BoP Lab / Buttonwillow Raceway Park

SRF3 vs P pace at Buttonwillow Raceway Park

Quickest here: SRF3 1:50.233 Caleb Shrader, Cal Club 2025 qualifying · P 1:32.872 Jim Devenport, Cal Club 2025 qualifying

Lap times% of SRF3

SRF3Psolid race · dashed qualifying · slower is lower

SRF3Psolid race · dashed qualifying · each class's best lap as a share of SRF3's at the same event (the reference class, changeable above); 100% is level, higher is quicker

	Event	SRF3			P
	Event	Qual best	Race best	Trap	Qual best	Race best	Trap	vs SRF3	% of SRF3
	Cal Club 2026 CALCL262026-02-21	1:50.913Asad Nikadambaev · fastest of 27 · top 5 within 1.1s+0.680s (+0.62%)	1:52.070Asad Nikadambaev · fastest of 27 · top 5 within 0.8s+1.245s (+1.12%)	138.9Paul Marino+20.7 mph (+17.5%)	1:38.716Kevin 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%)	-14.783squal -12.197s	86.8%qual 89.0%
10 rule changes (SRF3: 4, P: 6)1 cars added · 1 engine · 1 induction · 1 suspension & brakes · 5 wording · 1 other · Prototype carbon-carbon and carbon-ceramic brake rotors now permitted instead of prohibited. · SRF3 adds HD Oil Cooler P/N G1148500 as alternative to standard cooler P/N G480503. · P class 13B rotary engine restrictor changes to 40mm SIR fuel injection or 41.5mm venturi carburetor. · Prototype class adds Radical SR3 spec line to Table 1 effective 9/1/25. · Prototype P2 cars may now run P2 spec or modified Prototype spec in Prototype class; clarified language and added Radical Cup series table. · SRF3 brakes restructured: Hawk Blue 801993 pads, Wilwood 800065 rotors only; adds Girling 880358, Wilwood 880357, Tilton 880360 master cylinders. · Prototype Engine Table A 2-cycle restrictor reduces from 40mm to 38mm venturi size. · Class P adds clarification notes on restrictor requirements, throttle bodies, Mazda 12A engine spec, and P2 auto-based engine rules. · SRF drivers with disabilities may modify seat and controls for safety and comfort with approval and logbook notation. · SRF SADEV-SRF3 6-speed sequential transmission gear ratios wording clarified, effective 2025-04-01.showhide 2026-01-01 P Request to Continue to Allow Carbon Brakes #39476suspension & brakessuspension & brakesPrototype carbon-carbon and carbon-ceramic brake rotors now permitted instead of prohibited. 2025-10-01 SRF3 Add HD Oil Cooler #38979otherotherSRF3 adds HD Oil Cooler P/N G1148500 as alternative to standard cooler P/N G480503. 2025-09-01 P 13B Rotary Engine Rules Change Request #38856engineunclearP class 13B rotary engine restrictor changes to 40mm SIR fuel injection or 41.5mm venturi carburetor. 2025-09-01 P Add Radical Cup series Radical SR3 spec line to Table 1 #38916cars addedcars addedPrototype class adds Radical SR3 spec line to Table 1 effective 9/1/25. 2025-09-01 P Clarify spec line cars language #38943wordingwordingPrototype P2 cars may now run P2 spec or modified Prototype spec in Prototype class; clarified language and added Radical Cup series table. 2025-09-01 SRF3 SRF Rule Updates #38853wordingwordingSRF3 brakes restructured: Hawk Blue 801993 pads, Wilwood 800065 rotors only; adds Girling 880358, Wilwood 880357, Tilton 880360 master cylinders. 2025-08-01 P RM 25-05 - Prototype Engine Table A, 2 Cycle Restrictor Change #38929inductionslowerPrototype Engine Table A 2-cycle restrictor reduces from 40mm to 38mm venturi size. 2025-05-01 P Add missing punctuation marks #38150wordingwordingClass P adds clarification notes on restrictor requirements, throttle bodies, Mazda 12A engine spec, and P2 auto-based engine rules. 2025-04-01 SRF3 Driver Safety & Comfort #37966wordingwordingSRF drivers with disabilities may modify seat and controls for safety and comfort with approval and logbook notation. 2025-04-01 SRF3 Update SADEV transmission specs #37992wordingwordingSRF SADEV-SRF3 6-speed sequential transmission gear ratios wording clarified, effective 2025-04-01.
