BoP Lab / Classes / F6

F6 vs SRF vs SMX vs FV pace at every track

Lap times across years say as much about the weather as the class. % of F6 is each class's best lap as a share of F6'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)

ASB-SpecEPF6×FAFCFE2FFFPvsFV ×FXGT1GT2GTXHPPP2SMvsSMX ×vsSRF ×SRF3STLSTUT1T2T3T4Show 49 inactive classes

Series Runoffs Super Tour Both

Reference class · the yardstick the % column and chart are measured against

Tracks · untick to narrow Auto Club Speedway Barber Motorsports Park Blackhawk Farms Raceway Buttonwillow Raceway Park Circuit of St. Louis (formerly Gateway Motorsports Circuit of the Americas Daytona International Speedway Grattan Raceway Hallett Motor Racing Circuit Homestead-Miami Speedway Indianapolis Motor Speedway Laguna Seca Michelin Raceway Road Atlanta Mid-Ohio Sports Car Course New Jersey Motorsports Park NOLA Motorsports Park Pacific Raceways Pittsburgh International Race Complex Portland International Raceway Pueblo Motorsports Park Road America Sebring International Raceway Sonoma Raceway Summit Point Raceway Thunderhill Raceway Park Virginia International Raceway Watkins Glen International Willow Springs Raceway World Wide Technology Raceway

Closest to the field: F6 100.0% of F6 Calvin Stewart, Virginia International Raceway Runoffs 2023 race · SMX 111.5% of F6 Cam Ebben, Road America Runoffs 2026 race · FV 115.0% of F6 Andrew Abbott, Virginia International Raceway Runoffs 2023 race

% of F6Lap times

F6SRFSMXFVsolid race · dashed qualifying · slower is lower

F6SRFSMXFVsolid race · dashed qualifying · each class's best lap as a share of F6's at the same event (the reference class, changeable above); 100% is level, less is quicker, so up the chart is quicker

