unclearFP and HP Fiat X-1/9 1300 Level 1 now permit intake manifolds 128BS and 128AS.
As printed in Fastrack
In FP spec lines, Fiat X-1/9 & Bertone 1300 (Prep. Level 1), add the following wording to the Drivetrain Notes section: "Intake manifold part numbers 128BS and 128AS are permitted." In HP spec lines,Fiat X-1/9 1300" (Prep Level 1), add the following wording to the Drivetrain Notes section: "Intake manifold part numbers 128BS and 128AS are permitted."
inductionHP Sprite/Midget 1275 allows MG-B alternate intake manifold with 1.5" SU carbs; balance tube shortening and flange modification permitted.
As printed in Fastrack
In HP Spec Lines, Austin-Healey Sprite Mk I, II, III, IV MG Midget Mk I, II, III, IV & 1500, change Drivetrain Notes as follows: "(2) 1.25” SU w/ no modifications (2) 1.5” SU w/ no modifications (on alternate manifold) Valves: (I) 33.0/(1.30) (E) 29.5/(1.16) Comp. ratio 12.0:1, Valve lift .450” Trans. Speeds: 4 Drivetrain Level 2 preparation only. Listed spec line weight does not change with alternate or stock transmission.
A specification table follows in the original; it is not shown here.
fasterHP Honda Civic DX/LX (92-95) wheels widen to 15x7, weight drops to 2350 lbs.
As printed in Fastrack
In HP, make the following changes to the "Honda Civic DX (92-95)" spec line: Spec Line Name: "Honda Civic DX/LX (92-95)" Wheels: "13x7 15x7" Wheelbase: "2/ 4 door: 2621/(103.2) 2/3 door: 2573/(101.3)" Weight: "2420 2350"
unclearEP Triumph TR2-TR4A allows 5-speed gearbox without overdrive; removes Weber carb and weight specification.
As printed in Fastrack
In EP Spec Lines, Triumph TR2, 3, 3A, 4, 4A, TR4, TR4A, IRS, make the following change to the Notes: "Front apron assembly may be made of alternate material. Three (3) Weber 40 DCOE on IR manifold with 28mm chokes @ 1990 lbs. Laycock overdrive, may use 5 speed gearbox without overdrive."
slowerHP Volvo 142/142E gains compression ratio limit 12.0:1 and valve lift limit .425".
As printed in Fastrack
In HP Spec Lines, Volvo 142/142E P-1800 Engine, Effective 11/1/2025 add the following wording to Notes: "Comp. Ratio limited to 12.0:1. Valve lift limited to .425”."
slowerHP Mini Cooper 07-15 valve lift reduced to .390", from .450".
As printed in Fastrack
In HP Spec Lines, Mini Cooper (07-13) (includes 09-15 convertible and 12-15 Coupe), Effective 11/1/2025 make the following changes to the Notes: "Compression ratio limited to 11.0:1, Valve lift limited to .450”.390"."
wordingFP and HP Volkswagen Rabbit descriptions updated: Convertible changed to Cabriolet in FP; Cabriolet added to three HP engine variants.
As printed in Fastrack
In FP Spec Lines, make the following spec line correction: "Volkswagen Rabbit (Includes Convertible Cabriolet)" In HP Spec Lines, make the following spec line correction: "Volkswagen Rabbit 1588 (Includes Cabriolet)" "Volkswagen Rabbit 1715 (Includes Cabriolet)" "Volkswagen Rabbit 1780 (Includes Cabriolet)"
wordingEP, FP, HP: rear drum brake to disc conversion clarified; rotors solid, diameter limited to largest front rotor permitted.
As printed in Fastrack
In GCR, Section 9.1.5.E.7., change as follows: "e. Cars fitted with rear drum brakes, can convert to rear disc brakes without penalty. Note that the “Brakes Std.” and “Brakes Alt.” listings on a vehicle’s spec line do not prohibit a car that was fitted with rear drum brakes stock, from converting to rear disc brakes under this rule. When converting from rear drum brakes to rear disc brakes: 1. Rear brake rotors must be solid and can be no larger in diameter than the largest permitted front brake rotor, as defined on the vehicle’s spec line. 2. Rear calipers and mounting brackets are unrestricted but must be made of a ferrous or aluminum material. The standard and alternate brake listings on a vehicle’s specification line, does not prohibit a car that was fitted with rear drum brakes as stock
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from converting to rear disc brakes under this rule. 3. The “Brakes Std.” and “Brakes Alt.” listings on a vehicle’s spec line do not prohibit a car that was fitted with rear drum brakes as stock from converting to rear disc brakes under this rule."
wordingEP, FP, HP throttle body inside dimensions must remain stock with +/-.25mm tolerance; butterfly dimensions stock in FP, HP only.
As printed in Fastrack
In GCR, Section 9.1.5.E., change as follows: 9.1.5.E.1.b.4: "The inside dimensions of the throttle body casting/housing (as measured at the throttle butterfly) must remain stock (tolerance of +/-.25mm), but the throttle body can otherwise be ported and polished." 9.1.5.E.2.b.4: "The inside dimensions of the throttle body casting/housing and all dimensions of the throttle butterfly must remain stock (tolerance of +/-.25mm)."
fasterHP Ford Festiva 88-93 minimum weight drops to 1600 lbs, variants to 1640 and 1680 lbs; compression ratio raised to 11.0:1.
As printed in Fastrack
In HP Spec Lines "Ford Festiva (88-93)" change as follows: Weight: "1700 1600 *1743 1640 **1785 1680" Notes: "Compression ratio limited to 10.5 11.0:1. Valve lift limited to .450”."
slowerEP Triumph GT6 switches to three Weber 40 DCOE carbs with 28mm chokes, weight rises 50 lbs to 1990.
As printed in Fastrack
In EP Spec Lines, make the following changes in the "Triumph GT6" spec line: Carburetor No. & Type: (2): "1.5” 1.75" Auto-type carburetor(s)" Notes: "Two (2) 1.75” auto-type carburetors @ 1940 lbs. Three (3) Weber 40 DCOE on IR manifold with 28mm chokes @ 1990 lbs. Laycock overdrive, May use 5 speed gearbox w/o overdrive."
fasterHP Sprite and Midget 1275cc and 1098cc Level 2 compression ratio raised to 12.0:1.
As printed in Fastrack
In HP Spec Lines, Austin-Healey Sprite MkI, II, III, IV MG Midget (ALL) - Level 2 - 1275cc, change Notes as follows: "(Effective 11/1/2024) Compression ratio limited to 11 12.0:1" In HP Spec Lines, Austin-Healey Sprite MkI, II, III, IV MG Midget (ALL) - Level 2 - 1098cc, change Notes as follows: "(Effective 11/1/2024) Compression ratio limited to 11 12.0:1"
wordingEP Mazda RX-8 (04-11) alternate spec line removed; one primary line remains.
As printed in Fastrack
Spec Lines, make the following changes to the two Mazda RX-8 spec lines. Remove spec line entirely: Mazda RX-8 (04-11) Remove the wording "alternate": Mazda RX-8 (04-11)(alternate) Spec Mazda (SM/SMX) None.
In HP Spec Lines, delete the following redundant spec lines in their entirety: Spec line #10 - VW Rabbit Cabriolet 1780 Spec line #3 - VW Scirocco 1588 Spec line #4 - VW Scirocco 1780 (8-valve) (83-88) Spec line #5 - VW Scirocco 1588
In EP spec line, Triumph GT6, make the following change in the Notes section: "Two (2) 1.75” auto-type carburetors @ 1970 40 lbs. Three (3) Weber 40 DCOE on IR manifold with 28mm chokes @ 1990 lbs. Laycock overdrive, May use 5 speed gearbox w/o overdrive. Three (3) Weber 40mm DCOE w/28mm venturi on individual runner manifold @ 2020 lb."
fasterEP Honda S2000 fuel injected throttle body inside diameter increases from 62mm to 64mm.
As printed in Fastrack
In EP spec line, Honda S2000, make the following changes to its spec line: Fuel Injected Equipped Throttle Body Inside Diameter: "62 64" Notes: "Comp. Ratio limited to 12.0:1. Valve lift limited to .500”. An adaptor plate can be used to mount the 62mm throttle body from '00-05 to the '06-09 intake manifold. The adaptor plate can be no more than 1.25" thick, and its bore must not exceed the "Fuel Injected Equipped Throttle Body Inside Diameter" maximum spec of 64mm."
wordingEP Triumph TR8 dry sump allowance moved from carburetor line to notes section.
As printed in Fastrack
In EP spec line, Triumph TR8 (78-81), move the "Dry sump allowed" wording to the appropriate location as follows: Carburetor. No. & Type: “Zenith Stromberg carbs or fuel injection. Dry sump is allowed.” Notes: “Comp. Ratio limited to 12.0:1, Valve lift limited to .500”. Dry sump is allowed.”
cars addedEP Porsche 944/924S combines 2.5L and 2.7L variants with new weights: 2250–2415 lbs depending on engine and year.
As printed in Fastrack
In EP Spec Lines, delete the Porsche 944/924S 2.5L (2V) (83-88) spec line entirely, and create a new spec line for Porsche 944/924S 2.5L(2V) 2.7L(2V) (83-89) as follows:
A specification table follows in the original; it is not shown here.
wordingEP Triumph TR8 78-81 removes alternate front hub allowance note; stock hubs now required.
As printed in Fastrack
In the EP Spec Lines, Triumph TR8 (78-81), remove the following wording from Notes: "Alternate front hubs are allowed provided they are of the same external dimensions as stock and weigh no less than the stock hubs."
wordingFP and HP Sprite, Midget, and Spitfire 1500 intake valve size corrected to 36.6/(1.44).
As printed in Fastrack
In FP Spec Lines, Austin-Healey Sprite Mk. I, II,III, IV MG Midget Mk I,II, III, IV & 1500, change Intake Valve Size as follows: "(I) 36.65.3/(1.44)" In FP Spec Lines, Triumph Spitfire Mk. IV & 1500, change Intake Valve Size as follows: "(I) 36.65.5/(1.440)" In HP Spec Lines, Triumph Spitfire 1500, change Intake Valve Size as follows: "(I) 36.65.5/(1.440)" In HP Spec Lines, Triumph Spitfire Mk. III & IV 1500, change Intake Valve Size as follows: "(I) 36.65.5/(1.440)"
slowerEP BMW Z3 2.5L intake restrictor reduced from 58mm to 56mm flat plate.
