F500 vs F5 vs SRF vs FF pace at Buttonwillow Raceway Park
Quickest here:FF 1:51.118 Eric Poulsen, Cal Club 2025 race
F500F5SRFFFsolid race · dashed qualifying · slower is lower
Event
F500
F5
SRF
FF
Qual best
Race best
Trap
Qual best
Race best
Trap
vs F500
Qual best
Race best
Trap
vs F500
Qual best
Race best
Trap
vs F500
Cal Club 2026 CALCL262026-02-21
1:53.098Edward Erlandson · fastest of 2+1.054s (+0.94%)
1:54.741Edward Erlandson · fastest of 2+3.623s (+3.26%)
133.7Edward Erlandson+19.0 mph (+16.5%)
6 rule changes (SRF: 3, FF: 3)3 tyres & wheels · 3 other · FF clarifies alternative tire eligibility: homologated 1989 or earlier with rocker or outboard suspension all four corners; push-rod/pull-rod cars may seek approval. · FF adds rocker arm and outboard suspension cars option to use Hoosier bias ply slicks or VFF tyres; clarifies mixing rules. · FF adds alternative tire options for older cars with rocker arm or outboard suspension: bias ply slicks or VFF radials.showhide
FF Formula F Alternative Tire Rule Proposed Clarifications #39281tyres & wheelsadded · tyres & wheelsFF clarifies alternative tire eligibility: homologated 1989 or earlier with rocker or outboard suspension all four corners; push-rod/pull-rod cars may seek approval.
FF Formula F Proposal to Invite Older Cars Via a Tire Rule Change #37802tyres & wheelsadded · tyres & wheelsFF adds alternative tire options for older cars with rocker arm or outboard suspension: bias ply slicks or VFF radials.
Cal Club 2025 CALCL252025-02-22
1:52.044Eric Poulsen · only car
1:51.118Eric Poulsen · only car
114.7Eric Poulsen
59 earlier rule changes on record, in force before Cal Club 2025 (from 2019)11 engine · 9 tyres & wheels · 8 suspension & brakes · 6 weight · 1 aero · 1 cars added · 1 induction · 14 wording · 8 other · FF and FC sequential gearbox weight penalty reduces from 25 lbs to 10 lbs minimum weight addition. · FF Honda Fit pistons: OEM 0.25mm oversize PN 13020-RB7-Z00 or Fast Forward PN FF800-110 now both allowed; standard diameter 73.240mm (2.8835 inches), minimum weight 198.0g. · FF EGR blanking plate rule clarified: VTEC activation valve must be retained and functioning, no modifications permitted. · FE and SRF protest fee rules redirected to GCR section 8.3.1.D for fees and procedure. · FF Honda Fit gains Fast Forward oversize piston ring option PN FF800-100 as alternative to Riken or Nippon. · FF Honda Fit engine adds Fast Forward part number alternatives for intake, exhaust, oil system, and scavenge pump components. · 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. · FF block relief permitted only as needed to fit an allowed crankshaft. · FF class cylinder head now permits optional coolant bleed line pipe thread fitting to swirl tower. · FF Honda LC1 ECU supplied by HPD is permitted effective 12/1/2020 with HPD lambda sensor. · F500 Suzuki GSXR600 engine years extended from 2003-2013 to 2003-2019. · FF Honda LC1 ECU implementation date clarified to pending, contingent on SCCA receiving sufficient support materials. · 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. · FF Kent Engine alternator becomes optional instead of not required. · FF permits HPD LC1 ECU with lambda sensor; E1 ECU no longer supported but existing units may continue. · FF rain tyres now allow Hoosier W3 Radial 185/60R13 front and 205/60R13 rear. · 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. · FF Honda Fit cylinder honing increased to 73.315mm and oversize pistons PN 13020-RB7-Z00 now permitted with matching ring packs. · FF intake manifold thermal wrap now permitted if easily removable for inspection; no coating allowed. · FF clarifies coolant and oil catch tank capacity requirements: coolant minimum one U.S. pint, oil minimum one U.S. quart per system.showhide
FF Change FF/FC Weight with Sequential Gearbox #36651weightfaster · weightFF and FC sequential gearbox weight penalty reduces from 25 lbs to 10 lbs minimum weight addition.
FF Alternative Oversize Honda Fit Pistons #37064engineadded · engineFF Honda Fit pistons: OEM 0.25mm oversize PN 13020-RB7-Z00 or Fast Forward PN FF800-110 now both allowed; standard diameter 73.240mm (2.8835 inches), minimum weight 198.0g.
FF Update to FF EGR Blanking Plate Rule #36633wordingwordingFF EGR blanking plate rule clarified: VTEC activation valve must be retained and functioning, no modifications permitted.
FF Honda Fit Oversize Piston Rings #35305engineadded · engineFF Honda Fit gains Fast Forward oversize piston ring option PN FF800-100 as alternative to Riken or Nippon.
SRF Update SRF Front W2 Rain Tire Part Number #34118tyres & wheels
FF Add Fast Forward Part Numbers for Honda Fit Engine #33752engineadded · engineFF Honda Fit engine adds Fast Forward part number alternatives for intake, exhaust, oil system, and scavenge pump components.
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.
FF Allow Optional Coolant Bleed Line to Correct a Known Problem #29673otheraddedFF class cylinder head now permits optional coolant bleed line pipe thread fitting to swirl tower.
FF Clarification regarding Honda LC1 ECU implementation date #29684wordingwordingFF Honda LC1 ECU supplied by HPD is permitted effective 12/1/2020 with HPD lambda sensor.
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.
FF Clarification regarding Honda LC1 ECU implementation #29135wordingwordingFF Honda LC1 ECU implementation date clarified to pending, contingent on SCCA receiving sufficient support materials.
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.
FF E&O FF Kent Engine alternator language #28204engineadded · engineFF Kent Engine alternator becomes optional instead of not required.
FF Honda Racing HPD low cost ECU proposal #27563engineadded · engineFF permits HPD LC1 ECU with lambda sensor; E1 ECU no longer supported but existing units may continue.
FF Update rain tire designation #28443tyres & wheelsadded · tyres & wheelsFF rain tyres now allow Hoosier W3 Radial 185/60R13 front and 205/60R13 rear.
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
FF Request for Oversize Honda Fit Pistons #25810enginefaster · engineFF Honda Fit cylinder honing increased to 73.315mm and oversize pistons PN 13020-RB7-Z00 now permitted with matching ring packs.
FF Heat Shield - Fit Intake #26102aeroadded · aeroFF intake manifold thermal wrap now permitted if easily removable for inspection; no coating allowed.
FF Request catch cans/tanks clarification #26158wordingwordingFF clarifies coolant and oil catch tank capacity requirements: coolant minimum one U.S. pint, oil minimum one U.S. quart per system.
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.