This track has been raced on 4 configurations (The Circuit, 2.57 mi; 19, 2.92 mi; 1.83 mi; 3.02 mi). Laps on different configurations are not comparable, so only events on the 2.57 mile layout are shown; switch above to see the others.
One run is left out as not that car's own laps (far quicker than the car managed in any other session and than anyone else in its class all week; usually a swapped transponder): Tom Burt in Cal Club 2025 PM (1:42.300; the car's best in any other session was 1:52.334 and the rest of the class's best all week 1:50.233).
5 laps are left out as timing errors (far too short to be a lap of this track). The rest of those sessions, sectors included, is used.
One row per driver and car (a driver who changed cars has a row for each). Each cell is that driver's best in that car across the selected events, with the session it was set in. Best 5-lap stint is the mean of the driver's quickest five consecutive race laps, and consistency is how far their median race lap sat behind their best in that race (small is a driver who does it every lap); both come from the race with the best stint. The fastest in each column is purple, and a car whose best lap is more than 115% of the fastest in its class is greyed (marked ">115%" beside the driver) and left out of the colour scale. Click a column to sort, a row to highlight it.
Theoretical lap is the sum of the best sectors, whichever laps they came from, and never slower than the best lap (where a car's fastest laps were recorded without sector times, its best lap is used). The 115% mark is about the car's best lap only: a car whose best lap is within 115% of the fastest in its class is never marked. Greyed sectors with no theoretical lap mean the sector times on file do not add up to a believable lap. Letters refer to the events above; Q is qualifying, R a race.
Sectors
S1 SF → IM1 0.65 mi
S2 IM1 → IM2 0.75 mi
S3 IM2 → SF 1.17 mi
Spd In → Out 0.03 mi
Sectors are numbered in lap order from start/finish, whatever each event's timing called them; the loop names are SCCA timing's.
By car
Car
Class
Drivers
Lap
Qual
Race
Trap
S1
S2
S3
Elan DP02/Mazda
P
1
1:32.576Jim Devenport
1:32.872Jim Devenport
1:33.972Jim Devenport
171.9Jim Devenport
25.461Jim Devenport
26.606Jim Devenport
40.217Jim Devenport
Dauntless Stohr
P
2
1:36.516Johnnie Crean
1:36.516Johnnie Crean
1:37.287John Manfroy
160.4John Manfroy
25.956Johnnie Crean
27.257John Manfroy
42.386John Manfroy
Dauntless Stohr
P
1
1:36.516Johnnie Crean
1:36.516Johnnie Crean
1:39.209Johnnie Crean
157.4Johnnie Crean
25.956Johnnie Crean
28.143Johnnie Crean
42.417Johnnie Crean
Dauntless-Stohr P07d
P
1
1:37.287John Manfroy
1:41.818John Manfroy
1:37.287John Manfroy
160.4John Manfroy
26.696John Manfroy
27.257John Manfroy
42.386John Manfroy
Stohr WF1
P
1
1:38.716Kevin Mitz
1:38.716Kevin Mitz
1:39.638Kevin Mitz
155.4Kevin Mitz
26.934Kevin Mitz
28.397Kevin Mitz
43.336Kevin Mitz
Penton Norma M20FC
P
1
1:39.296Joseph Moran
1:39.296Joseph Moran
1:40.832Joseph Moran
149.0Joseph Moran
27.106Joseph Moran
28.111Joseph Moran
43.651Joseph Moran
SCCA Ent SRF3
SRF3
38
1:50.233Caleb Shrader
1:50.233Caleb Shrader
1:50.825Caleb Shrader