As printed in Fastrack
Effective 4/1/2023 In EP Spec Line BMW Z3 2.5L, change Notes as follows: "58 56mm Flat Plate Intake Restrictor is required with both stock or alternate throttle body."
In EP Spec Line, Mazda RX-7 (12A/13B) (79-85), change Notes as follows: "Level 1 dry sump, intake manifold porting permitted. Alternate multi-piece hub and rotor allowed provided they are of the same dimensions as original and weigh a minimum of 10.2 lbs. 13B (only): Any 13B rotor housing and any non-turbo 6-port side and/or intermediate housing permitted. Use of differential from 94-97 Mazda MX-5/ Miata permitted."
inductionEP Mazda RX-2, RX-3, RX-4, and 12A RX-7 now allow 2 bbl fuel injected throttle body w/ 42mm chokes on dual-y manifold.
As printed in Fastrack
In EP Spec Lines, Mazda RX-2, change Carburetor. No. & Type as follows: "(1) Nikki 4 bbl carburetor w/ primary choke(s) bored to match secondary choke(s) on a stock manifold, or (1) Auto-type 2 bbl w/ 42mm choke(s) on a “dual-y” manifold”, or (1) 2 bbl fuel injected throttle body w/42mm choke(s) on a “dual-y” manifold." In EP Spec Lines, Mazda RX-3 & 3SP (72-78), change Carburetor. No. & Type as follows: "(1) Nikki 4 bbl carburetor w/ primary choke(s) bored to match secondary choke(s) on a stock manifold, or (1) Auto-type 2 bbl w/ 42mm choke(s) on a “dual-y” manifold”, or (1) 2 bbl fuel injected throttle body w/42mm choke(s) on a “dual-y” manifold." In EP Spec Lines, Mazda RX-4 (74-78), change Carburetor. No. & Type as follows: "(1) Nikki 4 bbl carburetor w/ primary choke(s) bored to match secondary choke(s) on a stock manifold, or (1) Auto-type 2 bbl w/
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42mm choke(s) on a “dual-y” manifold” In EP Spec Lines, Mazda RX-7 (12A/13B) (79-85), change Carburetor. No. & Type as follows: "12: (1) Nikki 4 bbl carburetor w/ primary choke(s) bored to match secondary choke(s) on a stock manifold, or (1) Auto-type 2 bbl w/ 42mm choke(s) on a “dual-y” manifold”, or (1) 2 bbl fuel injected throttle body w/42mm choke(s) on a “dual-y” manifold. 13B: (1) Auto-type 2 bbl w/ 42mmchoke(s) on a “dual-y” manifold, (1) 2 bbl fuel injected throttle body w/42mm choke(s) on a “dual-y” manifold, or stock 13B fuel injection."
wordingEP, FP, HP cylinder head ports limited to 1 inch maximum depth matching from mating surface.
As printed in Fastrack
In Production Category Specifications, GCR section 9.1.5.E.2.e.5., change as follows: "Cylinder head ports may be matched to the intake and exhaust manifolds to a depth of no more than 1 inch from the port mating surface."
unclearEP Mazda RX-7 12A/13B gains fuel injection option on dual-y manifold with 42mm choke(s).
As printed in Fastrack
Effective November 1, 2022, in EP Spec Lines, change Carburetor. No. & Type as follows: Mazda RX-7 (12A/13B) (79-85): "12A: (1) Nikki 4 bbl carburetor w/ primary choke(s) bored to match secondary choke(s) on a stock manifold or (1) Auto-type 2 bbl w/42mm choke(s) on a “dual-y” manifold. 13B: (1) Auto-type 2 bbl w/ 42mm choke(s) on a “dual-y” manifold, (1) 2 bbl fuel injected throttle body w/ 42mm choke(s) on a “dual-y” manifold, or stock 13B fuel injection." Mazda RX-7 (13B) (86-91): "(1) Auto-type 2 bbl w/ 42mm choke(s) on a “dual-y” manifold, (1) 2 bbl fuel injected throttle body w/ 42mm choke(s) on a “dual- y” manifold, or stock 13B fuel injection."
Request for Corrado Stroke & Displacement Correction
wordingEP Subaru BRZ and Toyota 86/Scion FR-S model year ranges updated to 13-20.
As printed in Fastrack
In EP Spec Lines, Subaru BRZ (2013), change title changes: "Subaru BRZ (13 - 20)" In EP Spec Lines, Toyota Scion FR-S (2013), change title changes: "Toyota 86 / Scion FR-S (13 - 20)"
slowerEP Mazda MX-5 Global Cup 16-22 minimum weight set to 2400 lbs; sequential gearbox allowed with +150 lbs penalty.
As printed in Fastrack
Effective 05/01/2022 In EP Spec Lines, Mazda MX-5 Global Cup (16-22), change as follows: Weight (lbs): "see notes 2400" Notes: "Car preparation is limited to what is permitted by the MX-5 Global Cup rules, and the car must meet all MX-5 Global Cup rules except as otherwise indicated within this spec line. Competitors must have the current MX-5 Global Cup rules in their possession and present them upon request. Sequential gearbox is allowed with +150lbs."
fasterEP/FP/HP open cars may now use carbon fiber hardtops if they retain OEM appearance in all exterior profiles.
As printed in Fastrack
In Production Category Specifications, GCR Section 9.1.5.E.9.a.12 change as follows: "Open cars must remove convertible soft tops and all attaching bracketry and hardware. If the stock windshield is retained, OEM and aftermarket hardtops are allowed. Aftermarket hardtops must retain OEM appearance in all exterior profiles, and carbon fiber construction is not allowed. Any hardtop must be attached by positive fasteners."
In EP Spec Lines, Mazda RX-8 (04-11) (alternate), make the following changes to Carburetor. No. & Type: "Renesis: Fuel Injection. 13B: d (1) Auto-type 2 bbl carb w/ 42mm choke(s) on a “dual-y” manifold, (1) 2 bbl fuel injected throttle body w/ 42mm choke(s) on a “dual-y” manifold, or stock 13B fuel injection."
wordingEP and FP Production clarifies idle control valve rules: stock devices allowed original, removed with blocked ports, or mechanical replaced with electronic stock type.
As printed in Fastrack
In Production, GCR Section 9.1.5.E.1.b.9, add the following: "Stock/original idle control devices can be utilized in their original, unmodified location and condition, or completely removed and any resulting openings blocked off. A mechanical stock/original idle control device can be replaced with an electronic stock/original type of idle control device, with the original mechanical idle ports in the throttle body blocked off." In Production, GCR Section 9.1.5.E.2.b.9, add the following: "Stock/original idle control devices can be utilized in their original, unmodified location and condition, or completely removed and any resulting openings blocked off. A mechanical stock/original idle control device can be replaced with an electronic stock/original type of idle control device, with the original mechanical idle ports in the throttle body blocked off."
slowerEP BMW Z3 2.5L intake restrictor reduced from 59mm to 58mm flat plate.
As printed in Fastrack
Effective 3/1/2022 In EP, make changes to BMW spec lines as follows: BMW Z3 2.5L - 59 58mm Flat Plate Intake Restrictor is required with both stock or alternate throttle body. BMW 328i/is E36 (96-99) - 62mm Flat Plate Intake Restrictor is required. BMW 328i/ci E46 (01-06) - 62mm Flat Plate Intake Restrictor is required. BMW 325i/is E46 (01-06) - 60mm Flat Plate Intake Restrictor is required. BMW 325i/is E36 (92-95) - 60mm Flat Plate Intake Restrictor is required. BMW 325is M-Technic (1994) - 60mm Flat Plate Intake Restrictor is required.
fasterFord Mustang 99-03 classified to EP at 2700/2768/2835 lbs; 94-98 Mustang weight reduced to 2550/2614/2678 lbs.
As printed in Fastrack
In EP Spec Lines, Ford Mustang (94-98), change weight as follows: "2700 2550 *2768 2614 **2835 2678" In EP Spec Lines, classify Ford Mustang (99-03) as follows:
A specification table follows in the original; it is not shown here.
tyres & wheelsEP, FP, HP Improved Touring cars may use any DOT-approved tire per section 9.3.45 in Production class.
As printed in Fastrack
In Production, GCR Section 9.1.5.B.5, change as follows: "Any Improved Touring car meeting all the requirements of ITCS 9.1.3 may compete in the Production class in which the same make, model and engine displacement car is classified. For Improved Touring cars competing in Production, the level of preparation and modifications will be as determined by ITCS 9.1.3 and not by PCS 9.1.5, however any DOT approved tire as defined by 9.3.45 is allowed."
wordingEP, FP, HP classes allow stock/original idle control devices unmodified or completely removed with openings blocked.
As printed in Fastrack
In GCR, Section 9.1.5.E.1.b.1., change as follows: “All inducted air must pass through the venturi(s) of the car’s carburetor(s), except that which passes through a stock/original idle control device.“ In GCR, Section 9.1.5.E.1.b.4., change as follows: “Fuel injection: All inducted air must pass through the throttle body and be subject to control by the throttle butterfly), except that which passes through a stock/original idle control device.“ In GCR, Section 9.1.5.E.1.b., add the following: ”9. Stock/original idle control devices can be utilized in their original, unmodified location and condition, or completely removed
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and any resulting openings blocked off. “ In GCR, Section 9.1.5.E.2.b.1., change as follows: “All inducted air must pass through the venturi(s) of the cars carburetor(s), except that which passes through a stock/original idle control device. “ In GCR, Section 9.1.5.E.2.b.4., change as follows: “Fuel Injection: All inducted air must pass through the throttle body and be subject to control by the throttle butterfly), except that which passes through a stock/original idle control device. “ In GCR, Section 9.1.5.E.2.b., add the following: “9. Stock/original idle control devices can be utilized in their original, unmodified location and condition, or completely removed and any resulting openings blocked off. “
wordingEP, FP, HP front-wheel-drive cars may alter body and suspension to install alternate transmission, transaxle, and axle shaft.
As printed in Fastrack
In Production, GCR sections 9.1.5.E.1.n.4. and 9.1.5.E.2.n.4. change as follows: "For rear wheel drive cars, the transmission tunnel and tunnel cover can be altered to allow the installation of an alternate transmission and/or driveshaft. For front wheel drive cars, the body, unibody, frame, suspension crossmembers/subframes and their components may be altered to the extent required to allow the installation of an alternate transmission, transaxle and/or driveshaft axle shaft."
wordingEP BMW Z3 2.5L allows alternate throttle body from 92-95 325i with Turner adapter; head casting 1738400 permitted with specific blocks.
