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BoP Lab / Buttonwillow Raceway Park

FE vs FM vs FB vs AS pace at Buttonwillow Raceway Park

FE at every track →

Lap times across years say as much about the weather as the class. % of FE is each class's best lap as a share of FE's on the same day, so the conditions drop out: 100% is level, less is quicker, and a move in it is the class getting faster or slower against the field.

Class · click a class to switch, + to compare alongside (up to 4: remove one to add another)
Reference · what % is measured against
Track configuration

Quickest here: AS 1:55.849 Roger Eagleton, Super Tour Feb 2025 race

1:561:5787 rule changes between Super Tour Apr 2019 and Super Tour Feb 202587 ▾14 rule changes between Super Tour Feb 2025 and Super Tour Feb 202614 ▾AS race best at Super Tour Feb 2025: 1:55.849 (Roger Eagleton)AS race best at Super Tour Feb 2026: 1:56.314 (Ross Murray)AS qualifying best at Super Tour Feb 2025: 1:56.445 (Roger Eagleton)AS qualifying best at Super Tour Feb 2026: 1:56.812 (Ross Murray)Super Tour Apr 2019Super Tour Apr2019Super Tour Feb 2025Super Tour Feb2025Super Tour Feb 2026Super Tour Feb2026
FEFMFBASsolid race · dashed qualifying · slower is lower
EventFEFMFBAS
Qual best Race best Trap Qual best Race best Trap vs FE % of FE Qual best Race best Trap vs FE % of FE Qual best Race best Trap vs FE % of FE 
Super Tour Feb 2026 CALCL262026-02-211:56.812Ross Murray · fastest of 2+0.367s (+0.32%)1:56.314Ross Murray · fastest of 2+0.465s (+0.40%)135.2Ross Murray+26.5 mph (+24.4%)
14 rule changes (FE: 3, AS: 11)5 engine · 5 weight · 2 induction · 2 othershowhide
  • AS Edelbrock manifold (& timing kit) to Chevy LS Spec Lines Request #39055weight
  • AS Restrictor Plate Change for Gen 2 Ford Coyote Engine #39501induction
  • FE FE & FE2 Rule Updates #39484engine
  • AS 1994 Mustang Spec Line Request #39104engine
  • AS Cadillac CTS-V BOP Weight Change #38640weight -50 lbs
  • FE FE & FE2 Bubble Tail #38978other
  • FE FE & FE2 Rule Updates #38901weight
  • AS RE: Previous Letter 37695 Update #38245weight -75 lbs
  • AS Errors and Omissions #38234engine
  • AS Errors and Omission #38055induction
  • AS Request to Add LS1/LS6 Intakes for 5.3L Truck Engine EnO #38197engine
  • AS Flotek Head Plunge Cut Inconsistencies #37502other
  • AS Notes clean up #37693weight
  • AS Race memo #37902engine
Super Tour Feb 2025 CALCL252025-02-221:56.445Roger Eagleton · fastest of 3 · top 3 within 4.0s1:55.849Roger Eagleton · fastest of 4 · top 4 within 5.3s108.7Roger Eagleton
87 rule changes (FE: 26, AS: 61)14 engine · 14 weight · 11 cars added · 10 suspension & brakes · 10 tyres & wheels · 4 aero · 3 induction · 6 wording · 15 othershowhide
  • AS Increase Coyote Engine Restrictor to 80mm #36177induction
  • AS Performance Pack for 2015+ Mustang #36867weight
  • AS Gear Ratios #37131engine
  • AS ECU specs for LS engine #37208engine
  • FE Brake Line to A-Arm Covers #37110suspension & brakes
  • AS Mustang transmission ratios #36662engine
  • FE Protest Fee Clarification #36540wording
  • FE Update on Letter 36620 with new Hoosier Contingency Decal Info #36625tyres & wheels
  • FE Hoosier Tire Decal Placement #36435tyres & wheels
  • AS Request for Classification of 2018-2023 mustang In #35764cars added
  • AS 6th gen Camaro limited prep #35733cars added
  • AS Chevrolet/Pontiac Camaro & Firebird (82-92) 5.7L V8 LS1 Alum BLK #35825cars added
  • AS Full Prep Head #35891other
  • AS Restricted Prep Aftermarket Parts Request #35682other
  • AS Allowance of 11 #35824tyres & wheels
  • AS Request to Classify 1970-1981 Camaro and Firebird in AS #33659cars added
  • AS Fuel Cell 12 #34194other
  • AS Please Classify the 6th Gen Into AS. #35448cars added
  • AS spec lines #35713cars added
  • FE Update FE Rain Light Rule #34707other
  • FE FE/FE2 rule update #35269other
  • AS Crate Motor Part Numbers #32944engine
  • AS Request wheel size change #33007tyres & wheels
  • AS Alternative Upper Front Control Arms for Dodge Challenger #33352engine
  • AS Front Brake Caliper Adapters for Dodge Challenger #33353suspension & brakes
  • FE Update FE SADEV Transmission Rule #33883other
  • FE Brake bias adjuster clarification #33084suspension & brakes