	Cal Club 2025 CALCL252025-02-22	1:50.233Caleb Shrader · fastest of 33 · top 5 within 0.4s	1:50.825Caleb Shrader · fastest of 32 · top 5 within 0.8s	118.2John Black	1:32.872Jim Devenport · fastest of 3 · top 3 within 8.1s	1:33.972Jim Devenport · fastest of 3 · top 3 within 7.7s	141.7Jim Devenport	-16.853squal -17.361s	84.8%qual 84.3%
35 earlier rule changes on record, in force before Cal Club 2025 (from 2019)6 tyres & wheels · 5 suspension & brakes · 2 weight · 1 cars added · 1 engine · 19 wording · 1 other · Prototype Staudacher and unrestricted engine notes corrected for minimum weight wording. · Prototype class renamed from P1 to P, affecting designation throughout rules with no performance changes. · SRF3 air filter rule removes K&N RC-9160 option, leaving only P/N WM301020 allowed. · SRF brake rotor minimum thickness increases from 12.20mm to 13.25mm, Wilwood vented rotor P/N 800065. · SRF3 Hoosier logo placement changes from four decals to three decals in different locations. · SRF Hoosier decal requirement reduced from four decals in specific locations to three decals with simpler placement rules. · SRF wet tires: P185/60R13 H20/W2 option removed; P185/65R13 W2 front now required with P205/60R13 W2 rear. · SRF3 alternator pulley minimum weight reduced from 12 oz to 11 oz. · SRF rain/brake light now requires Super Bright LEDs Inc. P/N PT-STRB-R24 with specific connector and rain light switch. · SRF requires Super Bright LEDs P/N PT-STRB-R24 rain/brake light with strobing capability and specific wiring. · SRF adds brake duct and pedal extension rules, rear shift cable clamp option, camber limit to 5.0°, radiator opening height 3.5" ±0.5", and P2 engine restrictor changes. · SRF radiator rule clarified: P/N 480466 replaceable with Automotive P/N 1R698, CU698 or manufacturer equivalent with documentation. · SRF Hoosier wet front tire updated to P/N 46100 P185/60R13 H20 or W2. · SRF Hoosier front rain tyre part number changes from 46100 to 46101 P185/65R13 W2. · SRF Renault Alliance solid front rotors banned; restrictor reduced 35mm to 34mm for 2011+ Kawasaki; minimum weight increased to 1100 lbs for 2009+ stock engines. · SRF3 tail sections allowed on SRFs with GEN3 airbox shimming up to 19 mm; alternate dash panel P/N 180100 or 180101 relocated in rules. · SRF tire rule wording changed from 'Tires: must be run as delivered' to 'Tires must be run as delivered.' · SRF brake rotor minimum thickness reduced from 13.25 to 12.20mm; seal and air filter rules clarified. · SRF front wet tire changes from P185/60R13 H20 to P185/65R13 W2; SRF3 adds mandatory G301048 restrictor plate Jan. 1, 2022. · SRF wet tyres add Hoosier P185/60R13 W2 front and P205/60R13 W2 rear as alternatives to H20. · SRF adds SADEV-SRF3 6-speed sequential option with final drive 3.20 versus OEM 5-speed 3.85. · SRF seal procedures clarified: unsealed components need CSR inspection and logbook notation instead of engine removal. · SRF3 alternator pulley restricted to P/N G902130 or G902130A, 12oz minimum weight. · SRF and SRF3 mandatory identification simplified: removed Ford Performance and Blue Oval decals, kept Hoosier logo placement. · SRF shocks, springs, bump stops sealed; rear springs 412-429 lbs/in P/N 280390 only; previous parts no longer allowed. · SRF3 shock absorber brand restriction removed; all shocks must be sealed by Enterprises. · SRF3 bump stop now must be SCCA P/N 280407 only, no modifications, optional, max one per shock. · SRF shock absorber bump stop clarified: only SCCA P/N 280407 allowed as