BoP Lab / Classes / STL

STL vs F5 vs FV pace at every track

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

AS +B-Spec +EP +vsF5 ×FA +FC +FE2 +FF +FP +vsFV ×FX +GT1 +GT2 +GTX +HP +P +P2 +SM +SMX +SRF3 +STL×STU +T1 +T2 +T3 +T4 +Show 50 inactive classes

Series Runoffs Super Tour Both

Reference · what % is 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: STL 100.0% of STL Kevin Boehm, Daytona International Speedway Runoffs 2015 race · F5 84.1% of STL Sven de Vries, Indianapolis Motor Speedway Runoffs 2021 race · FV 95.5% of STL Alex Scaler, Indianapolis Motor Speedway Runoffs 2021 race

% of STLLap times

STLF5FVsolid race · dashed qualifying · slower is lower

STLF5FVsolid race · dashed qualifying · each class's best lap as a share of STL's at the same event (the reference class, changeable above); 100% is level, less is quicker, so up the chart is quicker

	Event	STL			F5					FV
	Event	Qual best	Race best	Trap	Qual best	Race best	Trap	vs STL	% of STL	Qual best	Race best	Trap	vs STL	% of STL
	Road America Runoffs 20262026-09-28	2:30.537Derek Ketchie · fastest of 16 · top 5 within 2.9s-1.528s (-1.00%)	2:30.657Danny Steyn · fastest of 16 · top 5 within 0.6s-1.470s (-0.97%)	134.8Mike Taylor+2.6 mph (+2.0%)						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%)	+14.615squal +15.999s	109.7%qual 110.6%
4 rule changes (STL: 4)2 cars added · 1 weight · 1 wording · STL removes Mazda MX-5 Cup entirely; renames Spec MX5 Challenge to Spec MX5; renames Global Cup to MX-5 Cup (16-18); removes Global Cup (2019). · STL, STU weight calculation procedure clarified: positive percentages added first, negative subtracted second, then fixed weights applied. · STL adds Mazda BP 1.6, 1600cc, minimum weight 2160 lbs. · STL minimum weights increase across all engine sizes, 1300cc to 1850cc up to 195–250 lbs.showhide 2026-07-01 STL Spec Line Clean Up #40344cars addedremovedcars addedSTL removes Mazda MX-5 Cup entirely; renames Spec MX5 Challenge to Spec MX5; renames Global Cup to MX-5 Cup (16-18); removes Global Cup (2019). 2026-06-01 STL Calculating Weight #40224wordingwordingSTL, STU weight calculation procedure clarified: positive percentages added first, negative subtracted second, then fixed weights applied. 2026-04-01 STL Classifications #39885cars addedaddedSTL adds Mazda BP 1.6, 1600cc, minimum weight 2160 lbs. 2026-01-01 STL Weight adjustment for STL #39579weightslowerweightSTL minimum weights increase across all engine sizes, 1300cc to 1850cc up to 195–250 lbs.
	Road America Runoffs 20252025-09-29	2:32.065Jose Osiris Pena · fastest of 14 · top 5 within 3.4s+2.002s (+1.33%)	2:32.127Jose Osiris Pena · fastest of 13 · top 5 within 2.4s+1.882s (+1.25%)	132.2Jon Sewell-2.1 mph (-1.5%)						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%)	+14.609squal +12.036s	109.6%qual 107.9%
3 rule changes (STL: 3)1 cars added · 1 weight · 1 wording · Lotus Evora GT4 minimum weight drops to 2700 lbs; Elise Cup R to 2250 lbs; Elise SC and Exige SC to 2450–2550 lbs. · STL Mazda MX5 Challenge minimum weight now references GCR 9.1.7.1; mandatory component spec list removed, alternative tires only allowed. · STL STU Mazda Miata alternate front hubs Mazda Motorsports Development Part #0000-04-5HUB-S1 approved.showhide 2025-08-01 STL Lotus Weight Reduction #38772weight -50 lbsfasterweightLotus Evora GT4 minimum weight drops to 2700 lbs; Elise Cup R to 2250 lbs; Elise SC and Exige SC to 2450–2550 lbs. 2025-05-01 STL E&O: SMX Allowance in STL #37945wordingunclearSTL Mazda MX5 Challenge minimum weight now references GCR 9.1.7.1; mandatory component spec list removed, alternative tires only allowed. 2024-12-01 STL Request to Remove Miata Hubs from General category #37138cars addedaddedSTL STU Mazda Miata alternate front hubs Mazda Motorsports Development Part #0000-04-5HUB-S1 approved.