138.9Paul Marino
30.136Caleb Shrader
31.672Caleb Shrader
44.841Tom Burt
Mazda Miata
STL
17
1:51.665Jared Korth
1:54.963Nick Leverone
1:54.845Gavin Wardle
136.6Bryce Johnson
8.264Gavin Wardle
32.218Jared Korth
48.811Jared Korth
Mazda MX-5
STL
6
1:51.665Jared Korth
1:57.404Ryan Gutile
1:54.845Gavin Wardle
136.6Bryce Johnson
8.264Gavin Wardle
32.218Jared Korth
48.811Jared Korth
Mazda Miata
STL
10
1:52.983Wesley Mollno
1:54.963Nick Leverone
1:55.682Nick Leverone
133.4Wesley Mollno
30.815Jon Davies
32.820Jon Davies
49.197Wesley Mollno
Mazda MX-5 (2015)
STL
1
2:00.239Adrian Comstock
2:00.239Adrian Comstock
2:00.722Adrian Comstock
133.0Adrian Comstock
32.847Adrian Comstock
34.493Adrian Comstock
52.675Adrian Comstock
Mazda RX-8
STL
1
1:53.515David LeCren
2:09.464David LeCren
2:11.372David LeCren
121.0David LeCren
31.217David LeCren
32.486David LeCren
49.550David LeCren
Honda Civic Si
STL
1
1:56.438Jonathan Lugod
1:57.331Jonathan Lugod
1:56.438Jonathan Lugod
106.8Jonathan Lugod
31.787Jonathan Lugod
33.468Jonathan Lugod
50.873Jonathan Lugod
Honda Prelude
STL
1
1:56.961Carl Young
1:57.917Carl Young
1:56.961Carl Young
104.5Carl Young
31.994Carl Young
33.745Carl Young
50.892Carl Young
Acura integra
STL
1
2:24.310Jack McEachern
2:24.310Jack McEachern
2:24.550Jack McEachern
77.6Jack McEachern
38.960Jack McEachern
41.141Jack McEachern
1:02.410Jack McEachern
The best any driver of each car managed across the selected events, with who set it. Spellings and model years of the same car are grouped; click a row marked ▸ to see each version. Grouping is worked out from the names, so tell us if two cars are wrongly merged or split.
Rule changes between these events
Cal Club 2023 → Cal Club 2024 2023-02-24 to 2024-02-23
slowerSRF Renault Alliance solid front rotors banned; restrictor reduced 35mm to 34mm for 2011+ Kawasaki; minimum weight increased to 1100 lbs for 2009+ stock engines.
As printed in Fastrack
In SRF, GCR section 9.1.8.D.X.g, change as follows: "Brakes: Hawk Blue 9012 pads P/N 801993 must be used. Wilwood vented rotor P/N 800065 shall be used as delivered with no machining of any kind. Minimum thickness 12.20mm (0.481"). The 1985 Renault Alliance solid front rotor (Reference: Bendix PRT1318 or Centrix 121.11004) may be used on front, rear, or both axles, but each axle must be paired to the same type rotor. The Renault Alliance solid front rotors may not be used. Rubber caliper bushings may be replaced with bronze bushings P/N 1196185 or P/N 1196185. Original caliper pistons may be replaced with vented caliper piston P/N 1196184; no other modification allowed. Wilwood caliper with bracket universal fit P/N 800038 may be used as delivered with no modification of any kind. Wilwood knock back spring (2.63 lbs.) P/N 800045 may be used as delivered with no modification of any kind;
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maximum of one spring per caliper." P2 Engine Table Spec Line Engine Series
A specification table follows in the original; it is not shown here.
wordingSRF3 tail sections allowed on SRFs with GEN3 airbox shimming up to 19 mm; alternate dash panel P/N 180100 or 180101 relocated in rules.
