BoP Lab / Buttonwillow Raceway Park

F5 vs SRF vs GT2 pace at Buttonwillow Raceway Park

Quickest here: GT2 1:42.698 Tim Carroll, Cal Club 2026 qualifying

F5SRFGT2solid race · dashed qualifying · slower is lower

	Event	F5			SRF				GT2
	Event	Qual best	Race best	Trap	Qual best	Race best	Trap	vs F5	Qual best	Race best	Trap	vs F5
	Cal Club 2026 CALCL262026-02-21								1:42.698Tim Carroll · fastest of 8 · top 5 within 7.4s-3.120s (-2.95%)	1:44.128Tim Carroll · fastest of 8 · top 5 within 4.3s-2.798s (-2.62%)	155.7Rocky Crocker+37.8 mph (+32.1%)
11 rule changes (SRF: 3, GT2: 8)2 aero · 2 cars added · 2 engine · 1 induction · 4 othershowhide 2026-02-01 GT2 Allow Larger Air Cooled Engines in Porsche 911 GT2 #39249engine 2026-02-01 GT2 Classify T1 BMW in GT2 #39408cars added 2026-01-01 GT2 Additional Body Options to Replace Older Stock Car Bodies #39086other 2026-01-01 GT2 GT3 Turbo to GT2? #39365induction 2026-01-01 GT2 Tech Bulletins for GT2 and GT2-ST #39537cars added -100 lbs 2025-10-01 SRF Add HD Oil Cooler #38979other 2025-08-01 GT2 Rear Deck Lid for Older Air-Cooled Porsche #38506aero 2025-04-01 SRF Driver Safety & Comfort #37966other 2025-04-01 SRF Update SADEV transmission specs #37992other 2025-03-01 GT2 Hood Bulge allowed #37000engine 2025-03-01 GT2 OEM Wing Adjustment #37590aero
	Cal Club 2025 CALCL252025-02-22								1:45.818Brad McAllister · fastest of 6 · top 5 within 14.6s	1:46.926Brad McAllister · fastest of 6 · top 5 within 13.3s	117.9Guy Laidig
157 earlier rule changes on record, in force before Cal Club 2025 (from 2019)35 weight · 22 cars added · 21 engine · 19 induction · 11 suspension & brakes · 10 tyres & wheels · 8 aero · 16 wording · 15 other · F500 Rotax 493 and 593 intake boots: removed Moto Tassinari V3124-873B-2 from 493/593 non-HO allowance, added Moto Tassinari V3120-794A-2 option for non-HO. · F500 Rotax engines now permit Ingi Tech Sparker ignition DCP-CDI-P2 as alternate ECU. · F500 clarifies stepped diameter exhaust headers prohibited except at cylinder head flange area. · F500 Rotax 593 intake boot options clarified; oil injection pump removal now permitted. · F500 Majors and Runoffs cars must install AIM part #X47KPFSOLO2R0 data box mount for Solo or Solo 2. · F5 cars must install AIM part #X47KPFSOLO2R0 data box mount for Majors and Runoffs. · F5 clarifies mechanical shifting only; throttle-cut and flat-shifter devices permitted if driver retains full control. · F5 single-seat open-wheel cars: rigid suspension becomes limited suspension in class definition. · F500 Rotax 593 HO engine now permitted; 875 lbs minimum weight, MA0242SP1020A or MA0242SP1063A restrictor, specific intake boots and piston required. · F500 Suzuki GSXR600 engine years extended from 2003-2013 to 2003-2019. · F5 request to adjust external jetting device cockpit control denied; no rule change made. · F5 cockpit adjustment request response published in Fastrack letter 28359. · F500 Honda CBR600RR, Suzuki GSXR600, Yamaha R6 restrictor reduced to 28mm from 29mm. · F500 Honda CBR600RR, Suzuki GSXR600, and Yamaha R6 minimum weights increase to 900 lbs.showhide 