	Road America Runoffs 20242024-10-01	2:30.063Joe Moser · fastest of 18 · top 5 within 3.7s-1.357s (-0.90%)	2:30.245Joe Moser · fastest of 16 · top 5 within 4.2s-1.870s (-1.23%)	134.3Joe Moser+1.3 mph (+1.0%)						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%)	+14.589squal +12.580s	109.7%qual 108.4%
6 rule changes (STL: 4, FV: 2)2 engine · 1 aero · 1 weight · 2 wording · FV ferrous rotor must not be cross-drilled; pad cleaning grooves limit unchanged at three per side. · STL and STU now permit electric power steering pumps, OEM electric-assisted steering, or column-mounted electric steering assist systems. · STL normally aspirated minimum weights reduced: 1900cc to 2540 lbs, 1950cc to 2583 lbs, 2000cc to 2625 lbs; short-wheelbase FWD adds 1.25%; Honda B16/B17/B18C1 throttle to 51mm, B18C Type R and Mazda MZR to 50mm. · STL Mazda 12A: 5th and 6th intake port actuators and valves may no longer be removed or disabled. · STL 79-85 RX7 12A now allows auto-type 2 bbl carburetor with 42mm choke on dual-y manifold, not just stock Nikki. · FV front wheel bearings wording clarified; specification unchanged.showhide 2024-10-01 FV Disc Brakes #36822wordingwordingFV ferrous rotor must not be cross-drilled; pad cleaning grooves limit unchanged at three per side. 2024-02-01 STL ST Electric-Assisted Steering Systems #35066aeroaddedaeroSTL and STU now permit electric power steering pumps, OEM electric-assisted steering, or column-mounted electric steering assist systems. 2024-02-01 STL BOP Adjustments #35112weightfasterweightSTL normally aspirated minimum weights reduced: 1900cc to 2540 lbs, 1950cc to 2583 lbs, 2000cc to 2625 lbs; short-wheelbase FWD adds 1.25%; Honda B16/B17/B18C1 throttle to 51mm, B18C Type R and Mazda MZR to 50mm. 2024-02-01 STL Mazda 12A #35320engineremovedengineSTL Mazda 12A: 5th and 6th intake port actuators and valves may no longer be removed or disabled. 2024-01-01 STL Alternate Carburetor Request for 79-85 RX7 12a #35181engineaddedengineSTL 79-85 RX7 12A now allows auto-type 2 bbl carburetor with 42mm choke on dual-y manifold, not just stock Nikki. 2023-12-01 FV FV Wheel Bearing Clarification #35150wordingwordingFV front wheel bearings wording clarified; specification unchanged.
	Virginia International Raceway Runoffs 20232023-09-23	2:05.779Danny Steyn · fastest of 22 · top 5 within 3.4s+0.305s (+0.24%)	2:06.682Joe Moser · fastest of 20 · top 5 within 1.5s-1.150s (-0.90%)	131.8Danny Steyn+0.1 mph (+0.1%)						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%)	+9.929squal +9.860s	107.8%qual 107.8%
2 rule changes (STL: 2)1 cars added · 1 wording · STL ITA and ITS RX7, and ITS/ITA/ITB/ITC 1985+ models clarified to require tires per 9.1.4.2. · Spec MX5 in STL allows ACT clutch 0000-02-5004-G6, wheels 17x8, Toyo RR and RA1 235-40-17 tyres, or alternatives on 17x7 per rules.showhide 2023-06-01 STL Clarify STL table B - IT spec notes on Tires #34187wordingwordingSTL ITA and ITS RX7, and ITS/ITA/ITB/ITC 1985+ models clarified to require tires per 9.1.4.2. 2023-01-01 STL Spec MX5 in STL #33473cars addedaddedSpec MX5 in STL allows ACT clutch 0000-02-5004-G6, wheels 17x8, Toyo RR and RA1 235-40-17 tyres, or alternatives on 17x7 per rules.