As printed in Fastrack
In Spec Racer Ford, GCR section 9.1.8.D.1.E, change as follows: "j. Optional Bodywork Modification: Viewing the tail section of the car from behind, draw a vertical line at the left and right ends of the outer vents from the bottom edge of the bodywork up to a point two (2) inches below the crease at the lower edge of the vented panel. Make a vertical cut at each line. The horizontal cut is to be one (1) inch below the crease at the base of the vented panel. Leave a one (1) inch radius at each corner. Air Scoop (P/N 190000) must be installed in conjunction with rear cutout per Enterprises installation instructions. SRF3 tail sections are allowed on SRFs. For purposes of tail section to center section fitment with the GEN3 airbox, shimming is allowed at the rear of the center section. Shim material may be up to 19 mm (0.75") thick along the 1" upper square sidepod
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tube. Mounting location cannot be modified or added. Shim material must be securely attached, but must not be welded. An alternate dash panel has been approved for use in Spec Racer Fords. The dash will be furnished by Enterprises only. P/N 180100 or 180101 k. Required Bodywork Modification: A 22.5" diameter wheel arch shall be cut in each side of the tail section. Viewing the tail section from the side, draw a vertical line at the drive axle centerline. Locate the top of the wheel arch at a point measured from the bottom edge of the tail section 9.25" vertically along the centerline. The 22.5" diameter circle intersects the bottom edge of the tail section 11.1" either side of the centerline. The tail section may be reinforced in the forward and aft portions of the wheel arch. Dimension tolerance is +/- 0.75". l. An alternate dash panel has been approved for use in Spec Racer Fords. The dash will be furnished by Enterprises only. P/N 180100 or 180101."
wordingSTL ITA/ITS RX7 and 1985+ ITA/ITS/ITB/ITC vehicles clarified to conform to section 9.1.4.2 tire specifications.
As printed in Fastrack
In STL Spec Lines, Table B: Alternate Vehicle and Engine Allowances, change Notes as follows: ITA-spec and ITS-spec RX7: "Must completely conform to ITCS specifications. Tires must conform to 9.1.4, Tires & Wheels. Tires must also conform to 9.1.4.2.Tires." ITS, ITA, ITB, or ITC vehicles (1985- ): "Must completely conform to ITCS specifications. Tires must conform to 9.1.4, Tires & Wheels. Tires must also conform to 9.1.4.2.Tires."
unclearSRF Hoosier wet front tire updated to P/N 46100 P185/60R13 H20 or W2.
As printed in Fastrack
In SRF, GCR section 9.1.8.D.1.X.f, change as follows: "Wet: Front – Hoosier P/N 46100 P185/60R13 H20 or W2 Rear – Hoosier P/N 46105 P205/60R13 H20 or W2 Ground clearance is 2.5" with driver as raced when P185/60R13 (H20 or W2) tires are used."
wordingSRF radiator rule clarified: P/N 480466 replaceable with Automotive P/N 1R698, CU698 or manufacturer equivalent with documentation.
As printed in Fastrack
In SRF, GCR section 9.1.8.D.1.V.j, change as follows: "Radiator - Enterprises new style P/N 480465 (requires baffle P/N 480464) or P/N 480466 can be used. P/N 480466, may can be replaced with Automotive P/N 1R698, CU698 or equivalent OEM manufacturer justified by one cross-reference chart equivalent, as long as the size, shape, and material are the same as the original P/N. The capacity, core thickness, etc., cannot be changed even if allowed under the above. The competitor is responsible for providing this documentation of the cross-reference P/N."
wordingSRF rain/brake light now requires Super Bright LEDs Inc. P/N PT-STRB-R24 with specific connector and rain light switch.
As printed in Fastrack
In SRF, GCR section 9.1.8.D.1.W.l, change as follows: "A Super Bright LEDs Inc. rain / brake light comprised of a single standard trailer oval lamp, 2-1/4 inches x 6-1/2 inches, with incandescent or LED illumination, P/N PT-STRB-R24, is required in the original roll hoop mounting location. This rule supersedes GCR section 9.3.32.B.2 effective 1/1/2024 through 12/31/2024. No changes may be made to the original 3-pin connector on the wiring harness. The secondary filament of the brake light assembly shall must be connected to a switch enabling its use as a rain light."
wordingSRF requires Super Bright LEDs P/N PT-STRB-R24 rain/brake light with strobing capability and specific wiring.