2025-02-01 GT2 GT2/ST - Remove Aftermarket/Racing ABS penalty #36538weight 2025-01-01 GT2 Panoz Esperante GTS BOP #36686cars added 2025-01-01 GT2 Correct language regarding OEM Areo Devices #37137aero 2025-01-01 GT2 GT2 Sunbeam Tiger Alternate Carburetor #37198induction 2024-10-01 SRF Update SRF3 Air Filter Rule #36681other 2024-10-01 SRF Update SRF Brake Rotor Thickness #36687suspension & brakes 2024-10-01 SRF Hoosier Tire Decal Placement #36739tyres & wheels 2024-09-01 SRF Protest Fee Clarification #36540wording 2024-09-01 SRF Update to Letter 36619 with new Hoosier Contingency Decal Info #36624tyres & wheels 2024-08-01 SRF Update Rain Tire Rule and Hoosier Decal Placement #36436tyres & wheels 2024-07-01 GT2 GT2-ST Rule Clarification #36093wording 2024-07-01 GT2 GT4 cars may run in GT2-ST #36235weight 2024-05-01 GT2 Request for Spec Line 1010 Reconsideration #35009weight +300 lbs 2024-05-01 GT2 Request to Eliminate the FPR from the Corvette (-2013) with LS2 #35878induction 2024-03-01 GT2 Classify Corvette C8 (2020- ) into GT2/ST #33759cars added 2024-03-01 GT2 Requesting classification for a 2015 Mitjet ST in GT2 #35408cars added 2024-02-01 GT2 Rear Blade Spoiler Clarification #35261aero 2024-02-01 GT2 GT Direct Injection allowance and rules #35437engine 2024-02-01 GT2 REDUCE C6 CORVETTE WEIGHT WITH OEM 7 LITER ENGINE REDUCE BY 150LB #35385weight -150 lbs 2024-02-01 GT2 GT2/3 remove Direction Injection not allowed in Spec line notes #35439engine 2024-01-01 GT2 Dodge Viper Gen 3 hybrid Kit Update Request #35200induction 2024-01-01 SRF Update SRF Rain / Brake Rule #34706suspension & brakes 2024-01-01 SRF Update SRF Brake Light Rule v1 #34853suspension & brakes 2024-01-01 SRF SRF / SRF3 Rule Updates #35268weight 2023-12-01 GT2 Errors in GTCS Headings and Use of the Terms Category and ClassChange existing GTL and GTA Rules #34453weight 2023-10-01 GT2 Late E & O #34966wording 2023-10-01 SRF SRF Radiator Rule Update #34805other 2023-09-01 GT2 GT2 Mazda 20B 3 rotor ENO #34765weight -220 lbs 2023-07-01 GT2 appendix letter #33635 #34206weight 2023-07-01 GT2 Remove Weight and Restrictor Penalty for Corvette C7 Body #34342weight 2023-06-01 SRF Hoosier SRF Wet Front Tire Rule Update #34189tyres & wheels 2023-05-01 GT2 Request to class 2011 Porsche Cayman S #33771cars added 2023-05-01 GT2 Please classify Fields Cardinal V8 #33784cars added 2023-05-01 SRF Update SRF Front W2 Rain Tire Part Number #34118tyres & wheels 2023-04-01 GT2 Adding Ginetta G56 GTA Factory ProTune for GT2 Class #33825engine 2023-03-01 SRF Update SRF Brake Rule #33469suspension & brakes 2023-02-01 GT2 GT2 Mazda 13B Turbo #33729induction 2023-01-01 GT2 Request Permission to Use a Substitute Turbo #33337induction 2023-01-01 GT2 Request to Reduce Restriction on C7 GT2 Corvette #33342induction 2023-01-01 GT2 Toyota 4A-F and 4A-FE 1.6L DOHC 16V Engine Request #33415engine 2023-01-01 GT2 GT2 Mazda 13b turbocharger part # update #33437induction 2023-01-01 GT2 GT2-ST BMW E36/46 spec line remove #33610aero 2023-01-01 GT2 GT3 Choke option effective 1-01-2023 #33669induction 2023-01-01 GT2 GT3 2.0L