BoP Lab / Classes / SRF
SRF vs P pace at every track
Lap times across years say as much about the weather as the class. % of SRF is each class's best lap as a share of SRF'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.
Closest to the field: SRF 100.0% of SRF Cliff White, Daytona International Speedway Runoffs 2015 race
| Event | SRF | P | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Qual best | Race best | Trap | Qual best | Race best | Trap | vs SRF | % of SRF | |||
| Road America Runoffs 20262026-09-28 | 2:02.281Perry Richardson · fastest of 10 · top 5 within 1.3s+1.101s (+0.91%) | 2:03.283Lawrence Loshak · fastest of 10 · top 5 within 0.8s+1.161s (+0.95%) | 165.6Jason Miller+0.7 mph (+0.4%) | |||||||
4 rule changes (SRF: 3, P: 1)2 engine · 1 wording · 1 other · SRF rain/brake light part number and GCR section reference corrected for original roll hoop mounting. · SRF3 spark plugs limited to NGK LTR7IX-11 P/N G301041 only; washers and sealing rings prohibited. · Prototype carbon-carbon and carbon-ceramic brake rotors permitted; rotor material now unrestricted. · SRF3 adds HD Oil Cooler P/N G1148500 option alongside standard P/N G480503, no fan permitted.show
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| Road America Runoffs 20252025-09-29 | 2:01.180Lee Alexander · fastest of 14 · top 5 within 1.5s | 2:02.122Bart Wolf · fastest of 13 · top 5 within 2.1s | 165.0Jason Miller | |||||||
37 rule changes (SRF: 30, P: 7)5 tyres & wheels · 4 engine · 3 cars added · 2 suspension & brakes · 1 aero · 1 weight · 14 wording · 7 other · 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. · SRF drivers with disabilities may modify seat and controls for safety and comfort with SCCA approval, noted in logbook, for that driver only. · SRF SADEV-SRF3 6-speed sequential transmission: effective date clarified to 1 April 2025 onward. · 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. · SRF3 air filter rule removes K&N RC-9160 option, specifies Weems P/N WM301020 only. · SRF Wilwood vented rotor minimum thickness increases to 13.25mm, 0.522 inches. · SRF3 Hoosier decal placement changed from four logos on nose and tail to three logos on sides and center front. · FE and SRF protest fee rules redirected to GCR section 8.3.1.D for fees and procedure. · SRF Hoosier contingency decal requirement reduced from four decals in specific locations to three decals with simplified placement. · SRF wet tyres: front P185/60R13 H20 or W2 and rear P205/60R13 H20 or W2 removed; front P185/65R13 W2 and rear P205/60R13 W2 now required. Hoosier decal placement specified. · SRF rain/brake light must be Super Bright LEDs Inc. P/N PT-STRB-R24; secondary filament must connect to rain light switch. · SRF brake light must be Super Bright LEDs Inc. P/N PT-STRB-R24, with SCCA Enterprises P/N 180427A pigtail and strobing rain light kit. · SRF adds mandatory front brake ducts 12–36 inches, throttle pedal heel-toe extension, braided stainless flex lines, camber limit 5.0 degrees, radiator opening height 3½ ± ½ inches, rear shift cable clamp P/N WM302007A. · SRF radiator options expanded: Enterprises P/N 480465 with baffle 480464, 480466, or Automotive 1R698 and CU698 allowed if cross-reference equivalent. · SRF wet front tyre changes to Hoosier P/N 46100 P185/60R13 H20 or W2 with 2.5" ground clearance. · SRF front W2 rain tyre Hoosier part number changes from 46100 to 46101 P185/65R13. · SRF removes 1985 Renault Alliance solid front rotor option; restrictor sizes decrease 1mm for newer Kawasaki and multi-brand engines; minimum weights increase to 1100 lbs. · SRF tire rule wording clarified: tires must be run as delivered. · SRF brake rotor minimum thickness reduced from 13.25 mm to 12.20 mm; seals and air filter specs clarified. · SRF wet tyres front P185/65R13 W2 option added; air box clarified as-delivered; SRF3 restrictor plate G301048 mandatory Jan 1 2022; P2 motorcycle engines up to 1005cc with 35mm restrictor, 2009+ stock 1075 lbs, 2008 stock 1025 lbs, modifie… · SRF wet tyres add Hoosier W2 option alongside existing H20 from October 4, 2021. · SRF adds SADEV-SRF3 6-speed sequential transmission option with ratios 3.0–0.92:1 and 3.20 final drive. · SRF seal requirements clarified: seals now must be on driveline components in designated locations; unsealed components removed and inspected by CSR or Enterprises rather than engine shipped for testing. · SRF3 alternator pulley specified as P/N G902130 or G902130A, minimum 12oz. · SRF and SRF3 mandatory identification revised: removed Ford Performance and Blue Oval decals, added Hoosier logo placement. · SRF rear springs limited to P/N 280390 only, previous part numbers no longer allowed; ground clearance wording clarified. · SRF Penske shock P/N 280396 bump stop P/N 280407 becomes mandatory, maximum one per shock, effective 05/01/2020. · SRF rain and brake rule supersedes GCR 9.3.32.B.2 effective 1/1/2024 through 12/31/2024. · SRF adds tire warmer prohibition and specifies Hoosier dry and wet tire part numbers. · SRF front nose weight minimum reduced from 35 to 32 lbs. · SRF2 becomes Regional Only; SRF3 nomenclature changed from GEN3 to Ford 1.6L conversion; SRF and SRF3 no longer compete together for points. · SRF drivers may now use Dash Windscreen Kit P/N 1180103 or P/N 180102.show
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| Indianapolis Motor Speedway Runoffs 20172017-09-25 | 1:51.573Thomas Kirchman · fastest of 50 · top 5 within 2.8s | 1:53.769Todd Harris · fastest of 45 · top 5 within 0.2s | ||||||||
| No rule changes on record between these events | ||||||||||
| Mid-Ohio Sports Car Course Runoffs 20162016-09-19 | 1:37.344Mike Miserendino · fastest of 27 · top 5 within 0.8s | 1:37.621Todd Harris · fastest of 27 · top 5 within 0.6s | ||||||||
| No rule changes on record between these events | ||||||||||
| Daytona International Speedway Runoffs 20152015-09-21 | 2:14.306Cliff White · fastest of 39 · top 5 within 1.2s | 2:16.700Cliff White · fastest of 38 · top 5 within 0.5s | ||||||||
By track
| Track | Events | Typical % of SRF | Best | Latest |
|---|---|---|---|---|
| Road America | 2 | 0 of 2 with SRF | ||
| Daytona International Speedway | 1 | 100.0% | 100.0%Runoffs 2015 | 100.0%Runoffs 2015 |
| Indianapolis Motor Speedway | 1 | 100.0% | 100.0%Runoffs 2017 | 100.0%Runoffs 2017 |
| Mid-Ohio Sports Car Course | 1 | 100.0% | 100.0%Runoffs 2016 | 100.0%Runoffs 2016 |
About this data
Every event the class ran, at any track, oldest to newest on the chart and newest first in the table. Each point is the class's best lap as a share of SRF's best on the same day: the weather and the day cancel out, so one figure compares across years where lap times cannot; a class that suits one track more than another still reads differently there. It still moves when the yardstick's own balance changes or its field thins, and an event the yardstick did not run has no point. A best from fewer than three cars is greyed. The rule changes that took effect between two events are folded between their rows.