  • FE FE Front and Rear Wing Update & Clarification #33089aero
  • AS Request to add Hoosier W2 #33031other
  • AS correction of Dodge Challenger specification line #33151wording
  • FE Engine Heat Shield & Insulation #33019engine
  • AS Request CTS-V Spec Line Error Correction #30242weight
  • FE Update FE/FE2 Tire Rule #32613tyres & wheels
  • FE Master cylinder clarification #32669engine
  • AS Proposed Revisions to SCCA GCR 2021 Appendix M, Part 3 #30295other
  • AS specification line consolidation and correction #31846wording
  • AS correction of SMG specification line #31847suspension & brakes
  • AS Alternate cylinder heads for full prep engine builds - Evaluation #31851engine
  • FE Two FE2 Rule Updates #31524other
  • AS Request for adjustable Front Upper Control Arms on 4th Gen F-Body #30457other
  • AS Request Pontiac GTO tire size change #30881weight
  • FE FE Tire Rule Changes #30754tyres & wheels
  • FE Radiator Screens Clarification #30792wording
  • AS Request CTS-V Spec Line Error Correction #30242weight
  • AS Request to consolidate SN95 Mustang '94-'04 Mustang spec lines #30428cars added
  • AS American Sedan Transmission Rule Change Request #30595weight
  • AS Correction to specifications inadvertently deleted #30691wording
  • AS weight adjustments #30700weight +50 lbs
  • FE FE Radiator Screens #30575other
  • AS AS Mustang LP 4.6 3V Classification Transmission Request #29886weight
  • AS Request CF driveshaft on CTS-V for durability improvement #30117engine
  • AS Adjustment to model years of 5th generation RP Camaro #30348engine
  • AS Request for 2015 -2017 Ford Mustang Spec Line #29514cars added
  • AS Request Trunk lid / Rear Hatch clarification #29591wording
  • AS Common Weight for CTS-V Tire #29759weight
  • AS Correction to specifications inadvertently deleted #30041cars added
  • AS Request Additional Engine Options for Dodge Challenger Spec Line #29543engine
  • AS Rule simplification spec line communization #29824weight
  • FE FE / FE2 Spring Updates #29689suspension & brakes
  • FE FE Gurney Flap Spec Update #29445aero
  • AS Dodge Challenger AS Spec Line Clarification #28698induction
  • AS Dodge Challenger AS Spec Line Clarification #2 #28699aero
  • AS Support for R-Type Specification Tires #27450tyres & wheels
  • AS Spec Tire Request #27519tyres & wheels
  • AS Restrictor Plate Change for RP 2011+ Mustang with Coyote Engine #27675induction
  • AS 2005-2009 Restricted Prep 4.6 3V #27908engine
  • AS Request for 2005-2009 Restricted Prep 4.6 3V Parts #27909engine
  • AS Request for Full Preparation Classification for 2010-2014 Camaro #28030other
  • AS Cylinder Heads #28696engine
  • AS Request for Max Rotor Diameter Change #28748suspension & brakes
  • AS Request increase rotor diameter #28797other
  • FE FE Gurney flap wicker clarification #28885aero
  • AS weight adjustments for 2020 season #28785weight -50 lbs
  • FE FE spring rule update changed to November 1, 2020 #28814suspension & brakes
  • AS Rear Trailing Arms #28007suspension & brakes
  • AS Weight reduction for cars running iron heads #28010weight
  • AS 05-10 Mustang with HR cam classification #28226cars added
  • AS 10-15 Camaro Full Prep classification #28227cars added
  • FE Request for FE / FE2 preparation rules update #27722weight
  • FE FE / FE2 Update Rules #27624weight
  • AS Request to add SMG to 9.1.6.B.1 AS Intent #27140other
  • FE FE Wet Tire E&O #27365tyres & wheels
  • AS Request Ride Height Clarification #26598suspension & brakes
  • FE FE Tire Update #27029tyres & wheels
  • AS Request to Revert to 2017 Weights #25885weight
  • FE FE Anti-Roll Bar Clarification #26912suspension & brakes
  • FE FE / FE2 Updated Bubble Tail Rule #26913other
Super Tour Apr 2019 ST19APR262019-04-26
2 earlier rule changes on record, in force before Super Tour Apr 2019 (from 2019)1 cars added · 1 tyres & wheelsshowhide
  • FE Request to Update Hoosier Rain Tire Part Number for the FE cars #26235tyres & wheels
  • AS SMG Mustang eligibility in American sedan #26224cars added
About this data
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 FE" is the class's best as a share of FE'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 FE'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.