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BoP Lab / Buttonwillow Raceway Park

F500 vs F5 vs SRF vs P pace at Buttonwillow Raceway Park

Class · click a class to switch, + to compare alongside (up to 4: remove one to add another)
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: P 1:32.872 Jim Devenport, Cal Club 2025 qualifying

1:331:341:351:361:371:381:399 rule changes between Cal Club 2025 and Cal Club 20269 ▾P race best at Cal Club 2025: 1:33.972 (Jim Devenport)P race best at Cal Club 2026: 1:37.287 (John Manfroy)P qualifying best at Cal Club 2025: 1:32.872 (Jim Devenport)P qualifying best at Cal Club 2026: 1:38.716 (Kevin Mitz)Cal Club 20252025Cal Club 20262026
F500F5SRFPsolid race · dashed qualifying · slower is lower
EventF500F5SRFP
Qual bestRace bestTrapQual bestRace bestTrapvs F500Qual bestRace bestTrapvs F500Qual bestRace bestTrapvs F500
Cal Club 2026 CALCL262026-02-211:38.716Kevin Mitz · fastest of 3 · top 3 within 3.1s+5.844s (+6.29%)1:37.287John Manfroy · fastest of 3 · top 3 within 3.5s+3.315s (+3.53%)160.4John Manfroy+18.7 mph (+13.2%)
9 rule changes (SRF: 3, P: 6)2 induction · 2 weight · 1 suspension & brakes · 4 othershowhide
  • P Request to Continue to Allow Carbon Brakes #39476suspension & brakes
  • SRF Add HD Oil Cooler #38979other
  • P 13B Rotary Engine Rules Change Request #38856induction
  • P Add Radical Cup series Radical SR3 spec line to Table 1 #38916other
  • P Clarify spec line cars language #38943weight
  • P RM 25-05 - Prototype Engine Table A, 2 Cycle Restrictor Change #38929induction
  • P Add missing punctuation marks #38150weight
  • SRF Driver Safety & Comfort #37966other
  • SRF Update SADEV transmission specs #37992other
Cal Club 2025 CALCL252025-02-221:32.872Jim Devenport · fastest of 3 · top 3 within 8.1s1:33.972Jim Devenport · fastest of 3 · top 3 within 7.7s141.7Jim Devenport
46 earlier rule changes on record, in force before Cal Club 2025 (from 2019)9 tyres & wheels · 8 suspension & brakes · 6 engine · 5 weight · 1 cars added · 1 induction · 8 wording · 8 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
  • P Correct text in engine table notes #37606engine
  • P Update Prototype class designation #37653tyres & wheels
  • SRF Update SRF3 Air Filter Rule #36681other
  • SRF Update SRF Brake Rotor Thickness #36687suspension & brakes
  • SRF Hoosier Tire Decal Placement #36739tyres & wheels
  • SRF Protest Fee Clarification #36540wording
  • SRF Update to Letter 36619 with new Hoosier Contingency Decal Info #36624tyres & wheels
  • SRF Update Rain Tire Rule and Hoosier Decal Placement #36436tyres & wheels
  • SRF Update SRF Rain / Brake Rule #34706suspension & brakes
  • SRF Update SRF Brake Light Rule v1 #34853suspension & brakes
  • SRF SRF / SRF3 Rule Updates #35268weight
  • SRF SRF Radiator Rule Update #34805other
  • SRF Hoosier SRF Wet Front Tire Rule Update #34189tyres & wheels
  • SRF Update SRF Front W2 Rain Tire Part Number #34118tyres & wheels
  • SRF Update SRF Brake Rule #33469suspension & brakes
  • 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.
  • F5 Ensure availability of ECU for Rotax engines #32695engineadded · engineF500 Rotax engines now permit Ingi Tech Sparker ignition DCP-CDI-P2 as alternate ECU.
  • F5 Clarify stepped exhaust header references #32743wordingwordingF500 clarifies stepped diameter exhaust headers prohibited except at cylinder head flange area.
  • F5 593 carb boot availability and oil pump clarification #32527wordingwordingF500 Rotax 593 intake boot options clarified; oil injection pump removal now permitted.
  • SRF SRF Tire Rule Update #32614tyres & wheels
  • SRF Brake, seal, and air filter clarifications #32670suspension & brakes
  • F5 E&O class name #32194otheraddedF500 Majors and Runoffs cars must install AIM part #X47KPFSOLO2R0 data box mount for Solo or Solo 2.
  • F5 Data Box Mounting Plate #31638otheraddedF5 cars must install AIM part #X47KPFSOLO2R0 data box mount for Majors and Runoffs.
  • SRF Three Updates to SRF Rules #31523weight
  • F5 Clarify allowable assisted shifting systems #30871wordingwordingF5 clarifies mechanical shifting only; throttle-cut and flat-shifter devices permitted if driver retains full control.
  • F5 Request to correct terminology #30976wordingwordingF5 single-seat open-wheel cars: rigid suspension becomes limited suspension in class definition.
  • SRF SRF Wet Tires #30849tyres & wheels
  • SRF SADEV-SRF3 Transmission #30926other
  • SRF SRF Update Maintenance, Repairs and Seals #30961engine
  • 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.
  • SRF SRF3 Alternator Pulley #30684weight
  • SRF Mandatory identification: #30223engine
  • SRF SRF Shocks, Springs and Ride Height. #29688suspension & brakes
  • F5 Request to Update Suzuki Engine Years for F500 #29453engineadded · engineF500 Suzuki GSXR600 engine years extended from 2003-2013 to 2003-2019.
  • F5 Request for Cockpit Adjustment of External Jetting Devices #28359wordingunclearF5 request to adjust external jetting device cockpit control denied; no rule change made.
  • F5 Two Stroke Motors (reply to #28359 WDYT) #28816engine
  • F5 Re letter requesting driver adjustable carb mixture #28840other
  • F5 #28359 WDYT Request for Cockpit Adjustment #28875wordingunclearF5 cockpit adjustment request response published in Fastrack letter 28359.
  • SRF SRF Bump Stop Correction #27019suspension & brakes
  • F5 Change 600cc restrictor size #27883inductionslower · inductionF500 Honda CBR600RR, Suzuki GSXR600, Yamaha R6 restrictor reduced to 28mm from 29mm.
  • SRF SRF Rain / Brake Rule - BoD approved as follows #34958suspension & brakes
  • SRF SRF Tire Warmer Rule #27622tyres & wheels
  • SRF SRF / SRF3 Nose Weight Reduction #27706weight
  • SRF SRF / SRF3 Majors & Regional Class Updates #27723other
  • 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.
  • SRF SRF Dash Windscreen Kit #27028other

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.