BoP Lab / Classes / F6

F6 vs FX pace at every track

Lap times across years say as much about the weather as the class. % of F6 is each class's best lap as a share of F6's on the same day, so the conditions drop out: 100% is level, less is quicker, and a move in it is the class getting faster or slower against the field.

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Series Runoffs Super Tour Both

Reference · what % is measured against

Tracks · untick to narrow Barber Motorsports Park Buttonwillow Raceway Park Circuit of the Americas Hallett Motor Racing Circuit Indianapolis Motor Speedway Michelin Raceway Road Atlanta Mid-Ohio Sports Car Course NOLA Motorsports Park Pittsburgh International Race Complex Portland International Raceway Road America Sebring International Raceway Virginia International Raceway Watkins Glen International World Wide Technology Raceway

Closest to the field: F6 100.0% of F6 Calvin Stewart, Virginia International Raceway Runoffs 2023 race

% of F6Lap times

F6FXsolid race · dashed qualifying · slower is lower

F6FXsolid race · dashed qualifying · each class's best lap as a share of F6's at the same event (the reference class, changeable above); 100% is level, less is quicker, so up the chart is quicker

	Event	F6			FX
	Event	Qual best	Race best	Trap	Qual best	Race best	Trap	vs F6	% of F6
	Road America Runoffs 20262026-09-28	2:18.489Calvin Stewart · fastest of 13 · top 5 within 4.2s-0.617s (-0.44%)	2:20.255James Weida · fastest of 13 · top 5 within 2.0s+1.415s (+1.02%)	143.0Calvin Stewart-4.5 mph (-3.1%)
2 rule changes (FX: 2)1 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.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.
	Road America Runoffs 20242024-10-01	2:19.106Calvin Stewart · fastest of 22 · top 5 within 1.3s	2:18.840James Weida · fastest of 22 · top 5 within 1.0s	147.6Calvin Stewart
4 rule changes (FX: 4)1 cars added · 1 weight · 1 wording · 1 other · FX Ligier JS F4 1st Gen minimum weight drops 15 lbs to 1405; 2nd Gen rises 31 lbs to 1375. · 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. · 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. 2024-04-01 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. 2023-11-01 FX FM Rules Update #34841otherunclearFX Formula Mazda specifications updated; attached table not provided.
	Virginia International Raceway Runoffs 20232023-09-23	1:57.437Calvin Stewart · fastest of 9 · top 5 within 4.7s	1:58.816Calvin Stewart · fastest of 9 · top 5 within 3.6s	144.0Calvin Stewart
3 rule changes (FX: 3)1 cars added · 1 weight · 1 wording · USF2000 Van Diemen with Mazda MZR LF-DE 2.0L added to FC as spec line car; removed from FX. · FX: Remove FB and FM from combined-class preferences in GCR 1.4.2.D. · 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. 2023-02-01 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. 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
9 rule changes (FX: 9)3 tyres & wheels · 2 cars added · 1 engine · 1 induction · 1 weight · 1 wording · 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. · 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.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. 2022-02-01 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.
	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
5 rule changes (FX: 5)2 cars added · 1 tyres & wheels · 1 wording · 1 other · FX USF2000 Tube Frame gains Hoosier radial tyre option, FC-compliant shocks, Wilwood brakes, and Bosch spark plugs. · 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. · 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.showhide 2021-08-01 FX Rules Adjustment #30950otheraddedFX USF2000 Tube Frame gains Hoosier radial tyre option, FC-compliant shocks, Wilwood brakes, and Bosch spark plugs. 2021-06-01 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. 2021-01-01 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.
	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
6 earlier rule changes on record, in force before Runoffs 2020 (from 2020)4 cars added · 2 wording · Formula Ireland / Formula FX added to FX class, must comply with Table 1 notes. · Formula Ireland/Formula FX cars pending specification submission for possible FX table addition. · 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. · FX Formula Mazda no longer requires tire marking; must comply with December 2019 GCR rules. · Pro Formula F 2000 and USF2000 Tube Frame engine and car rules simplified; FC rules and FRP MAZDA MZR F2000 specs now apply directly.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. 2020-07-01 FX Request to be added to FX group #28991cars addedaddedFormula Ireland/Formula FX cars pending specification submission for possible FX table addition. 2020-04-01 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. 2020-03-01 FX Request to remove tire marking language from FM #28415wordingwordingFX Formula Mazda no longer requires tire marking; must comply with December 2019 GCR rules. 2020-02-01 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.

By track

Track	Events	Typical % of F6	Best	Latest
Road America	3	100.0%2 of 3 with F6	100.0%Runoffs 2024	100.0%Runoffs 2026
Virginia International Raceway	2	100.0%1 of 2 with F6	100.0%Runoffs 2023	100.0%Runoffs 2023
Indianapolis Motor Speedway	1	0 of 1 with F6

About this data

Every event the class ran, at any track, oldest to newest on the chart and newest first in the table. Each point is the class's best lap as a share of F6's best on the same day: the weather and the day cancel out, so one figure compares across years where lap times cannot; a class that suits one track more than another still reads differently there. It still moves when the yardstick's own balance changes or its field thins, and an event the yardstick did not run has no point. A best from fewer than three cars is greyed. The rule changes that took effect between two events are folded between their rows.