BoP Lab / Classes / STL

STL vs P2 pace at every track

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

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

Closest to the field: STL 100.0% of STL Kevin Boehm, Daytona International Speedway Runoffs 2015 race · P2 77.7% of STL Tim Day Jr, Indianapolis Motor Speedway Runoffs 2021 race

% of STLLap times

STLP2solid race · dashed qualifying · slower is lower

STLP2solid race · dashed qualifying · each class's best lap as a share of STL's at the same event (the reference class, changeable above); 100% is level, less is quicker, so up the chart is quicker

	Event	STL			P2
	Event	Qual best	Race best	Trap	Qual best	Race best	Trap	vs STL	% of STL
	Road America Runoffs 20262026-09-28	2:30.537Derek Ketchie · fastest of 16 · top 5 within 2.9s-1.528s (-1.00%)	2:30.657Danny Steyn · fastest of 16 · top 5 within 0.6s-1.470s (-0.97%)	134.8Mike Taylor+2.6 mph (+2.0%)	2:10.606Greg 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%)	-21.216squal -19.931s	85.9%qual 86.8%
4 rule changes (STL: 4)3 weight · 1 removedshowhide 2026-07-01 STL Spec Line Clean Up #40344removed 2026-06-01 STL Calculating Weight #40224weight 2026-04-01 STL Classifications #39885weight 2026-01-01 STL Weight adjustment for STL #39579weight
	Road America Runoffs 20252025-09-29	2:32.065Jose Osiris Pena · fastest of 14 · top 5 within 3.4s+2.002s (+1.33%)	2:32.127Jose Osiris Pena · fastest of 13 · top 5 within 2.4s+1.882s (+1.25%)	132.2Jon Sewell-2.1 mph (-1.5%)
4 rule changes (STL: 3, P2: 1)3 weight · 1 tyres & wheelsshowhide 2025-08-01 STL Lotus Weight Reduction #38772weight -50 lbs 2025-05-01 STL E&O: SMX Allowance in STL #37945weight 2024-12-01 P2 2000 cc Pinto Engine Car Weight #37187weight 2024-12-01 STL Request to Remove Miata Hubs from General category #37138tyres & wheels
	Road America Runoffs 20242024-10-01	2:30.063Joe Moser · fastest of 18 · top 5 within 3.7s-1.357s (-0.90%)	2:30.245Joe Moser · fastest of 16 · top 5 within 4.2s-1.870s (-1.23%)	134.3Joe Moser+1.3 mph (+1.0%)	2:07.405Bart 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%)	-21.923squal -22.658s	85.4%qual 84.9%
9 rule changes (STL: 4, P2: 5)4 engine · 2 induction · 1 tyres & wheels · 1 weight · 1 othershowhide 2024-05-01 P2 CN Spec ECU #35835engine 2024-05-01 P2 E&O - Correct FIA Group CN spec line notes #35900tyres & wheels 2024-02-01 STL ST Electric-Assisted Steering Systems #35066other 2024-02-01 STL BOP Adjustments #35112weight 2024-02-01 STL Mazda 12A #35320induction 2024-01-01 P2 E&O - Clarify B.1 modified engine range in AMAC spec lines #35225engine 2024-01-01 P2 Replacement Engine Crankcase for 07/08 Suzuki GSX-R1000 Engines #35340engine 2024-01-01 STL Alternate Carburetor Request for 79-85 RX7 12a #35181induction 2023-12-01 P2 Correct Table 1 for Engine Date Range Specifications #35182engine
	Virginia International Raceway Runoffs 20232023-09-23	2:05.779Danny Steyn · fastest of 22 · top 5 within 3.4s+0.305s (+0.24%)	2:06.682Joe Moser · fastest of 20 · top 5 within 1.5s-1.150s (-0.90%)	131.8Danny Steyn+0.1 mph (+0.1%)	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%)	-17.853squal -17.189s	85.9%qual 86.3%
10 rule changes (STL: 2, P2: 8)3 tyres & wheels · 3 weight · 2 engine · 1 cars added · 1 wordingshowhide 2023-06-01 STL Clarify STL table B - IT spec notes on Tires #34187tyres & wheels 2023-05-01 P2 Clarify minimum side body height requirement #34143tyres & wheels 2023-05-01 P2 Clarify closed cockpit single seat car allowance #34144wording 2023-04-01 P2 Remove redundant effective date language and update engine table #34012engine 2023-04-01 P2 E&O - Correct dimensional equivalents #34038weight 2023-01-01 P2 Request to Classify Sebeco NP01 #33378cars added 2023-01-01 P2 Radical spec line clarifications #33485weight 2023-01-01 P2 E&O original class intent #33519weight 2023-01-01 P2 Update Engine Table Spec Line B.1 #33608engine 2023-01-01 STL Spec MX5 in STL #33473tyres & wheels
	Virginia International Raceway Runoffs 20222022-09-24	2:05.474Danny Steyn · fastest of 24 · top 5 within 2.3s-1.729s (-1.36%)	2:07.832Danny Steyn · fastest of 22 · top 5 within 1.9s+0.559s (+0.44%)	131.7Trever Degioanni-3.2 mph (-2.3%)	1:47.566Tim 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%)	+8.002squal -17.908s	106.3%qual 85.7%
