BoP Lab / Buttonwillow Raceway Park

FF vs FA vs T1 vs FE2 pace at Buttonwillow Raceway Park

Quickest here: FF 1:51.118 Eric Poulsen, Cal Club 2025 race · FA 1:35.792 Greg Labadie, Cal Club 2026 qualifying · T1 1:46.465 Ian Barberi, Cal Club 2025 qualifying · FE2 1:39.265 Jon McClintock, Cal Club 2026 qualifying

Lap times% of FF

FFFAT1FE2solid race · dashed qualifying · slower is lower

FFFAT1FE2solid race · dashed qualifying · each class's best lap as a share of FF's at the same event (the reference class, changeable above); 100% is level, higher is quicker

	Event	FF			FA					T1					FE2
	Event	Qual best	Race best	Trap	Qual best	Race best	Trap	vs FF	% of FF	Qual best	Race best	Trap	vs FF	% of FF	Qual best	Race best	Trap	vs FF	% of FF
	Cal Club 2026 CALCL262026-02-21	1:53.098Edward Erlandson · fastest of 2+1.054s (+0.94%)	1:54.741Edward Erlandson · fastest of 2+3.623s (+3.26%)	133.7Edward Erlandson+19.0 mph (+16.5%)	1:35.792Greg Labadie · only car-3.750s (-3.77%)	1:37.275Greg Labadie · only car-2.623s (-2.63%)	163.8Greg Labadie+36.4 mph (+28.6%)	-17.466squal -17.306s	84.8%qual 84.7%	1:59.760Ed Gless · only car+13.295s (+12.49%)	1:59.123Ed Gless · only car+11.689s (+10.88%)	120.7Ed Gless-18.6 mph (-13.3%)	+4.382squal +6.662s	103.8%qual 105.9%	1:39.265Jon McClintock · fastest of 3 · top 3 within 1.5s-0.093s (-0.09%)	1:40.253Jon McClintock · fastest of 3 · top 3 within 2.2s+0.541s (+0.54%)	156.6Paul Marino+29.4 mph (+23.1%)	-14.488squal -13.833s	87.4%qual 87.8%
25 rule changes (FF: 3, FA: 7, T1: 13, FE2: 2)4 cars added · 4 induction · 4 tyres & wheels · 4 weight · 1 aero · 1 engine · 1 removed · 6 wording · FA Pro Mazda: lower intake manifold now unrestricted, throttle body raised to 80mm, wing height must not exceed 99cm, bodywork width must not exceed 132cm. · T1 Corvette C6 LS1/LS6 Spec Line reinstated: 3200 lbs minimum weight, 70mm restrictor required. · FA MZR gains alternate Noor P/N 0088-8-00 intake manifold with AT Power runners as option to Elan or Mazda Speed Elite. · FA Formula 1000 motorcycle-based engine loses maximum compression ratio 14.5:1 limit. · FA Formula 1000 allows carbon fiber external panels, forward-facing gaps, raises floor to 125mm, adds eight 75×125mm rub blocks, expands diffuser to 110cm with 75mm radius transitions. · FF clarifies alternative tire eligibility for cars homologated 1989 or earlier with rocker arm or outboard suspension on all four corners. · T1 Spec Line restrictor changes from 70mm flat plate to unspecified new specification. · Unable to summarize: letter states intent but provides no actual rule changes to S2000 specification. · T1 non-GT4 cars: multiple restrictors enlarged (70mm to 73mm, 75mm to 78mm, 55mm to 60mm, 61mm to 70mm); one weight increased to 3600. · T1 BMW M3 E92 (08-13) Spec Line 1090 removed entirely. · FA class adds USF Pro 2000 car eligibility for Formula Atlantic racing. · FE and FE2 Enterprises must use bubble tail P/N WM138014; FE2 allows only this configuration. · FA Ligier JS F3 front tires may be Hoosier 43363 240/580R13 MS, rear 43368 300/590R13 MS. · FF adds rocker arm and outboard suspension cars optional bias ply and VFF tires; removes front-as-rear rule, adds mixing restrictions. · Porsche 981 GT4 Clubsport added to T1 as spec line 4085, minimum weight 3100 lbs with driver. · T1 Honda S2000 minimum weight reduced from 2950 lbs to 2900 lbs. · T1 BMW E46 M3 permits BMW #GS7D36SG aftermarket sequential transmission in SL# 1060 and 1070. · T1 BMW M3 E92 minimum weight reduced to 3300 lbs. · T1 Mustang Darkhorse R gets 315 front and rear tyres, loses 500 lbs minimum weight to 3600. · FE2 allows driver safety and comfort modifications for disabled drivers with SCCA approval, not transferable to other drivers. · Cadillac CT4-V Blackwing added to T1 Spec Line 1115, 3564cc, 3750 lbs minimum weight. · FA Formula Renault 2.0 (10-17) spec notes clarified: engine sealed, manual compliance required, tire choice unrestricted, no alterations except repairs. · FF allows older cars with rocker arm or outboard suspension to use bias ply slicks or VFF tires instead of radials. · T1 Mustang Spec 1430 restrictor opens 60mm to 65mm; Spec 1460 weight rises to 3500 lbs, restrictor 70mm; Corvette 1190 restrictor opens 67mm to 70mm; BMW 1090 restrictor narrows 40mm to 35mm; BMW 1100 weight rises to 3350 lbs.showhide 2026-02-01 FA Pro Mazda Classification and Performance Enhancement Proposal #39411inductionfasterFA Pro Mazda: lower intake manifold now unrestricted, throttle body raised to 80mm, wing height must not exceed 99cm, bodywork width must not exceed 132cm. 2026-02-01 T1 LS1 into Corvette C6 Spec Line Request #39716cars addedneutralT1 Corvette C6 LS1/LS6 Spec Line reinstated: 3200 lbs minimum weight, 70mm restrictor required. 2026-01-01 FA Alternate Intake Manifold for MZR #38223inductionunclearFA MZR gains alternate Noor P/N 0088-8-00 intake manifold with AT Power runners as option to Elan or Mazda Speed Elite. 2026-01-01 FA Engine Compression Rule Change Request #39302enginefasterFA Formula 1000 motorcycle-based engine loses maximum compression ratio 14.5:1 limit. 2026-01-01 FA Change Formula 1000 allowances #39608aerofasterFA Formula 1000 allows carbon fiber external panels, forward-facing gaps, raises floor to 125mm, adds eight 75×125mm rub blocks, expands diffuser to 110cm with 75mm radius transitions. 2026-01-01 FF Formula F Alternative Tire Rule Proposed Clarifications #39281wordingneutralFF clarifies alternative tire eligibility for cars homologated 1989 or earlier with rocker arm or outboard suspension on all four corners. 2026-01-01 T1 additional T1 adjustment #39520inductionunclearT1 Spec Line restrictor changes from 70mm flat plate to unspecified new specification. 2025-12-01 T1 Keep S2000 Classification #39344wordingunclearUnable to summarize: letter states intent but provides no actual rule changes to S2000 specification. 2025-12-01 T1 Correcting and updating T1 GT4 spec lines #39394weight 2025-12-01 T1 BOP adjustments to non GT4 T1 cars #39406induction +100 lbsfasterT1 non-GT4 cars: multiple restrictors enlarged (70mm to 73mm, 75mm to 78mm, 55mm to 60mm, 61mm to 70mm); one weight increased to 3600. 2025-12-01 T1 Remove T1 Spec Line #39407removedneutralT1 BMW M3 E92 (08-13) Spec Line 1090 removed entirely. 2025-11-01 FA Re-Consider USF Pro 2000 Car for Formula Atlantic Class #38783cars addedneutralFA class adds USF Pro 2000 car eligibility for Formula Atlantic racing. 2025-10-01 FE2 FE & FE2 Bubble Tail #38978wordingneutralFE and FE2 Enterprises must use bubble tail P/N WM138014; FE2 allows only this configuration. 2025-07-01 FA Ligier JS F3 Tire Choice #38434tyres & wheelsneutralFA Ligier JS F3 front tires may be Hoosier 43363 240/580R13 MS, rear 43368 300/590R13 MS. 2025-05-01 FF Page 228, FF tire rule 9.1.1.10.e #38251tyres & wheelsneutralFF adds rocker arm and outboard suspension cars optional bias ply and VFF tires; removes front-as-rear rule, adds mixing restrictions. 2025-05-01 T1 Acceptance of Porsche 981 GT4 Clubsport into T1 #36664cars addedneutralPorsche 981 GT4 Clubsport added to T1 as spec line 4085, minimum weight 3100 lbs with driver. 2025-05-01 T1 Request to Restore T1 Honda S2000 to Proper Weights #37644weight -50 lbsfasterT1 Honda S2000 minimum weight reduced from 2950 lbs to 2900 lbs. 2025-05-01 T1 DCT Transmission in E46 #37964wordingneutralT1 BMW E46 M3 permits BMW #GS7D36SG aftermarket sequential transmission in SL# 1060 and 1070. 2025-05-01 T1 Reduce E92 M3 Minimum Weight to 3050 #38092weightfasterT1 BMW M3 E92 minimum weight reduced to 3300 lbs. 2025-05-01 T1 Finalize Spec Line for T1 Darkhorse #38106tyres & wheelsfasterT1 Mustang Darkhorse R gets 315 front and rear tyres, loses 500 lbs minimum weight to 3600. 2025-04-01 FE2 Driver Safety & Comfort #37965wordingneutralFE2 allows driver safety and comfort modifications for disabled drivers with SCCA approval, not transferable to other drivers. 2025-04-01 T1 Cadillac CT4-V Blackwing #38003cars addedneutralCadillac CT4-V Blackwing added to T1 Spec Line 1115, 3564cc, 3750 lbs minimum weight. 2025-03-01 FA Update Formula Renault 2.0 spec line notes #37853wordingneutralFA Formula Renault 2.0 (10-17) spec notes clarified: engine sealed, manual compliance required, tire choice unrestricted, no alterations except repairs. 2025-03-01 FF Formula F Proposal to Invite Older Cars Via a Tire Rule Change #37802tyres & wheelsfasterFF allows older cars with rocker arm or outboard suspension to use bias ply slicks or VFF tires instead of radials. 2025-03-01 T1 Correct and make new T1 BOP adjustments. #37737weight +75 lbsunclearT1 Mustang Spec 1430 restrictor opens 60mm to 65mm; Spec 1460 weight rises to 3500 lbs, restrictor 70mm; Corvette 1190 restrictor opens 67mm to 70mm; BMW 1090 restrictor narrows 40mm to 35mm; BMW 1100 weight rises to 3350 lbs.
