BoP Lab / Classes / FX

FX vs P2 pace at every track

Lap times across years say as much about the weather as the class. % of FX is each class's best lap as a share of FX'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 +FA +FC +FE2 +FF +FP +FV +FX×GT1 +GT2 +GTX +HP +P +vsP2 ×SM +SMX +SRF3 +STL +STU +T1 +T2 +T3 +T4 +Show 51 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 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 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: FX 100.0% of FX Jacob Loomis, Road America Runoffs 2020 race · P2 93.8% of FX Robert Iversen, Road America Runoffs 2020 qualifying

% of FXLap times

FXP2solid race · dashed qualifying · slower is lower

FXP2solid race · dashed qualifying · each class's best lap as a share of FX's at the same event (the reference class, changeable above); 100% is level, less is quicker, so up the chart is quicker

	Event	FX			P2
	Event	Qual best	Race best	Trap	Qual best	Race best	Trap	vs FX	% of FX
	Road America Runoffs 20262026-09-28				2:10.606Greg Gyann · fastest of 11 · top 5 within 5.3s+3.201s (+2.51%)	2:09.441Mike Reupert · fastest of 11 · top 5 within 4.2s+1.119s (+0.87%)	155.0Matt Strand+2.4 mph (+1.6%)
3 rule changes (FX: 2, P2: 1)2 weight · 1 wording · FX sealed engines now subject to section 9.3.42 requirements instead of full inspection and reassembly costs. · FX Ligier JS F422 minimum weight reduces to 1360 lbs from 1375 lbs. · P2 2000 cc Pinto engine car minimum weight set to 1335 lbs.showhide 2026-08-01 FX Update sealed engine teardown section #40622wordingwordingFX sealed engines now subject to section 9.3.42 requirements instead of full inspection and reassembly costs. 2024-12-01 FX Request to Change to Weight for Ligier JS F422 #37124weight -15 lbsfasterweightFX Ligier JS F422 minimum weight reduces to 1360 lbs from 1375 lbs. 2024-12-01 P2 2000 cc Pinto Engine Car Weight #37187weightslowerweightP2 2000 cc Pinto engine car minimum weight set to 1335 lbs.
	Road America Runoffs 20242024-10-01				2:07.405Bart Wolf · fastest of 14 · top 5 within 3.0s-1.109s (-0.86%)	2:08.322Bart Wolf · fastest of 13 · top 5 within 0.6s-1.471s (-1.13%)	152.5Lucian Pancea-0.6 mph (-0.4%)
9 rule changes (FX: 4, P2: 5)1 cars added · 1 engine · 1 weight · 5 wording · 1 other · FX Ligier JS F4 1st Gen minimum weight drops 15 lbs to 1405; 2nd Gen rises 31 lbs to 1375. · P2 Spec Line E engine notes clarify oil system, ECU, and exhaust remain unrestricted; wording only. · P2 FIA Group CN notes clarify V de V European Proto Endurance Challenge bodywork, rear diffuser, wing, wheels, assisted shifting allowed; regulations link provided. · FX adds Ligier JS F422 second generation classification, new car permitted. · FX Formula 4 removed reference to FIA Technical Regulations 2015 and subsequent safety requirements; tire choice remains unrestricted. · P2 AMAC and related cars: clarified B.1 modified engine range to 2008 and older stock engines only, with 38mm restrictor and 1025 lbs minimum weight. · P2 Suzuki GSX-R1000 engine: 2007–2008 crankcase 11300-21860 may be replaced with 2016–2019 GSX-S1000 part 11301-04840. · P2 Table 1 engine date ranges clarified: Stock Engine replaced with specific marques Suzuki, Yamaha, Honda, BMW for 2009-newer and 2008-older rows. · FX Formula Mazda specifications updated; attached table not provided.showhide 2024-07-01 FX Adjust minimum weights to align with pro F4 rules #36221weight -15 lbsfasterweightFX Ligier JS F4 1st Gen minimum weight drops 15 lbs to 1405; 2nd Gen rises 31 lbs to 1375. 