	Virginia International Raceway Runoffs 20222022-09-24	2:05.474Danny Steyn · fastest of 24 · top 5 within 2.3s-1.729s (-1.36%)	2:07.832Danny Steyn · fastest of 22 · top 5 within 1.9s+0.559s (+0.44%)	131.7Trever Degioanni-3.2 mph (-2.3%)	1:57.689James Weida · fastest of 11 · top 5 within 3.9s+0.328s (+0.28%)	2:21.862Sven de Vries · fastest of 10 · top 5 within 14.3s+24.290s (+20.66%)	142.9Calvin Stewart+0.1 mph (+0.1%)	+14.030squal -7.785s	111.0%qual 93.8%	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%)	+10.261squal +9.642s	108.0%qual 107.7%
15 rule changes (STL: 5, F5: 6, FV: 4)4 engine · 1 tyres & wheels · 1 weight · 7 wording · 2 other · F500 Rotax 493 and 593 intake boots: removed Moto Tassinari V3124-873B-2 from 493/593 non-HO allowance, added Moto Tassinari V3120-794A-2 option for non-HO. · F500 Rotax engines now permit Ingi Tech Sparker ignition DCP-CDI-P2 as alternate ECU. · F500 clarifies stepped diameter exhaust headers prohibited except at cylinder head flange area. · F500 Rotax 593 intake boot options clarified; oil injection pump removal now permitted. · F500 Majors and Runoffs cars must install AIM part #X47KPFSOLO2R0 data box mount for Solo or Solo 2. · 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. · STU single throttle body weight reduction removed; minimum weights revised down to 2990 lbs at 3000cc from 3300 lbs. · STL and STU Improved Touring vehicles must now conform to section 9.1.4 Tires & Wheels. · F5 cars must install AIM part #X47KPFSOLO2R0 data box mount for Majors and Runoffs. · FV Crower connecting rods SP93280B and BC6417 allowed as direct replacement, must meet OEM minimum weight. · STL/STU intake manifold and cylinder head porting clarified as free; intake and exhaust porting wording removed. · STL Mazda Renesis flat plate restrictor increases from 55mm to 60mm. · STL 79-85 RX7 12A allows emissions removal and jet correction on stock Nikki carb. · FV allows Crower SP93280B and Brian Crower Racing Rods connecting rods as direct replacements, matching OEM minimum weight.showhide 2022-09-01 F5 Intake Boots Correction #33028wordingwordingF500 Rotax 493 and 593 intake boots: removed Moto Tassinari V3124-873B-2 from 493/593 non-HO allowance, added Moto Tassinari V3120-794A-2 option for non-HO. 2022-08-01 F5 Ensure availability of ECU for Rotax engines #32695engineaddedengineF500 Rotax engines now permit Ingi Tech Sparker ignition DCP-CDI-P2 as alternate ECU. 2022-07-01 F5 Clarify stepped exhaust header references #32743wordingwordingF500 clarifies stepped diameter exhaust headers prohibited except at cylinder head flange area. 2022-06-01 F5 593 carb boot availability and oil pump clarification #32527wordingwordingF500 Rotax 593 intake boot options clarified; oil injection pump removal now permitted. 2022-03-01 F5 E&O class name #32194otheraddedF500 Majors and Runoffs cars must install AIM part #X47KPFSOLO2R0 data box mount for Solo or Solo 2. 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. 2022-03-01 STL Single TB Weight Modifiers #31449weightfasterweightSTU single throttle body weight reduction removed; minimum weights revised down to 2990 lbs at 3000cc from 3300 lbs. 2022-03-01 STL Improved Touring Tires #32063tyres & wheelstyres & wheelsSTL and STU Improved Touring vehicles must now conform to section 9.1.4 Tires & Wheels. 2022-01-01 F5 Data Box Mounting Plate #31638otheraddedF5 cars must install AIM part #X47KPFSOLO2R0 data box mount for Majors and Runoffs. 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. 2022-01-01 STL Throttling Device Clarification #31323wordingwordingSTL/STU intake manifold and cylinder head porting clarified as free; intake and exhaust porting wording removed. 2022-01-01 STL Mazda Renesis Restriction #31467enginefasterengineSTL Mazda Renesis flat plate restrictor increases from 55mm to 60mm. 2022-01-01 STL Clarification of 79-85 RX7 Spec line #31621wordingwordingSTL 79-85 RX7 12A allows emissions removal and jet correction on stock Nikki carb. 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.