	Cal Club 2025 CALCL252025-02-22	1:52.044Eric Poulsen · only car	1:51.118Eric Poulsen · only car	114.7Eric Poulsen	1:39.542Greg Labadie · only car	1:39.898Greg Labadie · only car	127.4Greg Labadie	-11.220squal -12.502s	89.9%qual 88.8%	1:46.465Ian Barberi · fastest of 2	1:47.434Ian Barberi · fastest of 3 · top 3 within 11.8s	139.3Drew Delmonico	-3.684squal -5.579s	96.7%qual 95.0%	1:39.358Paul Marino · fastest of 4 · top 4 within 1.5s	1:39.712Paul Marino · fastest of 4 · top 4 within 1.7s	127.2Tom Hope	-11.406squal -12.686s	89.7%qual 88.7%
181 earlier rule changes on record, in force before Cal Club 2025 (from 2019)34 cars added · 25 weight · 16 induction · 10 engine · 8 tyres & wheels · 5 aero · 3 suspension & brakes · 2 removed · 77 wording · 1 other · FA adds Tatuus F.3 T-318 or FR-19 as spec line car in Table 2 for Formula Regional European Championship. · T1 Mustang gains 125 lbs to 3600, restrictor shrinks 65mm to 60mm. Corvette gains 50 lbs to 3500, restrictor shrinks 70mm to 67mm. BMW deleted. · T1 E46 M3 Spec Line 1050 allows VAC Motorsports throttle body VAC-TB-S54 on 3.250L engine instead of Dinan. · T1 Chevrolet Corvette C8 (2023-23) minimum weight reduced from 3600 lbs to 3500 lbs. · T1 Chevrolet Camaro Gen 5 restrictor increases from 75mm to 80mm flat plate. · T1 Audi R8 GT4 Spec Line #4020 maximum tyre size changes to 315 DOT, 305/645, or 30/65-18 (f), 33/68-18 (r) Non-DOT. · T1 GT4 tire sizes adjusted across ten cars: most non-DOT rear to 305/660, Audi and McLaren 305/645, Camaro and Mustang 305/680. · BMW M4 GT4 (G82) added to T1 GT4 at 3525 lbs minimum weight with Red power stick control. · T1 Spec Lines now permits 5.5 inch clutch in Engine Notes. · T1 GT4 Spec Line 4020 restrictor opens from 44mm to 45mm, minimum weight drops to 3400 lbs. · Mustang Darkhorse R added to T1 homologated cars at 3,250 lbs minimum with 305/315 tires, ineligible for Runoffs until 3 Super Tour events. · T1 Corvette may roll or flatten wheel opening lips for tire clearance; plastic fenders may remove lips if edge thickness matches basic material. · T1 E46 M3 S54 can now use Dinan Throttle Body #D760-3400 on 3.250L engine. · FF and FC cars with sequential gearbox must add 10 lbs. to minimum weight, down from 25 lbs. · FF Honda Fit allows Fast Forward 0.25mm oversize pistons PN FF800-110 as alternative; piston diameter spec clarified to 2.8835 inches. · FF VTEC activation valve must function; EGR blanking plate rule clarified with Fast Forward part numbers. · Mercedes AMG-C63 S (2023) classified in T1 with 4000 lbs minimum weight and 3700 restrictor. · T1 Honda S2000 classified with 2400 lb minimum weight, 2950 cc displacement, 4.75" supercharger pulley. · Pontiac GTO 2006-2009 LS1 added to T1 as Spec Line 1590, 5700 cc, 3400 lbs minimum. · C8 Corvette T1 restrictor plate increases from 70mm to 72mm flat plate. · T1 NEW class removes 23 spec lines including Acura NSX, Ferrari, Porsche 996, Nissan Z cars, and others; Porsche 997 spec line 1680 expiration removed. · FF Honda Fit gains Fast Forward FF800-100 oversize piston ring pack option. · T1-GT4 batch adjustments: five cars lighter, two heavier, restrictors and ECU maps changed, five models now eligible for Runoffs. · T1 spec lines 1000, 1010, 1020, 1040, 1360, 1400–1410, 1520–1680, 1700–1720 deleted entirely. · T1 Chevrolet Corvette C5 LS2 added with 6000cc displacement, 3300 lbs minimum weight, 72mm flat plate restrictor. · T1 Chevrolet Corvette C7 (14-19) including Z51, Grandsport newly classified as homologated car. · T1 Gen 5 Camaro minimum weight drops 75 lbs to 3475; restrictor increases 70mm to 75mm. · T1 Aston Martin Vantage permitted to use OEM Sportshift II transmission. · Pontiac GTO 2006-2009 re-integrated into T1 with LS2 at 3400 lbs, 72mm restrictor, and LS3 at 3500 lbs, 61mm restrictor. · T1 Porsche 997-1 GT3 Cup added at spec line 4210, minimum weight 3050 lbs. · Chevrolet Camaro GT4-R classified in T1 GT4 Spec Line 4035, minimum weight 3375 lbs, 315 max tire, 63mm restrictor, ineligible for Runoffs. · T1 Dodge Viper ACR / SRT RT-10 and ACR/ACR-X spec lines 1350 and 1370 remove 12/23 expiration. · T1 GT4 McLaren 570S, Mercedes AMG GT4, and Porsche 718 Cayman GT4 CS MR now eligible for Runoffs competition. · T1 GT4 BMW M4 Spec Line Number changed from 4050 to 4030. · T1 Corvette C5 gains approved aero parts: carbon rear spoiler, vented front splitter, side skirts, with 50 lb weight reduction allowed. · T1 Dodge Viper ACR/ACR-X restrictor increases from 50mm to 60mm flat plate. · T1 Dodge Viper ACR/ACR-X: Spec Line 1370 restrictor increases to 55mm, Line 1390 decreases to 55mm. · T1 Ford Mustang S197 05-14 now requires OEM 8.8 differential housing. · T1 Chevrolet Camaro Gen 5 LS7 gets two spec lines: 1131 with 70mm restrictor, 1136 with 53mm restrictor, both 3450 lbs minimum. · T1 Chevrolet Camaro Gen 5, Corvette C5 and C6: engine resleeve restricted to stock parameters only, no longer LS3 bore/stroke. · FA Pro Formula Mazda front wheels widen to 10 in. max; rear wheels narrow to 14 in. min. · T1 Ford Mustang S197 (05-14) reinstated with 3550 lbs minimum weight, 75mm restrictor, Voodoo engine permitted. · FA Pro Formula Mazda maximum bodywork width behind front wheels increases to 51.97 inches. · FA MSR Formula Mazda FMzR added to Table 2 classification. · T1 GT4 weights clarified for nine cars, ranging from 3200 lbs Porsche 718 Cayman to 3575 lbs Aston Martin. · T1-GT4 McLaren 570S and Mercedes AMG GT4 front tires widen to 315 mm. · T1 Chevrolet Camaro Gen5 LS3-6160 adds 70mm flat plate restrictor, weight 3550 lbs. · FF Honda Fit engine adds Fast Forward part number alternatives for intake, exhaust, oil system, and scavenge pump components. · T1 cars with aftermarket sequential transmissions get 10-inch max bellhousing; non-sequential cars gain 100 lbs weight break. · T1 GT4 all nine cars lose 125 lbs minimum weight with driver, from 3200–3575 to 3075–3450. · T1 removes GCR Section 9.1.9.1.A. and T1 Spec Lines entirely, sunsetting pre-2023 Touring 1 rules. · GT4 McLaren 570S maximum tire size changes to 285 front, 315 rear. · FA BDA engine displacement specification line added to Table 1, effective 2023-01-01. · Eight GT4 models added to T1 with weights from 3200 to 3575 lbs and restricted power per SRO 2022 rules. · Formula Renault 2.0 (10-17) reclassified from FX to FA; weight reduced to 1280 lbs, restrictor removed. · FA Swift 016 2.3L restrictor increases from 31mm to 32mm SIR; minimum weight drops 30 lbs to 1420. · Pro Formula Mazda allows street or bridge port, unrestricted apex seals, 70mm throttle body, 99cm wing height max, 132cm bodywork width max. · T1 Cadillac CTS/CTS-V, Chevrolet Camaro, Pontiac Firebird, Pontiac GTO 6162 OEM minimum weight reduced to 3475 lbs. · T1-LP Ford Mustang FP350S restrictor increases from 70mm to 75mm. · Mercedes Benz AMG GT4 2017-2021 classified T1 Maximum at 3400 lbs minimum weight with HP-controlled SRO Power Level 2 engine. · FA Ligier JS F3 must comply with Formula Regional Americas rules instead of FIA Formula 3 Regional Technical Regulations. · FA sealed engines must undergo full inspection; competitor pays reassembly and