2024-05-01 P2 CN Spec ECU #35835wordingwordingP2 Spec Line E engine notes clarify oil system, ECU, and exhaust remain unrestricted; wording only. 2024-05-01 P2 E&O - Correct FIA Group CN spec line notes #35900wordingwordingP2 FIA Group CN notes clarify V de V European Proto Endurance Challenge bodywork, rear diffuser, wing, wheels, assisted shifting allowed; regulations link provided. 2024-04-01 FX Add Classification for 2nd Gen Ligier JS F422 #35844cars addedaddedFX adds Ligier JS F422 second generation classification, new car permitted. 2024-03-01 FX Clarify Formula 4 Rules in FX #35700wordingunclearFX Formula 4 removed reference to FIA Technical Regulations 2015 and subsequent safety requirements; tire choice remains unrestricted. 2024-01-01 P2 E&O - Clarify B.1 modified engine range in AMAC spec lines #35225wordingwordingP2 AMAC and related cars: clarified B.1 modified engine range to 2008 and older stock engines only, with 38mm restrictor and 1025 lbs minimum weight. 2024-01-01 P2 Replacement Engine Crankcase for 07/08 Suzuki GSX-R1000 Engines #35340engineaddedengineP2 Suzuki GSX-R1000 engine: 2007–2008 crankcase 11300-21860 may be replaced with 2016–2019 GSX-S1000 part 11301-04840. 2023-12-01 P2 Correct Table 1 for Engine Date Range Specifications #35182wordingwordingP2 Table 1 engine date ranges clarified: Stock Engine replaced with specific marques Suzuki, Yamaha, Honda, BMW for 2009-newer and 2008-older rows. 2023-11-01 FX FM Rules Update #34841otherunclearFX Formula Mazda specifications updated; attached table not provided.
	Virginia International Raceway Runoffs 20232023-09-23				1:48.590Greg Gyann · fastest of 12 · top 5 within 1.7s+1.024s (+0.95%)	1:48.829Lucian Pancea · fastest of 11 · top 5 within 0.9s-27.005s (-19.88%)	150.9Lucian Pancea-0.2 mph (-0.2%)
11 rule changes (FX: 3, P2: 8)2 cars added · 2 engine · 1 weight · 6 wording · USF2000 Van Diemen with Mazda MZR LF-DE 2.0L added to FC as spec line car; removed from FX. · P2 minimum side body height must equal front axle centerline height, viewed from side. · P2 closed cockpit single seat cars now prohibited unless Table 1 spec line permits. · P2 engine table spec line B.1 redundant effective date language removed and table updated. · P2 motorcycle restrictor reduced 35mm to 34mm for 2011+ Kawasaki; minimum weights increased to 1100 lbs for 2009+ engines; cockpit length corrected to 23.622 inches. · FX: Remove FB and FM from combined-class preferences in GCR 1.4.2.D. · Sebeco NP01-EVO and Elan NP01 added to P2 with Mazda 2.0L MZR, no restrictor required, 1600 lb minimum weight. · P2 Radical SR3/SR4, Cup, Club Sport, Pro-Sport, PR6: assisted shifting clarified from A-assisted to Aassisted; Cup engine restrictor changed from Unrestricted to Not required. · P2 chassis now allows composite materials partially installed; anti-intrusion panels attachment simplified; Stohr and converted models clarified. · Formula Renault 2.0 (10-17) reclassified from FX to FA spec line; minimum weight reduced 1300 to 1280 lbs, restrictor removed.showhide 2023-06-01 FX USF2000 Van Diemen with Mazda MZR LF-DE 2.0L in FC #34329cars addedaddedUSF2000 Van Diemen with Mazda MZR LF-DE 2.0L added to FC as spec line car; removed from FX. 2023-05-01 P2 Clarify minimum side body height requirement #34143wordingwordingP2 minimum side body height must equal front axle centerline height, viewed from side. 2023-05-01 P2 Clarify closed cockpit single seat car allowance #34144wordingwordingP2 closed cockpit single seat cars now prohibited unless Table 1 spec line permits. 2023-04-01 P2 Remove redundant effective date language and update engine table #34012wordingwordingP2 engine table spec line B.1 redundant effective date language removed and table updated. 