As printed in Fastrack
In EP Spec Lines, BMW Z3 2.5L, change Notes as follows: "Comp. Ratio Limited to 12.0:1, Valve lift limited to .500”. To replace stock drive-by-wire throttle body, a Alternate throttle body from BMW 92-95 325i (part #13541748105) is permitted only with Turner Motorsports adapter plate (part #TEN9990850) is permitted. Cylinder head casting number 1738400 permitted with use of the allowed iron block (casting number 1748933 or 1738566)."
slowerEP Porsche 944S2 89-91 requires 56mm flat plate intake restrictor; comp ratio max 12.0:1, valve lift max 0.500".
As printed in Fastrack
In EP Spec Lines, Porsche 944S2 (89-91), change Notes as follows: "Comp. Ratio limited to 12.0:1, Valve lift limited to .500”, Dry sump is allowed. 56mm Flat Plate Intake Restrictor is required. In order to facilitate the installation of the FPR, additional spacers/plates may be added to convert the mating area of the throttle body and the intake manifold into a flat surface. These pieces must maintain the stock 60mm throttle body bore, the FPR must be a separate piece that can be independently removed and measured, and the total thickness of all pieces (including the FPR) cannot add up to more than 1” in thickness. Can use the stock fuel tank if stock rear bumper and bumper support structure retained."
Classing Clarification for 1986 Toyota Corolla FX16
wordingHP Toyota MR-2 1.6L (85-89) track corrected to 15.47 inches front and rear.
As printed in Fastrack
In the HP "Toyota MR-2 1.6L (85-89)" spec line, please correct the Track column as follows: "1532 47 / 1532 47" In GCR, Section 9.1.5.C.4, please change as follows: "Track specifications will be set at 103% of the car’s stock track, plus 2.5 inches."
Request to Allow F22c Engine for 2000-2003 Honda S2000
unclearEP Lotus/Caterham 7 America carburetor changed from IT fuel injection prep to fuel injection.
As printed in Fastrack
In EP Spec Lines, Lotus / Caterham 7 America, change as follows: Carburetor No. & Type: "IT fuel injection prep Fuel injection" Notes: "Engine is limited to IT preparation except modifications permitted in sections 9.1.5.E.2.e, 9.1.5.E.2.f, and 9.1.5.E.2.h."
slowerEP, FP, HP clarifies percentage weight penalties sum first, then apply to base weight, rounding to nearest pound.
As printed in Fastrack
In GCR, Section 9.1.5.C. add as follows: "5. For percentage-based weight penalties, all applicable percentage values shall be summed first, and then applied to the vehicle’s minimum specified base weight, as listed in the PCS. The minimum vehicle weight shall be rounded to the nearest pound. For example, a car with a 1950lbs minimum specified base weight, that’s running a non-stock gear-engagement transmission and non-stock brake rotors and/or calipers, would calculate its minimum weight as follows: 5% transmission penalty + 2% brakes penalty = 7% total penalty 7% total penalty * 1950 lbs base weight = 2086.5 lbs 2086.5 lbs rounded to nearest pound = 2087 lbs minimum weight"
Change Classification of 84-87 Mazda 626 from FP to HP
suspension & brakesEP Austin-Healey 3000 Mk. I, II, III now allows TR-6 front calipers and discs as alternate.
As printed in Fastrack
In EP, Spec Lines, Austin-Healey 3000 Mk. I, II, III, add to Brakes Alt.: mm/(in.) as follows: "Rear Disc: #H82462 Front calipers & discs from TR-6 (std. or alt)"
Mk2 VW Consistency and Cleanup of FP and HP Spec Lines
wordingEP, FP, HP Level 1 and Level 2 induction systems: clarified carburetor and fuel injection rules, jets/needles/rods unrestricted in Level 2.
As printed in Fastrack
In Production, GCR section 9.1.5.E.1.b.1, make changes as follows: "All inducted air must pass through the venturi(s) of the car’s carburetor(s). Any carburetor(s) with restricted venturi(s) must retain such venturi(s) in the original location within the carburetor. The throttle plate, shaft location, and bore diameter (as measured at the throttle plate) shall remain as specified. Carburetor jets, jet needles, metering rods and needle valves are unrestricted. Choke mechanisms, plates, rods, and actuating cables, wires, or hoses can be removed. The number and type of carburetors must not be changed from stock, unless otherwise specified by the vehicles spec line. In all other regards, standard and approved optional carburetor(s) are unrestricted. All single carbureted cars may fit a permitted optional carburetor. Where the use of one (1) 40 DCN, DCNF, IDF carburetor is
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specified, a permitted optional carburetor may be substituted. Permitted optional carburetors are:" In GCR section 9.1.5.E.1.b.4, make changes as follows: "Fuel injection: All inducted air must pass through the throttle body and be subject to control by the throttle butterfly. The stock throttle body casting/housing must be retained. The inside dimensions of the throttle body casting/housing (as measured at the throttle butterfly) and all dimensions of the throttle butterfly must remain stock, but . T the throttle body can otherwise be ported and polished. The dimensions of the throttle butterfly must remain stock. The throttle butterfly shaft shall not be relocated. The outside diameter of the portion of the throttle butterfly shaft located in the throttle body bore must be no smaller than stock. The contour of the interface between the throttle butterfly shaft and the butterfly must remain stock. The throttle butterfly and any throttle butterfly to shaft screws/bolts can be attached to the throttle butterfly shaft by any means including welding or brazing. Holes or slots can be created in the throttle butterfly for purposes of idle adjustment only. The number of injectors must remain stock. The mounting position and the injection point must be stock. Electronic fuel injection may be substituted for the stock type of fuel injection. In all other respects the fuel injection system is unrestricted." In GCR section 9.1.5.E.2.b.1, make changes as follows: "All inducted air must pass through the venturi(s) of the car’s carburetor(s). Carburetor jets, jet needles, metering rods and needle valves are unrestricted. Choke mechanisms, plates, rods, and actuating cables, wires, or hoses can be removed. The number and type of carburetors must not be changed from stock, unless otherwise specified by the vehicles spec line. In all other regards, standard and approved optional carburetor(s) must not be modified. All single carbureted cars may fit a permitted optional carburetor. Where the use of one (1) 40 DCN, DCNF, IDF carburetor is specified, a permitted optional carburetor may be substituted. Permitted optional carburetors are:"
wordingEP BMW Z3 2.5L iron block casting 1738566-C designation removed, wording clarification only.
As printed in Fastrack
In EP, BMW Z3 2.5L, make changes to the spec line as follows: "Cylinder head casting number 1738400 permitted with use of the allowed iron block (casting number 1748933 or 1738566-C).
slowerEP BMW 2.8L, 328i E36/E46, and 325i E36 blocks now iron only; 325i E46 aluminum only.
As printed in Fastrack
In EP, correct the following spec lines as shown: BMW Z3 2.5L, add to "Notes" section: "Cylinder head casting number 1738400 permitted with use of the allowed iron block (casting number 1748933-C)." BMW Z3 2.8L (97-00), modify "Block Mat'l" section: "Alum or Iron" BMW 328i/is E36 (96-99), modify "Block Mat'l" section: "Alum or Iron"
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BMW 328i/ci E46 (01-06), modify "Block Mat'l" section: "Alum or Iron" BMW 325i/is E46 (01-06), modify "Block Mat'l" section: "Alum or Iron" BMW 325i/is E36 (92-95), modify "Block Mat'l" section: "Alum or Iron"
wordingHP Mini Cooper model year ranges for convertibles revised: 02-06 now includes 05-08, 07-13 now includes 09-15.
As printed in Fastrack
In HP Spec Lines, change as follows: "Mini Cooper (includes convertible) (02-06) (includes 05-08 convertible)" In HP Spec Lines, change as follows: "Mini Cooper (includes convertible) (07-13) (includes 09-15 convertible)"
wordingEP Caterham 7 Spec Line removes redundant suspension note, clarifies engine prep limits and comp ratio to 10.0:1.
As printed in Fastrack
In EP, modify the "Notes" section of the "Lotus/Caterham 7 America" spec line as follows: "Level 2 suspension preparation. Engine is limited to IT preparation except modifications permitted in sections 9.1.5.E.2.e., 9.1.5.E.2.f, and 9.1.5.E.2.h. and f. Comp. Ratio limited to 10.0: 1, Valve lift limited to .380”." Note that the "Level 2 suspension preparation" limitation is already mandated by the fact that this is a "Prep Level 2" classified vehicle. Removal of that wording from the "Notes" section is purely due to redundancy, and not to change the allowed preparation.
slowerEP BMW Z3 2.5L compression ratio capped 12.0:1, valve lift .500, 59mm restrictor required; Z3 2.8L same limits added; 944S2 compression 12.0:1, valve lift .500, 56mm restrictor required.
As printed in Fastrack
In EP, BMW Z3 2.5L, change notes as follows: "Comp. Ratio limited to 12.0:1, Valve lift limited to .500”. To replace stock drive-by-wire throttle body, alternate throttle body from BMW 92-95 325i (part #13541748105) with Turner Motorsports adapter plate (part #TEN9990850) is permitted. 59mm Flat Plate Intake Restrictor is required with both stock or alternate throttle body. Alternate throttle body from BMW 92-95 325i part number 13541748105 permitted only with Turner Motorsports adapter plate part number TEN9990850 to replace drive-by- wire throttle body." In EP, BMW Z3 2.8L (97-00), add to the notes as follows:
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"Comp. Ratio limited to 12.0:1, Valve lift limited to .500”. 59mm Flat Plate Intake Restrictor is required." In EP, Porsche 944S2 (89-91), add to the spec line as follows: Fuel Injected Equipped Throttle Body Inside Diameter - "60mm" stock "Comp. Ratio limited to 12.0:1, Valve lift limited to .500”, Dry sump is allowed. 56mm Flat Plate Intake Restrictor is required. Can use the stock fuel tank if stock rear bumper and bumper support structure retained."
In HP, Nissan/Datsun PL510, make changes to the spec line as follows: Carburetor No & Type: "(1) 40 DCN or, DCNF w/ 32mm choke(s),. 32mm choke(s) req'd, or (1) 36mm DCNVH. (2) auto type side draft(s) w/ 32mm choke(s) on I.R. manifold @ 90lbs penalty." Notes: "Compression ratio limited to 12.0:1, Valve lift limited to .450”. (2) auto type side drafts w/ 32mm choke(s) on I.R. manifold allowed @ 2050 (*2101 **2153). Nissan/Datsun 240Z/260Z/280Z front rotors and calipers and rear aluminum drums are permitted."
slowerEP BMW fuel injected throttle body maximum inside diameter set to 64mm.