resealing costs. · FA Formula Lites FL15 and FR Americas Ligier JS F3 engine sealing requirements clarified to reference respective series technical regulations. · FA transmission rule clarified: transverse shafts prohibited except final drive and motorcycle gearbox in Formula 1000. · FA Swift 016 2.5 liter aero spec now references 2.3 liter notes instead of N notes. · T1 Dodge Viper ACR displacement rises to 8400 OEM, minimum weight drops to 3550 lbs. · T1 Limited T1 wording changed to clarify all T1 cars permitted specifications. · T1 Mazda RX-7 classified: 2700 lbs minimum weight, 44mm restrictor, 13B Rotary with single Garrett Turbo #3076. · FA Pro Formula Mazda now allows street port or bridge port, previously porting was prohibited. · T1 Cadillac CTS/CTS-V, Chevrolet Camaro, Pontiac Firebird, Pontiac GTO LS3 minimum weight reduced to 3475 lbs. · T1 Camaro maximum displacement 7011 loses 50 lbs, to 3500. · T1 removes 33mm brake rotor thickness limit; rotors now unrestricted on thickness. · FA adds Honda K20Z3 2.0L engine spec at 1350 lbs minimum and Mazda MZR 2.0L spec at 1300 lbs minimum to Table 1. · T1 Mazda MX-5 Miata MazdaSpeed minimum weight rises to 2550 lbs, restrictor increases to 42mm. · T1 Chevrolet Corvette Cadillac XLR classified for model years through 2019. · FA Mazda MZR 2.0 spec line removes redundant '2.0' designation; Honda Civic K20Z3 spec line unchanged. · FA Toyota 1800 moves from Table 1 to Table 2 (Spec Line Cars). · FA Swift 016 Mazda MZR/Ford Duratec wheel width specification clarified: front 10, rear 14 minimum and 15 maximum. · T1 BMW E46/E36/Z3 minimum weight increases to 2700 lbs, 3.4L engine car to 2750 lbs. · FA rule wording clarified: Table 1 for purpose-built and ex-pro cars, Table 2 for spec line cars with exceptions noted. · FA Mazda MZR/Ford Duratec 2296cc and 2500cc moved from Table 1 to Table 2. · FA Mazda MZR 2.0 and Honda Civic K20Z3 remove sequential designation from 5-speed transmission spec. · T1 Dodge Viper SRT-10 restrictor increases from 45mm to 57mm. · T1 Chevrolet Corvette Cadillac XLR LS6 engine now permits Casting #799 heads with no other head modifications. · FA Mazda MZR 2.0 limited to Ralt RT40, RT41, Swift 008, 014 chassis; Honda Civic K20Z3 removes Swift 016 chassis. · T1 Ford Mustang Shelby/GT350/GT500 5.0L Coyote restrictor opens from 65mm to 70mm flat plate. · T1 Dodge Viper SRT-10 restrictor increases from 45mm to 57mm. · T1-LP Chevrolet Corvette C7 restrictor increases from 70 to 73 mm. · T1-LP Corvette Z06 06-13 now allows aluminum chassis replacement with equivalent OE steel chassis. · FA Swift 016 2.3 liter engine name corrected to Mazda MZR/Ford Duratec. · FA Swift 016 2.5 liter engine name corrected to Mazda MZR/Ford Duratec. · FA removes four spec lines and replaces Ford Duratec/Mazda MZR with Honda B16 at 1615cc, 1175 lbs minimum. · T1 Chevrolet Camaro with 6162 displacement minimum weight reduced to 3500 lbs. · T1-LP Chevrolet Corvettes C5 Z06, C6 Grand Sport, and Z06 dry sump kit notes clarified to remove contradictions. · FA Spec Line C loses 25 lbs to 1175; Line I loses 75 lbs to 1175; Line K gains 15 lbs to 1175. · FA purpose built and ex-Pro Atlantic cars lose 25 lb sequential transmission penalty wording. · FA Ligier JS F3 car name corrected in FR Americas spec line. · FA Ford Duratec/Mazda MZR 2500 spec line D wording cleanup: 4-valve becomes 4 valves per cylinder. · FA Honda Civic K20Z3 intake manifold and throttle body assembly now allows AT Power Direct-To-Head 45mm individual throttle bodies as alternative to HPD parts. · FF block relief permitted only as needed to fit allowed crankshaft. · FA Ford Duratec/Mazda MZR intake restrictor reduced from 32mm to 30mm SIR; Swift 016 2.5 Mazda restrictor reduced from 35mm to 33mm SIR. · FA Toyota 4A-GE engines cleaned up, spec lines A and B engine designations corrected. · FA Ford BD Series max displacement increases from 1600 to 1615 cc, minimum weight stays 1200 lbs. · FA Ford Duratec/Mazda MZR and Honda B16 both now 1615cc max displacement; Honda B16 removes NA requirement. · FA Pro Formula Mazda engine specs moved from Table 1 to Table 2 notes; Renesis Rotary details consolidated. · FA F3 Americas spec line updated effective 2021-03-01; specific changes not legible in provided text. · T1 LP removes 50 lbs weight allowance for stock headers, adds aero device allowance up to 100 lbs, permits headers. · T1 Ford Mustang Challenge 3-valve maximum displacement changes to 4600/5000. · T1 BMW E46 now allows carbon or fiberglass OEM-style dashboards with 25 pound penalty. · T1 Ford Mustang/Thunderbird limited to Shelby/Shelby GT350/GT500 models through 2018. · Dodge Viper ACR classified in T1 with 8400cc displacement, 3600 lbs minimum weight, 55mm restrictor. · BMW M2CS Club Sport classified in T1-LP Spec Lines effective 2021-02-01. · Porsche 997.1 GT3 Cup (2006-2011) classified in T1 at 3600cc, 3150 lbs minimum weight. · Formula Lites Crawford FL15 newly classified in FA. · T1 Chevrolet Corvette Z06 years extended from 06-12 to 06-13. · FF class cylinder head may now have optional coolant bleed line fitting to top of head for air release. · FF Honda LC1 ECU by HPD permitted effective 12/1/2020, must use HPD lambda sensor. · T1 Corvette C8 Z51 gets wider wheels and tyres, weight drops 100 lbs to 3550. · FE2 oil cooler wording clarified: optional air-to-oil cooler allowed, Setrab 50-625-7612 or equivalent max 13 inches wide by 6.5 inches high. · FF Honda LC1 ECU implementation date changed from 3/1/2020 to pending availability of support materials. · T1 rear wing Gurney flap wording clarified: Gurney flap in chord length and mounting height rules. · FA stock engines not given weight adjustment; modified engines now allowed in class. · FA engine modifications wording clarified: bore/crankshaft/stroke/flywheel unrestricted if displacement limit met, distributor/transistor ignition allowed without engine modification, compression ratio increasable by machining/gasket chang… · FA transmission rules clarified: no more than five forward speeds and operational reverse gear unless Table 2 notes otherwise. · FA Swift 016 Mazda Duratec Gurney flap wording clarified; terminology and mounting rules unchanged. · T1 and T2 Corvettes may convert leaf spring suspension to coilover with 800 lb max spring rate allowed. · FA Volkswagen 1835cc SOHC removed from Table 1. · FA engine rules clarified: blocks and heads must be OEM unless Tables note exceptions. · T1 Porsche 996 GT3 Cup eligible model years changed from 2002-2005 to 1998-2004. · T1 Corvette and Cadillac XLR permitted to install SCRSPLR-001 rear spoiler with OE bodywork. · T1 Gen 5 Camaro allowed 366mm OEM rear rotor and caliper without weight penalty. · FA Formula 1000 motorcycle-based engine compression ratio raised to 14.5:1 from 13.5:1. · FA removes Ex-FSV front wheel width 6–8 inches and rear 8–10 inches provisions; all cars use front 10 inches, rear 14–15 inches. · FA Formula 3 engines now allowed through 2017, previously 2008, with 30mm restrictor required. · FF alternator changes from not required to optional. · T1 Porsche 996 Spec Lines now allows 996 Cup Replica