2023-04-01 P2 E&O - Correct dimensional equivalents #34038enginefasterengineP2 motorcycle restrictor reduced 35mm to 34mm for 2011+ Kawasaki; minimum weights increased to 1100 lbs for 2009+ engines; cockpit length corrected to 23.622 inches. 2023-02-01 FX E&O - Remove references to FB and FM in GCR section 1.4.2.D #33725wordingwordingFX: Remove FB and FM from combined-class preferences in GCR 1.4.2.D. 2023-01-01 P2 Request to Classify Sebeco NP01 #33378cars addedaddedSebeco NP01-EVO and Elan NP01 added to P2 with Mazda 2.0L MZR, no restrictor required, 1600 lb minimum weight. 2023-01-01 P2 Radical spec line clarifications #33485wordingwordingP2 Radical SR3/SR4, Cup, Club Sport, Pro-Sport, PR6: assisted shifting clarified from A-assisted to Aassisted; Cup engine restrictor changed from Unrestricted to Not required. 2023-01-01 P2 E&O original class intent #33519wordingwordingP2 chassis now allows composite materials partially installed; anti-intrusion panels attachment simplified; Stohr and converted models clarified. 2023-01-01 P2 Update Engine Table Spec Line B.1 #33608engine 2022-12-01 FX Reclassify 2010-2017 Formula Renault 2.0 as a spec line car in FA #33395weightfasterweightFormula Renault 2.0 (10-17) reclassified from FX to FA spec line; minimum weight reduced 1300 to 1280 lbs, restrictor removed.
	Virginia International Raceway Runoffs 20222022-09-24	1:51.480Trevor A Russell · fastest of 5 · top 5 within 9.7s	2:08.711Dimitrios Tsesmetzis · fastest of 4 · top 4 within 6.8s	137.2Trevor A Russell	1:47.566Tim Day Jr · fastest of 12 · top 5 within 3.0s-1.545s (-1.42%)	2:15.834Greg Gyann · fastest of 12 · top 5 within 10.1s+25.576s (+23.20%)	151.1Robert Iversen+1.8 mph (+1.2%)	+7.123squal -3.914s	105.5%qual 96.5%
19 rule changes (FX: 9, P2: 10)3 cars added · 3 tyres & wheels · 2 weight · 1 engine · 1 induction · 8 wording · 1 other · Pro Formula F2000 tube frame transmission cut to 4 forward gears; sequential carries 25 lb. weight penalty. · FX Formula Mazda minimum weight set to 1270 lb. · FX Formula Mazda drops four-port Renesis engine option; weight minimum now per notes. · Formula Renault 2.0 (10-17) now requires 45mm Flat Plate Intake Restrictor; fairings before or after prohibited. · USF2000 Tube Frame adds Performance Electronics PE3-8400 ECU as alternative to Pectel T2. · P2 chassis construction clarified: full composite allowed; partial composite must roll without composite parts installed. · P2 classification wording cleaned up in GCR section 9.1.8.C and GCR contents. · P2 Oldsmobile cam rules correct spelling from 'after market' to 'aftermarket' in two sections. · P2 adds Beasley B2 at 1350 lbs with Mazda 12A, 40.5mm venturi, and up to 16.5in wing chord. · P2 wings: terminology change from 'cord' to 'chord', and 'only' removed from Bobsy and Jondal notes. · P2 Converted F5 cars renamed F500, must retain F500 suspension, minimum width 55 inches. · Formula Mazda FX rule reference updated to current specifications document; tire marking no longer required. · FX Formula 4 tire choice unrestricted; must provide FIA certification rules upon request. · FX USF2000 Tube Frame front tyre changes from Hoosier radial 20.5 x 7.0 x 13 to any Hoosier 20.5 x 7.0 x 13. · FX Formula Renault 2.0 (00-09) and (10-17) tire choice unrestricted; no other component alterations except repairs. · P2 motorcycle engines gain 5cc to 1505cc max, two-stroke gains 5cc to 1205cc max, automotive engines add 50 lbs minimum weight to 1350 lbs. · P2 Control Area definition clarified: rectangular zone from rear edge of front tires to front edge of rear tires, full car width. · P2 specification line B.1 engine table entry amended; details of change not provided in excerpt. · P2 Control Area definition clarified: rear tire edge and front tire edge bounds, car's lower surface width, floor extensions and aerodynamic attachments included, vertical structures prohibited.showhide 2022-08-01 FX Pro Formula F2000/USF2000 Transmission E&O #32823engineslowerenginePro Formula F2000 tube frame transmission cut to 4 forward gears; sequential carries 25 lb. weight penalty. 