX inches.
  • P2 Add spec line for Beasley B2 #32147cars addedcars addedP2 adds Beasley B2 spec line with 1350 lbs, Mazda 12A, 40.5mm venturi, 16.5in wing.
  • P2 E&O Table 1 spec line wing terminology #32148wordingwordingP2 wing specs correct terminology from 'cord' to 'chord' for 16.5in single or dual element wings.
  • P2 E&O class name #32196wordingwordingP2 Converted F5 cars reclassified as Converted F500 cars; suspension must comply with F500 requirements, minimum width 55 inches.
  • GT1 Wheel Widths #31844tyres & wheelsslowerGT1 allows 17-inch wheels newly; 18-inch wheels require 50 lb penalty; maximum widths 12 front/13 rear, or 13/14 for 18-inch.
  • P2 E&O Engine section #31969enginefasterP2 motorcycle engines increase to 1505cc max, two-stroke to 1205cc max; automotive engines gain 50 lbs minimum weight to 1350.
  • P2 E&O letter #31539 – Control Area definition #31783aeroslowerP2 Control Area definition narrowed; aerodynamic attachments and vertical structures like turning vanes now prohibited.
  • P2 BoP adjustment effective 1-1-22 #31538wordingunclearP2 Engine Table Spec Line B.1 changed effective 1-1-22, details not provided in excerpt.
  • P2 E&O clarification of "Control Area" definition #31539wordingwordingP2 Control Area definition clarified: floor extensions and aerodynamic attachments on bottom or top side now explicitly included.
  • GT1 Request car classification #31032cars addedcars addedGT3 Fun Cup Beetle EVO3 classified with 1984 cc sealed SOHC engine, 2060 lbs minimum weight.
  • P2 P2 CN Engine Rebuild Clarification #31000wordingwordingP2 CN Honda K20A-FD2 engine rebuild rules clarified: machining prohibition replaced with specific restrictions on balancing, porting, polishing, valve jobs, cylinder honing.
  • GT1 Request to Update GTA Obsolete Part Numbers #30615wordingwordingGTA part numbers updated: 0-80541-1 to 0-80541-2 in two sections and 6010 to 6014X in TA2 Appendix.
  • P2 F5 P2 Conversion #30856aerofasterConverted F5 cars in P2 minimum width reduced to 55 inches from F5 spec.
  • P2 Clarify minimum body width requirement #30859wordingwordingP2 clarifies minimum body width requirement between front and rear wheels for Ralt RT40, RT41, Swift 008, 014.
  • P2 E&O tonneau cover provision in cockpit opening section #30459wordingwordingP2 tonneau covers now allowed to meet minimum dimensions; equipment attachment requirements clarified.
  • P2 Remove effective dates in Table 1 #30468wordingwordingP2 multiple chassis models remove effective dates from Table 1 specifications.
  • P2 E&O Maximum Valves Per Cylinder #30560engineengineP2 engines limited to 4 valves per cylinder maximum across all three spec lines.
  • P2 Add a new spec line for a 2-cycle, 3-cylinder engine up to 820cc #30272cars addedcars addedP2 adds new spec line for 2-cycle 3-cylinder engine up to 820cc with 10 front and 14-15 rear wheel width.
  • P2 Balance of Performance adjustments effective 01-01-2021 #29822inductionfasterP2 Honda K20A-FD2 intake restrictor reduced from 55mm to 50mm, making cars faster.
  • GT1 GT Category Wording #29193wordingunclearGT1, GT2, GT3, GTL, GTX now permit turbocharging/supercharging if listed on spec line.
  • P2 E&O clarification of P2 rear wing requirements #29205aeroaeroP2 rear wing requirements clarified: standard wing 6×12 inches, end plates 14-inch square; alternate 110cm width wing 9×18 inches, end plates 14×18 inches.
  • GT1 Request to Allow New Trans Am Legal Engines in GT1 #29002engineslowerGT1 adds Trans Am spec engines: Chevrolet R07, Ford FR9, Dodge R7, each with 50 lbs. weight penalty.
  • GT1 TA2 Gurney flap wicker clarification #28874wordingwordingTA2 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.
  • GT1 STO Gurney flap wicker clarification #28883wordingwordingSTO rear wing wording clarified: 'wicker' changed to 'Gurney flap' in maximum chord and mounting height rules.
  • GT1 GT1 Gurney flap wicker clarification #28886wordingwordingGT1 Gurney flap wicker clarification: terminology standardized from lips/tabs/wicker to flaps throughout specifications.
  • GT1 GT Gurney flap wicker clarification #28909wordingwordingGT classes clarify Gurney flap wording, replacing wickerbill/tab terminology with flap; specifications unchanged.
  • P2 Classify Elan NP01 in P2 Table 1 #28812cars addedcars addedElan NP01 classified in P2 Table 1 as Spec Line car with 2000cc displacement and P2 Engine Table restrictor.