Rear deck lid. · T1 Acura NSX Turbo World Challenge and Audi TTRS GTS 2011 now require DOT tires per GCR section 9.3. · FA engine note clarification removes Table E reference, Pro Formula Mazda directed to Table 1. · FF allows Honda HPD LC1 low-cost ECU with lambda sensor; E1 ECU no longer supported but existing units permitted if sealed. · FF rain tyres now allow Hoosier W3 Radial in addition to existing Hoosier Wet option. · T1 BMW E46 wagon with S54 engine allowed; displacement corrected from 3200 to 3250cc. · T1 adds Subaru WRX/WRX STI 2005-2020 at 3000 lbs minimum weight with 46 mm restrictor. · T1 Ford Mustang GT (15-17) and GT5.0L (2018-) weight raised to 3500 lbs; Brembo BBK 380mm now at no penalty; restrictors removed from notes. · T1 Ford Mustang/Thunderbird 5000 Coyote OEM reclassified to include 2015–2017 and 2018+ model years with 65mm restrictor for 18+. · T1 BMW M3 E92 carbon dash allowed with 25 lb penalty. · T1 Corvette C5 Z06, C6 coupe, C6 Grand Sport, and Z06 may convert leaf springs to conventional coilover suspension. · Formula 1000 motorcycle-based engine classified into FA, throttle bodies and ECUs unrestricted. · F1000 reclassified into FA with specification changes effective 2020-01-01. · FA Swift 016 2.3L Mazda Duratec restrictor reduced from 33mm to 31mm SIR, making it slower. · FA wheel dimension rules moved from Bodywork subsection to General section; no specification changes. · FA Mazda MZR 2.0 now limited to Ralt RT40, Ralt RT41, and Swift 014 chassis only. · FE and FE2 minimum weight increased to 1270 lbs including driver; spring options and tire warmer ban added. · FA Honda Civic K20Z3 engines consolidated: three separate base/uprated specs removed, replaced with single unified 1350 lb minimum weight spec for Swift 014/016. · FA Swift 014 Mazda MZR 2.0 piston minimum weight reduced from 320g to 280g. · T1-LP Chevrolet Camaro 1LE 2016- weight drops to 3500 lbs, restrictor increases to 70mm flat plate. · Ford Mustang Challenge returns to T1 as E&O, 4600 cc, 3300 lbs minimum, no restrictor. · T1 Chevrolet Corvette Cadillac XLR year range corrected from 04-09. · T1 Camaro, CTS, Firebird, GTO restrictor increases from 67mm to 70mm flat plate. · FA Line N minimum weight increases to 1375 lbs. · T2-T4 clarifies DOT tire requirements; must have minimum U speed rating and be DOT certified; touring spec line supersedes other rules. · FA cars must install AIM part #X47KPFSOLO2R0 data box mount for Majors and Runoffs. · Ford Mustang EcoBoost 3.5L classified in T1 at 3300 lbs minimum weight with 31mm restrictor. · T1 Corvette C5 body allowed C7 carbon aero parts, plus 50 lbs. · T1 Audi TTRS must conform to July 24th, 2015 revision 7 GTS rules instead of December 14th, 2011 revision 3. · T1 minimum ride height established at 3.5 inches, measured at rocker panel without driver. · T1 Porsche 928 S4/GTS-R minimum weight reduced to 3200 lbs, throttle restrictor removed. · Porsche 928 S4/928 GTS-R newly classified in T1 at 3500 lbs minimum with 60mm flat plate restrictor. · FA Formula 3 car sequential gearbox weight penalty of 25 lbs removed; minimum weight now 1215 lbs. · T1-LP Ford Mustang GT 5.0L 2018+ classified at 3400 lbs with 65mm flat plate restrictor. · FA Swift 014-Mazda MZR 2.0 engine now requires OE block casting #LF95 and specific OE components instead of sealed Elite Engines sourcing. · FA Swift 016 Mazda Duratec 2.3L and 2.5L minimum weight increases from 1420 to 1450 lbs. · FF Honda Fit permitted to use 0.25mm oversize pistons, cylinder honing increased to 73.315mm maximum. · FF heat shield rule clarified: thermal wrap allowed on manifold exterior if easily removable for inspection. · FF catch tank minimum capacity rules clarified: coolant catch tank now one U.S. pint minimum, oil catch tank one U.S. quart minimum. · T1-LP Mustang GT350(R) spec line replaced with 2015+ model parameters including 5163cc engine, 3650 lbs curb weight, 315 tire size. · Ford Mustang FP350S (2018) classified in T1-LP at 3600 lbs with 18×11 wheels and 315 tires. · T1 suspension rules clarified: spherical bearings and bushings now explicitly permitted, alternate control arms allowed. · T1 Porsche 996 drops 200 lbs to 3000; 996 GT3 Cup drops 150 lbs to 3000; 997 drops 50 lbs to 3100. · Porsche 997 T1 Maximum now allows OEM PDK transmission alongside existing drivetrain options. · T1 Acura NSX Turbo World Challenge weight to 3100 lbs, restrictor to 44mm. · T1-T3 spec cars receive clarifications on permitted modifications, documentation requirements, and rule conformance; no performance changes.showhide 2025-02-01 FA Classify FR European Championship car as spec line car in Table 2 #37658cars addedneutralFA adds Tatuus F.3 T-318 or FR-19 as spec line car in Table 2 for Formula Regional European Championship. 2025-02-01 T1 T1 Parity Compared to GT4 #37170weight +125 lbsslowerT1 Mustang gains 125 lbs to 3600, restrictor shrinks 65mm to 60mm. Corvette gains 50 lbs to 3500, restrictor shrinks 70mm to 67mm. BMW deleted. 2025-02-01 T1 Clarification of Request Approval #37273 #37399engineunclearT1 E46 M3 Spec Line 1050 allows VAC Motorsports throttle body VAC-TB-S54 on 3.250L engine instead of Dinan. 2025-02-01 T1 C8 Corvette Facts #37400weight -100 lbsfasterT1 Chevrolet Corvette C8 (2023-23) minimum weight reduced from 3600 lbs to 3500 lbs. 2025-02-01 T1 Camaro Gen 5 Competitive Disadvantage #37440inductionfasterT1 Chevrolet Camaro Gen 5 restrictor increases from 75mm to 80mm flat plate. 2025-02-01 T1 Tire Changes in the Rules for GT4 #37497tyres & wheelsunclearT1 Audi R8 GT4 Spec Line #4020 maximum tyre size changes to 315 DOT, 305/645, or 30/65-18 (f), 33/68-18 (r) Non-DOT. 2024-12-01 T1 Changes to T1 Tires for GT4 and Other Cars #35383tyres & wheelsunclearT1 GT4 tire sizes adjusted across ten cars: most non-DOT rear to 305/660, Audi and McLaren 305/645, Camaro and Mustang 305/680. 2024-12-01 T1 G82 M4 GT4 inclusion in T1 #35864cars addedneutralBMW M4 GT4 (G82) added to T1 GT4 at 3525 lbs minimum weight with Red power stick control. 2024-12-01 T1 Alt. Clutch Allowance #36606wordingneutralT1 Spec Lines now permits 5.5 inch clutch in Engine Notes. 2024-12-01 T1 BOP Changes Need Updates #36667weight -150 lbsfasterT1 GT4 Spec Line 4020 restrictor opens from 44mm to 45mm, minimum weight drops to 3400 lbs. 2024-12-01 T1 Request Ford Performance Darkhorse R in T1 #37136cars addedneutralMustang Darkhorse R added to T1 homologated cars at 3,250 lbs minimum with 305/315 tires, ineligible for Runoffs until 3 Super Tour events. 2024-12-01 T1 Car Mods for T1 Corvette under line item 1150 #37173wordingneutralT1 Corvette may roll or flatten wheel opening lips for tire clearance; plastic fenders may remove lips if edge thickness matches basic material. 2024-12-01 T1 Increased Bore Throttle Bodies for E46 M3 S54 Engine #37273enginefasterT1 E46 M3 S54 can now use Dinan Throttle Body #D760-3400 on 3.250L engine. 2024-11-01 FF Change FF/FC Weight with Sequential Gearbox #36651weightfasterFF and FC cars with sequential gearbox must add 10 lbs. to minimum weight, down from 25 lbs. 2024-11-01 FF Alternative Oversize Honda Fit Pistons #37064wordingneutralFF Honda Fit allows Fast Forward 0.25mm oversize pistons PN FF800-110 as alternative; piston diameter spec clarified to 2.8835 inches. 