2022-08-01 FX Formula Mazda Minimum Weight #33010weightslowerweightFX Formula Mazda minimum weight set to 1270 lb. 2022-08-01 FX Formula Mazda Spec Line E&O Corrections #33011cars addedremovedcars addedFX Formula Mazda drops four-port Renesis engine option; weight minimum now per notes. 2022-07-01 FX Formula Renault 2.0 (10-17) Intake Restrictor #32745inductionslowerinductionFormula Renault 2.0 (10-17) now requires 45mm Flat Plate Intake Restrictor; fairings before or after prohibited. 2022-07-01 FX Allow Performance Electronics PE3-8400 for USF2000 MZR #32767cars addedaddedUSF2000 Tube Frame adds Performance Electronics PE3-8400 ECU as alternative to Pectel T2. 2022-05-01 P2 E&O Clarification of Chassis Construction Requirements #32469wordingwordingP2 chassis construction clarified: full composite allowed; partial composite must roll without composite parts installed. 2022-05-01 P2 Clean up P2 wording #32525wordingwordingP2 classification wording cleaned up in GCR section 9.1.8.C and GCR contents. 2022-04-01 P2 After Market to Aftermarket #32373wordingwordingP2 Oldsmobile cam rules correct spelling from 'after market' to 'aftermarket' in two sections. 2022-03-01 P2 Add spec line for Beasley B2 #32147cars addedaddedP2 adds Beasley B2 at 1350 lbs with Mazda 12A, 40.5mm venturi, and up to 16.5in wing chord. 2022-03-01 P2 E&O Table 1 spec line wing terminology #32148wordingwordingP2 wings: terminology change from 'cord' to 'chord', and 'only' removed from Bobsy and Jondal notes. 2022-03-01 P2 E&O class name #32196wordingwordingP2 Converted F5 cars renamed F500, must retain F500 suspension, minimum width 55 inches. 2022-02-01 FX FM Rule Set Clarification #31881wordingwordingFormula Mazda FX rule reference updated to current specifications document; tire marking no longer required. 2022-02-01 FX E&O F4 Tires #31940tyres & wheelsaddedtyres & wheelsFX Formula 4 tire choice unrestricted; must provide FIA certification rules upon request. 2022-02-01 FX E&O USF2000 Tube Frame #31951tyres & wheelstyres & wheelsFX USF2000 Tube Frame front tyre changes from Hoosier radial 20.5 x 7.0 x 13 to any Hoosier 20.5 x 7.0 x 13. 2022-02-01 FX URGENT - FX- Formula Renault Tire #32058tyres & wheelsaddedtyres & wheelsFX Formula Renault 2.0 (00-09) and (10-17) tire choice unrestricted; no other component alterations except repairs. 2022-02-01 P2 E&O Engine section #31969weightslowerweightP2 motorcycle engines gain 5cc to 1505cc max, two-stroke gains 5cc to 1205cc max, automotive engines add 50 lbs minimum weight to 1350 lbs. 2022-01-01 P2 E&O letter #31539 – Control Area definition #31783wordingwordingP2 Control Area definition clarified: rectangular zone from rear edge of front tires to front edge of rear tires, full car width. 2021-12-01 P2 BoP adjustment effective 1-1-22 #31538otherunclearP2 specification line B.1 engine table entry amended; details of change not provided in excerpt. 2021-12-01 P2 E&O clarification of "Control Area" definition #31539wordingwordingP2 Control Area definition clarified: rear tire edge and front tire edge bounds, car's lower surface width, floor extensions and aerodynamic attachments included, vertical structures prohibited.