	Indianapolis Motor Speedway Runoffs 20212021-09-25	1:51.665Danny Steyn · fastest of 42 · top 5 within 1.7s-0.982s (-0.87%)	2:02.711Joe Moser · fastest of 37 · top 5 within 3.2s+10.122s (+8.99%)	131.8Max Gee	1:42.619Ryan Mayfield · fastest of 22 · top 5 within 1.6s-0.517s (-0.50%)	1:43.140Sven de Vries · fastest of 20 · top 5 within 1.7s+0.280s (+0.27%)	144.4James Weida	-19.571squal -9.046s	84.1%qual 91.9%	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	-5.477squal +5.814s	95.5%qual 105.2%
18 rule changes (STL: 15, F5: 3)3 cars added · 3 engine · 2 aero · 2 weight · 1 induction · 1 suspension & brakes · 4 wording · 2 other · STL Mazda Spec MX-5 removes redundant specification line referencing 2014 regulations. · F5 clarifies mechanical shifting only; throttle-cut and flat-shifter devices permitted if driver retains full control. · F5 single-seat open-wheel cars: rigid suspension becomes limited suspension in class definition. · F500 Rotax 593 HO engine now permitted; 875 lbs minimum weight, MA0242SP1020A or MA0242SP1063A restrictor, specific intake boots and piston required. · STL Volkswagen 2.0L TFSI 1984 cc engine permitted without turbocharger, meeting all other STL specs. · STL Pontiac Solstice/Saturn Sky allowed 4 inch ride height. · STL Mazda B5 DOHC added to class; must meet all STL regulations. · STL Honda B16A (JDM) restrictor reduced from 54mm to 53mm. · ST oil coolers and filters now explicitly listed as addable or substitutable parts in vents and breathers section. · STL GM Ecotec LNF now permits any Ecotec engine family with 55mm flat plate restrictor. · ST 90-05 Mazda Miata allowed alternate front wheel hub Mazda Motorsports Development Part #0000-04-5HUB-S1. · ST cars may now relocate ABS actuation hardware and wiring anywhere in the engine compartment. · STL rear wing trailing edge may be mounted no further rearward than the center of the rearmost part approved bodywork. · STL alternate transmissions now allow OEM gear sets and input shaft modifications for fitment. · STL RWD strut-front cars lose 2.5% weight penalty, others lose 3% penalty for FWD parity. · STL Honda F20C drops 2% weight penalty, minimum weight reduced. · STL Honda B16/B17/B18C1 restrictor reduced to 53mm, B18C variants and Mazda MZR to 52mm. · ST aero devices and reference areas must include end plates, exclude fasteners under 1/2" protrusion.showhide 2021-09-01 STL Request to clean up Spec MX-5 Redundancy #31069wordingwordingSTL Mazda Spec MX-5 removes redundant specification line referencing 2014 regulations. 2021-08-01 F5 Clarify allowable assisted shifting systems #30871wordingwordingF5 clarifies mechanical shifting only; throttle-cut and flat-shifter devices permitted if driver retains full control. 2021-08-01 F5 Request to correct terminology #30976wordingwordingF5 single-seat open-wheel cars: rigid suspension becomes limited suspension in class definition. 2021-06-01 F5 Request to Allow Rotax 593 HO Engine #30712cars addedaddedF500 Rotax 593 HO engine now permitted; 875 lbs minimum weight, MA0242SP1020A or MA0242SP1063A restrictor, specific intake boots and piston required. 2021-06-01 STL VW Engine Request #30625engineaddedengineSTL Volkswagen 2.0L TFSI 1984 cc engine permitted without turbocharger, meeting all other STL specs. 2021-05-01 STL Solstice Ride Height #30183otheraddedSTL Pontiac Solstice/Saturn Sky allowed 4 inch ride height. 2021-05-01 STL Request Mazda B5 DOHC #30420cars addedaddedSTL Mazda B5 DOHC added to class; must meet all STL regulations. 