2024-10-01 FF Update to FF EGR Blanking Plate Rule #36633wordingneutralFF VTEC activation valve must function; EGR blanking plate rule clarified with Fast Forward part numbers. 2024-05-01 T1 Please Expedite classing the C63 Mercedes #35987cars addedneutralMercedes AMG-C63 S (2023) classified in T1 with 4000 lbs minimum weight and 3700 restrictor. 2024-04-01 T1 Honda S2000 #35582cars addedneutralT1 Honda S2000 classified with 2400 lb minimum weight, 2950 cc displacement, 4.75" supercharger pulley. 2024-03-01 T1 9.1.9.1 T1 new category item/ line 26 rule to expire Jan 1 2023 #35411cars addedneutralPontiac GTO 2006-2009 LS1 added to T1 as Spec Line 1590, 5700 cc, 3400 lbs minimum. 2024-02-01 T1 C8 Corvette T1 Restrictor Plate Request #35213inductionfasterC8 Corvette T1 restrictor plate increases from 70mm to 72mm flat plate. 2024-02-01 T1 The Cars Have Expired #35379removedneutralT1 NEW class removes 23 spec lines including Acura NSX, Ferrari, Porsche 996, Nissan Z cars, and others; Porsche 997 spec line 1680 expiration removed. 2024-01-01 FF Honda Fit Oversize Piston Rings #35305wordingneutralFF Honda Fit gains Fast Forward FF800-100 oversize piston ring pack option. 2024-01-01 T1 GT4 batch adjustment in T1 #35162other -85 lbsunclearT1-GT4 batch adjustments: five cars lighter, two heavier, restrictors and ECU maps changed, five models now eligible for Runoffs. 2024-01-01 T1 Remove T1 spec lines #35192wordingneutralT1 spec lines 1000, 1010, 1020, 1040, 1360, 1400–1410, 1520–1680, 1700–1720 deleted entirely. 2023-12-01 T1 New T1 add spec line for C5 corvette LS2 engines (Copy from C6) #33764cars addedneutralT1 Chevrolet Corvette C5 LS2 added with 6000cc displacement, 3300 lbs minimum weight, 72mm flat plate restrictor. 2023-12-01 T1 C7 Corvette Rule Change Request #34897cars addedneutralT1 Chevrolet Corvette C7 (14-19) including Z51, Grandsport newly classified as homologated car. 2023-12-01 T1 Camaro Gen 5 Weight Reduction Due to Competitive Disadvantage #35092weight -75 lbsfasterT1 Gen 5 Camaro minimum weight drops 75 lbs to 3475; restrictor increases 70mm to 75mm. 2023-12-01 T1 Addendum to Letter #35022: Drivetrain Rule #35105wordingneutralT1 Aston Martin Vantage permitted to use OEM Sportshift II transmission. 2023-12-01 T1 2004 - 2006 Pontiac GTO Re-Integration Back Into T1 #34403cars addedneutralPontiac GTO 2006-2009 re-integrated into T1 with LS2 at 3400 lbs, 72mm restrictor, and LS3 at 3500 lbs, 61mm restrictor. 2023-12-01 T1 Request to Classify Porsche 997-1 GT3 Cup #34561cars addedneutralT1 Porsche 997-1 GT3 Cup added at spec line 4210, minimum weight 3050 lbs. 2023-08-01 T1 Why no Camaro? #34421cars addedneutralChevrolet Camaro GT4-R classified in T1 GT4 Spec Line 4035, minimum weight 3375 lbs, 315 max tire, 63mm restrictor, ineligible for Runoffs. 2023-08-01 T1 Request to Remove Expiration from T1 spec lines #1350 & #1370 #34470wordingneutralT1 Dodge Viper ACR / SRT RT-10 and ACR/ACR-X spec lines 1350 and 1370 remove 12/23 expiration. 2023-08-01 T1 Remove #34475wordingneutralT1 GT4 McLaren 570S, Mercedes AMG GT4, and Porsche 718 Cayman GT4 CS MR now eligible for Runoffs competition. 2023-08-01 T1 Error in T1 GT4 numbering scheme- #34578wordingneutralT1 GT4 BMW M4 Spec Line Number changed from 4050 to 4030. 2023-08-01 T1 C5 Approved Aero That Was Mistakenly Deleted #34374aerofasterT1 Corvette C5 gains approved aero parts: carbon rear spoiler, vented front splitter, side skirts, with 50 lb weight reduction allowed. 2023-07-01 T1 Viper Cleanup #34107inductionfasterT1 Dodge Viper ACR/ACR-X restrictor increases from 50mm to 60mm flat plate. 2023-07-01 T1 Viper 8300 OEM FPR Size #34268inductionunclearT1 Dodge Viper ACR/ACR-X: Spec Line 1370 restrictor increases to 55mm, Line 1390 decreases to 55mm. 2023-07-01 T1 Ford Mustang S197 (05-14) Clarification #34450wordingneutralT1 Ford Mustang S197 05-14 now requires OEM 8.8 differential housing. 2023-07-01 T1 Gen 5 Camaro Engine #33875cars addedneutralT1 Chevrolet Camaro Gen 5 LS7 gets two spec lines: 1131 with 70mm restrictor, 1136 with 53mm restrictor, both 3450 lbs minimum. 2023-07-01 T1 Inquiry to letter #33682 #34071engineslowerT1 Chevrolet Camaro Gen 5, Corvette C5 and C6: engine resleeve restricted to stock parameters only, no longer LS3 bore/stroke. 2023-06-01 FA Simplify Pro Formula Mazda wheel allowance #34190tyres & wheelsunclearFA Pro Formula Mazda front wheels widen to 10 in. max; rear wheels narrow to 14 in. min. 2023-06-01 T1 Request to reinstate T1 S197 Mustang #34048cars addedneutralT1 Ford Mustang S197 (05-14) reinstated with 3550 lbs minimum weight, 75mm restrictor, Voodoo engine permitted. 2023-05-01 FA E&O - Correct Pro Formula Mazda spec line dimensional equivalent #34085aerofasterFA Pro Formula Mazda maximum bodywork width behind front wheels increases to 51.97 inches. 2023-05-01 FA Add new spec line for MSR Formula Mazda FMzR to Table 2 #34139cars addedneutralFA MSR Formula Mazda FMzR added to Table 2 classification. 2023-05-01 T1 T1 GT4 adjustments #33786wordingneutralT1 GT4 weights clarified for nine cars, ranging from 3200 lbs Porsche 718 Cayman to 3575 lbs Aston Martin. 2023-05-01 T1 Touring 1 Tire Sizes #34191tyres & wheelsfasterT1-GT4 McLaren 570S and Mercedes AMG GT4 front tires widen to 315 mm. 2023-04-01 T1 Clarification for Camaro Gen5 2010-2015 #33739inductionslowerT1 Chevrolet Camaro Gen5 LS3-6160 adds 70mm flat plate restrictor, weight 3550 lbs. 2023-03-01 FF Add Fast Forward Part Numbers for Honda Fit Engine #33752wordingneutralFF Honda Fit engine adds Fast Forward part number alternatives for intake, exhaust, oil system, and scavenge pump components. 2023-03-01 T1 Sequential Gearbox Limitations in T1 #33691wordingneutralT1 cars with aftermarket sequential transmissions get 10-inch max bellhousing; non-sequential cars gain 100 lbs weight break. 2023-03-01 T1 T1 GT4 adjustments #33786weightfasterT1 GT4 all nine cars lose 125 lbs minimum weight with driver, from 3200–3575 to 3075–3450. 2023-03-01 T1 Sunset of pre 2023 Touring 1 Rules. #33916wordingneutralT1 removes GCR Section 9.1.9.1.A. and T1 Spec Lines entirely, sunsetting pre-2023 Touring 1 rules. 2023-02-01 T1 Corrections to T1 Spec Lines #33678tyres & wheelsunclearGT4 McLaren 570S maximum tire size changes to 285 front, 315 rear. 2023-01-01 FA BDA Displacement #33431wordingneutralFA BDA engine displacement specification line added to Table 1, effective 2023-01-01. 2023-01-01 T1 GT4 section to Current T1 Rules. #33632cars addedneutralEight GT4 models added to T1 with weights from 3200 to 3575 lbs and restricted power per SRO 2022 rules. 2022-12-01 FA Reclassify 2010-2017 Formula Renault 2.0 as a spec line car in FA #33395cars addedfasterFormula Renault 2.0 (10-17) reclassified from FX to FA; weight reduced to 1280 lbs, restrictor removed. 2022-12-01 FA Change Swift 016 2.3L restrictor size and minimum weight #33472induction -30 lbsfasterFA Swift 016 2.3L restrictor increases from 31mm to 32mm SIR; minimum weight drops 30 lbs to 1420. 