As printed in Fastrack
In SRF, GCR section 9.1.8.D.1.W.l, change as follows: "A Super Bright LEDs Inc. P/N PT-STRB-R24 (SCCA Enterprises P/N 180427A) rain / brake light, P/N PT-STRB-R24, is required in the original roll hoop mounting location. This rule supersedes GCR section 9.3.32.B.2 effective 1/1/2024 through 12/31/2024. No changes may be made to the original 3-pin connector on the wiring harness. An SCCA Enterprises P/N 1190503 Strobing Brake Light Pigtail is required. The secondary filament of the brake light assembly must be connected to a switch enabling its use as a strobing rain light. A Strobing Brake Light Kit P/N 1168003 is available, which includes the brake light and pigtail."
STL Alternate Carburetor Request for 79-85 RX7 12a
unclearSTL Mazda RX-7 12A (79-85) now allows auto-type 2 bbl with 42mm choke(s) on dual-y manifold as alternate to stock Nikki 4 bbl.
As printed in Fastrack
In STL Table B: Alternate Vehicle and Engine Allowances, Mazda RX-7 12A (79-85), change Notes as follows: "Street Porting of the engine only. Bridge porting, peripheral porting, and eyelash porting are prohibited. Contact SCCA National Office for details of Street porting. Stock Nikki 4 bbl carburetor on a stock manifold only. or auto-type 2 bbl w/42mm choke(s) on a “dual-y” manifold. Allow the standard removal of emissions related components, and allow air and fuel jets to be corrected. Modification of the water jacket in the area of the spark plug for cooling purposes is permitted."
otherSRF adds brake duct and pedal extension rules, rear shift cable clamp option, camber limit to 5.0°, radiator opening height 3.5" ±0.5", and P2 engine restrictor changes.
As printed in Fastrack
In SRF, GCR section 9.1.8.D.1.H, add the following: "NO MODIFICATIONS ALLOWED. Front brake ducts are required, attached to the openings in the lower radiator baffles, any flexible 4" duct material allowed, installed length minimum 12" maximum 36" in length. Must be securely fastened, Bracket Part # P/N 800368 can be used. Shall Must serve no other purpose. An extension may be welded to the side of the throttle pedal to improve heel-and-toe braking. Master cylinder casting / location must be used as delivered on P/N 180110 Pedal Mounting support. Aeroquip style -3 braided stainless flex lines only, must attach to all brake components without modification. Brake pad "anti-rattle" clips must be removed." In SRF, GCR section 9.1.8.D.1.V, add the following:
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"ii. Rear SADEV shift cable aluminum two-piece style clamp may be used. The P/N WM302007A clamp must serve no other purpose." In SRF, GCR section 9.1.8.D.1.X.k, add the following: "Negative camber shall must not exceed 5.0 degrees absolute maximum front and rear." In SRF, GCR section 9.1.8.D.1.AA.b, add the following: "2. Height of the radiator opening vertical surface 3 1/2“ +/- 1/2"." P2 Engine Table B.1 2008 and older Stock Suzuki, Yamaha, Honda, BMW 38.5mm P2 Engine Table B.2 Not required P2 Engine Table B.3 38.5mm Modified Engine 950 lbs. 1005cc max P2 Engine Table B.1 2008 and older 37mm P2 Engine Table B.2 Not required P2 Engine Table B.3 39mm Stock Engine 1050 lbs.
wordingSTL and STU power steering rules clarified to permit electric-assisted and hydraulic-assisted steering systems.
As printed in Fastrack
In GCR, Section 9.1.4.M.16., change as follows: "Power steering may be modified in any of the following ways: a. disconnected , pump, belt, pulley, and hoses may be removed. Hoses may also be looped. Steering rack or box may be modified internally to work without pump. b. an OEM manual steering rack for that model may be fitted c. an electric power steering pump may be fitted d. an OEM electric-assisted steering system may be used or any column mounted electric steering assist may be used e. an OEM hydraulic-assisted steering system may be used"
fasterSTL Acura/Honda B-series and Mazda MZR restrictors reduced 2mm; minimum weights down 25–75 lbs for 1900–2000cc engines.