15 rule changes (STL: 5, P2: 10)4 tyres & wheels · 2 engine · 2 induction · 2 weight · 1 aero · 2 wording · 2 othershowhide 2022-05-01 P2 E&O Clarification of Chassis Construction Requirements #32469tyres & wheels 2022-05-01 P2 Clean up P2 wording #32525wording 2022-04-01 P2 After Market to Aftermarket #32373other 2022-03-01 P2 Add spec line for Beasley B2 #32147weight 2022-03-01 P2 E&O Table 1 spec line wing terminology #32148aero 2022-03-01 P2 E&O class name #32196other 2022-03-01 STL Single TB Weight Modifiers #31449weight 2022-03-01 STL Improved Touring Tires #32063tyres & wheels 2022-02-01 P2 E&O Engine section #31969engine 2022-01-01 P2 E&O letter #31539 – Control Area definition #31783tyres & wheels 2022-01-01 STL Throttling Device Clarification #31323induction 2022-01-01 STL Mazda Renesis Restriction #31467induction 2022-01-01 STL Clarification of 79-85 RX7 Spec line #31621wording 2021-12-01 P2 BoP adjustment effective 1-1-22 #31538engine 2021-12-01 P2 E&O clarification of "Control Area" definition #31539tyres & wheels
	Indianapolis Motor Speedway Runoffs 20212021-09-25	1:51.665Danny Steyn · fastest of 42 · top 5 within 1.7s-0.982s (-0.87%)	2:02.711Joe Moser · fastest of 37 · top 5 within 3.2s+10.122s (+8.99%)	131.8Max Gee	1:33.235Tim 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	-27.389squal -18.430s	77.7%qual 83.5%
23 rule changes (STL: 15, P2: 8)5 engine · 3 induction · 2 aero · 2 suspension & brakes · 2 tyres & wheels · 2 weight · 1 cars added · 1 wording · 5 othershowhide 2021-09-01 P2 P2 CN Engine Rebuild Clarification #31000engine 2021-09-01 STL Request to clean up Spec MX-5 Redundancy #31069other 2021-08-01 P2 F5 P2 Conversion #30856other 2021-08-01 P2 Clarify minimum body width requirement #30859tyres & wheels 2021-06-01 STL VW Engine Request #30625engine 2021-05-01 P2 E&O tonneau cover provision in cockpit opening section #30459other 2021-05-01 P2 Remove effective dates in Table 1 #30468other 2021-05-01 P2 E&O Maximum Valves Per Cylinder #30560engine 2021-05-01 STL Solstice Ride Height #30183suspension & brakes 2021-05-01 STL Request Mazda B5 DOHC #30420cars added 2021-05-01 STL Honda B16A (JDM) Restrictor change #30531induction 2021-04-01 STL ST Oil Coolers E&O Correction to 9.1.4.2.H #30388wording 2021-03-01 P2 Add a new spec line for a 2-cycle, 3-cylinder engine up to 820cc #30272engine 2021-03-01 STL GM Ecotec engines in STL #30247engine 2021-03-01 STL Super Touring Alternate Miata Hubs #30345tyres & wheels 2021-02-01 STL Brake Component Relocation #29990suspension & brakes 2021-02-01 STL Super Touring Wing Clarification #30111aero 2021-02-01 STL Transmission Options #30118other 2021-01-01 STL Request for FWD and RWD Parity #29728weight 2021-01-01 STL Request to Remove Honda F20C 2% Weight Penalty #29815weight 2021-01-01 STL Request for FWD and RWD Parity #30023induction 2020-12-01 P2 Balance of Performance adjustments effective 01-01-2021 #29822induction 2020-12-01 STL Request clarification on wing measurement #29640aero
	Road America Runoffs 20202020-10-02	2:31.420Danny Steyn · fastest of 33 · top 5 within 3.1s	2:32.115Joe Moser · fastest of 30 · top 5 within 1.5s	132.9Darin Treakle	2:08.514Robert Iversen · fastest of 12 · top 5 within 3.0s	2:09.793Robert Iversen · fastest of 12 · top 5 within 3.9s	153.1Robert Iversen	-22.322squal -22.906s	85.3%qual 84.9%
17 rule changes (STL: 11, P2: 6)6 induction · 4 engine · 2 aero · 2 cars added · 1 tyres & wheels · 1 weight · 1 wordingshowhide 2020-09-01 P2 E&O clarification of P2 rear wing requirements #29205aero 2020-08-01 STL Minimum Weight Determination #27695weight 2020-08-01 STL ST Gurney flap Wicker clarification #29012aero 2020-07-01 STL Request for Addition to GT3 Approved Turbo List #27576induction 2020-06-01 P2 Classify Elan NP01 in P2 Table 1 #28812cars added 2020-06-01 STL Request to add 2016-2019 GMX-5 Spec line #28604cars added 2020-06-01 STL Request to update PN for MX-5 #28622wording 2020-06-01 STL Correction - Clarification Honda/Acura B18B engine Letter # 