2022-10-01 FA Pro Formula Mazda Dimension E&O #33160wordingneutralPro Formula Mazda allows street or bridge port, unrestricted apex seals, 70mm throttle body, 99cm wing height max, 132cm bodywork width max. 2022-08-01 T1 Correct Camaro Spec Line From Letter #30791 response to 3475lbs #32824weight -25 lbsfasterT1 Cadillac CTS/CTS-V, Chevrolet Camaro, Pontiac Firebird, Pontiac GTO 6162 OEM minimum weight reduced to 3475 lbs. 2022-06-01 T1 Fix FP350S limited prep and Shelby 350 full prep issues #31680inductionfasterT1-LP Ford Mustang FP350S restrictor increases from 70mm to 75mm. 2022-06-01 T1 Request to Classify AMG GT4 #32610cars addedneutralMercedes Benz AMG GT4 2017-2021 classified T1 Maximum at 3400 lbs minimum weight with HP-controlled SRO Power Level 2 engine. 2022-05-01 FA Update FR Americas rulebook requirement #32491wordingneutralFA Ligier JS F3 must comply with Formula Regional Americas rules instead of FIA Formula 3 Regional Technical Regulations. 2022-05-01 FA Clarify verification of sealed engine compliance #32522wordingneutralFA sealed engines must undergo full inspection; competitor pays reassembly and resealing costs. 2022-05-01 FA Clarify Formula Lites and FR Americas sealed engine requirement #32523wordingneutralFA Formula Lites FL15 and FR Americas Ligier JS F3 engine sealing requirements clarified to reference respective series technical regulations. 2022-04-01 FA E&O FA Transmission section #32251wordingneutralFA transmission rule clarified: transverse shafts prohibited except final drive and motorcycle gearbox in Formula 1000. 2022-04-01 FA E&O Swift 016 2.5 liter Aero column #32363wordingunclearFA Swift 016 2.5 liter aero spec now references 2.3 liter notes instead of N notes. 2022-04-01 T1 Viper/Z06 Parity #31942weight -50 lbsfasterT1 Dodge Viper ACR displacement rises to 8400 OEM, minimum weight drops to 3550 lbs. 2022-04-01 T1 Discrepancy in T1 allowances #32293wordingneutralT1 Limited T1 wording changed to clarify all T1 cars permitted specifications. 2022-04-01 T1 T1 RX7 classification #32352cars addedneutralT1 Mazda RX-7 classified: 2700 lbs minimum weight, 44mm restrictor, 13B Rotary with single Garrett Turbo #3076. 2022-03-01 FA Closing the Gap #31934inductionfasterFA Pro Formula Mazda now allows street port or bridge port, previously porting was prohibited. 2022-03-01 T1 Weight reduction E&O #30791weight -25 lbsfasterT1 Cadillac CTS/CTS-V, Chevrolet Camaro, Pontiac Firebird, Pontiac GTO LS3 minimum weight reduced to 3475 lbs. 2022-03-01 T1 Performance Adjustment Request for Camaro #31521weight -50 lbsfasterT1 Camaro maximum displacement 7011 loses 50 lbs, to 3500. 2022-03-01 T1 Remove 33m Brake rotor thickness rule #31954suspension & brakesfasterT1 removes 33mm brake rotor thickness limit; rotors now unrestricted on thickness. 2022-02-01 FA Reorganize Tables 1 and 2 #31985cars addedneutralFA adds Honda K20Z3 2.0L engine spec at 1350 lbs minimum and Mazda MZR 2.0L spec at 1300 lbs minimum to Table 1. 2021-12-01 T1 Turbo Miata Help #31315weight +200 lbsslowerT1 Mazda MX-5 Miata MazdaSpeed minimum weight rises to 2550 lbs, restrictor increases to 42mm. 2021-12-01 T1 Fix the T1 Corvette heading #31528wordingneutralT1 Chevrolet Corvette Cadillac XLR classified for model years through 2019. 2021-09-01 FA E&O Table 2 engine names #31085wordingneutralFA Mazda MZR 2.0 spec line removes redundant '2.0' designation; Honda Civic K20Z3 spec line unchanged. 2021-08-01 FA Move Toyota 1800 to Table 2 #30822cars addedneutralFA Toyota 1800 moves from Table 1 to Table 2 (Spec Line Cars). 2021-08-01 FA E&O Swift 016 wheel width reference #30939wordingneutralFA Swift 016 Mazda MZR/Ford Duratec wheel width specification clarified: front 10, rear 14 minimum and 15 maximum. 2021-08-01 T1 T1 E46 BOP E&O for Letter # 29970 #30934weight +100 lbsslowerT1 BMW E46/E36/Z3 minimum weight increases to 2700 lbs, 3.4L engine car to 2750 lbs. 2021-07-01 FA Update FA rules package #30717wordingneutralFA rule wording clarified: Table 1 for purpose-built and ex-pro cars, Table 2 for spec line cars with exceptions noted. 2021-07-01 FA Move Mazda MZR/Ford Duratec 2296cc and 2500cc to Table 2 #30718wordingneutralFA Mazda MZR/Ford Duratec 2296cc and 2500cc moved from Table 1 to Table 2. 2021-07-01 FA Clean up Table 2 Mazda MZR 2.0L and Honda Civic K20Z3 spec lines #30719wordingneutralFA Mazda MZR 2.0 and Honda Civic K20Z3 remove sequential designation from 5-speed transmission spec. 2021-07-01 T1 Request BoP for the Viper in 1 LP #29968inductionfasterT1 Dodge Viper SRT-10 restrictor increases from 45mm to 57mm. 2021-07-01 T1 LS6 Alternative Head Question #30074wordingneutralT1 Chevrolet Corvette Cadillac XLR LS6 engine now permits Casting #799 heads with no other head modifications. 2021-06-01 FA E&O Mazda MZR 2.0 and Honda Civic K20Z3 chassis eligibility #30632wordingneutralFA Mazda MZR 2.0 limited to Ralt RT40, RT41, Swift 008, 014 chassis; Honda Civic K20Z3 removes Swift 016 chassis. 2021-06-01 T1 T1-LP - Add Performance Pack, Bullet, Mach 1 to 18+ Mustang #29849inductionfasterT1 Ford Mustang Shelby/GT350/GT500 5.0L Coyote restrictor opens from 65mm to 70mm flat plate. 2021-06-01 T1 Request BoP for the Viper in 1 LP #29968inductionfasterT1 Dodge Viper SRT-10 restrictor increases from 45mm to 57mm. 2021-06-01 T1 Request to classify C7 and 13Viper in T1 LP #29969inductionfasterT1-LP Chevrolet Corvette C7 restrictor increases from 70 to 73 mm. 2021-06-01 T1 Request LP Z06 steel chassis #30589wordingneutralT1-LP Corvette Z06 06-13 now allows aluminum chassis replacement with equivalent OE steel chassis. 2021-05-01 FA Correct engine name in Swift 016 2.3 liter spec line #30447wordingneutralFA Swift 016 2.3 liter engine name corrected to Mazda MZR/Ford Duratec. 2021-05-01 FA Correct engine name in Swift 016 2.5 liter spec line #30448wordingneutralFA Swift 016 2.5 liter engine name corrected to Mazda MZR/Ford Duratec. 2021-05-01 FA Revise Table 1 Spec Lines and clarify application of Engine Notes #30456cars addedunclearFA removes four spec lines and replaces Ford Duratec/Mazda MZR with Honda B16 at 1615cc, 1175 lbs minimum. 2021-05-01 T1 Request For Reduction in Weight/Penalties for Camaro #30443weightfasterT1 Chevrolet Camaro with 6162 displacement minimum weight reduced to 3500 lbs. 2021-05-01 T1 Fix dry sump Contradictions in T1-LP vs T2 #30596wordingneutralT1-LP Chevrolet Corvettes C5 Z06, C6 Grand Sport, and Z06 dry sump kit notes clarified to remove contradictions. 2021-04-01 FA Update Table 1 Weights for Spec Lines C, I, and K #30355weight -25 lbsfasterFA Spec Line C loses 25 lbs to 1175; Line I loses 75 lbs to 1175; Line K gains 15 lbs to 1175. 2021-04-01 FA Remove redundant reference in Table 2 spec line #30366wordingfasterFA purpose built and ex-Pro Atlantic cars lose 25 lb sequential transmission penalty wording. 2021-04-01 FA Correct the name of the FR Americas car #30369wordingneutralFA Ligier JS F3 car name corrected in FR Americas spec line. 2021-04-01 FA Clean up Spec Line D in Table 1 #30372wordingneutralFA Ford Duratec/Mazda MZR 2500 spec line D wording cleanup: 4-valve becomes 4 valves per cylinder. 