BoP Lab / Buttonwillow Raceway Park

FM vs P pace at Buttonwillow Raceway Park

Lap times across years say as much about the weather as the class. % of FM is each class's best lap as a share of FM'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.

Quickest here: P 1:32.872 Jim Devenport, Super Tour Feb 2025 qualifying

FMPsolid race · dashed qualifying · slower is lower

	Event	FM			P
	Event	Qual best	Race best	Trap	Qual best	Race best	Trap	vs FM	% of FM
	Super Tour Feb 2026 CALCL262026-02-21				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%)
6 rule changes (P: 6)2 cars added · 2 engine · 1 wording · 1 other · Prototype carbon-carbon and carbon-ceramic brake rotors permitted; rotor material now unrestricted. · Prototype 13B rotary restrictor changes to 40mm SIR fuel injection or 41.5mm venturi carburetor. · Prototype class adds Radical SR3 to Table 1 Spec Line Cars. · Prototype P2 cars may now run P2 specification or modify to Prototype rules in Prototype class; Radical Cup series added as spec line car. · Prototype Engine Table A 2-cycle restrictor reduced from 40mm to 38mm venturi size. · Class P adds engine and car notes: Line D no restrictor at 1150 lbs; Line G CN Honda K20A-FD2 unrestricted ITBs at 1500 lbs; Beasley B2 Mazda 12A 40.5mm venturi; P2 2000cc auto rules clarified.showhide 2026-01-01 P Request to Continue to Allow Carbon Brakes #39476otheraddedPrototype carbon-carbon and carbon-ceramic brake rotors permitted; rotor material now unrestricted. 2025-09-01 P 13B Rotary Engine Rules Change Request #38856engineunclearPrototype 13B rotary 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 addedaddedPrototype class adds Radical SR3 to Table 1 Spec Line Cars. 2025-09-01 P Clarify spec line cars language #38943cars addedaddedPrototype P2 cars may now run P2 specification or modify to Prototype rules in Prototype class; Radical Cup series added as spec line car. 2025-08-01 P RM 25-05 - Prototype Engine Table A, 2 Cycle Restrictor Change #38929engineslower · enginePrototype Engine Table A 2-cycle restrictor reduced from 40mm to 38mm venturi size. 2025-05-01 P Add missing punctuation marks #38150wordingaddedClass P adds engine and car notes: Line D no restrictor at 1150 lbs; Line G CN Honda K20A-FD2 unrestricted ITBs at 1500 lbs; Beasley B2 Mazda 12A 40.5mm venturi; P2 2000cc auto rules clarified.
	Super Tour Feb 2025 CALCL252025-02-22				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
2 rule changes (P: 2)2 wording · Prototype Spec Lines B and D: wording corrections to engine table notes; no performance change. · Prototype class renamed from P1 to P, with P1 and P2 designations removed throughout GCR sections 9.1, 9.2.2, 9.3.37, and appendices.showhide 2025-02-01 P Correct text in engine table notes #37606wordingwordingPrototype Spec Lines B and D: wording corrections to engine table notes; no performance change. 2025-02-01 P Update Prototype class designation #37653wordingwordingPrototype class renamed from P1 to P, with P1 and P2 designations removed throughout GCR sections 9.1, 9.2.2, 9.3.37, and appendices.
	Super Tour Apr 2019 ST19APR262019-04-26

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 FM" is the class's best as a share of FM'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 FM'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.