	Indianapolis Motor Speedway Runoffs 20212021-09-25	1:38.596Vaughn Glace · fastest of 15 · top 5 within 4.1s	1:38.833Vaughn Glace · fastest of 15 · top 5 within 4.3s	138.6Vaughn Glace	1:33.235Tim Day Jr · fastest of 16 · top 5 within 3.3s+1.409s (+1.53%)	1:35.322Tim Day Jr · fastest of 10 · top 5 within 4.8s+2.841s (+3.07%)	150.3Robert Iversen	-3.511squal -5.361s	96.4%qual 94.6%
13 rule changes (FX: 5, P2: 8)3 cars added · 2 engine · 1 tyres & wheels · 6 wording · 1 other · P2 CN Honda K20A-FD2 engine rebuild clarified: balancing, porting, polishing prohibited; valve jobs and honing must follow factory procedures. · FX USF2000 Tube Frame gains Hoosier radial tyre option, FC-compliant shocks, Wilwood brakes, and Bosch spark plugs. · P2 Converted F5 cars must retain F5 suspension and meet P2 non-spec requirements except minimum width is 55 inches. · P2 minimum body width clarified: cannot extend inward beyond vertical plane through tire centerlines. · FX USF2000 Tube Frame now allows any Hoosier radial tire 20.5×7.0×13 front, 22.5×8.0×13 rear. · Formula Renault 2.0 / Fran-Am 2000 added to FX class at 1250 lbs with 8-inch front, 10-inch rear wheels, sealed engine. · P2 tonneau covers now allowed to meet minimum dimensions; cockpit equipment attachment wording clarified. · P2 removes effective date 01/01/2021 from six car spec lines in Table 1. · P2 engine specs B.1, B.2, B.3 limited to maximum 4 valves per cylinder. · P2 adds new spec line for 2-cycle 3-cylinder engine up to 820cc with 10 front, 14–15 rear wheel width. · FX adds 2010–2017 Formula Renault 2.0, must comply with Table 1 notes. · FX FormulaSPEED FS2.0 now references online specifications instead of requiring World Speed Inc. documentation by April 2020. · P2 motorcycle-engine cars: 2009+ stock 37mm restrictor, 2008- stock 35mm, modified 1075 lbs. Honda K20A 50mm restrictor. Various spec cars: restrictors increased or decreased 0.5–3mm.showhide 2021-09-01 P2 P2 CN Engine Rebuild Clarification #31000wordingwordingP2 CN Honda K20A-FD2 engine rebuild clarified: balancing, porting, polishing prohibited; valve jobs and honing must follow factory procedures. 2021-08-01 FX Rules Adjustment #30950otheraddedFX USF2000 Tube Frame gains Hoosier radial tyre option, FC-compliant shocks, Wilwood brakes, and Bosch spark plugs. 2021-08-01 P2 F5 P2 Conversion #30856wordingwordingP2 Converted F5 cars must retain F5 suspension and meet P2 non-spec requirements except minimum width is 55 inches. 2021-08-01 P2 Clarify minimum body width requirement #30859wordingwordingP2 minimum body width clarified: cannot extend inward beyond vertical plane through tire centerlines. 