2021-04-01 FA Table 2 Honda K20Z3 request #30386inductionfasterFA Honda Civic K20Z3 intake manifold and throttle body assembly now allows AT Power Direct-To-Head 45mm individual throttle bodies as alternative to HPD parts. 2021-04-01 FF Kent crankshaft clarification #30426wordingneutralFF block relief permitted only as needed to fit allowed crankshaft. 2021-03-01 FA E&O FA Intake Restrictors #30273inductionslowerFA Ford Duratec/Mazda MZR intake restrictor reduced from 32mm to 30mm SIR; Swift 016 2.5 Mazda restrictor reduced from 35mm to 33mm SIR. 2021-03-01 FA Clean up Spec Lines A and B in Table 1 #30274wordingneutralFA Toyota 4A-GE engines cleaned up, spec lines A and B engine designations corrected. 2021-03-01 FA Clean up Spec Line C in Table 1 #30275enginefasterFA Ford BD Series max displacement increases from 1600 to 1615 cc, minimum weight stays 1200 lbs. 2021-03-01 FA Clean up Spec Lines J and L in Table 1 #30276wordingneutralFA Ford Duratec/Mazda MZR and Honda B16 both now 1615cc max displacement; Honda B16 removes NA requirement. 2021-03-01 FA Move engine specifications to Pro Formula Mazda spec line notes #30278wordingneutralFA Pro Formula Mazda engine specs moved from Table 1 to Table 2 notes; Renesis Rotary details consolidated. 2021-03-01 FA Update F3 Americas spec line #30280wordingunclearFA F3 Americas spec line updated effective 2021-03-01; specific changes not legible in provided text. 2021-03-01 T1 T1 LP Aero adjustments #30196aerounclearT1 LP removes 50 lbs weight allowance for stock headers, adds aero device allowance up to 100 lbs, permits headers. 2021-02-01 T1 Request to Clarify Miller Mustang Classification #28728engineunclearT1 Ford Mustang Challenge 3-valve maximum displacement changes to 4600/5000. 2021-02-01 T1 BMW E46 Carbon Dash #29806weightslowerT1 BMW E46 now allows carbon or fiberglass OEM-style dashboards with 25 pound penalty. 2021-02-01 T1 Request to Update T1 Mustang Spec Line #30001wordingneutralT1 Ford Mustang/Thunderbird limited to Shelby/Shelby GT350/GT500 models through 2018. 2021-02-01 T1 Dodge Viper 8400 OEM??? #30174cars addedneutralDodge Viper ACR classified in T1 with 8400cc displacement, 3600 lbs minimum weight, 55mm restrictor. 2021-02-01 T1 Class BMW M2CS Club Sport #30195cars addedneutralBMW M2CS Club Sport classified in T1-LP Spec Lines effective 2021-02-01. 2021-02-01 T1 997.1 GT3 Cup #30229cars addedneutralPorsche 997.1 GT3 Cup (2006-2011) classified in T1 at 3600cc, 3150 lbs minimum weight. 2021-01-01 FA Request to classify Formula Lites Crawford FL15 #29702cars addedneutralFormula Lites Crawford FL15 newly classified in FA. 2021-01-01 T1 Correct T1 Limited Prep Years #29708wordingneutralT1 Chevrolet Corvette Z06 years extended from 06-12 to 06-13. 2020-12-01 FF Allow Optional Coolant Bleed Line to Correct a Known Problem #29673wordingneutralFF class cylinder head may now have optional coolant bleed line fitting to top of head for air release. 2020-12-01 FF Clarification regarding Honda LC1 ECU implementation date #29684wordingneutralFF Honda LC1 ECU by HPD permitted effective 12/1/2020, must use HPD lambda sensor. 2020-12-01 T1 Changes to Corvette C8 #29898tyres & wheels -100 lbsfasterT1 Corvette C8 Z51 gets wider wheels and tyres, weight drops 100 lbs to 3550. 2020-09-01 FE2 FE/FE2 Oil Cooler #29293wordingneutralFE2 oil cooler wording clarified: optional air-to-oil cooler allowed, Setrab 50-625-7612 or equivalent max 13 inches wide by 6.5 inches high. 2020-08-01 FF Clarification regarding Honda LC1 ECU implementation #29135wordingneutralFF Honda LC1 ECU implementation date changed from 3/1/2020 to pending availability of support materials. 2020-08-01 T1 Touring Gurney flap wicker clarification #29013wordingneutralT1 rear wing Gurney flap wording clarified: Gurney flap in chord length and mounting height rules. 2020-07-01 FA Request to Adjust FB Weight for Stock Engines #29005wordingneutralFA stock engines not given weight adjustment; modified engines now allowed in class. 2020-06-01 FA E&O permitted engine modifications #28831wordingneutralFA engine modifications wording clarified: bore/crankshaft/stroke/flywheel unrestricted if displacement limit met, distributor/transistor ignition allowed without engine modification, compression ratio increasable by machining/gasket chang… 2020-06-01 FA E&O Transmissions #28832wordingneutralFA transmission rules clarified: no more than five forward speeds and operational reverse gear unless Table 2 notes otherwise. 2020-06-01 FA Swift 016 Gurney flap wicker clarification #28884wordingneutralFA Swift 016 Mazda Duratec Gurney flap wording clarified; terminology and mounting rules unchanged. 2020-06-01 T1 Consider coil spring conversion Corvette in T2 #28824suspension & brakesneutralT1 and T2 Corvettes may convert leaf spring suspension to coilover with 800 lb max spring rate allowed. 2020-05-01 FA Remove redundant spec line in Table 1 #28720removedneutralFA Volkswagen 1835cc SOHC removed from Table 1. 2020-05-01 FA E&O general engine rules #28772wordingneutralFA engine rules clarified: blocks and heads must be OEM unless Tables note exceptions. 2020-05-01 T1 Additional Clarification on 996 Cup in T1 From Letter #28040 #28060wordingneutralT1 Porsche 996 GT3 Cup eligible model years changed from 2002-2005 to 1998-2004. 2020-05-01 T1 Request SPEC Corvette Rear Spolier #28182aeroneutralT1 Corvette and Cadillac XLR permitted to install SCRSPLR-001 rear spoiler with OE bodywork. 2020-05-01 T1 T1 Rear Brake Rotor Size Exemption for Gen 5 Camaro #28402wordingneutralT1 Gen 5 Camaro allowed 366mm OEM rear rotor and caliper without weight penalty. 2020-04-01 FA Request higher compression ratio and prior weights for F1000 cars #28162enginefasterFA Formula 1000 motorcycle-based engine compression ratio raised to 14.5:1 from 13.5:1. 2020-04-01 FA Remove redundant wheel dimension provisions #28554wordingneutralFA removes Ex-FSV front wheel width 6–8 inches and rear 8–10 inches provisions; all cars use front 10 inches, rear 14–15 inches. 2020-04-01 FA E&O Formula 3 spec line #28596enginefasterFA Formula 3 engines now allowed through 2017, previously 2008, with 30mm restrictor required. 2020-04-01 FF E&O FF Kent Engine alternator language #28204wordingneutralFF alternator changes from not required to optional. 2020-04-01 T1 Request 996 GT3 Trunk for Wing Allowance. #28153wordingneutralT1 Porsche 996 Spec Lines now allows 996 Cup Replica Rear deck lid. 2020-04-01 T1 All Touring, Change DOT Tire Language 9.1.9.1, 9.3.45 #28452wordingneutralT1 Acura NSX Turbo World Challenge and Audi TTRS GTS 2011 now require DOT tires per GCR section 9.3. 2020-03-01 FA FA weight correction/clarification #28430wordingneutralFA engine note clarification removes Table E reference, Pro Formula Mazda directed to Table 1. 2020-03-01 FF Honda Racing HPD low cost ECU proposal #27563engineneutralFF allows Honda HPD LC1 low-cost ECU with lambda sensor; E1 ECU no longer supported but existing units permitted if sealed. 2020-03-01 FF Update rain tire designation #28443tyres & wheelsneutralFF rain tyres now allow Hoosier W3 Radial in addition to existing Hoosier Wet option. 