	Event	F6			SRF					SMX					FV
	Event	Qual best	Race best	Trap	Qual best	Race best	Trap	vs F6	% of F6	Qual best	Race best	Trap	vs F6	% of F6	Qual best	Race best	Trap	vs F6	% of F6
	Road America Runoffs 20262026-09-28	2:18.489Calvin Stewart · fastest of 13 · top 5 within 4.2s-0.617s (-0.44%)	2:20.255James Weida · fastest of 13 · top 5 within 2.0s+1.415s (+1.02%)	143.0Calvin Stewart-4.5 mph (-3.1%)						2:36.472Skyler Cottrell · fastest of 21 · top 5 within 0.4s+0.240s (+0.15%)	2:36.414Cam Ebben · fastest of 21 · top 5 within 1.1s-0.677s (-0.43%)	128.4Christian Hoagland-0.6 mph (-0.5%)	+16.159squal +17.983s	111.5%qual 113.0%	2:46.536Zachary Whitston · fastest of 37 · top 5 within 1.7s+2.435s (+1.48%)	2:45.272Brian Farnham · fastest of 34 · top 5 within 1.3s-1.464s (-0.88%)	117.4Rick Shields+0.2 mph (+0.1%)	+25.017squal +28.047s	117.8%qual 120.3%
5 rule changes (SRF: 3, SMX: 2)2 engine · 2 wording · 1 other · SRF rain/brake light part number and GCR section reference corrected for original roll hoop mounting. · SM/SMX Mazda rear toe link part number revised from 0000-04-5361426 to 0000-04-5361. · SM/SMX part number 0000-10-6900 replaced with 0000-06-5016-KT in GCR 9.1.7.C.1.j.1.c. · SRF3 spark plugs limited to NGK LTR7IX-11 P/N G301041 only; washers and sealing rings prohibited. · SRF3 adds HD Oil Cooler P/N G1148500 option alongside standard P/N G480503, no fan permitted.showhide 2026-09-01 SRF GCR Rain/Brake Light Correction #40579wordingwordingSRF rain/brake light part number and GCR section reference corrected for original roll hoop mounting. 2026-07-01 SMX Rear Toe Link #40271wordingwordingSM/SMX Mazda rear toe link part number revised from 0000-04-5361426 to 0000-04-5361. 2026-04-01 SMX Part Number Change Request #39914otherunclearSM/SMX part number 0000-10-6900 replaced with 0000-06-5016-KT in GCR 9.1.7.C.1.j.1.c. 2026-03-01 SRF SRF3 Spark Plugs #39899engineengineSRF3 spark plugs limited to NGK LTR7IX-11 P/N G301041 only; washers and sealing rings prohibited. 2025-10-01 SRF Add HD Oil Cooler #38979engineaddedengineSRF3 adds HD Oil Cooler P/N G1148500 option alongside standard P/N G480503, no fan permitted.
	Road America Runoffs 20252025-09-29									2:36.232Cam Ebben · fastest of 20 · top 5 within 0.2s+0.581s (+0.37%)	2:37.091Michael Tinis · fastest of 19 · top 5 within 0.3s+0.813s (+0.52%)	129.1Camden Gruber-0.4 mph (-0.3%)			2:44.101Andrew Abbott · fastest of 34 · top 5 within 1.3s+1.458s (+0.90%)	2:46.736Zachary Whitston · fastest of 29 · top 5 within 0.6s+1.902s (+1.15%)	117.2Zachary Whitston+0.7 mph (+0.6%)
7 rule changes (SRF: 2, SMX: 5)5 wording · 2 other · SMX drivers must submit data acquisition files on time or face suspension and $250 fine. · SMX penalty language clarified: level 1 and 3 infractions may carry $1,000 fines, level 2 and 4 may carry $500 fines. · SMX tire marking rules clarified: one set Toyo RR P235/40/ZR17 per weekend, impound after first dry session, damaged tires may be replaced with used only. · SMX competitors must submit AiM data files within 60 minutes instead of 30 after timed sessions. · 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. · SMX OE instrument cluster must stay unmodified and connected; aftermarket dash allowed if wiring only re-routed; alternate gauges now permitted; foot pedal comfort mods allowed without relocation.showhide 2025-06-01 SMX SMX Data Submission - Penalties #38248otheraddedSMX drivers must submit data acquisition files on time or face suspension and $250 fine. 2025-06-01 SMX Committee) SMX Penaly Clarification updated language #38337wordingwordingSMX penalty language clarified: level 1 and 3 infractions may carry $1,000 fines, level 2 and 4 may carry $500 fines. 2025-05-01 SMX Clarify Tire Marking Regs #38004wordingwordingSMX tire marking rules clarified: one set Toyo RR P235/40/ZR17 per weekend, impound after first dry session, damaged tires may be replaced with used only. 2025-05-01 SMX SMX Data Submission Timeframe #38039wordingwordingSMX competitors must submit AiM data files within 60 minutes instead of 30 after timed sessions. 