delivered, maximum one per shock, effective 05/01/2020. · SRF rain and brake rule wording updated; supersedes GCR 9.3.32.B.2 effective 1/1/202 through 12/31/2024. · SRF bans tire warmers and cooling methods other than natural air convection or conduction. · SRF front nose weight minimum reduced from 35 to 32 lbs. · SRF3 reclassified as Spec Racer Ford 3 with 1.6L conversion; SRF2 becomes Regional Only Class. · SRF drivers may now use Dash Windscreen Kit P/N 1180103 or P/N 180102. · SRF3 nose assembly must use approved multi-piece design; no modifications allowed except as specified. · SRF3 brakes now allow Hawk Blue 9012 pads P/N 801993 only; shocks simplified to Penske P/N 280396 sealed assembly only, with optional SCCA Enterprises bump rubber P/N 280407 from 05/01/2020.showhide 2025-02-01 P Correct text in engine table notes #37606wordingwordingPrototype Staudacher and unrestricted engine notes corrected for minimum weight wording. 2025-02-01 P Update Prototype class designation #37653wordingwordingPrototype class renamed from P1 to P, affecting designation throughout rules with no performance changes. 2024-10-01 SRF3 Update SRF3 Air Filter Rule #36681wordingunclearSRF3 air filter rule removes K&N RC-9160 option, leaving only P/N WM301020 allowed. 2024-10-01 SRF3 Update SRF Brake Rotor Thickness #36687suspension & brakesslowerSRF brake rotor minimum thickness increases from 12.20mm to 13.25mm, Wilwood vented rotor P/N 800065. 2024-10-01 SRF3 Hoosier Tire Decal Placement #36739wordingwordingSRF3 Hoosier logo placement changes from four decals to three decals in different locations. 2024-09-01 SRF3 Update to Letter 36619 with new Hoosier Contingency Decal Info #36624wordingwordingSRF Hoosier decal requirement reduced from four decals in specific locations to three decals with simpler placement rules. 2024-08-01 SRF3 Update Rain Tire Rule and Hoosier Decal Placement #36436tyres & wheelsslowerSRF wet tires: P185/60R13 H20/W2 option removed; P185/65R13 W2 front now required with P205/60R13 W2 rear. 2024-06-01 SRF3 SRF3 Alternator Pulley Update In #36095weightfasterSRF3 alternator pulley minimum weight reduced from 12 oz to 11 oz. 2024-01-01 SRF3 Update SRF Rain / Brake Rule #34706wordingwordingSRF rain/brake light now requires Super Bright LEDs Inc. P/N PT-STRB-R24 with specific connector and rain light switch. 2024-01-01 SRF3 Update SRF Brake Light Rule v1 #34853wordingwordingSRF requires Super Bright LEDs P/N PT-STRB-R24 rain/brake light with strobing capability and specific wiring. 2024-01-01 SRF3 SRF / SRF3 Rule Updates #35268otherotherSRF adds brake duct and pedal extension rules, rear shift cable clamp option, camber limit to 5.0°, radiator opening height 3.5" ±0.5", and P2 engine restrictor changes. 2023-10-01 SRF3 SRF Radiator Rule Update #34805wordingwordingSRF radiator rule clarified: P/N 480466 replaceable with Automotive P/N 1R698, CU698 or manufacturer equivalent with documentation. 2023-06-01 SRF3 Hoosier SRF Wet Front Tire Rule Update #34189tyres & wheelsunclearSRF Hoosier wet front tire updated to P/N 46100 P185/60R13 H20 or W2. 2023-05-01 SRF3 Update SRF Front W2 Rain Tire Part Number #34118tyres & wheelstyres & wheelsSRF Hoosier front rain tyre part number changes from 46100 to 46101 P185/65R13 W2. 2023-03-01 SRF3 Update SRF Brake Rule #33469suspension & brakesslowerSRF Renault Alliance solid front rotors banned; restrictor reduced 35mm to 34mm for 2011+ Kawasaki; minimum weight increased to 1100 lbs for 2009+ stock engines. 2023-03-01 SRF3 Update SRF Bodywork Fitment Rule #33765wordingwordingSRF3 tail sections allowed on SRFs with GEN3 airbox shimming up to 19 mm; alternate dash panel P/N 180100 or 180101 relocated in rules. 