2020-03-01 T1 Request for E46 wagon with S54 engine in T1 #27427wordingneutralT1 BMW E46 wagon with S54 engine allowed; displacement corrected from 3200 to 3250cc. 2020-02-01 T1 Request to include Subaru WRX/STI 02-18 in T1 #24916cars addedneutralT1 adds Subaru WRX/WRX STI 2005-2020 at 3000 lbs minimum weight with 46 mm restrictor. 2020-02-01 T1 Request Ford Mustang FP350S T1-LP weight and restrictor change #26662weight +100 lbsslowerT1 Ford Mustang GT (15-17) and GT5.0L (2018-) weight raised to 3500 lbs; Brembo BBK 380mm now at no penalty; restrictors removed from notes. 2020-02-01 T1 Request to classify Ford Coyote 3rd Gen OEM #27145cars addedslowerT1 Ford Mustang/Thunderbird 5000 Coyote OEM reclassified to include 2015–2017 and 2018+ model years with 65mm restrictor for 18+. 2020-02-01 T1 Request alternate dashboard #27276weightslowerT1 BMW M3 E92 carbon dash allowed with 25 lb penalty. 2020-02-01 T1 Request for Allowance of Coil Springs on Limited Prep C6 Corvette #27713suspension & brakesfasterT1 Corvette C5 Z06, C6 coupe, C6 Grand Sport, and Z06 may convert leaf springs to conventional coilover suspension. 2020-01-01 FA Request to merge FB into FA #25611cars addedfasterFormula 1000 motorcycle-based engine classified into FA, throttle bodies and ECUs unrestricted. 2020-01-01 FA Suggestions for FB/F1000 into FA #27319cars addedunclearF1000 reclassified into FA with specification changes effective 2020-01-01. 2020-01-01 FA Change Swift 016 - 2.3 liter Mazda Duratec restrictor size #27880inductionslowerFA Swift 016 2.3L Mazda Duratec restrictor reduced from 33mm to 31mm SIR, making it slower. 2019-12-01 FA Move wheel dimensions from Bodywork subsection to #27493wordingneutralFA wheel dimension rules moved from Bodywork subsection to General section; no specification changes. 2019-12-01 FA Table 2 Mazda MZR 2.0 E&O #27640wordingneutralFA Mazda MZR 2.0 now limited to Ralt RT40, Ralt RT41, and Swift 014 chassis only. 2019-12-01 FE2 FE / FE2 Update Rules #27624weightslowerFE and FE2 minimum weight increased to 1270 lbs including driver; spring options and tire warmer ban added. 2019-10-01 FA Follow up to Letter #27344 on Honda Powered FA Rules #27363wordingneutralFA Honda Civic K20Z3 engines consolidated: three separate base/uprated specs removed, replaced with single unified 1350 lb minimum weight spec for Swift 014/016. 2019-08-31 FA Swift 014 Mazda MZR 2.0 E&O #27305enginefasterFA Swift 014 Mazda MZR 2.0 piston minimum weight reduced from 320g to 280g. 2019-08-31 T1 T1 LP 2016 Camaro and Later #27198weight -100 lbsfasterT1-LP Chevrolet Camaro 1LE 2016- weight drops to 3500 lbs, restrictor increases to 70mm flat plate. 2019-08-01 T1 Request to return Ford Mustang Challenge Car to T1 #26751cars addedneutralFord Mustang Challenge returns to T1 as E&O, 4600 cc, 3300 lbs minimum, no restrictor. 2019-08-01 T1 Correct years in T1 FP Corvette spec #27023wordingneutralT1 Chevrolet Corvette Cadillac XLR year range corrected from 04-09. 2019-07-01 T1 Request BoP Baten - T1 Camaro - Follow up to Letter # 26145 #26900inductionfasterT1 Camaro, CTS, Firebird, GTO restrictor increases from 67mm to 70mm flat plate. 2019-05-31 FA Adjust Line N restrictor size and minimum weight #26691weight +30 lbsslowerFA Line N minimum weight increases to 1375 lbs. 2019-05-31 T1 Clarify DOT tires touring #26556tyres & wheelsneutralT2-T4 clarifies DOT tire requirements; must have minimum U speed rating and be DOT certified; touring spec line supersedes other rules. 2019-05-01 FA Add data plate requirement #26707wordingneutralFA cars must install AIM part #X47KPFSOLO2R0 data box mount for Majors and Runoffs. 2019-05-01 T1 Request to Classify EcoBoost Mustang #25841cars addedneutralFord Mustang EcoBoost 3.5L classified in T1 at 3300 lbs minimum weight with 31mm restrictor. 2019-05-01 T1 Request Corvette aerodynamic aids #26265aeroslowerT1 Corvette C5 body allowed C7 carbon aero parts, plus 50 lbs. 2019-05-01 T1 Audi TTRS VTS Documentation Revision #26578wordingunclearT1 Audi TTRS must conform to July 24th, 2015 revision 7 GTS rules instead of December 14th, 2011 revision 3. 2019-05-01 T1 Request Ride Height Clarification #26599wordingneutralT1 minimum ride height established at 3.5 inches, measured at rocker panel without driver. 2019-05-01 T1 Opposes Unfair weight and throttle restrictor #26719weight -300 lbsfasterT1 Porsche 928 S4/GTS-R minimum weight reduced to 3200 lbs, throttle restrictor removed. 2019-04-01 T1 Request to classify the Porsche 928GTS/S4 in Touring 1 #26315cars addedneutralPorsche 928 S4/928 GTS-R newly classified in T1 at 3500 lbs minimum with 60mm flat plate restrictor. 2019-03-01 FA Request to add FA engine spec lines #26183weightfasterFA Formula 3 car sequential gearbox weight penalty of 25 lbs removed; minimum weight now 1215 lbs. 2019-03-01 T1 Request Mustang GT Limited Prep 2018 Classification #24431cars addedneutralT1-LP Ford Mustang GT 5.0L 2018+ classified at 3400 lbs with 65mm flat plate restrictor. 2019-02-01 FA FA MZR 2.0 Engine Specification #25814wordingneutralFA Swift 014-Mazda MZR 2.0 engine now requires OE block casting #LF95 and specific OE components instead of sealed Elite Engines sourcing. 2019-02-01 FA FA 016 weight increase #26063weightslowerFA Swift 016 Mazda Duratec 2.3L and 2.5L minimum weight increases from 1420 to 1450 lbs. 2019-02-01 FF Request for Oversize Honda Fit Pistons #25810enginefasterFF Honda Fit permitted to use 0.25mm oversize pistons, cylinder honing increased to 73.315mm maximum. 2019-02-01 FF Heat Shield - Fit Intake #26102wordingneutralFF heat shield rule clarified: thermal wrap allowed on manifold exterior if easily removable for inspection. 2019-02-01 FF Request catch cans/tanks clarification #26158wordingneutralFF catch tank minimum capacity rules clarified: coolant catch tank now one U.S. pint minimum, oil catch tank one U.S. quart minimum. 2019-01-01 T1 Class 2015+ Mustang GT350(R) #21466wordingneutralT1-LP Mustang GT350(R) spec line replaced with 2015+ model parameters including 5163cc engine, 3650 lbs curb weight, 315 tire size. 2019-01-01 T1 Request to Classify Ford FP350S in T1-LP #25341cars addedneutralFord Mustang FP350S (2018) classified in T1-LP at 3600 lbs with 18×11 wheels and 315 tires. 2019-01-01 T1 Amendment to Request #25555 #25556wordingneutralT1 suspension rules clarified: spherical bearings and bushings now explicitly permitted, alternate control arms allowed. 2019-01-01 T1 Request to balance 996 v 997 T1 weight #25658weightfasterT1 Porsche 996 drops 200 lbs to 3000; 996 GT3 Cup drops 150 lbs to 3000; 997 drops 50 lbs to 3100. 2019-01-01 T1 Request to Add PDK Transmission to 997 Porsche Spec Line #25668wordingneutralPorsche 997 T1 Maximum now allows OEM PDK transmission alongside existing drivetrain options. 2019-01-01 T1 T1 World Challenge/Grand AM Spec Cars #25687weightslowerT1 Acura NSX Turbo World Challenge weight to 3100 lbs, restrictor to 44mm. 2019-01-01 T1 Add Clarification to Spec Car Classifications Vehicle Spec #25774wordingneutralT1-T3 spec cars receive clarifications on permitted modifications, documentation requirements, and rule conformance; no performance changes.

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