choke/weight option #33670weight 2023-01-01 GT2 BOP adjustment for GT2 & GT2-ST #33681induction 2022-12-01 GT2 GT2 (TA2)/GTA Part Number Update #33315induction 2022-12-01 GT2 Ginetta G56 GTA - Optional Wheels #33357tyres & wheels 2022-11-01 GT2 Allow the MAShaw Body Kit on the GT2/ST Spec Line for BMW E36/E46 #32447aero 2022-10-01 GT2 Request for C5/C6 Corvette Restrictor Size Review #32982induction 2022-09-01 F5 Intake Boots Correction #33028wordingwordingF500 Rotax 493 and 593 intake boots: removed Moto Tassinari V3124-873B-2 from 493/593 non-HO allowance, added Moto Tassinari V3120-794A-2 option for non-HO. 2022-09-01 GT2 Tail lights on all GT category race cars. #32799suspension & brakes 2022-09-01 GT2 Addendum to letter #32514 Ginetta GTA G56 #33076cars added 2022-08-01 F5 Ensure availability of ECU for Rotax engines #32695engineadded · engineF500 Rotax engines now permit Ingi Tech Sparker ignition DCP-CDI-P2 as alternate ECU. 2022-08-01 GT2 Information requested for carbon roofs on BMW E36/E46 cars in GT2 #32682wording 2022-08-01 GT2 Request to Allow the 95mm S54 BMW Crankshaft in GT2-ST #32698other 2022-08-01 GT2 Request to classify Audi R8 FIA GT4 to GT2 #32805cars added 2022-07-01 F5 Clarify stepped exhaust header references #32743wordingwordingF500 clarifies stepped diameter exhaust headers prohibited except at cylinder head flange area. 2022-06-01 F5 593 carb boot availability and oil pump clarification #32527wordingwordingF500 Rotax 593 intake boot options clarified; oil injection pump removal now permitted. 2022-06-01 SRF SRF Tire Rule Update #32614tyres & wheels 2022-06-01 SRF Brake, seal, and air filter clarifications #32670suspension & brakes 2022-05-01 GT2 Typo in rules for shocks #32308suspension & brakes 2022-05-01 GT2 additional response to letters #31898 & 32083 #32424weight +140 lbs 2022-03-01 F5 E&O class name #32194otheraddedF500 Majors and Runoffs cars must install AIM part #X47KPFSOLO2R0 data box mount for Solo or Solo 2. 2022-03-01 GT2 Request to Classify Ginetta G40 in GT2 #31597cars added 2022-03-01 GT2 2021 Supra GR GT4 #31737cars added 2022-03-01 GT2 Proposed Technical Bulletin #31900induction 2022-02-01 GT2 GT2/ST Porsche Cayman #31451 correct TBR size error #31991wording 2022-01-01 F5 Data Box Mounting Plate #31638otheraddedF5 cars must install AIM part #X47KPFSOLO2R0 data box mount for Majors and Runoffs. 2022-01-01 GT2 Restrictor Clarification for 2015 Cayman #31451induction 2021-12-01 SRF Three Updates to SRF Rules #31523weight 2021-10-01 GT2 Turbo Request for 13B Engine #30656induction 2021-10-01 GT2 Request car classification #31032cars added 2021-09-01 GT2 Correct letter 30565 GT2/ST #31088weight 2021-08-01 F5 Clarify allowable assisted shifting systems #30871wordingwordingF5 clarifies mechanical shifting only; throttle-cut and flat-shifter devices permitted if driver retains full control. 2021-08-01 F5 Request to correct terminology #30976wordingwordingF5 single-seat open-wheel cars: rigid suspension becomes limited suspension in class definition. 