As printed in Fastrack
In GCR, 9.1.4.H.1., change as follows: "Minimum weights for cars with normally aspirated piston engines will be determined by 1.35 lbs/cc displacement for the installed engine (see the following table). Displacement is the factory displacement for the installed engine. For the purpose of weight assignment, engine displacement will be rounded to the nearest 50cc (e.g., 2176cc = 2200cc and 2175cc = 2150cc)." In GCR, 9.1.4.H.1., change Minimum Weight on Chart as follows: Factory Engine Displacement 1900: "Effective 3-1-24: 2565 2540" Factory Engine Displacement 1950: "Effective 3-1-24: 2633 2583"
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Factory Engine Displacement 2000: "Effective 3-1-24: 2700 2625" In GCR, 9.1.4.H.3., change as follows: "Front wheel drive cars with a strut type front suspension may reduce their minimum weight by 2.5 percent. Effective 3- 1-24: Front wheel drive cars with 95" or less wheelbase must add 1.25% to their minimum weight." In STL Spec Lines, change Notes as follows: Acura/Honda B16: "Effective 3-1-24: 53 51mm" Acura/Honda B17: "Effective 3-1-24: 53 51mm" Acura/Honda B18C1: "Effective 3-1-24: 53 51mm" Acura/Honda B18C (JDM Type R), B18C5 (USDM Type R), B18C6 (UK and Euro Type R), B18C7 (Australia Type R): "Effective 3-1-24:52 50mm" Mazda MZR: "Effective 3-1-24: 52 50mm"
slowerSRF wet tires: P185/60R13 H20/W2 option removed; P185/65R13 W2 front now required with P205/60R13 W2 rear.
As printed in Fastrack
In SRF, GCR section 9.1.8.D.1.X.f, change as follows: "Wet: Front – Hoosier P/N 46100 P185/60R13 H20 or W2 Rear – Hoosier P/N 46105 P205/60R13 H20 or W2 Ground clearance is 2.5” with driver as raced when P185/60R13 (H20 or W2) tires are used. OR Front – Hoosier P/N 46101 P185/65R13 W2 Rear – Hoosier P/N 46105 P205/60R13 W2
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1. It is forbidden to regroove tires. 2. The use of tire warmers or cooling methods other than natural air convection or conduction is prohibited. The penalty for violation will be the loss of qualifying times and/or the disqualification of race results. 3. Hoosier SRF/SRF3 Decal Placement: Four (4) "Hoosier" decals are required in the following locations: Two (2) 11" X 3" decals on the vertical plane of the front nose to the outside of the cooling opening on each side and two (2) 18" X 5" decals, one on each side of the engine cover or above the rear wheel openings on the vertical plane. Hoosier decals are available, free of charge, from all Hoosier tire distributors including SCCA Enterprises."
SRF3 Update to Letter 36619 with new Hoosier Contingency Decal Info
wordingSRF Hoosier decal requirement reduced from four decals in specific locations to three decals with simpler placement rules.
As printed in Fastrack
In SRF, GCR section 9.1.8.D.1.X.f.3, change as follows: "Four (4) "Hoosier" decals are required in the following locations: Two (2) 11" X 3" decals on the vertical plane of the front nose to the outside of the cooling opening on each side and two (2) 18" X 5" decals, one on each side of the engine cover or above the rear wheel openings on the vertical plane. Hoosier decals are available, free of charge, from all Hoosier tire distributors including SCCA Enterprises Per Hoosier's contingency program, three (3) decals are required to qualify for contingency awards. One (1) decal must be located on each side of the car and one (1) decal must be visible on the front."
slowerSRF brake rotor minimum thickness increases from 12.20mm to 13.25mm, Wilwood vented rotor P/N 800065.