As printed in Fastrack
In EP, Fuel Injected Equipped Throttle Body Inside diameter, make changes as follows: Add "64" as maximum inside diameter and delete any other wording.
fasterHP Datsun 1200 carburetor choke size increases from 26mm to 30mm.
As printed in Fastrack
In HP Spec Lines, Nissan/Datsun 1200, make changes as follows in Carburetor No. & Type: "(1) 40 DCN, DCNF, IDF, 26mm choke(s) req’d. w/ 30mm choke(s), (2) auto type side draft w/ 30mm choke(s) on I.R. manifold."
wordingFP and EP Mazda Miata models standardized to 55mm throttle body diameter; brake spec clarified.
As printed in Fastrack
In FP, Mazda Miata 1.6L (90-97), make changes as follows: Brakes Std.: "Factory spec @ all 4 wheels (F) 235 x 18 Vented Disc (R) 231 x 9 Solid Disc" Throttle body Diameter: "stock throttle body I.D. 55mm" In EP, Mazda MX-5/Miata 1.6L (-1993), make changes as follows: Brakes Std.: "(F) 235 (9.3) x 18 Vented Disc (R) 231 (9.1) x 9 Solid Disc"
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Throttle body Diameter: "stock throttle body I.D. 55mm" In EP, Mazda MX-5/Miata 1.8L (90-97), make changes as follows: Brakes Std.: "(F) 235 ( 9.3) x 18 Vented Disc (R) 231 (9.1) x 9 Solid Disc" Throttle body Diameter: "stock throttle body I.D. 55mm" In EP, Mazda MX-5/Miata (94-97), make changes as follows: Brakes Std.: "(F) 235 x 18 Vented Disc (R) 231 x 9 Solid Disc" Throttle body Diameter: "stock throttle body I.D. 55mm" In EP, Mazda MX-5/Miata (99-03), make changes as follows: Brakes Std.: "(F) 235 (9.3) x 18 Vented Disc (R) 231 (9.1) x 9 Solid Disc" Throttle body Diameter: "stock throttle body I.D. 55mm"
Re-organize Prep2 Cylinder Head Rules for Clarity & Consistency
wordingEP, FP, HP cylinder head rules reorganized for clarity; no performance change.
As printed in Fastrack
In Production, GCR section 9.1.5.E.2.e, delete section and replace as follows: e. The Cylinder Head can only be modified: 1. To install an alternate camshaft, and/or adjustable cam gears. 2. To port match on the port mating surface to a depth of no more than one inch. 3. To facilitate the installation of permitted alternate components, provided the modification serves no other function. 4. To achieve the maximum specified compression ratio by the machining of the deck surface. 5. To completely plug the holes resulting from the removal of EGR valves and air nozzles. The plugs must
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serve no other purpose. 6. To completely plug the stock fuel injection ports in the cylinder head, if the stock fuel injection is removed and carburetors are utilized. The plugs must serve no other purpose. 7. To utilize O-rings to replace or supplement a cylinder head gasket. 8. To fit valve seats. Valve seats are unrestricted. Valve seat angles are unrestricted. The valve seat insert can be no taller than one half inch. "e. Cylinder Head 1. The cylinder head may be modified to allow installation of permitted alternate components, provided the modification serves no other purpose. 2. Valve seats and valve seat angles are unrestricted. The valve seat may be no taller that one half inch. 3. The cylinder head deck surface may be machined to achieve the specified compression ratio and to allow the installation of o-rings to replace or supplement the cylinder head gasket. 4. Holes resulting from the removal of EGR valves, air nozzles and fuel injectors (if the stock fuel injection system is removed and carburetors substituted) may be plugged, provided the plugs serve no other purpose. 5. Cylinder head ports may be matched to the intake manifold to a depth of no more than 1 inch from the port mating surface."
Request bodywork for Austin Healey Bugeye Sprite MK1
wordingFP and HP Austin-Healey Sprite Mk I and MG Midget variants may replace rear bodywork aft of cockpit with stock-appearing alternate material components.
As printed in Fastrack
In FP, Austin-Healey Sprite Mk I, II, III, IV / MG Midget Mk I, II, III, IV, & 1500, add to the notes as follows: "Sprite Mk I only may replace exterior rear body work, aft of the cockpit and rearmost door opening, with stock appearing components of an alternate material." In HP, Austin-Healey Sprite Mk I, II, III, IV / MG Midget Mk I, II, III, IV, Prep 1, 948cc, add to the notes as follows: "Sprite Mk I only may replace exterior rear body work, aft of the cockpit and rearmost door opening, with stock appearing components of an alternate material." In HP, Austin-Healey Sprite Mk I, II, III, IV / MG Midget Mk I, II, III, IV, & 1500, Prep 1/2, 1275cc, add to
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the notes as follows: "Sprite Mk I only may replace exterior rear body work, aft of the cockpit and rearmost door opening, with stock appearing components of an alternate material." In HP, Austin-Healey Sprite Mk I, II, III, IV / MG Midget (ALL), Prep 2, 1275cc, add to the notes as follows: "Sprite Mk I only may replace exterior rear body work, aft of the cockpit and rearmost door opening, with stock appearing components of an alternate material." In HP, Austin-Healey Sprite Mk I, II, III, IV / MG Midget (ALL), Prep 2, 1098cc, add to the notes as follows: "Sprite Mk I only may replace exterior rear body work, aft of the cockpit and rearmost door opening, with stock appearing components of an alternate material." In HP, Austin-Healey Sprite Mk I, II, III, IV / MG Midget Mk I, II, III, IV, & 1500, Prep1, 1098cc, add to the notes as follows: "Sprite Mk I only may replace exterior rear body work, aft of the cockpit and rearmost door opening, with stock appearing components of an alternate material."
wordingProduction carb rules clarified: carburetor options, fuel injection throttle body dimensions, and intake manifold restrictions reorganised and refined.
As printed in Fastrack
In Production, GCR section 9.1.5.E.1.b., make changes as follows: 9.1.5.E.1.b – Drive Train Level 1, Induction System “1. All inducted air must pass through the venturi(s) of the car’s carburetor(s). Carburetor jets, jet needles, metering rods and needle valves are unrestricted. Choke mechanisms, plates, rods, and actuating cables, wires, or hoses can be removed. The number of carburetors must not be changed from stock, unless otherwise specified by the vehicles spec line. All single carbureted cars may fit a permitted optional carburetor. On cars w Where the use of one (1) 40 DCN, DCNF, IDF carburetor is required specified, a permitted optional carburetor may be substituted. Permitted optional carburetors are: can fit
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one (1) of the following permitted optional carburetors: 1. Weber 32 DGV/DGAV/DGEV 2. Weber 32/36 DGV/DGAV/DGEV 3. Weber 32/36 DFV/DFAV/DFEV 4. Weber 34 DAT/DATR/DATRA/DMTR 5. Holley-Weber 5200. Carburetor jets, jet needles, metering rods and needle valves are unrestricted. Choke mechanisms, plates, rods, and actuating cables, wires, or hoses can be removed. Where Weber carburetors are specified, Weber type carburetors can be substituted. The following are p Permitted Weber type carburetors are:
A specification table follows in the original; it is not shown here.
wordingEP, FP, HP carburetors clarified: jets, needles, metering rods, needle valves unrestricted; choke parts removable; permitted optional carburetors listed.
As printed in Fastrack
In Production GCR section 9.1.5.E.2.b.1., make changes as follows: 9.1.5.E.2.b.1., – Drive Train Level 2, Induction System “All inducted air must pass through the venturi(s) of the car’s carburetor(s). Carburetor jets, jet needles, metering rods and needle valves are unrestricted. Choke mechanisms, plates, rods, and actuating cables, wires, or hoses can be removed. The number of carburetors must not be changed from stock, unless otherwise specified by the vehicles spec line. All single carbureted cars may fit a permitted optional carburetor. Where the use of one (1) 40 DCN, DCNF, IDF carburetor is specified, a permitted optional carburetor may be substituted. Permitted optional carburetors are:
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1. Weber 32 DGV/DGAV/DGEV 2. Weber 32/36 DGV/DGAV/DGEV 3. Weber 32/36 DFV/DFAV/DFEV 4. Weber 34 DAT/DATR/DATRA/DMTR 5. Holley-Weber 5200. The stock or permitted alternate carburetor must not be modified. Carburetor jets, jet needles, metering rods and needle valves are unrestricted. Choke mechanisms, plates, rods, and actuating cables, wires, or hoses can be removed. The number of carburetors must not be changed from stock. Where Weber carburetors are specified, a permitted Weber type carburetor can be substituted. Permitted Weber type carburetors are:
A specification table follows in the original; it is not shown here.
wordingEP Mazda RX-8 firewall modification allowed for 13B engine fitment in stock location.
As printed in Fastrack
In EP, Mazda RX-8 (04-11) (alternate), add to notes as follows: “Firewall may be modified as necessary for fitment of 13B into stock chassis engine mount location. Firewall must be sealed in the area of the modification.”
fasterEP, FP, HP clarified: tapered holes in ball joints now allowed for bolt conversion; wheel bearings and hubs unrestricted at any wheel.
As printed in Fastrack
Note from CRB: 9.1.5.E.5.b.2 in “Suspension and Steering Level 2: Suspension Components” states that “Suspension control arms, bushings, bearings, and ball joints are unrestricted.” However, allowance to ream out ANY tapered hole from a stock ball joint does not exist, unless being done to a specifically unrestricted component, like a suspension control arm. This is not the intent to restrict in that manner, and should be clarified: In GCR section 9.1.5.E.5.b.2, add wording as follows: “Suspension bushings, bearings, and ball joints are unrestricted. Tapered holes can be drilled or reamed, to allow a bolt to be used in place of a ball joint.”
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Note from CRB 9.1.5.E.2.o.5 in “Final Drive” states that “Axle shafts, bearings, bearing carriers, hubs, and universal joints/CV joints are unrestricted.” Therefore any of those items, all of which are defined in the GCR, that are part of the final drivetrain system of the vehicle, are indeed unrestricted. However, this rule would not apply to a non-driven axle, as it is not part of the drivetrain. It is agreed that allowing unrestricted bearings and hubs should not be limited to only the driven axle, and it should be applied to both axles/at any wheel: In GCR section 9.1.5.E.5.b. add wording as follows: “6. Wheel bearings and hubs are unrestricted.”
wordingEP open cars may now use aftermarket hardtops if they retain OEM appearance; specific model hardtop allowances removed.