2025-04-01 SRF Driver Safety & Comfort #37966otheraddedSRF drivers with disabilities may modify seat and controls for safety and comfort with SCCA approval, noted in logbook, for that driver only. 2025-04-01 SRF Update SADEV transmission specs #37992wordingwordingSRF SADEV-SRF3 6-speed sequential transmission: effective date clarified to 1 April 2025 onward. 2024-12-01 SMX E&O SMX Regs 9.1.7.1.D.5.u-.w #37070wordingwordingSMX OE instrument cluster must stay unmodified and connected; aftermarket dash allowed if wiring only re-routed; alternate gauges now permitted; foot pedal comfort mods allowed without relocation.
	Road America Runoffs 20242024-10-01	2:19.106Calvin Stewart · fastest of 22 · top 5 within 1.3s	2:18.840James Weida · fastest of 22 · top 5 within 1.0s	147.6Calvin Stewart						2:35.651Ethan Lampe · fastest of 23 · top 5 within 0.7s	2:36.278Ethan Jacobs · fastest of 22 · top 5 within 0.7s	129.5Michael Borden	+17.438squal +16.545s	112.6%qual 111.9%	2:42.643Andrew Whitston · fastest of 27 · top 5 within 2.3s-1.351s (-0.82%)	2:44.834Andrew Abbott · fastest of 27 · top 5 within 0.9s-0.982s (-0.59%)	116.5Brian Farnham-0.7 mph (-0.6%)	+25.994squal +23.537s	118.7%qual 116.9%
16 rule changes (SRF: 10, SMX: 4, FV: 2)2 suspension & brakes · 1 engine · 1 tyres & wheels · 8 wording · 4 other · FV ferrous rotor must not be cross-drilled; pad cleaning grooves limit unchanged at three per side. · 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. · SMX Spec MX-5 camera requirement: non-functioning recorder now will instead of may warrant penalty or disqualification. · SM and SMX must run latest AIM Data Logger Spec MX-5 ECU Protocol, effective 2024-09-01. · SMX Mazda MX-5 OE versus OEM definitions clarified in GCR section 9.1.7.1; wording change only. · SM and SMX now allow an alternate shifter bushing at the bottom of the shift lever. · 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. · FV front wheel bearings wording clarified; specification unchanged. · SRF radiator options expanded: Enterprises P/N 480465 with baffle 480464, 480466, or Automotive 1R698 and CU698 allowed if cross-reference equivalent.showhide 2024-10-01 FV Disc Brakes #36822wordingwordingFV ferrous rotor must not be cross-drilled; pad cleaning grooves limit unchanged at three per side. 2024-10-01 SRF Update SRF3 Air Filter Rule #36681wordingremovedSRF3 air filter rule removes K&N RC-9160 option, specifies Weems P/N WM301020 only. 2024-10-01 SRF Update SRF Brake Rotor Thickness #36687suspension & brakessuspension & brakesSRF Wilwood vented rotor minimum thickness increases to 13.25mm, 0.522 inches. 2024-10-01 SRF Hoosier Tire Decal Placement #36739wordingwordingSRF3 Hoosier decal placement changed from four logos on nose and tail to three logos on sides and center front. 2024-09-01 SMX SMX Camera Rule Correction #36496wordingwordingSMX Spec MX-5 camera requirement: non-functioning recorder now will instead of may warrant penalty or disqualification. 2024-09-01 SMX Committee) AIM ECU Protocol #36556engineaddedengineSM and SMX must run latest AIM Data Logger Spec MX-5 ECU Protocol, effective 2024-09-01. 2024-09-01 SMX Committee) OE versus OEM Definitons #36608wordingwordingSMX Mazda MX-5 OE versus OEM definitions clarified in GCR section 9.1.7.1; wording change only. 2024-09-01 SMX Committee) Shifter Bushing #36611otheraddedSM and SMX now allow an alternate shifter bushing at the bottom of the shift lever. 2024-09-01 SRF Protest Fee Clarification #36540wordingwordingFE and SRF protest fee rules redirected to GCR section 8.3.1.D for fees and procedure. 2024-09-01 SRF Update to Letter 36619 with new Hoosier Contingency Decal Info #36624wordingwordingSRF Hoosier contingency decal requirement reduced from four decals in specific locations to three decals with simplified placement. 2024-08-01 SRF Update Rain Tire Rule and Hoosier Decal Placement #36436tyres & wheelstyres & wheelsSRF 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. 