2021-06-01 FX FX/FRP Tire Rule #30723tyres & wheelsaddedtyres & wheelsFX USF2000 Tube Frame now allows any Hoosier radial tire 20.5×7.0×13 front, 22.5×8.0×13 rear. 2021-05-01 FX Classify the 2000-2009 Formula Renault 2.0 / Fran-Am 2000 #30460cars addedaddedFormula Renault 2.0 / Fran-Am 2000 added to FX class at 1250 lbs with 8-inch front, 10-inch rear wheels, sealed engine. 2021-05-01 P2 E&O tonneau cover provision in cockpit opening section #30459wordingwordingP2 tonneau covers now allowed to meet minimum dimensions; cockpit equipment attachment wording clarified. 2021-05-01 P2 Remove effective dates in Table 1 #30468wordingwordingP2 removes effective date 01/01/2021 from six car spec lines in Table 1. 2021-05-01 P2 E&O Maximum Valves Per Cylinder #30560engineengineP2 engine specs B.1, B.2, B.3 limited to maximum 4 valves per cylinder. 2021-03-01 P2 Add a new spec line for a 2-cycle, 3-cylinder engine up to 820cc #30272cars addedaddedP2 adds new spec line for 2-cycle 3-cylinder engine up to 820cc with 10 front, 14–15 rear wheel width. 2021-01-01 FX Request for Car Classification to Compete in Formula X #29933cars addedaddedFX adds 2010–2017 Formula Renault 2.0, must comply with Table 1 notes. 2020-12-01 FX Update specifications for FormulaSPEED cars #29674wordingwordingFX FormulaSPEED FS2.0 now references online specifications instead of requiring World Speed Inc. documentation by April 2020. 2020-12-01 P2 Balance of Performance adjustments effective 01-01-2021 #29822engineunclearP2 motorcycle-engine cars: 2009+ stock 37mm restrictor, 2008- stock 35mm, modified 1075 lbs. Honda K20A 50mm restrictor. Various spec cars: restrictors increased or decreased 0.5–3mm.
	Road America Runoffs 20202020-10-02	2:16.968Jacob Loomis · fastest of 12 · top 5 within 2.7s	2:17.553Jacob Loomis · fastest of 11 · top 5 within 3.5s	139.3Brad Drew	2:08.514Robert Iversen · fastest of 12 · top 5 within 3.0s	2:09.793Robert Iversen · fastest of 12 · top 5 within 3.9s	153.1Robert Iversen	-7.760squal -8.454s	94.4%qual 93.8%
12 rule changes (FX: 6, P2: 6)5 cars added · 1 aero · 1 engine · 1 induction · 3 wording · 1 other · Formula Ireland / Formula FX added to FX class, must comply with Table 1 notes. · P2 rear wing rules clarified: standard wing 6×12 inches, end plates 14-inch square; alternate 1-meter formula wing 110cm wide, 9×18 inches, end plates 14×18 inches. · Formula Ireland/Formula FX cars pending specification submission for possible FX table addition. · Elan NP01 added to P2 Table 1 as Spec Line car with 2000cc displacement and 42mm restrictor. · P2 Enterprises Sports Racer now permits 55mm flat plate intake restrictor Part # WM303013 as alternative to SIR. · Ex-Pro Formula Super Vee added to FX with 1600cc VW engine, 1190 lb minimum weight, 6-inch front and 8-inch rear wheels. · FormulaSPEED with 2.0L Mazda MZR engine, 8in front/10in rear wheels, adjustable dual rear planes, 1350 lbs moves from FA to FX. · P2 Enterprise Sports Racer 2.3L engine must use SIR or Flat