As printed in Fastrack
In GCR section 9.1.5.E.9.a.12, remove wording as follows: “Open cars must remove convertible soft tops, and attaching bracketry and fasteners. Open cars retaining the stock windshield may retain the stock removable hardtop if attached to the car by positive fasteners. Open cars must remove convertible soft tops and all attaching bracketry and hardware. If the stock windshield is retained, OEM and aftermarket hardtops are allowed. Aftermarket hardtops must retain OEM appearance in all exterior profiles, and carbon fiber construction is not allowed. Any hardtop must be attached by positive fasteners.” In EP, remove wording from spec line notes as follows:
fasterEP Mazda RX-7 12A and 13B (79-85) lose up to 80 lbs; 13B (86-91) loses up to 79 lbs.
As printed in Fastrack
In EP, Mazda RX-7(12A/13B)(79-85), change the weights as follows:
A specification table follows in the original; it is not shown here.
Other letters
Clean-up to Standardize L1 & L2 Rules
#40891 from Production Committee · Recommended to the Board · Minutes (2026-10 Fastrack)
In GCR, Section 9.1.5.E.1.o.5., change as follows: "Axle shafts, bearings, bearing carriers, hubs, and universal joints/CV joints, and differential covers are unrestricted." In GCR, Section 9.1.5.E.1.m.6. change as follows: "Engine mounts of alternate design and/or material can be used, but there can be no change to the engine’s fore, aft or vertical location except as permitted in 9.1.5.E.1.o.6 7. Engine mounts must attach to the engine in their stock location." In GCR, Section 9.1.5.E.1.n.1. change as follows: "The Transmission and its mount(s) areis unrestricted, providing that it is fit in the same basic location as stock. Sequential shifting transmissions are prohibited. Pneumatic, hydraulic or electric actuation of the gear shift mechanism is prohibited."
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In GCR, Section 9.1.5.E.1.o.6. change as follows: "Transverse engine cars can rotate the engine about the crankshaft centerline to align axle shafts/constant velocity joints. On rear engine/rear drive cars the engine/drivetrain can be relocated vertically upward, to a maximum of one inch, to allow alignment of suspension and driveline components. Differential mounts are unrestricted, provided the differential remains in the stock location except as permitted in 9.1.5.E.1.o.7." In GCR, create section 9.1.5.E.1.o.7. as follows: "Transverse engine cars can rotate the engine about the crankshaft centerline to align axle shafts/constant velocity joints. On rear engine/rear drive cars the engine/drivetrain can be relocated vertically upward, to a maximum of one inch, to allow alignment of suspension and driveline components."
After much investigation and discussion into these items, and reflection upon the proceedings that brought them to light, it was determined that a wide variety of vehicles throughout the Production Category have modifications to diff covers, diff mounts, and trans mounts that could potentially be ruled illegal to the rules as they were written. Therefore, the rules addressing these items were heavily scrutinized for both clarity and intent, which then drove the decision to make the changes as published. It is believed that these revisions both clean up multiple "grey areas" and are within reason of the Prep. Level 2 ruleset. The Prod Committee understands that the timing and the optics of the situation are poor, but this doesn't affect the determination that changes to these rules to more accurately represent intent was needed.
Thank you for your request, but this is not recommended as it is considered outside of Production philosophy. Please note that through the GTL ruleset (Appendix N), a 12A or 13B rotary can be ran in a Miata. Through the inclusion of GTL into FP, that car could then legally be ran in FP to that GTL classification. This configuration can also run legally in STL.
Allow Unrestricted Mounting of Differential and Transmission
In GCR, Section 9.1.5.E.2.m.6. change as follows: "Engine mounts of alternate design and/or material can be used, but there can be no change to the engine’s fore, aft or vertical location except as permitted in 9.1.5.E.1.o.6 2.o.7. Engine mounts must attach to the engine in their stock location." In GCR, Section 9.1.5.E.2.n.1. change as follows: "The Transmission and its mount(s) areis unrestricted, providing that it is fit in the same basic location as stock. Sequential shifting transmissions are prohibited. Pneumatic, hydraulic or electric actuation of the gear shift mechanism is prohibited." In GCR, Section 9.1.5.E.2.o.6. change as follows: "Transverse engine cars can rotate the engine about the crankshaft centerline to align axle shafts/constant velocity joints. On
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rear engine/rear drive cars the engine/drivetrain can be relocated vertically upward, to a maximum of one inch, to allow alignment of suspension and driveline components. Differential mounts are unrestricted, provided the differential remains in the stock location except as permitted in 9.1.5.E.2.o.7." In GCR, create section 9.1.5.E.2.o.7. as follows: "Transverse engine cars can rotate the engine about the crankshaft centerline to align axle shafts/constant velocity joints. On rear engine/rear drive cars the engine/drivetrain can be relocated vertically upward, to a maximum of one inch, to allow alignment of suspension and driveline components."
Make it Clear that Differential Covers are Unrestricted
In GCR, Section 9.1.5.E.2.o.5., change as follows: "Axle shafts, bearings, bearing carriers, hubs, and universal joints/CV joints, and differential covers are unrestricted."
In section 9.1.5.E.11, make the following modification: "Glass headlight, front parking, side marker and signal light components must be removed. Plastic headlight, front parking, side marker and signal light components can be removed. The headlight bezels/rims must remain in their stock locations but can be replaced by components of an alternate material, provided their appearance remains stock. If the stock headlight, front parking, side marker or signal light lenses/covers are removed the resulting openings must be covered with wire mesh screen or solid panels of the same or a flatter contour than the stock lenses/covers. The openings created by the removal of these items must be covered with screens or panels. These covers must be the same or flatter contour as the stock lenses/covers, and may be attached to or integrated into surrounding bodywork. Headlight bezels/rims must remain in their stock locations but can be
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replaced by components of an alternate material, provided their appearance remains stock." In section 9.1.5.E.11.A, make the following modification: "Retractable or “pop up” headlight assemblies can be run in their open, partially opened, closed position or removed in their entirety. The openings created by the removal of the assembly must be covered with screens or panels. These covers must be the same or flatter contour as the stock assembly in its closed position, and may be attached to or integrated into surrounding bodywork, but need not retain any bezels/rims."
This is not recommended at this time. Several adjustments have been made to this classification in the past year and the data gathered has shown an improvement in performance. The PAC would like to continue to monitor this before any additional changes are considered.
Fiat 124 Spider EP 1995cc Increase Choke Size from 36mm to 40mm
This vehicle specification saw a weight decrease and a choke size increase in 2025, and the full impact of those changes may not yet be fully reflected or understood. At this point, it would be helpful to either gather additional on-track performance race data or provide further context and supporting information to clarify why the current specification is believed to be uncompetitive as it stands.
Thank you for your request, but the PAC would like to see this car run some under its current configuration before additional changes will be considered.
The rule states "Cars equipped with power steering as standard equipment can modify, substitute, disable and/or remove the power pump, related hoses and mounting brackets." Any changes made to the power steering system would have to be defended within this rule as written. If you have a more specific or detailed question, please submit another letter.
Revisions to Transmission Rules Consistent with Spec Line Format
In GCR, Section 9.1.5.E.1.n., change as follows: "5. The "Trans. Speeds" number of transmission speeds l isted in a car’s specification line indicates the maximum is the number of forward gears that may be operable by the driver from the normal seated position (e.g. a 6 speed transmission with 1 forward gear removed/disabled is considered a 5 speed transmission). 6. The "Trans. Speeds" number listed in a car’s specification line indicates the maximum number of forward gears that may be operable by the driver from the normal seated position (e.g. a 6 speed transmission with 1 forward gear removed/disabled is considered a 5 speed transmission)."
Please Provide Update on Current State of Letter 34738
Thank you for your letter, but this request is Not Recommended at this time. The performance potential of the 2.8L BMW's in EP has proven to be adequate.
We appreciate your perspective and feedback. After thorough consideration of the survey responses, input from our tire manufacturers, the current state of wheel size variation and competition balance within each class, potential performance benefits that could be realized by the proposed changes, the ever-increasing costs of racing, and the current environment of Road Racing in general, the PAC has come to the conclusion to NOT make any large, sweeping changes to the current wheel specs at this time. It is evident that this is a sensitive and polarizing subject with no clear answer to what the best direction is for the Production Category, and that is ultimately why this decision is being made. Note that instances where a discrepancy appears to exist versus typical max wheel spec practices may still be considered for adjustment. The PAC wishes to thank all survey participants, as their responses did highlight how varied the opinions are on this subject, as well
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as any other input that was provided to help make this decision.
Thank you for your letter. Per all documentation that the Prod Advisory Committee has been able to find and review, the 56mm throttle body size that is currently listed on the "Ford Mustang (99-03)" spec line is correct. If the letter writer has reliable documentation that contradicts this, please provide it for additional consideration. Additionally, the currently indicated weight and wheel size are also correct as listed for EP competition.
Thank you for your letter. The current 50lbs difference between the 2.5L Z4 and 2.5L Z3 is fair until additional data and results prove otherwise. They are not the same car, with different suspension design, bodywork, and aero drag (increased frontal area does not always increase aero drag). The brake sizes are very similar, and both are permitted the same max 18x8 wheel width. If there are concerns with sourcing a 17" or 18" racing slick, then consider running a 15" wheel like most current BMW Z3 and E36 racers in EP are doing.
Thank you for your letter. Permitting a non-original intake manifold is against Production Category philosophy. If further positive performance adjustments are desired for this car, other options will need to be proposed and considered that are more in line with class philosophy.
Thank you for your letter, however, the Flat-Plate Restrictors that are currently applied across a variety of BMW's in EP are accurate to current intent, with respect to power output, competition weight, chassis differences, etc. between them.
Thank you for your letter. The 2.5L engine in the Z3 and Z4 are nearly identical (bore, stroke, horsepower, torque, manifolds, etc.) and it is reasonable to expect that their performance potential when prepared to Production specifications will also be similar. In light of this fact, the use of the same FPR on the 2.5L Z4 as the Z3 is necessary to bring the Z4 into the EP performance envelope. The Z4 races at a heavier minimum weight than the Z3 due to its improved rear suspension and larger brakes front and rear. Lastly, "slick" race tires are available for 17” diameter wheels. The letter writer is encouraged to campaign the car so that further data can be collected and analyzed, in order to help determine if any further adjustments are warranted.