2021-05-01 STL Honda B16A (JDM) Restrictor change #30531engineslowerengineSTL Honda B16A (JDM) restrictor reduced from 54mm to 53mm. 2021-04-01 STL ST Oil Coolers E&O Correction to 9.1.4.2.H #30388wordingwordingST oil coolers and filters now explicitly listed as addable or substitutable parts in vents and breathers section. 2021-03-01 STL GM Ecotec engines in STL #30247engineaddedengineSTL GM Ecotec LNF now permits any Ecotec engine family with 55mm flat plate restrictor. 2021-03-01 STL Super Touring Alternate Miata Hubs #30345cars addedaddedST 90-05 Mazda Miata allowed alternate front wheel hub Mazda Motorsports Development Part #0000-04-5HUB-S1. 2021-02-01 STL Brake Component Relocation #29990suspension & brakessuspension & brakesST cars may now relocate ABS actuation hardware and wiring anywhere in the engine compartment. 2021-02-01 STL Super Touring Wing Clarification #30111aeroaeroSTL rear wing trailing edge may be mounted no further rearward than the center of the rearmost part approved bodywork. 2021-02-01 STL Transmission Options #30118otheraddedSTL alternate transmissions now allow OEM gear sets and input shaft modifications for fitment. 2021-01-01 STL Request for FWD and RWD Parity #29728weightfasterweightSTL RWD strut-front cars lose 2.5% weight penalty, others lose 3% penalty for FWD parity. 2021-01-01 STL Request to Remove Honda F20C 2% Weight Penalty #29815weightfasterweightSTL Honda F20C drops 2% weight penalty, minimum weight reduced. 2021-01-01 STL Request for FWD and RWD Parity #30023inductionslowerinductionSTL Honda B16/B17/B18C1 restrictor reduced to 53mm, B18C variants and Mazda MZR to 52mm. 2020-12-01 STL Request clarification on wing measurement #29640aeroaeroST aero devices and reference areas must include end plates, exclude fasteners under 1/2" protrusion.
	Road America Runoffs 20202020-10-02	2:31.420Danny Steyn · fastest of 33 · top 5 within 3.1s	2:32.115Joe Moser · fastest of 30 · top 5 within 1.5s	132.9Darin Treakle	2:20.954Calvin Stewart · fastest of 16 · top 5 within 1.8s	2:21.391James Weida · fastest of 14 · top 5 within 1.5s	143.2Aaron Ellis	-10.724squal -10.466s	93.0%qual 93.1%	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	+13.701squal +12.574s	109.0%qual 108.3%
23 rule changes (STL: 11, F5: 6, FV: 6)6 engine · 5 cars added · 5 tyres & wheels · 1 induction · 6 wording · F500 Suzuki GSXR600 engine years extended from 2003-2013 to 2003-2019. · STL and STU clarify weight adjustment calculation order: engine adjustments first, then chassis percentage additions, subtractions, and fixed pounds. · STL STU rear wing Gurney flap terminology clarified from wicker to Gurney flap in mounting and chord rules. · F5 request to adjust external jetting device cockpit control denied; no rule change made. · F5 driver adjustable carburettor mixture: refer to separate Fastrack letter #28359 for ruling. · F5 cockpit adjustment request response published in Fastrack letter 28359. · FV now permits 4 bolt wheels in addition to existing specifications. · FV now allows 4-bolt pattern wheels in addition to existing specifications. · GT3 and STU add Borg-Warner EFR6258 turbocharger to approved turbo lists. · STL adds Mazda MX-5 Global Cup 16-18 at 2450 lbs minimum and 2019 at 2550 lbs minimum. · STL Mazda MX-5 Club 06-15 allowed header part number 0000-06-5407-NC. · STL Acura/Honda B18 and B18C engines: restrictor sizes swapped, B18C1 removed from allowed variants. · STL Honda B18 loses 53mm restrictor requirement; B18C1 added with 54mm restrictor, B18C1 removed from other variants. · STU GM Ecotech LNF now permitted without turbo, with LE5 head and intake manifold, meeting STL specs. · STL