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BoP Lab / Buttonwillow Raceway Park

F5 vs FB vs F6 vs FV pace at Buttonwillow Raceway Park

Class · click a class to switch, + to compare alongside (up to 4: remove one to add another)
ASB-SpecEPF5×vsF6×FAvsFB×FCFE2FFFPvsFV×FXGT1GT2GTXHPPP2SMSMXSRF3STLSTUT1T2T3T4Show 12 inactive classes
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: FV 1:58.898 Mace Gjerman, Cal Club 2026 race

1:592:002:012:022:03FV race best at Cal Club 2025: 2:01.197 (Gavin Sweeney)FV race best at Cal Club 2026: 1:58.898 (Mace Gjerman)FV qualifying best at Cal Club 2025: 2:02.354 (Gavin Sweeney)FV qualifying best at Cal Club 2026: 2:02.562 (Gavin Sweeney)Cal Club 2025Cal Club2025Cal Club 2026Cal Club2026
F5FBF6FVsolid race · dashed qualifying · slower is lower
EventF5FBF6FV
Qual bestRace bestTrapQual bestRace bestTrapvs F5Qual bestRace bestTrapvs F5Qual bestRace bestTrapvs F5
Cal Club 2026 CALCL262026-02-212:02.562Gavin Sweeney · fastest of 7 · top 5 within 3.3s+0.208s (+0.17%)1:58.898Mace Gjerman · fastest of 7 · top 5 within 6.0s-2.299s (-1.90%)124.6Gavin Sweeney+21.2 mph (+20.5%)
No rule changes on record between these events
Cal Club 2025 CALCL252025-02-222:02.354Gavin Sweeney · fastest of 5 · top 5 within 10.3s2:01.197Gavin Sweeney · fastest of 5 · top 5 within 9.6s103.5Gavin Sweeney
34 earlier rule changes on record, in force before Cal Club 2025 (from 2019)6 tyres & wheels · 5 engine · 2 cars added · 2 weight · 1 induction · 15 wording · 3 other · FV ferrous rotor must not be cross-drilled; pad cleaning grooves limit unchanged at three per side. · FV front wheel bearings wording clarified; specification unchanged. · 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. · FV connecting rod options expanded to include BrianCrower part BC6417 and Newland Group part 4M113077. · FV connecting rods minimum weight 425.0 grams, center-to-center length 130 +0.10/-0.25 mm; Crower, BrianCrower, Newland Group parts allowed if meeting specs. · F5 cars must install AIM part #X47KPFSOLO2R0 data box mount for Majors and Runoffs. · FV Crower connecting rods SP93280B and BC6417 allowed as direct replacement, must meet OEM minimum weight. · FV allows Crower SP93280B and Brian Crower Racing Rods connecting rods as direct replacements, matching OEM minimum weight. · 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 driver adjustable carburettor mixture: refer to separate Fastrack letter #28359 for ruling. · F5 cockpit adjustment request response published in Fastrack letter 28359. · FV now permits 4 bolt wheels in addition to existing specifications. · FV now allows 4-bolt pattern wheels in addition to existing specifications. · FV rain tyre changes to Hoosier #44266 22.5 x 5.0 x 15 WET or W3. · F500 Honda CBR600RR, Suzuki GSXR600, Yamaha R6 restrictor reduced to 28mm from 29mm. · FV allows non-spec Hoosier tyres at Regional races only; Majors, Super Tour, and Runoffs require spec tyres from 1/1/2020. · Formula Vee now allows 22.5 x 5.5 x 15 rear tires on front axle; rain tire mandated as Hoosier #44266 22.5 x 5.0 x 15 from 1/1/2020. · FV wheels may now be 15-inch 4.5J steel VW with same 5-bolt pattern as standard 4J, within track limits. · FV exhaust exit opening repositioned: minimum one inch, maximum four inches behind rear body. · F500 Honda CBR600RR, Suzuki GSXR600, and Yamaha R6 minimum weights increase to 900 lbs. · FV allows fifteen-inch steel wheels at 4J or 4.5J width, standard VW sedan or within track dimensions. · FV exhaust outlet opening max distance from body rear increased from 3 to 4 inches. · FV disc brake assembly minimum weight clarified to 16.5 lbs total; caliper minimum weight requirement of 1.65 lbs removed. · FV intake manifold horizontal tube measurement location clarified; removed specific distance ranges from rule text.showhide
  • FV Disc Brakes #36822wordingwordingFV ferrous rotor must not be cross-drilled; pad cleaning grooves limit unchanged at three per side.