2010-2014 VW Golf E Production Classification Request
Thank you for your letter. This request is not recommended based on the fact that the letter writer requested an alternate intake manifold be included in the classification. This is contrary to class philosophy. The request can be remade without the alternate intake manifold, if there's desire to campaign it as such.
Thank you for your letter and bringing up this idea. The Prod Advisory Committee would have no problem with considering such a circumstance on a case-by-case basis, but don't see a need or a path forward for creating a sweeping allowance in the Production Ruleset for such a thing. Again though, if someone wanted to make a request to classify a specific turbocharged vehicle into the Production category, but without the turbocharger, that is a discussion that would certainly be had and studied for feasibility.
Thank you for your letter but this is not recommended. Permitting the '99+ head would create an engine & chassis combo that never existed from the factory. Additionally, the advantage this classification has is being permitted a full-prep chassis allowance, which the '99 Miata in EP does not have. This explains why they have the same weights, where one has a full-prep chassis, and the other is capable of slightly more power. Lastly, although sourcing pre-99 1.8L Miata heads might be more difficult than finding '99+ 1.8L Miata heads, it is by no means impossible, especially when compared to what many other Production racers go through to source desired and usable OEM parts for their cars.
In GCR, Section 9.1.5.E.9.a.11., change as follows: "(Effective 6/1/2025) Glass headlight, front parking, side marker and signal light components must be removed. Plastic headlight, front parking, side marker and signal light components can be removed. The headlight bezels/rims must remain in their stock locations but can be replaced by components of an alternate material, provided their appearance remains stock. If the stock headlight, front parking, side marker or signal light lenses/covers are removed the resulting openings must be covered with wire mesh screen or solid panels of the same or a flatter contour than the stock lenses/covers."
Thank you for your letter. By permitting SMX cars to double-dip into EP, it would place a potentially large number of cars directly into the middle of the Production race group that are not prepped as or intended to run as Production cars, especially within the FP and HP fields, and potentially impact race finishes, points, and contingencies for cars that were actually prepped for and intended to race in Production. Additionally, there are modifications allowed in SMX that are not allowed in Limited-Prep Production (which all new classifications are to be classed as), meaning an allowance would need to be made that's against Production philosophy in order to allow SMX to run in a Prod class. The duty of the PAC is to grow and support Production classes for Production racers, and for these reasons, this request is not
Thank you for your letter. Please see response to Letter #37651, where the requested weight change was made to this classification. The additional request for "unlimited" cam lift is outside of Prep Level 2 philosophy.
Thank you for your letter, but this allowance is not recommended. The boring of stock cylinders to a Prod permitted overbore appears to be doable with these engines, and having custom pistons made to fit the new overbore is a reasonable and typical component for building a Prod engine to the existing rules.
TR8 Axle Housing and Differential Gears, Injection Request.
Thank you for your letter, but this allowance is not recommended. The alternate axle housing and diff that's being requested are outside of class philosophy, and although stock/legal rear housings and applicable diff options might not be cheap and plentiful, they do still readily exist. Additionally, if Fuel Injection is desired, the TR8 spec line is already allowed to run its stock fuel injection system and modify it within the permitted rules.
Please Accommodate a Modern Tire Option, 100TW, 200TW
Thank you for your letter, but this is not recommended. Competitors are already allowed to run whatever tire they choose in the Production Category provided it is fitted to a permitted wheel per their spec line. There is zero intention or desire to begin making special weight/competition balance allowances for whatever different tires a competitor may choose to run.
Thank you for your letter. After discussion with the letter writer, it was determined that STU would be a better fit to consider running this existing car at its existing prep level, as it can be campaigned there as-is right now with no additional classification activity necessary. If the letter writer does wish to eventually prep his car to and run it within the Production Category Ruleset, then a request to classify into EP could be reconsidered at that time.
Thank you for your letter. The Wheel & Tire Survey is currently in the final stages of development and approval. It should be sent out in early September prior to the Runoffs.
Thank you for your letter. Per 9.3.28, this request needs to be addressed to the Road Racing Technical Manager for approval: “9.3.28. HAND CONTROLS: Hand controls may be approved on a case-by-case basis. Such approval shall be in writing from the Road Racing Technical Manager and shall be in the driver’s possession at all competitions.”
Clarification of Rule 9.3.26 Fuel Cell Specifications
Thank you for your letter. Without knowing your specific car, as long as it fits the statement of requirements of the first sentence of 9.3.26 your interpretation is correct.
Thank you for your letter, but allowing a higher quantity of gears beyond what a car came with originally, is not within class philosophy. If the competitive balance of a particular car is in question, then a suggestion should be made for an adjustment that's within the usual philosophy of the Production category.
Thank you for your letter, however your suggested changes are not recommended at this time. Several changes were made within the EP class following the completion of the 2023 Season, including some to this vehicle. The Production Advisory Committee and CRB require additional and data before any additional adjustments will be considered.
Competition Adjustment for Caterham 7, Pages 477-478 of the GCR
Thank you for your letter, but adjustments for this specification are not recommended at this time. It is known that the Caterham is down in trap speed relative to most of its competitors, but it's also one of the class leaders in most of the other performance metrics, including acceleration rate up to a certain point before aero dependency becomes a large factor. If enough power is added to overcome that top-speed deficiency on faster tracks, then the car will become an outlier in acceleration rate between and out of corners, and dominate on slower speed tracks. The goal is to try and balance the average all of the performance attributes for every car, across an average of every track, and it is believed that the Caterham currently falls within that goal.
Thank you for your letter. Please look for a "What Do You Think?" survey to come out later this year regarding the future of the tire & wheel rules/specs in the Production Category. This is something that the Committee is actively working on now.
Thank you for your thoughts on this subject, as it has created much discussion within the Production Advisory Committee (PAC) regarding wheel and tire widths in the Production Category. The PAC has ultimately decided that yes, Member Input will be sought on this subject, regarding the future of wheel and tire width limitations within the Production Category. Expect a survey to be released within the first quarter of 2024 to gather the opinions of active/recent Production competitors on this subject.
Thank you for your letter. In EP, the 280Z is classified 135lbs heavier than the 280ZX because the 280Z spec line has the following allowances that the 280ZX does not get: - Carb option, with two Hitachi-SU with 46mm throttle bores. - Level1 dry sump, connecting rods, intake manifold porting, crankshaft, rocker arms and cam followers. There is no current reasoning for why this should be changed. If the letter writer feels that the 280Z is classified at too high of a weight versus its competitors, and a case can be made for it to receive a weight break, then that could be considered with a sperate letter.
Thank you for your letter. This chassis was never sold in the US with a 1.8L engine, nor did a prior classification ever exist that could be re-instated, and the current direction for the Production Category is to not create any new full-prep classifications. Due these points, creating this classification is not recommended.
In GCR, Section 9.1.5.E.1.b.2., change as follows: "Stock or permitted alternate sidedraft carburetor(s) can use an adaptor plate and/or a spacer in addition to any stock spacer, between the carburetor(s) and the intake manifold. Material for the adaptor plate and spacer is unrestricted. No adaptor plate or spacer can serve any purpose other than to space out and/or mate the carburetor(s) to the permitted intake manifold. The adapter or spacer cannot create a plenum or change the carburetor(s) orientation. The maximum thickness for the adapter, spacer, stock spacer or combination of all is 1.25”. For the purpose of these rules an Isolator is a spacer. Classifications that have no fuel injection allowance on their spec line may substitute a fuel injected throttle body in place of each of its permitted carb(s). This alternate throttle body must have a Choke with the same diameter of the approved carb(s). A Flat Plate Intake
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Restrictor matching the specified choke dimension may also be used. The fuel injector(s) must be part of the throttle body." In GCR, Section 9.1.5.E.1.b.3., change as follows: "Stock or permitted alternate downdraft carburetor(s) can use an adaptor plate and/or a spacer in addition to any stock spacer, between the carburetor(s) and the intake manifold. Material for the adaptor plate and spacer is unrestricted. No adaptor plate or spacer can serve any purpose other than to space out, or mate the carburetor(s) to the permitted intake manifold. The adapter or spacer cannot change the carburetor(s) orientation. Adaptors and spacers can have a bore larger than the throttle bore of the stock or permitted alternate carburetor(s). The maximum thickness for the adapter, spacer, stock spacer or combination of all is 1.25”. For the purpose of these rules an Isolator is a spacer. Stock carb(s), permitted alternate side-draft carb(s), permitted alternate downdraft carb(s), and permitted alternate fuel injected throttle bodies can use an adaptor plate/spacer to mount to the permitted intake manifold, in addition to any stock spacer. Material for the adaptor plate/spacer is unrestricted. No adaptor plate/spacer can serve any purpose other than to space out and/or mate to the permitted intake manifold. The adapter plate/spacer cannot create a plenum or change the orientation of the mounting. The bore diameter of the adaptor plate/spacer is unrestricted. The maximum thickness for the adapter plate/spacer and any stock spacer (if used) is 1.25”. For the purpose of these rules an Isolator is a Spacer." In GCR, Section 9.1.5.E.2.b.2., change as follows: "Stock or permitted alternate sidedraft carburetor(s) can use an adaptor plate and/or a spacer in addition to any stock spacer, between the carburetor(s) and the intake manifold. Material for the adaptor plate and spacer is unrestricted. No adaptor plate or spacer can serve any purpose other than to space out and/or mate the carburetor(s) to the permitted intake manifold. The adapter or spacer cannot create a plenum or change the carburetor(s) orientation. The maximum thickness for the adapter, spacer, stock spacer or combination of all is 1.25”. For the purpose of these rules an Isolator is a spacer. Classifications that have no fuel injection allowance on their spec line may substitute a fuel injected throttle body in place of each of its permitted carb(s). This alternate throttle body must have a Choke with the same diameter of the approved carb(s). A Flat Plate Intake Restrictor matching the specified choke dimension may also be used. The fuel injector(s) must be part of the throttle body." In GCR, Section 9.1.5.E.2.b.3., change as follows: "Stock or permitted alternate downdraft carburetor(s) can use an adaptor plate and/or a spacer in addition to any stock spacer, between the carburetor(s) and the intake manifold. Material for the adaptor plate and spacer is unrestricted. No adaptor plate or spacer can serve any purpose other than to space out, or mate the carburetor(s) to the permitted intake manifold. The adapter or spacer cannot change the carburetor(s) orientation. Adaptors and spacers can have a bore larger than the throttle bore of the stock or permitted alternate carburetor(s). The maximum thickness for the adapter, spacer, stock spacer or combination of all is 1.25”. For the purpose of these rules an Isolator is a spacer. Stock carb(s), permitted alternate side-draft carb(s), permitted alternate downdraft carb(s), and permitted alternate fuel injected throttle bodies can use an adaptor plate/spacer to mount to the permitted intake manifold, in addition to any stock spacer. Material for the adaptor plate/spacer is unrestricted. No adaptor plate/spacer can serve any purpose other than to space out and/or mate to the permitted intake manifold. The adapter plate/spacer cannot create a plenum or change the orientation of the mounting. The bore diameter of the adaptor plate/spacer is unrestricted. The maximum thickness for the adapter plate/spacer and any stock spacer (if used) is 1.25”. For the purpose of these rules an Isolator is a Spacer."