2021-08-01 GT2 Request the 04-06 Pontiac GTO WC Car Be Added to the GT2/ST Chart #30339cars added 2021-08-01 GT2 Request to Update GTA Obsolete Part Numbers #30615wording 2021-08-01 GT2 GTX class correction to GT2/ST #30973cars added 2021-08-01 SRF SRF Wet Tires #30849tyres & wheels 2021-08-01 SRF SADEV-SRF3 Transmission #30926other 2021-08-01 SRF SRF Update Maintenance, Repairs and Seals #30961engine 2021-07-01 GT2 Porsche Cayman Engine Modification and Engine Request #30472engine 2021-07-01 GT2 Request weight clarification Viper CC #30565weight 2021-07-01 GT2 Variance, 2021 TA2 Rules vs GCR Appendix L #30641weight 2021-06-01 F5 Request to Allow Rotax 593 HO Engine #30712cars addedaddedF500 Rotax 593 HO engine now permitted; 875 lbs minimum weight, MA0242SP1020A or MA0242SP1063A restrictor, specific intake boots and piston required. 2021-06-01 SRF SRF3 Alternator Pulley #30684weight 2021-04-01 GT2 GT2 tiger firing order #30421engine 2021-03-01 GT2 GT2-ST CORVETTE CHANGES #30029weight +100 lbs 2021-03-01 GT2 Request underfloor clarification #30121tyres & wheels 2021-03-01 GT2 29742 Change new wording to read as: #30329engine 2021-03-01 SRF Mandatory identification: #30223engine 2021-02-01 GT2 ABS Restrictions #30064other 2021-02-01 GT2 RM 21-01 C6 & C7 clarification #30192weight 2021-01-01 GT2 Request change to engine firing order rule #29742engine 2021-01-01 GT2 Request E-46 BMW M3 balance of performance #29833weight -100 lbs 2020-12-01 GT2 Request for Bigger Engine in Plymouth Breeze #29380engine 2020-12-01 SRF SRF Shocks, Springs and Ride Height. #29688suspension & brakes 2020-10-01 F5 Request to Update Suzuki Engine Years for F500 #29453engineadded · engineF500 Suzuki GSXR600 engine years extended from 2003-2013 to 2003-2019. 2020-10-01 GT2 rescind GT2 stock car bodies removal #29219other 2020-10-01 GT2 E&O Typos in Appendix L #29447wording 2020-10-01 GT2 GT2 wing width wording correction #29469aero 2020-09-01 GT2 GT Category Wording #29193induction 2020-09-01 GT2 Corvette GT2-ST intake manifold #29221induction 2020-09-01 GT2 997.2 E&O link to 27915 #29373other 2020-08-01 GT2 Request for allowance Trans Am SGT #28951weight 2020-08-01 GT2 Omitted GT2 fender/hood openings #29171other 2020-07-01 F5 Request for Cockpit Adjustment of External Jetting Devices #28359wordingunclearF5 request to adjust external jetting device cockpit control denied; no rule change made. 2020-07-01 F5 Two Stroke Motors (reply to #28359 WDYT) #28816engine 2020-07-01 F5 Re letter requesting driver adjustable carb mixture #28840other 2020-07-01 F5 #28359 WDYT Request for Cockpit Adjustment #28875wordingunclearF5 cockpit adjustment request response published in Fastrack letter 28359. 2020-07-01 GT2 TA2 Gurney flap wicker clarification #28874aero 2020-07-01 GT2 STO Gurney flap wicker clarification #28883aero 2020-07-01 GT2 GT Gurney flap wicker clarification #28909aero 2020-06-01 GT2 Request to Adjust Weight of OEM 8.4 Viper #28739weight -50 lbs 2020-06-01 GT2 Request to Adjust Weight of OEM Chevrolet Corvette #28896weight -50 lbs 2020-05-01 GT2 Request Corvette engine parity #28576engine 2020-05-01 SRF SRF Bump Stop Correction #27019suspension & brakes 