  • FV FV Wheel Bearing Clarification #35150wordingwordingFV front wheel bearings wording clarified; specification unchanged.
  • 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.
  • F5 E&O class name #32194otheraddedF500 Majors and Runoffs cars must install AIM part #X47KPFSOLO2R0 data box mount for Solo or Solo 2.
  • FV Connecting Rod Update Request for 9.1.1.C Formula Vee (FV) 5.C.6 #32160engineadded · engineFV connecting rod options expanded to include BrianCrower part BC6417 and Newland Group part 4M113077.
  • FV E&O clarification of connecting rod center-to-center length #32183wordingwordingFV connecting rods minimum weight 425.0 grams, center-to-center length 130 +0.10/-0.25 mm; Crower, BrianCrower, Newland Group parts allowed if meeting specs.
  • F5 Data Box Mounting Plate #31638otheraddedF5 cars must install AIM part #X47KPFSOLO2R0 data box mount for Majors and Runoffs.
  • FV Update direct replacement connecting rod information #31843wordingwordingFV Crower connecting rods SP93280B and BC6417 allowed as direct replacement, must meet OEM minimum weight.
  • FV Formula V Connecting Rod Replacement #31448engineadded · engineFV allows Crower SP93280B and Brian Crower Racing Rods connecting rods as direct replacements, matching OEM minimum weight.
  • 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.
  • 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.
  • 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 #28840wordingunclearF5 driver adjustable carburettor mixture: refer to separate Fastrack letter #28359 for ruling.
  • F5 #28359 WDYT Request for Cockpit Adjustment #28875wordingunclearF5 cockpit adjustment request response published in Fastrack letter 28359.
  • FV Support for Recommended Item - 4 bolt wheels in FV #29084cars addedaddedFV now permits 4 bolt wheels in addition to existing specifications.
  • FV Support for 4-bolt pattern wheels #28955 #29118tyres & wheelsadded · tyres & wheelsFV now allows 4-bolt pattern wheels in addition to existing specifications.
  • FV Update rain tire designation #28444tyres & wheelstyres & wheelsFV rain tyre changes to Hoosier #44266 22.5 x 5.0 x 15 WET or W3.
  • F5 Change 600cc restrictor size #27883inductionslower · inductionF500 Honda CBR600RR, Suzuki GSXR600, Yamaha R6 restrictor reduced to 28mm from 29mm.
  • FV FV Allow non-spec tire in Regional competition #26284tyres & wheelsadded · tyres & wheelsFV allows non-spec Hoosier tyres at Regional races only; Majors, Super Tour, and Runoffs require spec tyres from 1/1/2020.
  • FV Request to Allow Rear Tires on the Front of Formula Vee #26537tyres & wheelsadded · tyres & wheelsFormula Vee now allows 22.5 x 5.5 x 15 rear tires on front axle; rain tire mandated as Hoosier #44266 22.5 x 5.0 x 15 from 1/1/2020.
  • FV Clarification on Wheel Bolt Pattern #27603tyres & wheelsadded · tyres & wheelsFV wheels may now be 15-inch 4.5J steel VW with same 5-bolt pattern as standard 4J, within track limits.
  • FV Allowed Modifications E&O #27398wordingwordingFV exhaust exit opening repositioned: minimum one inch, maximum four inches behind rear body.
  • 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.
  • FV E&O Wheels #27230tyres & wheelsadded · tyres & wheelsFV allows fifteen-inch steel wheels at 4J or 4.5J width, standard VW sedan or within track dimensions.
  • FV Exhaust termination rule E&O #26702wordingwordingFV exhaust outlet opening max distance from body rear increased from 3 to 4 inches.
  • FV E&O Dimensions #26674other
  • FV Request to clarify Disc Brake rules bearing retainer & weights #26262weightslower · weightFV disc brake assembly minimum weight clarified to 16.5 lbs total; caliper minimum weight requirement of 1.65 lbs removed.
  • FV FV Intake Manifold Clarification #26008wordingwordingFV intake manifold horizontal tube measurement location clarified; removed specific distance ranges from rule text.

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.