Thank you for your letter. There is no direct replacement cast-iron block that fits into the BMW Z4 chassis, so this proposed allowance is not feasible.
Thank you for your letter, but this request is not recommended. This specific classification has been granted several positive spec line adjustments in recent years, and it is not believed that any further are necessary at this time.
Thank you for your letter. Please see response to Letter #34010 in current Fastrack.
Remove 9.1.5.E.8.c
#34010 from Production Committee · Recommended to the Board · Minutes (2023-06 Fastrack)
In Production, Section, 9.1.5.E.8.c. remove as follows: "(Effective 01-01-2024) Cars using 13” wheels may run 8 inch wide (max) wheels, but only with Race Tires America American Racer 20.0-8.0-13, bias ply, non-belted tire. Cars using 15” wheels may run 10 inch wide (max) wheels, but only with Race Tires America American Racer 23.5-10.0-15, bias ply, non-belted tire."
Remove 9.1.5.E.8.c
#34010 from Production Committee · Member feedback requested · Minutes (2023-04 Fastrack)
The Production Advisory Committee is seeking member input regarding the possibility of removing rule 9.1.5.E.8.c: "9.1.5.E.8.c - Cars using 13” wheels may run 8 inch wide (max) wheels, but only with Race Tires America American Racer 20.0- 8.0-13, bias ply, non-belted tire. Cars using 15” wheels may run 10 inch wide (max) wheels, but only with Race Tires America American Racer 23.5-10.0-15, bias ply, non-belted tire." The original intent of this rule was to provide a second viable racing tire option to the Production Category when Goodyear stopped production of its bias-ply tires several years ago. At the time, Race Tires America made promises to supply their American Racer asphalt tire in appropriate sizes and road-racing compounds for use in Prod, but was not willing to say that it could be used on a 7" wide tire, which most 13" and 15" wheel applications in Production are limited to. Therefore this
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allowance was made, with the anticipation that Race Tires America would support it, it would become a viable option in the category, and racers would take up this option. Since then, the following has happened: - Goodyear has returned to making bias-ply slick tires, as well as a radial slick tire, for Prod competitors. - The American Racer tire is only produced in the softest compound that Race Tires America offers, which is not intended or viable for the longer circuit-racing events that the SCCA competes in. - The existence of this rule has been used to argue that even further special tire & wheel package allowances should be made, creating confusion regarding the direction and intent of the tire & wheel rules within the Prod category. As of this writing, it is not believed that any current Production racer is actively utilizing this rule, in order to run this tire & wheel package. If there is, and they would like to see this rule continue as-is, please let us know.
Please Revisit Tire and Wheel Width Rule Letter #33728
Thank you for your letter. There is no change to the original response to letter #33728, which requested that vehicles which are specified to run a MAX 13" diameter wheel be allowed to run a 15x7" wheel when using the B-Spec Hankook or SM Hoosier tire. It pointed at rule 9.1.5.E.8.c as justification to why this should be allowed. Rule 9.1.5.E.8.c allows for an increase in wheel WIDTH only, when running a specific America Racer tire. It does not allow for an increase in wheel diameter, versus what is on a vehicles spec line, which is not the same as what's being requested here. Furthermore, its existence alone is not enough of a justifiable reason for the PAC to make further special tire and wheel package allowances, which are outside the scope of the Production Category. If the goal is to just find a cheaper alternative than the radial or bias-ply slick tires that are common in Prod, with competitiveness not being a concern, then a competitor is free to use a DOT race or street tire that fits their MAX
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wheel size, as specified on their vehicles spec line.
Thank you for your letter, but it is believed that the method of adjusting the performance potential of this vehicle in question is appropriate for the effect that is desired. By trying to limit its performance potential by weight alone, that would only exacerbate the issue with how it competes in terms of straight-line and acceleration ability versus cornering and braking ability. Through the installation if a Flat Plate Restrictor, and not weight, the desired effect is to reduce the top-end and acceleration potential, while allowing it to still brake and corner in a manner that is competitive and within reason versus the rest of the class.
Headlight and Marker Light Covers, Mounting, and Gaps
Thank you for your letter. It is believed that the rules are adequate as written. It is ultimately the competitor’s responsibility to adhere to them in an appropriate and reasonable manner, and be able to defend the modifications they have made to their car versus the rulebook. It is clearly defined what lights can/must be removed, that the resulting holes left after the removal of these lights must be covered with a screen/panel, and how that screen/panel can be contoured. A reasonable interpretation would be to ensure that the screen/panel closely replicates the shape and location of the light(s) it is replacing, and that the stock shape and profile of the vehicle remains intact. But again, it is ultimately the competitors responsibility to defend the legality of their car versus the rules and how they are written.
Allow B-Spec cars to run in Prod & align with 9.1.5.B.5
#33596 from Production Committee · Recommended to the Board · Minutes (2023-01 Fastrack)
In GCR, Production Category, Section 9.1.5.B.5. change as follows: “Any Improved Touring car meeting all the requirements of ITCS 9.1.3 may compete in the Production class in which the same make, model and engine displacement car is classified. For Improved Touring cars competing in Production, the level of preparation and modifications will be as determined by ITCS 9.1.3 and not by PCS 9.1.5, including tire limitations as defined in 9.1.3.D.8.a.2. however any DOT approved tire as defined by 9.3.45 is allowed. This is intended to allow Improved Touring competitors to become more familiar with Production to assist them in determining whether to modify their cars to meet the requirements of PCS 9.1.5 and also to permit Improved Touring competitors to compete in all events open to Production cars.” In GCR, Production Category, Section 9.1.5.B. add the following:
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"6. Any B-Spec car meeting all the requirements of BSCS 9.1.10 may compete in the Production class in which the same make, model and engine displacement car is classified. For B-Spec cars competing in Production, the level of preparation and modifications will be as determined by BSCS 9.1.10 and not by PCS 9.1.5, including tire limitations as defined by 9.1.10.E.7."
Thank you for your letter. Not recommended to make this a category/class wide allowance, as it will become perceived as a “must have” modification. Most vehicles do not need it, and those that do can continue to be looked at and allowed on a case- by-case basis.
Thank you for your letter. Rule 9.1.5.E.5.c.5 already states the following: "Suspension pickup/pivot axis points can be reinforced but must remain in the stock location." Adding a shock/strut/tie bar would be considered the reinforcing of stock suspension pickup points, and therefore legal within this rule.
Letter writer was asked to provide a VTS and additional information for this potential classification. After multiple attempts, this was never received, therefore this request is Not Recommended at this time due to lack of information. If the letter writer would like to request it again with the appropriate info, then it can be reconsidered at that time.
Request Allowance for Stock Tank With Stock Crash Protection
Thank you for your letter. The allowed alternate head is only permitted with the allowed alternate block, as an entire originally mated together engine assembly. The purpose is not to allow mixing and matching of heads and blocks between the iron block engine and the aluminum block engine.
Thank you for your letter. The spec line for this vehicle includes the part number for the correct throttle body adapter plate to match its stock intake manifold to its approved alternate throttle body. The adapter plate the letter writer is referencing is for the incorrect 3.0L intake manifold.
Thank you for your letter. The practice of removing the front windshield frame-work from convertible cars has been a long- standing allowance in Prod, and there is no desire or need to deviate from that. If a competitor decides to retain that structure, and even add a hardtop if they want, that is also allowed. Specific roll-cage construction rules exist for either configuration.
Thank you for your letter. With other adjustments that have been recently made in EP to other front running classifications, an additional change with the RX7's is not recommended at this time. The overall competition balance of the class will continue to be monitored as this racing season continues.
Global MX5 Cup Car Ignores Production Class Philosophy.
Thank you for your letter. A response was made to this consideration in the October 2021 Fastrack, via #31071, and there has been no additional reasoning to reconsider.
Consider Disable/Remove Stock Variable Lift/Timing Systems
Thank you for your letter. After inspection of the GCR, it was determined that there's sufficient ability in the current rules for cam shafts, cam gears, rockers, sensors, wiring, and ECU's for stock Variable Lift & Timing systems (VANOS, VTEC, VVT-i, etc.) to be legally disabled or removed within them. This determination is being published as an "FYI".
Thank you for your letter. In order to properly determine if a performance related competition adjustment is warranted for this vehicle, the PAC needs to see it adequately built and campaigned towards the limit of the Production ruleset.
Thank you for your letter, but this is not recommended. Trying to balance the potential of different tires through weight breaks would be a difficult and unrealistic exercise, with constantly moving targets. It would also create an even bigger disparity in how different cars achieve their lap times. Competitors are free to use whatever tires they'd like, but their competitiveness cannot be guaranteed.
Thank you for your letter. Please see response to letter #31858, where several other changes were made in EP in an effort to improve the competition balance of the class. Due to those changes, this additional requested change is not recommended at this time, as the results of these changes needs to be seen.
Correcting/Standardizing the Prod Measurement Charts
Thank you for your letter. In late 2020 the PAC requested that SCCA's Technical Services go through all of the Production spec lines and standardize how the specs are presented. They should be uniform to what is shown in the column headers, so that where applicable, they are presented in both units, with metric being shown first and English being shown second in parenthesis. This process has now been completed, and the updated formatting will be present in the 2021 December GCR. As this was a lengthy process of manually inputting these values by hand, it is requested that each competitor verify that the content of their spec line still appears to be accurate, and provide feedback if any discrepancies are found.