As printed in Fastrack
In SRF, GCR section 9.1.8.D.1.X.g, change as follows: "Brakes: Hawk Blue 9012 pads P/N 801993 must be used. Wilwood vented rotor P/N 800065 shall must be used as delivered with no machining of any kind. Minimum thickness 12.20mm (0.481”) 13.25mm (0.522”)."
wordingSRF3 Hoosier logo placement changes from four decals to three decals in different locations.
As printed in Fastrack
In SRF, GCR section 9.1.8.D.2.B, change as follows: "Mandatory identification: "SRF3" near the side car numbers. "Hoosier" logo (4) on both sides front lower outer corners of the nose and each side of the tail. Three (3) "Hoosier" logos, one (1) on each side of the car and one (1) on the center front of the car."
STL Request to Remove Miata Hubs from General category
wordingSTL/STU: 90-05 Mazda Miata alternate front wheel hubs moved from General to specific part approval.
As printed in Fastrack
In GCR, Section 9.1.4.M.18., change as follows: "18. Allow alternate front wheel front hubs, Mazda Motorsports Development Part #0000-04-5HUB-S1, for the 90-05 Mazda Miata: Mazda Motorsports Development Part #0000-04-5HUB-S1."
wordingPrototype Staudacher and unrestricted engine notes corrected for minimum weight wording.
As printed in Fastrack
In Prototype Engine Table, Spec Line B, change the notes as follows: "Staudacher cars may run 950 lb min. wt. minimum weight with 38.5mm flat plate intake restrictor." In Prototype Engine Table, Spec Line D, change the notes as follows: "No restrictor required at 1150 lb min. wt. minimum weight."
wordingPrototype class renamed from P1 to P, affecting designation throughout rules with no performance changes.
As printed in Fastrack
In Categories and Classes, GCR section 9.1, change as follows: "9.1.8. SPORTS RACING CATEGORY CLASSES A Sports Racing (ASR) Regional Class Prototype 1 (P1)" In Homologation Requirements, GCR section 9.2.2, change as follows: "All Formula, Sports Racing, and P1, and P2 cars must be constructed in strict accordance with the rules and regulations contained in the current GCR unless specifically excepted." In Non-Metallic Wheel/Chassis Construction, GCR section 9.3.37, change as follows:
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"Non-metallic wheel construction is prohibited. Non-metallic chassis construction is prohibited, except in ASR, P1, FS and FA." In Appendix B, GCR section 1.4.2.G, change as follows: "It is preferable not to combine GT1, AS, T1, T2, T3, and STU with P1, P2, SRF, FP, HP, or GTL." In Appendix C, GCR section 2.6.G, change as follows: "A 14 or 15 year-old must complete his first SCCA driver school in a car not classed in GT1, GT2, FA, FB, F S, ITR, ASR, P1, P2, or T1." In Appendix E, section 1, change as follows: "Depending on the length and banking of the oval course being used, it is recommended that Regions consider restricting the faster classes (GT1, FA, and P 1) from competition at oval track events." In Sports Racing Category, GCR section 9.1.8.1, change as follows: "The SCCA Sports Racing Category shall be for automobiles which are designed and constructed for road racing competition, offering provisions for a driver and passenger, or a driver alone (single-seater). They shall conform to the following requirements. Sports Racers Cars except SRF & SRF3 homologated prior to 1-1-2014 are eligible to compete as P1 or P2 as long as they meet applicable class rules,; no re-homologation is required." "Single seat Formula car chassis (Ex.: FA, FC, FF, FV) fitted with enclosed bodies (as specified in these rules) may run in a Sports Racing/Prototype Class (ASR, P 1, P2) provided they comply with the requirements of the Classification Specification and GCR Section 9." In Sports Racing Category, GCR section 9.1.8.2, change as follows: "In an effort to control shock/damper technology and cost to a level reasonable for Road Racing, in ASR, P1, and P2, any fluid dampers are allowed with the following restrictions:"
Cal Club 2025 → Cal Club 2026 2025-02-22 to 2026-02-21
wordingSRF drivers with disabilities may modify seat and controls for safety and comfort with approval and logbook notation.