Mazda MZR restrictor reduced from 54 mm to 53 mm. · STL Mazda MZR restrictor reduces from 55 mm to 53 mm. · FV rain tyre changes to Hoosier #44266 22.5 x 5.0 x 15 WET or W3. · STL Mazda Spec MX5 Challenge adds approved wheel part numbers 0000-04-5706-GM, 0000-04-5706-SL to notes. · F500 Honda CBR600RR, Suzuki GSXR600, Yamaha R6 restrictor reduced to 28mm from 29mm. · 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. · FV wheels may now be 15-inch 4.5J steel VW with same 5-bolt pattern as standard 4J, within track limits.showhide 2020-10-01 F5 Request to Update Suzuki Engine Years for F500 #29453engineaddedengineF500 Suzuki GSXR600 engine years extended from 2003-2013 to 2003-2019. 2020-08-01 STL Minimum Weight Determination #27695wordingwordingSTL and STU clarify weight adjustment calculation order: engine adjustments first, then chassis percentage additions, subtractions, and fixed pounds. 2020-08-01 STL ST Gurney flap Wicker clarification #29012wordingwordingSTL STU rear wing Gurney flap terminology clarified from wicker to Gurney flap in mounting and chord rules. 2020-07-01 F5 Request for Cockpit Adjustment of External Jetting Devices #28359wordingunclearF5 request to adjust external jetting device cockpit control denied; no rule change made. 2020-07-01 F5 Two Stroke Motors (reply to #28359 WDYT) #28816engine 2020-07-01 F5 Re letter requesting driver adjustable carb mixture #28840wordingunclearF5 driver adjustable carburettor mixture: refer to separate Fastrack letter #28359 for ruling. 2020-07-01 F5 #28359 WDYT Request for Cockpit Adjustment #28875wordingunclearF5 cockpit adjustment request response published in Fastrack letter 28359. 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. 2020-07-01 STL Request for Addition to GT3 Approved Turbo List #27576cars addedaddedGT3 and STU add Borg-Warner EFR6258 turbocharger to approved turbo lists. 2020-06-01 STL Request to add 2016-2019 GMX-5 Spec line #28604cars addedaddedSTL adds Mazda MX-5 Global Cup 16-18 at 2450 lbs minimum and 2019 at 2550 lbs minimum. 2020-06-01 STL Request to update PN for MX-5 #28622cars addedaddedSTL Mazda MX-5 Club 06-15 allowed header part number 0000-06-5407-NC. 2020-06-01 STL Correction - Clarification Honda/Acura B18B engine Letter # 26209 #28873wordingwordingSTL Acura/Honda B18 and B18C engines: restrictor sizes swapped, B18C1 removed from allowed variants. 2020-05-01 STL STL Honda B18 restrictor changes #28794enginefasterengineSTL Honda B18 loses 53mm restrictor requirement; B18C1 added with 54mm restrictor, B18C1 removed from other variants. 2020-04-01 STL Change GM LNF 2.0 Allowance to LSJ Engine for Viable STL 2.0 #27884engineaddedengineSTU GM Ecotech LNF now permitted without turbo, with LE5 head and intake manifold, meeting STL specs. 2020-04-01 STL Acura/Honda B18C engine chart. Reduce the current 54 mm flat plat #28663engineslowerengineSTL Mazda MZR restrictor reduced from 54 mm to 53 mm. 2020-04-01 STL Mazda MZR engine chart. Reduce the current 55 mm flat plate to 53 #28664engineslowerengineSTL Mazda MZR restrictor reduces from 55 mm to 53 mm. 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. 2020-03-01 STL Request to add wheel part numbers #28342cars addedaddedSTL Mazda Spec MX5 Challenge adds approved wheel part numbers 0000-04-5706-GM, 0000-04-5706-SL to notes. 2020-01-01 F5 Change 600cc restrictor size #27883inductionslowerinductionF500 Honda CBR600RR, Suzuki GSXR600, Yamaha R6 restrictor reduced to 28mm from 29mm. 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. 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.