26209 #28873engine 2020-05-01 P2 SCCA Enterprises ESR / P2 engine restrictor testing #28669induction 2020-05-01 STL STL Honda B18 restrictor changes #28794induction 2020-04-01 P2 Add ESR inlet restrictor #27869induction 2020-04-01 STL Change GM LNF 2.0 Allowance to LSJ Engine for Viable STL 2.0 #27884engine 2020-04-01 STL Acura/Honda B18C engine chart. Reduce the current 54 mm flat plat #28663induction 2020-04-01 STL Mazda MZR engine chart. Reduce the current 55 mm flat plate to 53 #28664induction 2020-03-01 P2 Request for Fly by Wire Rule Wording Change #28247engine 2020-03-01 STL Request to add wheel part numbers #28342tyres & wheels 2020-01-01 P2 Request for addition of BMW Engine in P2 Engine Table #27821engine
	Virginia International Raceway Runoffs 20192019-10-05	2:07.203Danny Steyn · fastest of 36 · top 5 within 1.8s	2:07.273Cliff Ira · fastest of 35 · top 5 within 1.4s	134.8Cliff Ira	1:49.111Robert Iversen · fastest of 14 · top 5 within 0.8s	1:50.258Greg Gyann · fastest of 13 · top 5 within 0.4s	149.4Robert Iversen	-17.015squal -18.092s	86.6%qual 85.8%
20 rule changes (STL: 11, P2: 9)6 weight · 5 engine · 4 induction · 2 suspension & brakes · 1 cars added · 1 tyres & wheels · 1 wordingshowhide 2019-10-01 P2 Update Engine Table Line E notes #27414engine 2019-10-01 STL Request to Classify Spec MX-5 Challenge in STL #27399cars added 2019-08-31 P2 Update P2 Engine Table spec lines to reflect 3/1/2019 #27254engine 2019-07-01 P2 E&O Transmissions #27006tyres & wheels 2019-07-01 STL Request clarification for manifold and throttle in STU #27004induction 2019-06-01 P2 Request to restrict all cars #26246weight 2019-05-31 STL Request Restrictor Plate correction #26779induction 2019-05-01 STL Request Ride Height Clarification #26597suspension & brakes 2019-03-01 P2 Change Engine Table Lines B.1 & B.5 #25777engine 2019-03-01 P2 Change Line A.1 restrictor size #26429induction 2019-03-01 STL Request to Allow VW 1.8L Engine #25614engine 2019-03-01 STL Request to reduce weight of RX8 with Renesis rotary #25781weight -100 lbs 2019-03-01 STL Request for Open Brake Pads On Mazda MX-5 Cup NC #25821suspension & brakes 2019-03-01 STL Request to clarify B18C1 GSR Honda B motor table #26209weight 2019-03-01 STL Port Matching #26415wording 2019-01-01 P2 Request to Allow 1345cc Hayabusa Engines for Spec Line P2 Cars #25595engine 2019-01-01 P2 Change CN inlet restrictor implementation date #25816induction 2019-01-01 P2 Clarify Honda K20A-FD2 parts requirement #25950weight 2019-01-01 STL Request to equalize FPR Reduction on all B-Series Vtec Engines #24746weight 2019-01-01 STL Request E&O for Mazda Miata Spec Line #25955weight
	Sonoma Raceway Runoffs 20182018-10-10	1:49.138Danny Steyn · fastest of 19 · top 5 within 2.5s	1:49.754Danny Steyn · fastest of 17 · top 5 within 2.5s	103.2Craig McHaffie	1:28.784Tim 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	-17.683squal -20.354s	83.9%qual 81.4%
No rule changes on record between these events
	Indianapolis Motor Speedway Runoffs 20172017-09-25	1:52.647Adam Roberts · fastest of 57 · top 5 within 0.8s	1:52.589Eric Kutil · fastest of 50 · top 5 within 1.2s		1:31.826Jeff Shafer · fastest of 26 · top 5 within 4.9s	1:32.481Jeff Shafer · fastest of 24 · top 5 within 3.8s		-20.108squal -20.821s	82.1%qual 81.5%
No rule changes on record between these events
	Mid-Ohio Sports Car Course Runoffs 20162016-09-19	1:35.439John Schmitt · fastest of 34 · top 5 within 1.5s	1:36.625Kevin Boehm · fastest of 31 · top 5 within 0.6s		1:20.188Jeff Shafer · fastest of 18 · top 5 within 4.0s	1:20.904Jeff Shafer · fastest of 16 · top 5 within 2.2s		-15.721squal -15.251s	83.7%qual 84.0%
No rule changes on record between these events
	Daytona International Speedway Runoffs 20152015-09-21	2:09.672Kevin Boehm · fastest of 37 · top 5 within 2.5s	2:10.269Kevin Boehm · fastest of 37 · top 5 within 2.1s		1:51.825Chris Farrell · fastest of 17 · top 5 within 3.6s	1:52.355Jeff Shafer · fastest of 17 · top 5 within 2.8s		-17.914squal -17.847s	86.2%qual 86.2%

By track

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

About this data

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