As printed in Fastrack
In SRF, GCR section 9.1.8.D.1.D, add the following: "f. Driver Safety and Comfort modifications to seat and controls for drivers with disabilities may be made only by approval. These modifications must be reported to SCCA Enterprises and noted in the car logbook. The modifications are approved only for the noted driver with disabilities. If the car is used by or sold to another driver, it must be returned to the previous standard configuration."
unclearSTL Mazda MX5 Challenge minimum weight now references GCR 9.1.7.1 instead of 2500 lbs; spec components removed, only alternative tires allowed.
As printed in Fastrack
In STL Spec Lines, Table B, Mazda Spec MX5 Challenge, change as follows: Minimum Weight: "2500 See 9.1.7.1." Notes: "Mazda MX5 Challenge car must utilize the following components: Roush CNC cylinder head 0000-01-5300,Mahle standard or +0.005 0000-01-5310, OEM camshaft, 11:1 compression ratio, header 0000-06-5407-NC, exhaust 0000-06-5427-NC, cold air intake 0000- 06-5150-KT, ECU flash 0000-01-5379, Pagid front brake pads 0000-03-5104-SP or endurance pads 0000-03- 5104-EN, Pagid rear brake pads 0000-03-5114-SP or endurance pads 0000-03-5114-EN, Penske front shock 0000-04-5291-SA, Penske rear shock 0000-04-5292-SA, Penske rear mount kit 0000-04-5358, Front mount kit 0000-04-5359, Front offset bushing 0000-04-5407-NC, Eibach front springs 0000-04-9700-08, Eibach rear springs 0000-04-9400-07, Eibach helper springs 0000-04-
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9926, Eibach front sway bar 0000-04-5306-FT, Eibach rear sway bar 0000-04-5306-RR, Interior finish panels 0000-07-5822, C&R radiator/oil cooler assembly 0000-01-5504-CR, Oil cooler adapter and lines 0000-01-5511-KT, ACT clutch 0000-02-5004-G6, wheels 17x8 #0000-04-5706-GM, # 0000- 04-5706-SL, and Toyo RR 235-40-17 dry, Toyo RA1 235-40-17 wet. Alternative tires on 17x7 wheels per STL rules. No other Super Touring modifications or allowances permitted except as noted in this spec line. Must conform completely to GCR 9.1.7.1, except alternative tires (only) per STL regs allowed."
Applies to Mazda Miata on this page: Jared Korth, Ricardo Arruda, Gavin Wardle, Ryan Gutile, Bryce Johnson, Andy Chittum, Adrian Comstock
wordingClass P adds clarification notes on restrictor requirements, throttle bodies, Mazda 12A engine spec, and P2 auto-based engine rules.
As printed in Fastrack
In P Engine Table, Spec Line D notes, add the following: "No restrictor required at 1150 lbs. minimum weight." In P Engine Table, Spec Line G notes, add the following: "Group CN non-composite chassis with Honda K20A-FD2 may use unrestricted individual throttle bodies at 1500 lbs. minimum weight." In P Table 1, Beasley B2 spec line notes, add the following: "Engine must be Mazda 12A rotary with 40.5mm venturi. Car must comply with all other Prototype requirements." In P Table 1, P2 cars built to 2000cc auto-based specification spec line notes, add the following:
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"Car must comply with all other P2 rules applicable to cars using stock production-based four-cylinder automotive engines. Note: Competitors are also free to modify their cars to comply with the general Prototype rules and Engine Table Spec Line H instead."