	Virginia International Raceway Runoffs 20192019-10-05	2:07.203Danny Steyn · fastest of 36 · top 5 within 1.8s	2:07.273Cliff Ira · fastest of 35 · top 5 within 1.4s	134.8Cliff Ira	1:57.361Wiley Mcmahan · fastest of 15 · top 5 within 3.8s	1:57.572Wiley Mcmahan · fastest of 15 · top 5 within 4.0s	142.8Eric McRee	-9.701squal -9.842s	92.4%qual 92.3%	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	+11.016squal +8.509s	108.7%qual 106.7%
18 rule changes (STL: 11, F5: 1, FV: 6)3 cars added · 3 engine · 3 weight · 1 suspension & brakes · 1 tyres & wheels · 5 wording · 2 other · FV exhaust exit opening repositioned: minimum one inch, maximum four inches behind rear body. · STL adds Mazda Spec MX-5 Challenge, 2000cc displacement, 2500 lb minimum weight, with mandatory Roush, Penske, Eibach, and other specified components. · F500 Honda CBR600RR, Suzuki GSXR600, and Yamaha R6 minimum weights increase to 900 lbs. · FV allows fifteen-inch steel wheels at 4J or 4.5J width, standard VW sedan or within track dimensions. · STU allows alternate intake manifolds on case-by-case basis; stock throttle device and manifold otherwise required. · FV exhaust outlet opening max distance from body rear increased from 3 to 4 inches. · STL Acura/Honda B18 except C engine restrictor increased from 53mm to 54mm flat plate. · FV front track maximum 52.500 inches; rear track 49.125–50.750 inches; spacers now allowed. · STL and STU ride height measurement clarified: lowest rocker panel point without driver, excluding pinch weld. · FV disc brake assembly minimum weight clarified to 16.5 lbs total; caliper minimum weight requirement of 1.65 lbs removed. · STL adds VW 1.8L R4 20VT 1781 cc, 1781 minimum weight, naturally aspirated only. · STL Mazda Renesis minimum weight reduced to 2700 lbs. · STL Mazda MX-5 Cup brake pad compound now open. · STL adds Acura/Honda B18C1 GSR with 1797cc displacement, 54mm flat plate restrictor required, porting outside 1" allowance prohibited. · STL Mazda 12 and 13B now permit port matching; porting ban removed. · FV intake manifold horizontal tube measurement location clarified; removed specific distance ranges from rule text. · STL B17 now requires 54mm flat plate restrictor; B18C Type R variants move to 54mm restrictor, weight chart baseline. · STL Mazda Miata removes maximum displacement limit; minimum weight corrected to unspecified figure.showhide 2019-10-01 FV Allowed Modifications E&O #27398wordingwordingFV exhaust exit opening repositioned: minimum one inch, maximum four inches behind rear body. 2019-10-01 STL Request to Classify Spec MX-5 Challenge in STL #27399cars addedaddedSTL adds Mazda Spec MX-5 Challenge, 2000cc displacement, 2500 lb minimum weight, with mandatory Roush, Penske, Eibach, and other specified components. 2019-08-31 F5 Request for Weight Increase for Motorcycle Powered Cars #27214weight +25 lbsslowerweightF500 Honda CBR600RR, Suzuki GSXR600, and Yamaha R6 minimum weights increase to 900 lbs. 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 STL Request clarification for manifold and throttle in STU #27004wordingwordingSTU allows alternate intake manifolds on case-by-case basis; stock throttle device and manifold otherwise required. 2019-05-31 FV Exhaust termination rule E&O #26702wordingwordingFV exhaust outlet opening max distance from body rear increased from 3 to 4 inches. 2019-05-31 STL Request Restrictor Plate correction #26779enginefasterengineSTL Acura/Honda B18 except C engine restrictor increased from 53mm to 54mm flat plate. 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. 2019-05-01 STL Request Ride Height Clarification #26597wordingwordingSTL and STU ride height measurement clarified: lowest rocker panel point without driver, excluding pinch weld. 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. 2019-03-01 STL Request to Allow VW 1.8L Engine #25614cars addedaddedSTL adds VW 1.8L R4 20VT 1781 cc, 1781 minimum weight, naturally aspirated only. 2019-03-01 STL Request to reduce weight of RX8 with Renesis rotary #25781weight -100 lbsfasterweightSTL Mazda Renesis minimum weight reduced to 2700 lbs. 2019-03-01 STL Request for Open Brake Pads On Mazda MX-5 Cup NC #25821otheraddedSTL Mazda MX-5 Cup brake pad compound now open. 2019-03-01 STL Request to clarify B18C1 GSR Honda B motor table #26209cars addedaddedSTL adds Acura/Honda B18C1 GSR with 1797cc displacement, 54mm flat plate restrictor required, porting outside 1" allowance prohibited. 2019-03-01 STL Port Matching #26415enginefasterengineSTL Mazda 12 and 13B now permit port matching; porting ban removed. 2019-02-01 FV FV Intake Manifold Clarification #26008wordingwordingFV intake manifold horizontal tube measurement location clarified; removed specific distance ranges from rule text. 2019-01-01 STL Request to equalize FPR Reduction on all B-Series Vtec Engines #24746enginefasterengineSTL B17 now requires 54mm flat plate restrictor; B18C Type R variants move to 54mm restrictor, weight chart baseline. 2019-01-01 STL Request E&O for Mazda Miata Spec Line #25955otherunclearSTL Mazda Miata removes maximum displacement limit; minimum weight corrected to unspecified figure.