  • P2 SCCA Enterprises ESR / P2 engine restrictor testing #28669engineengineP2 Enterprises Sports Racer adds 55mm flat plate intake restrictor Part # WM303013 as alternative to SIR.
  • P2 Add ESR inlet restrictor #27869inductionslowerP2 Enterprise Sports Racer 2.3L engine now requires SIR or Flat Plate restrictor sized in 0.5mm increments.
  • P2 Request for Fly by Wire Rule Wording Change #28247wordingwordingP2 fly-by-wire throttle control wording clarified: stock ECUs with drive-by-wire must activate original throttle shaft mechanism.
  • GT1 Windshield Clips #27323wordingwordingGT1, GT2, GT3, GTL, GTX may omit windshield clips if factory glass is bonded per original specifications.
  • GT1 Request to classify the Ford Coyote 3rd Gen OEM #27146cars addedcars addedGT2/ST Ford 5.0L Coyote 3rd Gen OEM added at 3200 lbs with Boss intake manifold permitted.
  • GT1 Request Factory Five Daytona coupe classification #26308cars addedcars addedFactory Five Type 65 Coupe R with Ford 302/351 or 5.0/5.2L NA added to GTX-MISC at 2600 lbs.
  • GT1 Request to Adjust Transmission Penalty #27750weightfasterGT1 sequential shifting transmission weight penalty reduced from 75 to 50 lbs.
  • GT1 Request to Reduce Additional Weight for 18 #27751weightfasterGT1 non-18-inch-wheel cars now get 18-inch wheels with 50 lb penalty, down from 100 lb.
  • GT1 Request for Five Star Nascar Compliant Bodywork #27756cars addedcars addedGT1 Spec Lines allows 5 Star NASCAR Camaro 2018+ body for General Motors Corporation.
  • P2 Request for addition of BMW Engine in P2 Engine Table #27821cars addedcars addedP2 adds BMW to motorcycle-based engine options in 4-cycle line alongside Kawasaki, Suzuki, Yamaha, Honda.
  • P2 Update Engine Table Line E notes #27414inductionslowerP2 Honda K20A-FD2 non-composite chassis must use 55mm flat plate intake restrictor at 1500 lbs minimum weight.
  • GT1 Request to classify Porsche 944/968 #26242cars addedcars addedGT1 Porsche 944/968 classified: 2981cc twin turbo, 2585 lbs minimum weight.
  • P2 Update P2 Engine Table spec lines to reflect 3/1/2019 #27254inductionslowerP2 motorcycle engines: Stock restrictor 36.5mm to 35mm, modified 37.5mm to 34mm; B.5 restrictor 37.5mm to 33mm. All weights increase 25 lbs.
  • GT1 Clarify Trans Am Legal Bodywork and Wing #26953aerofasterGT1 allows Trans Am rear wing, 12" chord, 72" span, 1/2" wicker, 100 sq in endplates, no weight penalty.
  • P2 E&O Transmissions #27006otherslowerP2 cars limited to power application on maximum two wheels, effective 2019-07-01.
  • P2 Request to restrict all cars #26246weightslowerP2 Enterprise minimum weight increases to 1375 lbs; peak horsepower of sealed ESR engine reduced per CRB specification.
  • GT1 Request GTX Fuel injection for previous GT-1 tube frame cars #26141inductionfasterGTX tube frame cars gain fuel injection with 90mm maximum throttle body size.
  • GT1 Request to Classify Ligier JS2 R #26535cars addedcars addedLigier JS2 R classified in GTX, no performance parameters specified in filing.
  • GT1 Request Ride Height Clarification #26600wordingwordingGT1 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.
  • P2 Change Engine Table Lines B.1 & B.5 #25777inductionslowerP2 stock engine restrictor shrinks to 35.0mm and weight rises to 1025 lbs; modified engine restrictor to 34.0mm, weight to 1125 lbs; line B.5 restrictor to 33.0mm, weight to 1185 lbs.
  • P2 Change Line A.1 restrictor size #26429inductionslowerP2 Line A.1 restrictor reduced from 40mm to 38mm.
  • GT1 GTX Homologation table update #26034cars addedcars addedGTX FIA GT3: Audi R8 40mm restrictor 2900 lbs, BMW Z4 70mm 2800 lbs, Ferrari 488 35mm restrictor 3025 lbs classified.
  • P2 Request to Allow 1345cc Hayabusa Engines for Spec Line P2 Cars #25595enginefasterP2 Spec Line cars now allow 1345cc Hayabusa stock engines at 1050 lbs with 30mm restrictor.
  • P2 Change CN inlet restrictor implementation date #25816wordingwordingP2 Group CN Honda K20A-FD2 55mm restrictor implementation delayed from 1/1/2019 to 3/1/2019.
  • P2 Clarify Honda K20A-FD2 parts requirement #25950inductionslowerP2 Honda K20A-FD2 in CN chassis must use stock intake manifold with 64mm throttle body and 55mm restrictor at 1500 lbs minimum weight.

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 GT1" is the class's best as a share of GT1'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 GT1'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.