Effective 9/1/25 in SRF, GCR section 9.1.8.D.1.V.ff, add the following: "SRF3 Oil Cooler, P/N G480503 may be used as mounted per the GEN3 Assembly Manual. No fan permitted for SRF. HD Oil Cooler kit P/N G1148500 may be used as mounted per the GEN3 Conversion Manual." Effective 9/1/25 in SRF, GCR section 9.1.8.D.X.g, change as follows: "Brakes: Hawk Blue 9012 pads P/N 801993 must be used. Wilwood vented rotor P/N 800065 must be used as delivered with no machining of any kind. Minimum thickness 13.25mm (0.522”). The Renault Alliance solid front rotors may not be used. Rubber caliper bushings may be replaced with bronze bushings P/N 1196185 or P/N 1196185. Original caliper pistons may be replaced with vented caliper piston P/N 1196184; no other modification allowed. Wilwood caliper with bracket universal fit P/N 800038
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may be used as delivered with no modification of any kind. Wilwood knock back spring (2.63 lbs.) P/N 800045 may be used as delivered with no modification of any kind; maximum of one spring per caliper. 1. Hawk Blue pads P/N 801993 only 2. Wilwood Vented Rotor P/N 800065 only, as delivered, with no machining of any kind. Minimum thickness 13.25mm (0.522") 3. Wilwood universal caliper Kit P/N 1180008 as delivered, caliper only P/N 800038; Wilwood knock back spring P/N 800045 may be used as delivered, with no machining of any kind, and only one spring per caliper 4. Renault caliper rubber bushings may be replaced with bronze bushings P/N 1196185 or P/N 1196185A 5. Renault caliper piston may be replaced with P/N 1196184 vented piston as delivered, with no machining of any kind 6. Girling .750" Master Cylinder P/N 880358 as delivered, with no machining of any kind 7. Wilwood .750" Master Cylinder P/N 880357 as delivered, with no machining of any kind 8. Tilton .750" Master Cylinder P/N 880360 as delivered, with no machining of any kind"
unclearP class 13B rotary engine restrictor changes to 40mm SIR fuel injection or 41.5mm venturi carburetor.
As printed in Fastrack
Effective 9/1/25 in Prototype Engine Table, Spec Line K, change the restrictor as follows: "40mm SIR with fuel injection or 41.5mm venturi with carburetor"
P Add Radical Cup series Radical SR3 spec line to Table 1
wordingPrototype P2 cars may now run P2 spec or modified Prototype spec in Prototype class; clarified language and added Radical Cup series table.
As printed in Fastrack
Effective 9/1/25, in Prototype, GCR section 9.1.8.B.K, change as follows: "P2 cars may compete in either the Prototype class or the P2 class but must participate in the Prototype class to the extent necessary to qualify for an invitation to the Runoffs in Prototype. P2 cars may be modified to comply with the general Prototype rules and Prototype Engine Table or may continue to run in P2 specification in the Prototype class as permitted in Table 1 below." Table 1 (Spec Line Cars)
A specification table follows in the original; it is not shown here.
otherSRF3 adds HD Oil Cooler P/N G1148500 as alternative to standard cooler P/N G480503.
As printed in Fastrack
In SRF, GCR section 9.1.8.D.1.V.ff, change as follows: "SRF3 Oil Cooler, P/N G480503 or HD Oil Cooler P/N G1148500 may be used as mounted per the GEN3 Assembly Manual. No fan permitted for SRF. HD Oil Cooler kit P/N G1148500 may be used as mounted per the GEN3 Conversion Manual."
suspension & brakesPrototype carbon-carbon and carbon-ceramic brake rotors now permitted instead of prohibited.
As printed in Fastrack
In Prototype, GCR section 9.1.8.B.F.2, change as follows: "Brake calipers may be ferrous or aluminum alloy. Effective 1/1/2026, carbon-carbon and carbon-ceramic brake rotors are prohibited and rotors must be ferrous. Brake rotor material is unrestricted."