	Sonoma Raceway Runoffs 20182018-10-10	1:49.138Danny Steyn · fastest of 19 · top 5 within 2.5s	1:49.754Danny Steyn · fastest of 17 · top 5 within 2.5s	103.2Craig McHaffie	1:41.807Jeff Jorgenson · fastest of 5 · top 5 within 6.6s	1:42.491David Lapham · fastest of 5 · top 5 within 9.5s	113.3David Lapham	-7.263squal -7.331s	93.4%qual 93.3%	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	+3.885squal +3.499s	103.5%qual 103.2%
No rule changes on record between these events
	Indianapolis Motor Speedway Runoffs 20172017-09-25	1:52.647Adam Roberts · fastest of 57 · top 5 within 0.8s	1:52.589Eric Kutil · fastest of 50 · top 5 within 1.2s		1:43.136Wiley Clinton McMahan · fastest of 38 · top 5 within 1.4s	1:42.860Wiley Clinton McMahan · fastest of 37 · top 5 within 1.6s		-9.729squal -9.511s	91.4%qual 91.6%	1:55.759Michael Varacins · fastest of 39 · top 5 within 1.0s	1:55.923Michael Varacins · fastest of 32 · top 5 within 1.3s		+3.334squal +3.112s	103.0%qual 102.8%
No rule changes on record between these events
	Mid-Ohio Sports Car Course Runoffs 20162016-09-19	1:35.439John Schmitt · fastest of 34 · top 5 within 1.5s	1:36.625Kevin Boehm · fastest of 31 · top 5 within 0.6s		1:28.528Calvin Stewart · fastest of 14 · top 5 within 3.9s	1:29.853Steven Thompson · fastest of 12 · top 5 within 4.5s		-6.772squal -6.911s	93.0%qual 92.8%	1:37.942Alex Scaler · fastest of 41 · top 5 within 0.3s	1:38.066Flinn Lazier · fastest of 38 · top 5 within 0.7s		+1.441squal +2.503s	101.5%qual 102.6%
No rule changes on record between these events
	Daytona International Speedway Runoffs 20152015-09-21	2:09.672Kevin Boehm · fastest of 37 · top 5 within 2.5s	2:10.269Kevin Boehm · fastest of 37 · top 5 within 2.1s		2:01.824W. Clint McMahan · fastest of 16 · top 5 within 3.0s	2:03.298Matthew Strand · fastest of 15 · top 5 within 4.9s		-6.971squal -7.848s	94.6%qual 93.9%	2:21.167Roger Siebenaler · fastest of 31 · top 5 within 0.8s	2:21.142Andrew Whitston · fastest of 30 · top 5 within 1.1s		+10.873squal +11.495s	108.3%qual 108.9%

By track

Track	Events	Typical % of STL	Best	Latest
Road America	4	100.0%	100.0%Runoffs 2020	100.0%Runoffs 2026
Virginia International Raceway	3	100.0%	100.0%Runoffs 2019	100.0%Runoffs 2023
Indianapolis Motor Speedway	2	100.0%	100.0%Runoffs 2017	100.0%Runoffs 2021
Daytona International Speedway	1	100.0%	100.0%Runoffs 2015	100.0%Runoffs 2015
Mid-Ohio Sports Car Course	1	100.0%	100.0%Runoffs 2016	100.0%Runoffs 2016
Sonoma Raceway	1	100.0%	100.0%Runoffs 2018	100.0%Runoffs 2018

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 STL'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.