2020-04-01 GT2 Request to revisit Panoz GT-S BoP #28280engine 2020-04-01 GT2 GT2-ST Corvette LS2 & L76 #28583weight 2020-04-01 GT2 GT2-ST Corvette L76 #28584weight 2020-03-01 GT2 Request 991.2 Porsche engine displacement verify typo #28194engine 2020-02-01 GT2 Windshield Clips #27323other 2020-02-01 GT2 Request to Add Chevrolet SS Body to Appendix L #27898wording 2020-01-01 F5 Change 600cc restrictor size #27883inductionslower · inductionF500 Honda CBR600RR, Suzuki GSXR600, Yamaha R6 restrictor reduced to 28mm from 29mm. 2020-01-01 GT2 Request Factory Five Daytona coupe classification #26308cars added 2020-01-01 GT2 Porsche 991.2 GT3 Cup GT2 Classification #27701cars added 2020-01-01 GT2 Request for Acura NSX Spec Line Changes #27755weight 2020-01-01 GT2 GT2 991.1 restrictor size change #27914induction 2020-01-01 GT2 GT2 996/997.1 weight change #27915weight -100 lbs 2020-01-01 GT2 GT2/ST Corvette comp adjustment #27920induction 202-01-01 SRF SRF Rain / Brake Rule - BoD approved as follows #34958suspension & brakes 2019-12-01 SRF SRF Tire Warmer Rule #27622tyres & wheels 2019-12-01 SRF SRF / SRF3 Nose Weight Reduction #27706weight 2019-12-01 SRF SRF / SRF3 Majors & Regional Class Updates #27723other 2019-08-31 F5 Request for Weight Increase for Motorcycle Powered Cars #27214weight +25 lbsslower · weightF500 Honda CBR600RR, Suzuki GSXR600, and Yamaha R6 minimum weights increase to 900 lbs. 2019-07-01 GT2 TA2 Weight Clarification #27077weight 2019-07-01 SRF SRF Dash Windscreen Kit #27028other 2019-05-31 GT2 Request to classify Toyota Supra with 3SGTE engine #25185cars added 2019-05-31 GT2 Request to Classify Acura NSX from T1 to GT2? #26121cars added 2019-05-31 GT2 Request for TA2 BOP in GT2 #26509weight 2019-05-01 GT2 Request for e36/e46 bmw 4500 cc v8 at 2950lbs in GT2/ST #26106engine 2019-05-01 GT2 Request GTX Fuel injection for previous GT-1 tube frame cars #26141engine 2019-05-01 GT2 Request to Classify Ligier JS2 R #26535cars added 2019-04-01 GT2 Request Ford Perfomance 5.2L crate engine FPR clarification #26159engine 2019-04-01 GT2 Request Ride Height Clarification #26600suspension & brakes 2019-03-01 GT2 Request Porsche Cayman year classification #26241other 2019-03-01 GT2 GT2/ST Porsche Cayman engine #26250engine 2019-01-01 GT2 ST/GT2 BMW Flossman Kit Clarification #22138wording 2019-01-01 GT2 Request Clarification/Revision of Appendix L (2013 TA2 Rules) #25110weight 2019-01-01 GT2 Request to classify BMW E82 (1 series) into GT2 #25539cars added 2019-01-01 GT2 2010 Cayman Street Tuner Into an STO Car,Addendum #25545weight 2019-01-01 GT2 Request - Classify Ford Performance 5.2l #25716cars added 2019-01-01 GT2 Add missing displacement, minimum weight. Remove #25765weight 2019-01-01 GT2 Request for Ford FP 350s Weight Reduction #25806weight 2019-01-01 GT2 Request to Classify EcoBoost Mustang #25842cars added 2019-01-01 GT2 Request to Remove Mazda RX 7 Body Work Penalty #26024weight 2019-01-01 GT2 GTX Homologation table update #26034cars added

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. 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.