Plate restrictor meeting peak horsepower, sized in whole or 0.5mm increments. · FX Formula Mazda no longer requires tire marking; must comply with December 2019 GCR rules. · P2 electronic throttle control wording clarified: ETC permitted if stock ECU throttle pedal activates original throttle shaft mechanism. · Pro Formula F 2000 and USF2000 Tube Frame engine and car rules simplified; FC rules and FRP MAZDA MZR F2000 specs now apply directly. · P2 adds BMW to permitted motorcycle-based engines alongside Kawasaki, Suzuki, Yamaha, Honda.showhide 2020-09-01 FX Follow up to to Letter#28991 Request for FX classification #29281cars addedaddedFormula Ireland / Formula FX added to FX class, must comply with Table 1 notes. 2020-09-01 P2 E&O clarification of P2 rear wing requirements #29205aeroaeroP2 rear wing rules clarified: standard wing 6×12 inches, end plates 14-inch square; alternate 1-meter formula wing 110cm wide, 9×18 inches, end plates 14×18 inches. 2020-07-01 FX Request to be added to FX group #28991cars addedaddedFormula Ireland/Formula FX cars pending specification submission for possible FX table addition. 2020-06-01 P2 Classify Elan NP01 in P2 Table 1 #28812cars addedaddedElan NP01 added to P2 Table 1 as Spec Line car with 2000cc displacement and 42mm restrictor. 2020-05-01 P2 SCCA Enterprises ESR / P2 engine restrictor testing #28669otheraddedP2 Enterprises Sports Racer now permits 55mm flat plate intake restrictor Part # WM303013 as alternative to SIR. 2020-04-01 FX Request to classify FSV in FX #28057cars addedaddedEx-Pro Formula Super Vee added to FX with 1600cc VW engine, 1190 lb minimum weight, 6-inch front and 8-inch rear wheels. 2020-04-01 FX Classify FormulaSPEED in FX #28715cars addedaddedFormulaSPEED with 2.0L Mazda MZR engine, 8in front/10in rear wheels, adjustable dual rear planes, 1350 lbs moves from FA to FX. 2020-04-01 P2 Add ESR inlet restrictor #27869inductionaddedinductionP2 Enterprise Sports Racer 2.3L engine must use SIR or Flat Plate restrictor meeting peak horsepower, sized in whole or 0.5mm increments. 2020-03-01 FX Request to remove tire marking language from FM #28415wordingwordingFX Formula Mazda no longer requires tire marking; must comply with December 2019 GCR rules. 2020-03-01 P2 Request for Fly by Wire Rule Wording Change #28247wordingwordingP2 electronic throttle control wording clarified: ETC permitted if stock ECU throttle pedal activates original throttle shaft mechanism. 2020-02-01 FX Change to FX Table 1 #28322wordingunclearPro Formula F 2000 and USF2000 Tube Frame engine and car rules simplified; FC rules and FRP MAZDA MZR F2000 specs now apply directly. 2020-01-01 P2 Request for addition of BMW Engine in P2 Engine Table #27821engineaddedengineP2 adds BMW to permitted motorcycle-based engines alongside Kawasaki, Suzuki, Yamaha, Honda.