2024-01-01 SRF Update SRF Rain / Brake Rule #34706otherotherSRF rain/brake light must be Super Bright LEDs Inc. P/N PT-STRB-R24; secondary filament must connect to rain light switch. 2024-01-01 SRF Update SRF Brake Light Rule v1 #34853otherotherSRF 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. 2024-01-01 SRF SRF / SRF3 Rule Updates #35268suspension & brakessuspension & brakesSRF 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. 2023-12-01 FV FV Wheel Bearing Clarification #35150wordingwordingFV front wheel bearings wording clarified; specification unchanged. 2023-10-01 SRF SRF Radiator Rule Update #34805otheraddedSRF radiator options expanded: Enterprises P/N 480465 with baffle 480464, 480466, or Automotive 1R698 and CU698 allowed if cross-reference equivalent.
	Virginia International Raceway Runoffs 20232023-09-23	1:57.437Calvin Stewart · fastest of 9 · top 5 within 4.7s	1:58.816Calvin Stewart · fastest of 9 · top 5 within 3.6s	144.0Calvin Stewart						2:11.435Nathan Nicholson · fastest of 18 · top 5 within 0.6s	2:12.616Noah Harmon · fastest of 16 · top 5 within 0.1s	127.8Noah Harmon	+13.800squal +13.998s	111.6%qual 111.9%	2:15.639Andrew Whitston · fastest of 27 · top 5 within 1.4s+0.523s (+0.39%)	2:16.611Andrew Abbott · fastest of 23 · top 5 within 1.6s-1.482s (-1.07%)	115.6Brian Farnham-0.2 mph (-0.2%)	+17.795squal +18.202s	115.0%qual 115.5%
3 rule changes (SRF: 3)2 tyres & wheels · 1 engine · 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.showhide 2023-06-01 SRF Hoosier SRF Wet Front Tire Rule Update #34189tyres & wheelstyres & wheelsSRF wet front tyre changes to Hoosier P/N 46100 P185/60R13 H20 or W2 with 2.5" ground clearance. 2023-05-01 SRF Update SRF Front W2 Rain Tire Part Number #34118tyres & wheelstyres & wheelsSRF front W2 rain tyre Hoosier part number changes from 46100 to 46101 P185/65R13. 2023-03-01 SRF Update SRF Brake Rule #33469enginefasterengineSRF 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.
	Virginia International Raceway Runoffs 20222022-09-24														2:15.116Brian Farnham · fastest of 29 · top 5 within 1.1s-0.596s (-0.44%)	2:18.093Andrew Whitston · fastest of 28 · top 5 within 1.2s-0.196s (-0.14%)	115.8Jonathan Weisheit+1.1 mph (+0.9%)
7 rule changes (SRF: 3, FV: 4)2 engine · 3 wording · 2 other · 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. · FV connecting rod options expanded to include BrianCrower part BC6417 and Newland Group part 4M113077. · FV connecting rods minimum weight 425.0 grams, center-to-center length 130 +0.10/-0.25 mm; Crower, BrianCrower, Newland Group parts allowed if meeting specs. · FV Crower connecting rods SP93280B and BC6417 allowed as direct replacement, must meet OEM minimum weight. · FV allows Crower SP93280B and Brian Crower Racing Rods connecting rods as direct replacements, matching OEM minimum weight. · 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…showhide 2022-06-01 SRF SRF Tire Rule Update #32614wordingwordingSRF tire rule wording clarified: tires must be run as delivered. 2022-06-01 SRF Brake, seal, and air filter clarifications #32670otherfasterSRF brake rotor minimum thickness reduced from 13.25 mm to 12.20 mm; seals and air filter specs clarified. 2022-03-01 FV Connecting Rod Update Request for 9.1.1.C Formula Vee (FV) 5.C.6 #32160engineaddedengineFV connecting rod options expanded to include BrianCrower part BC6417 and Newland Group part 4M113077. 2022-03-01 FV E&O clarification of connecting rod center-to-center length #32183wordingwordingFV connecting rods minimum weight 425.0 grams, center-to-center length 130 +0.10/-0.25 mm; Crower, BrianCrower, Newland Group parts allowed if meeting specs. 2022-01-01 FV Update direct replacement connecting rod information #31843wordingwordingFV Crower connecting rods SP93280B and BC6417 allowed as direct replacement, must meet OEM minimum weight. 2021-12-01 FV Formula V Connecting Rod Replacement #31448engineaddedengineFV allows Crower SP93280B and Brian Crower Racing Rods connecting rods as direct replacements, matching OEM minimum weight. 2021-12-01 SRF Three Updates to SRF Rules #31523otherotherSRF 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…
