BoP Lab / Buttonwillow Raceway Park

F5 vs SRF vs GTX pace at Buttonwillow Raceway Park

Quickest here: GTX 1:49.596 Rob Scholl, Cal Club 2025 race

F5SRFGTXsolid race · dashed qualifying · slower is lower

	Event	F5			SRF				GTX
	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								1:54.892Moze Cowper · only car	1:55.330Moze Cowper · only car+5.734s (+5.23%)	146.0Moze Cowper+29.6 mph (+25.4%)
6 rule changes (SRF: 3, GTX: 3)2 cars added · 1 engine · 3 othershowhide 2026-01-01 GTX Please Consider Adding a Spec Line to GTX Table 4 for the RCR T70 #39470cars added 2025-10-01 SRF Add HD Oil Cooler #38979other 2025-06-01 GTX Ligier P3 LS Swap #38164engine 2025-05-01 GTX Request to Classify Porsche GT2 RS Clubsport #37972cars added 2025-04-01 SRF Driver Safety & Comfort #37966other 2025-04-01 SRF Update SADEV transmission specs #37992other
	Cal Club 2025 CALCL252025-02-22									1:49.596Rob Scholl · only car	116.4Rob Scholl
82 earlier rule changes on record, in force before Cal Club 2025 (from 2019)19 cars added · 10 suspension & brakes · 8 engine · 8 tyres & wheels · 8 weight · 5 aero · 4 induction · 9 wording · 11 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 2025-01-01 GTX Correct language regarding OEM Areo Devices #37137aero 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 2024-05-01 GTX Request for Spec Line 1010 Reconsideration #35009weight +300 lbs 2024-02-01 GTX Rear Blade Spoiler Clarification #35261aero 2024-02-01 GTX GT Direct Injection allowance and rules #35437engine 2024-02-01 GTX GT2/3 remove Direction Injection not allowed in Spec line notes #35439engine 2024-01-01 GTX KTM X Bow GTX #34956cars added 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 GTX Errors in GTCS Headings and Use of the Terms Category and ClassChange existing GTL and GTA Rules #34453weight 2023-10-01 SRF SRF Radiator Rule Update #34805other 2023-07-01 GTX Request Ligier LMP3 Classification #34043cars added 2023-07-01 GTX Ligier JSP4 Request #34173cars added 2023-06-01 SRF Hoosier SRF Wet Front Tire Rule Update #34189tyres & wheels 2023-05-01 GTX Please classify Fields Cardinal V8 #33784cars added 2023-05-01 SRF Update SRF Front W2 Rain Tire Part Number #34118tyres & wheels 2023-03-01 SRF Update SRF Brake Rule #33469suspension & brakes 2022-12-01 GTX GT2 (TA2)/GTA Part Number Update #33315induction 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 GTX Tail lights on all GT category race cars. #32799suspension & brakes 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. 2022-07-01 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 GTX Classify 992 GT3 Cup #32649cars added 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 GTX Add Classification to the accepted Model Table #31981weight 2022-05-01 GTX Request to classify C7 Corvette Grand Sport IN GTX Misc #32254cars added 2022-05-01 GTX E&O list of eligible prototypes #32511other 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 GTX McLaren 720s GT3 #31955cars added 2022-02-01 GTX Remove restrictions from GTX-FIA GT3 #32039induction 2022-01-01 F5 Data Box Mounting Plate #31638otheraddedF5 cars must install AIM part #X47KPFSOLO2R0 data box mount for Majors and Runoffs. 2021-12-01 SRF Three Updates to SRF Rules #31523weight 2021-10-01 GTX Request car classification #31032cars added 2021-09-01 GTX Request to classify 2020 Porsche 718 GT4 Clubsport MR #30956cars added 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 GTX Request to Update GTA Obsolete Part Numbers #30615wording 2021-08-01 GTX 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 GTX Request classification of Grullon #30481cars added 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 2021-03-01 SRF Mandatory identification: #30223engine 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. 2020-09-01 GTX GT Category Wording #29193induction 2020-08-01 GTX Request Car classification #28935cars added 2020-08-01 GTX X-Bow GT4 #29088cars added 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 GTX TA2 Gurney flap wicker clarification #28874aero 2020-07-01 GTX STO Gurney flap wicker clarification #28883aero 2020-07-01 GTX GT Gurney flap wicker clarification #28909aero 2020-06-01 GTX Request to Re-classify SP Stock car to GTX #28333cars added 2020-05-01 GTX Request to Classify Lotus Evora GTS #27057cars added 2020-05-01 SRF SRF Bump Stop Correction #27019suspension & brakes 2020-02-01 GTX Windshield Clips #27323other 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 GTX Request Factory Five Daytona coupe classification #26308cars added 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 SRF SRF Dash Windscreen Kit #27028other 2019-05-01 GTX Request GTX Fuel injection for previous GT-1 tube frame cars #26141engine 2019-05-01 GTX Request to Classify Ligier JS2 R #26535cars added 2019-04-01 GTX Request Ride Height Clarification #26600suspension & brakes 2019-03-01 GTX Replace FIA references with SRO #26427other 2019-01-01 GTX 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.