	Virginia International Raceway Runoffs 20192019-10-05				1:49.111Robert Iversen · fastest of 14 · top 5 within 0.8s	1:50.258Greg Gyann · fastest of 13 · top 5 within 0.4s	149.4Robert Iversen
9 rule changes (P2: 9)4 engine · 1 cars added · 1 induction · 1 weight · 2 wording · P2 Honda K20A-FD2 non-composite chassis intake restrictor note clarified; restrictor implementation date removed. · P2 motorcycle engines: Stock restrictor to 35mm, Modified to 34mm; weights up to 1025 and 1125 lbs respectively. B.5 restrictor to 33mm, weight to 1185 lbs. · P2 cars limited to power application on maximum two wheels. · P2 Enterprise minimum weight increased to 1375 lbs.; peak horsepower of sealed ESR engine reduced per CRB specification. · P2 stock and modified engines get smaller restrictors (35.0mm, 34.0mm, 33.0mm) and heavier minimums (1025, 1125, 1185 lbs). · P2 Line A.1 restrictor reduced from 40mm to 38mm. · P2 Spec Line cars now allow 1345cc Hayabusa stock engines at 1050 lb minimum with 30mm restrictor. · P2 Group CN Honda K20A-FD2 55mm intake restrictor implementation delayed from 1 January to 3 March 2019. · P2 Honda K20A-FD2 Group CN must use stock intake manifold, 64mm throttle, 55mm restrictor at 1500 lbs minimum.showhide 2019-10-01 P2 Update Engine Table Line E notes #27414wordingwordingP2 Honda K20A-FD2 non-composite chassis intake restrictor note clarified; restrictor implementation date removed. 2019-08-31 P2 Update P2 Engine Table spec lines to reflect 3/1/2019 #27254engineslowerengineP2 motorcycle engines: Stock restrictor to 35mm, Modified to 34mm; weights up to 1025 and 1125 lbs respectively. B.5 restrictor to 33mm, weight to 1185 lbs. 2019-07-01 P2 E&O Transmissions #27006engineslowerengineP2 cars limited to power application on maximum two wheels. 2019-06-01 P2 Request to restrict all cars #26246weightslowerweightP2 Enterprise minimum weight increased to 1375 lbs.; peak horsepower of sealed ESR engine reduced per CRB specification. 2019-03-01 P2 Change Engine Table Lines B.1 & B.5 #25777inductionslowerinductionP2 stock and modified engines get smaller restrictors (35.0mm, 34.0mm, 33.0mm) and heavier minimums (1025, 1125, 1185 lbs). 2019-03-01 P2 Change Line A.1 restrictor size #26429engineslowerengineP2 Line A.1 restrictor reduced from 40mm to 38mm. 2019-01-01 P2 Request to Allow 1345cc Hayabusa Engines for Spec Line P2 Cars #25595cars addedaddedP2 Spec Line cars now allow 1345cc Hayabusa stock engines at 1050 lb minimum with 30mm restrictor. 2019-01-01 P2 Change CN inlet restrictor implementation date #25816wordingwordingP2 Group CN Honda K20A-FD2 55mm intake restrictor implementation delayed from 1 January to 3 March 2019. 2019-01-01 P2 Clarify Honda K20A-FD2 parts requirement #25950engineslowerengineP2 Honda K20A-FD2 Group CN must use stock intake manifold, 64mm throttle, 55mm restrictor at 1500 lbs minimum.
	Sonoma Raceway Runoffs 20182018-10-10				1:28.784Tim Day Jr · fastest of 17 · top 5 within 5.0s	1:32.071Chuck Bona · fastest of 18 · top 5 within 0.9s	144.4Tim Day Jr
No rule changes on record between these events
	Indianapolis Motor Speedway Runoffs 20172017-09-25				1:31.826Jeff Shafer · fastest of 26 · top 5 within 4.9s	1:32.481Jeff Shafer · fastest of 24 · top 5 within 3.8s
No rule changes on record between these events
	Mid-Ohio Sports Car Course Runoffs 20162016-09-19				1:20.188Jeff Shafer · fastest of 18 · top 5 within 4.0s	1:20.904Jeff Shafer · fastest of 16 · top 5 within 2.2s
No rule changes on record between these events
	Daytona International Speedway Runoffs 20152015-09-21				1:51.825Chris Farrell · fastest of 17 · top 5 within 3.6s	1:52.355Jeff Shafer · fastest of 17 · top 5 within 2.8s

By track

Track	Events	Typical % of FX	Best	Latest
Road America	3	100.0%1 of 3 with FX	100.0%Runoffs 2020	100.0%Runoffs 2020
Virginia International Raceway	3	100.0%1 of 3 with FX	100.0%Runoffs 2022	100.0%Runoffs 2022
Indianapolis Motor Speedway	2	100.0%1 of 2 with FX	100.0%Runoffs 2021	100.0%Runoffs 2021
Daytona International Speedway	1	0 of 1 with FX
Mid-Ohio Sports Car Course	1	0 of 1 with FX
Sonoma Raceway	1	0 of 1 with FX

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 FX'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.