	Indianapolis Motor Speedway Runoffs 20212021-09-25														1:57.479Andrew Whitston · fastest of 48 · top 5 within 0.8s+1.720s (+1.49%)	1:57.234Alex Scaler · fastest of 47 · top 5 within 1.0s+1.311s (+1.13%)	124.0Mark Edwards
6 rule changes (SRF: 6)1 cars added · 1 engine · 1 tyres & wheels · 2 wording · 1 other · 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.showhide 2021-08-01 SRF SRF Wet Tires #30849tyres & wheelsaddedtyres & wheelsSRF wet tyres add Hoosier W2 option alongside existing H20 from October 4, 2021. 2021-08-01 SRF SADEV-SRF3 Transmission #30926cars addedaddedSRF adds SADEV-SRF3 6-speed sequential transmission option with ratios 3.0–0.92:1 and 3.20 final drive. 2021-08-01 SRF SRF Update Maintenance, Repairs and Seals #30961wordingwordingSRF 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. 2021-06-01 SRF SRF3 Alternator Pulley #30684engineaddedengineSRF3 alternator pulley specified as P/N G902130 or G902130A, minimum 12oz. 2021-03-01 SRF Mandatory identification: #30223wordingwordingSRF and SRF3 mandatory identification revised: removed Ford Performance and Blue Oval decals, added Hoosier logo placement. 2020-12-01 SRF SRF Shocks, Springs and Ride Height. #29688otherotherSRF rear springs limited to P/N 280390 only, previous part numbers no longer allowed; ground clearance wording clarified.
	Road America Runoffs 20202020-10-02														2:43.994Hunter Phelps-Barron · fastest of 28 · top 5 within 0.6s	2:45.816Alex Scaler · fastest of 24 · top 5 within 1.5s	117.1Hunter Phelps-Barron
11 rule changes (SRF: 5, FV: 6)6 tyres & wheels · 1 cars added · 1 weight · 3 wording · FV now permits 4 bolt wheels in addition to existing specifications. · FV now allows 4-bolt pattern wheels in addition to existing specifications. · SRF Penske shock P/N 280396 bump stop P/N 280407 becomes mandatory, maximum one per shock, effective 05/01/2020. · FV rain tyre changes to Hoosier #44266 22.5 x 5.0 x 15 WET or W3. · FV allows non-spec Hoosier tyres at Regional races only; Majors, Super Tour, and Runoffs require spec tyres from 1/1/2020. · Formula Vee now allows 22.5 x 5.5 x 15 rear tires on front axle; rain tire mandated as Hoosier #44266 22.5 x 5.0 x 15 from 1/1/2020. · SRF rain and brake rule supersedes GCR 9.3.32.B.2 effective 1/1/2024 through 12/31/2024. · FV wheels may now be 15-inch 4.5J steel VW with same 5-bolt pattern as standard 4J, within track limits. · 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.showhide 2020-07-01 FV Support for Recommended Item - 4 bolt wheels in FV #29084cars addedaddedFV now permits 4 bolt wheels in addition to existing specifications. 2020-07-01 FV Support for 4-bolt pattern wheels #28955 #29118tyres & wheelsaddedtyres & wheelsFV now allows 4-bolt pattern wheels in addition to existing specifications. 2020-05-01 SRF SRF Bump Stop Correction #27019wordingwordingSRF Penske shock P/N 280396 bump stop P/N 280407 becomes mandatory, maximum one per shock, effective 05/01/2020. 2020-03-01 FV Update rain tire designation #28444tyres & wheelstyres & wheelsFV rain tyre changes to Hoosier #44266 22.5 x 5.0 x 15 WET or W3. 2020-01-01 FV FV Allow non-spec tire in Regional competition #26284tyres & wheelsaddedtyres & wheelsFV allows non-spec Hoosier tyres at Regional races only; Majors, Super Tour, and Runoffs require spec tyres from 1/1/2020. 2020-01-01 FV Request to Allow Rear Tires on the Front of Formula Vee #26537tyres & wheelsaddedtyres & wheelsFormula Vee now allows 22.5 x 5.5 x 15 rear tires on front axle; rain tire mandated as Hoosier #44266 22.5 x 5.0 x 15 from 1/1/2020. 202-01-01 SRF SRF Rain / Brake Rule - BoD approved as follows #34958wordingwordingSRF rain and brake rule supersedes GCR 9.3.32.B.2 effective 1/1/2024 through 12/31/2024. 2019-12-01 FV Clarification on Wheel Bolt Pattern #27603tyres & wheelsaddedtyres & wheelsFV wheels may now be 15-inch 4.5J steel VW with same 5-bolt pattern as standard 4J, within track limits. 2019-12-01 SRF SRF Tire Warmer Rule #27622tyres & wheelstyres & wheelsSRF adds tire warmer prohibition and specifies Hoosier dry and wet tire part numbers. 2019-12-01 SRF SRF / SRF3 Nose Weight Reduction #27706weightfasterweightSRF front nose weight minimum reduced from 35 to 32 lbs. 2019-12-01 SRF SRF / SRF3 Majors & Regional Class Updates #27723wordingwordingSRF2 becomes Regional Only; SRF3 nomenclature changed from GEN3 to Ford 1.6L conversion; SRF and SRF3 no longer compete together for points.