2022-06-01 SRF3 SRF Tire Rule Update #32614wordingwordingSRF tire rule wording changed from 'Tires: must be run as delivered' to 'Tires must be run as delivered.' 2022-06-01 SRF3 Brake, seal, and air filter clarifications #32670suspension & brakesfasterSRF brake rotor minimum thickness reduced from 13.25 to 12.20mm; seal and air filter rules clarified. 2021-12-01 SRF3 Three Updates to SRF Rules #31523tyres & wheelsunclearSRF front wet tire changes from P185/60R13 H20 to P185/65R13 W2; SRF3 adds mandatory G301048 restrictor plate Jan. 1, 2022. 2021-08-01 SRF3 SRF Wet Tires #30849tyres & wheelstyres & wheelsSRF wet tyres add Hoosier P185/60R13 W2 front and P205/60R13 W2 rear as alternatives to H20. 2021-08-01 SRF3 SADEV-SRF3 Transmission #30926cars addedunclearSRF adds SADEV-SRF3 6-speed sequential option with final drive 3.20 versus OEM 5-speed 3.85. 2021-08-01 SRF3 SRF Update Maintenance, Repairs and Seals #30961wordingwordingSRF seal procedures clarified: unsealed components need CSR inspection and logbook notation instead of engine removal. 2021-06-01 SRF3 SRF3 Alternator Pulley #30684engineslowerSRF3 alternator pulley restricted to P/N G902130 or G902130A, 12oz minimum weight. 2021-03-01 SRF3 Mandatory identification: #30223wordingwordingSRF and SRF3 mandatory identification simplified: removed Ford Performance and Blue Oval decals, kept Hoosier logo placement. 2020-12-01 SRF3 SRF Shocks, Springs and Ride Height. #29688suspension & brakessuspension & brakesSRF shocks, springs, bump stops sealed; rear springs 412-429 lbs/in P/N 280390 only; previous parts no longer allowed. 2020-06-01 SRF3 SRF Shocks #28791wordingwordingSRF3 shock absorber brand restriction removed; all shocks must be sealed by Enterprises. 2020-05-01 SRF3 Update Bump Stop Rule #28712suspension & brakessuspension & brakesSRF3 bump stop now must be SCCA P/N 280407 only, no modifications, optional, max one per shock. 2020-05-01 SRF3 SRF Bump Stop Correction #27019wordingwordingSRF shock absorber bump stop clarified: only SCCA P/N 280407 allowed as delivered, maximum one per shock, effective 05/01/2020. 202-01-01 SRF3 SRF Rain / Brake Rule - BoD approved as follows #34958wordingwordingSRF rain and brake rule wording updated; supersedes GCR 9.3.32.B.2 effective 1/1/202 through 12/31/2024. 2019-12-01 SRF3 SRF Tire Warmer Rule #27622tyres & wheelsslowerSRF bans tire warmers and cooling methods other than natural air convection or conduction. 2019-12-01 SRF3 SRF / SRF3 Nose Weight Reduction #27706weightfasterSRF front nose weight minimum reduced from 35 to 32 lbs. 2019-12-01 SRF3 SRF / SRF3 Majors & Regional Class Updates #27723wordingwordingSRF3 reclassified as Spec Racer Ford 3 with 1.6L conversion; SRF2 becomes Regional Only Class. 2019-07-01 SRF3 SRF Dash Windscreen Kit #27028wordingwordingSRF drivers may now use Dash Windscreen Kit P/N 1180103 or P/N 180102. 2019-05-31 SRF3 New SRF Sectional Nose Rule Addition #26914wordingwordingSRF3 nose assembly must use approved multi-piece design; no modifications allowed except as specified. 2019-05-01 SRF3 SRF Brakes and Shock Rule Changes #26629wordingwordingSRF3 brakes now allow Hawk Blue 9012 pads P/N 801993 only; shocks simplified to Penske P/N 280396 sealed assembly only, with optional SCCA Enterprises bump rubber P/N 280407 from 05/01/2020.

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. "% of SRF3" is the class's best as a share of SRF3's best at the same event (100% is level, less is quicker): weather and track condition move every class together, so this compares across years where the raw times do not. It still breaks when SRF3's own field changes or one session was wet and another dry. 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.