	Virginia International Raceway Runoffs 20192019-10-05														2:15.712Andrew Whitston · fastest of 26 · top 5 within 1.5s	2:18.289Zachary Whitston · fastest of 19 · top 5 within 0.4s	114.8Roger Siebenaler
7 rule changes (SRF: 1, FV: 6)1 aero · 1 suspension & brakes · 1 tyres & wheels · 1 weight · 3 wording · FV exhaust exit opening repositioned: minimum one inch, maximum four inches behind rear body. · FV allows fifteen-inch steel wheels at 4J or 4.5J width, standard VW sedan or within track dimensions. · SRF drivers may now use Dash Windscreen Kit P/N 1180103 or P/N 180102. · FV exhaust outlet opening max distance from body rear increased from 3 to 4 inches. · FV front track maximum 52.500 inches; rear track 49.125–50.750 inches; spacers now allowed. · FV disc brake assembly minimum weight clarified to 16.5 lbs total; caliper minimum weight requirement of 1.65 lbs removed. · FV intake manifold horizontal tube measurement location clarified; removed specific distance ranges from rule text.showhide 2019-10-01 FV Allowed Modifications E&O #27398wordingwordingFV exhaust exit opening repositioned: minimum one inch, maximum four inches behind rear body. 2019-08-31 FV E&O Wheels #27230tyres & wheelsaddedtyres & wheelsFV allows fifteen-inch steel wheels at 4J or 4.5J width, standard VW sedan or within track dimensions. 2019-07-01 SRF SRF Dash Windscreen Kit #27028aeroaddedaeroSRF drivers may now use Dash Windscreen Kit P/N 1180103 or P/N 180102. 2019-05-31 FV Exhaust termination rule E&O #26702wordingwordingFV exhaust outlet opening max distance from body rear increased from 3 to 4 inches. 2019-05-01 FV E&O Dimensions #26674suspension & brakessuspension & brakesFV front track maximum 52.500 inches; rear track 49.125–50.750 inches; spacers now allowed. 2019-04-01 FV Request to clarify Disc Brake rules bearing retainer & weights #26262weightslowerweightFV disc brake assembly minimum weight clarified to 16.5 lbs total; caliper minimum weight requirement of 1.65 lbs removed. 2019-02-01 FV FV Intake Manifold Clarification #26008wordingwordingFV intake manifold horizontal tube measurement location clarified; removed specific distance ranges from rule text.
	Sonoma Raceway Runoffs 20182018-10-10														1:52.637Skip Streets · fastest of 29 · top 5 within 1.6s	1:53.639Alex Scaler · fastest of 28 · top 5 within 0.4s	106.3Skip Streets
No rule changes on record between these events
	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									1:55.759Michael Varacins · fastest of 39 · top 5 within 1.0s	1:55.923Michael Varacins · fastest of 32 · top 5 within 1.3s
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									1:37.942Alex Scaler · fastest of 41 · top 5 within 0.3s	1:38.066Flinn Lazier · fastest of 38 · top 5 within 0.7s
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									2:21.167Roger Siebenaler · fastest of 31 · top 5 within 0.8s	2:21.142Andrew Whitston · fastest of 30 · top 5 within 1.1s

By track

Track	Events	Typical % of F6	Best	Latest
Road America	4	100.0%2 of 4 with F6	100.0%Runoffs 2024	100.0%Runoffs 2026
Virginia International Raceway	3	100.0%1 of 3 with F6	100.0%Runoffs 2023	100.0%Runoffs 2023
Indianapolis Motor Speedway	2	0 of 2 with F6
Daytona International Speedway	1	0 of 1 with F6
Mid-Ohio Sports Car Course	1	0 of 1 with F6
Sonoma Raceway	1	0 of 1 with F6

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 F6'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.