Thank you for your letter. How valve lift is to be measured on all Prep Level 2 cars is already defined in 9.1.5.E.2.f.7: “Where maximum valve lift is specified, valve lift is measured at the valve with zero lash or clearance. There are a few exceptions to this rule, where a spec line specifically allows for valve lift to be "measured as raced - w/ lash". These spec lines are from the original "Limited Prep" classifications that were made, many years ago, and that was the process/ruling at that time. As the "Prep Level 2" ruleset matured, and more waves of cars got classified to it, this measurement method was re-evaluated and changed to the current rule. Previous classifications have since been allowed to "grandfather" their original rules. Just as competition balance is monitored between Prep Level 1 and Prep Level 2 cars, the same is true for
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these original "pseudo-Limited Prep" classifications. Reverting this valve lift measurement process again would not make building these cars any easier, would not balance the performance potential of the field, and just tempt competitors to re-do their cam designs to chase an extra few thousandths of lift. Due to all of that, this request is not recommended.
Thank you for your letter. Specifically listing the allowed body styles in a spec line (i.e. coupe, sedan, convertible) isn't necessary. The competitor would just need to be able to prove that the vehicle/spec line they're choosing to complete with, did indeed ever come from the factory in the body configuration that they're using, if it was ever questioned.
Thank you for your letter. This is not recommended. An allowance for a non-stock identical copy of these pieces would be difficult to enforce, and used examples appear to be still available at a reasonable cost.
Thank you for your letter. The allowances that are being requested are all outside the philosophy of Prep Level 2. It is also believed that this classification can become competitive as classified, if fully built to the extent of the rules, and continued development.
Thank you for your letter. By fitting a vented rotor where a solid rotor existed originally, this would be considered the use of a "non-stock-size brake rotor", and be subject to the 2% "non-stock brakes" weight penalty.
Thank you for your letter. With the new "non-stock brake calipers and rotors" allowance, that come with a pre-defined weight penalty, a new "Alt Brakes" package that permits a larger and vented rotor versus stock, is not going to be issued without weight penalty. If the letter writer wishes to run the package as he describes, it could be done with the "non-stock brake calipers and rotors" weight penalty.
#27417 (Jesse Prather) Alternate Brakes for Production
Thank you for your letter. No changes will be made to the new brake allowance rules at this time. As more races happen with cars that are utilizing these new rules, effects to competition balance will be reviewed.
Thank you for your letter. It is not believed that any additional changes need to be made to these rules. They already state that a vehicle must use its standard carburetor or an approved optional carburetor. A competitor must be able to defend that the carb he/she is using is either the stock carb, or an approved optional carb via its spec line or general Prod approved optional carb list. Additionally, further rules exist that define how a stock or optional carb can be adapted to a stock (or permitted) manifold. If for some reason a specific car cannot possibly adapt an approved carb to its approved manifold, within the current rules, addressing that would be a case-by-case basis.
"Thank you for your letter. After reviewing collected on-vehicle data, lap and segment data, and historical performance levels and lap times at Road America for the class, a significant competitive imbalance or class speed creep does not appear to be evident. The PAC will continue to monitor the performance of this car, as well as the general balance across all of EP, at a variety of tracks."
Thank you for your letter. This change is not recommended. A "Targa-Type Top" is defined in the GCR as being fully removable above the driver's seats, while a "T-Type Top" is defined as having two separate removable sections, but that the roof is otherwise in a fixed position, and removing a fixed position roof is not within class philosophy.
Thank you for your letter. The first line in the proposed changes to the brake rules was specifically designed and worded to protect the continued use of all currently approved brake packages without any weight penalty, as listed in the "Brakes Std." and "Brakes Alt." columns of a vehicle's spec line. So if your vehicle already has an alternate package specified in the "Brakes Alt" column of its spec line, then its continued use would absolutely still be permitted without any weight penalty.
Opposition to Changes to the Brake Rules in Production
In Production, GCR Section 9.1.5.E.2.f.5, change as follows: "Pushrods are unrestricted. Rocker shafts and/or shaft pedestals, when utilized in the stock system, can be replaced by alternate shafts and/or pedestals and are unrestricted. Valve rocker arms, and/or rocker type cam followers are unrestricted, but the rocker ratios and/or rocker/ follower ratios must be stock."
Thank you for your letter. The CRB does not recommend any further modifications to the currently proposed changes to the brake rules, but your concerns will be passed along.
Support Letter 27417 Except 6 Piston Front 4 Piston Rear Calipers
Thank you for your letter. The CRB does not recommend expanding the number of pistons on alternate calipers to 6. The responses to the distributed survey were overwhelmingly in favor of limiting caliper piston count to a max of 4. Market research has also shown that quality 4-piston alternate calipers are quite plentiful, while on average the pricing of similar 6-piston calipers increases.
Thank you for your letter. Many factors go into trying to determine how much power a car will make in Prod trim, including analysis of the stock engine design, specs, and limitations, and an educated estimate is made of the gains it could see within the Production rule-set. With no additional information being presented, like on-track performance, vehicle dynamics data, or dyno plots, there is no new reasoning presented to drive a re-evaluation of this vehicles classification. The Production Committee always encourages competitors to build, campaign, and share, to help build better parity and competitiveness for not only their own vehicle, but for all of the Production category.
Thank you for your letter. The introduction of ABS into the Production Category was discussed and surveyed at great length, while additional changes to the Brakes section of the rule-book were being considered. However, due to competitor response and feeling to this specific issue, as well as several other changes also being made to the brake rules at the moment, it is not recommended to add ABS into the Production Category at this time.
Request to Allow Modernization of Prod Brake Rules
In Production, GCR section 9.1.5.E.7., Brakes Level 1 and 2, make changes as follows: "a. Stock calipers must be retained. Cars fitted with integral hat brake rotors can convert to a two piece design hat and brake rotor. The alternate design hat must be made of ferrous or aluminum material. Alternate discs can be used, but must be made of ferrous material. Alternate drums can be used, but must be made of a ferrous or aluminum material. Alternate discs and drums must be the stock diameter, width and design. Brake rotors can not be cross drilled or slotted unless fitted as stock. Stock brake calipers and stock-size brake rotors may be used without penalty, as defined in the “Brakes Std.” and “Brakes Alt.” columns of a vehicle’s spec line. b. Any other non-stock brake calipers and/or non-stock-size brake rotors may be used with a penalty of 2% of the base weight.
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1. Non-stock brake calipers must have a max of 4-pistons and the caliper body must be made of ferrous or aluminum material. Calipers must be mounted in the same location and orientation as the stock positioning. Mounting brackets are unrestricted, but must be made of ferrous or aluminum material. Stock caliper mounting tabs may be modified or removed to facilitate caliper installation. In all other regards, non-stock brake calipers are unrestricted. 2. Non-stock-size brake rotors are unrestricted, provided they fit inside the max wheel limitations on a vehicle’s spec line. c. All brake rotors must be made of ferrous material, and can be cross-drilled and/or slotted. A two-piece hat and rotor design may be utilized, but the hat must be made of ferrous or aluminum material. d. Alternate drums can be used, but must be made of ferrous or aluminum material, and be the stock diameter, width, and design. b e. Cars fitted with rear drum brakes, can convert to rear disc brakes without penalty. Note that the “Brakes Std.” and “Brakes Alt.” listings on a vehicle’s spec line do not prohibit a car that was fitted with rear drum brakes stock, from converting to rear disc brakes under this rule. When converting from rear drum brakes to rear disc brakes: 1. Rear brake rotors must be solid and can be no larger in diameter than the largest permitted front brake rotor, as defined on the vehicle’s spec line. Rear brake rotors must be solid and made of a ferrous material. Rear brake rotors cannot be cross drilled or slotted. 2. Rear brake rotor hats can be made of a ferrous or aluminum material. 3. 2. Rear calipers and mounting brackets are unrestricted but must be made of a ferrous or aluminum material. The standard and alternate brake listings on a vehicle’s specification line, does not prohibit a car that was fitted with rear drum brakes as stock from converting to rear disc brakes under this rule. c f. Dual braking systems are required. Any dual brake master cylinder(s) and pedal assembly can be fitted. Pressure equalizing and proportioning valve devices are unrestricted. d g. Servo assists are unrestricted. e h. Drum brake wheel cylinders are unrestricted. f i. Brake pads and brake linings are unrestricted. g j. Brake lines are unrestricted. h k. The hand brake and its operating mechanism can be removed. i l. Brake Ducting Brake air ducts can be fitted. Front duct inlet(s) cannot extend to the side beyond the center-lines of the front wheels, or beyond the forward most part of the front bodywork/air-dam. Rear duct inlet(s) must face forward, cannot extend to the side beyond the center-lines of the rear wheels, or be located more than 24” forward of the rear axle center-line. 1. Brake air ducts can be fitted. 2. The front brake duct inlet(s) must not extend to the side beyond the centerlines of the front wheels, or forward of the forward most part of the front of the body or front air dam. 3. Rear brake duct inlet(s) must face forward, they must be located no more than 24” forward of the rear axle centerline and must not extend to the side beyond the centerlines of the rear wheels. m.4. Backing plates and dust shields are unrestricted."
Thank you for your feedback. The survey results are still being gathered, and its results will be the primary driving force for any changes that may occur.
Proposed Performance Penalties for Porsche and BMW
Thank you for your letter. The Club Racing Board would like to see the effect of these recent adjustments before any additional changes would be made. If the letter writer would like to submit some factual test data such as dyno or head flow plots, that would be incredibly helpful as the PAC continues to seek equal parity.
Thank you for your letter. The performance potential of this vehicle will continue to be monitored, to ensure that its recent classification change still allows it to remain a viable option in the class. Competitors are encouraged to bring them out, so additional data can be collected.
Alternate Side draft Carburetor Intake Manifold (Prep 2)
Thank you for your letter. 9.1.5.E.2.b.7 is the governing rule for all intake manifold's for all Prep Level 2 vehicles, regardless of if the OEM piece or an allowed alternative is being used, unless otherwise specified on its spec line.
Thank you for your letter. It is believed that this would already be considered legal under the rule 9.1.5.E.1.m.1 and 9.1.5.E.1.m.1: "The use of alternate engine components which are normally expendable and considered replacement parts, such as fasteners, gaskets, seals, bearings, water pumps, etc., is permitted."
Thank you for your letter. The Production Advisory Committee (PAC) is committed to creating, managing, and balancing Production classifications and Production cars. The PAC does agree that every car actively being raced in B-Spec should have an available classification in Production. Effort has been made over the past several months to make the necessary additions to Production so that every make/model that was raced in BS at the 2019 Runoffs, now currently also has a Production classification that it could compete under. If there are any B Spec racers whose vehicle is still not included in Production, and they are interested in competing in Production, they are urged to send in a letter for Production classification. Please note that by running under a Production classification, the competitor
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is expected to compete to the 9.1.5 Production Category rules of the GCR. Please also note the current existence of Production Category rule 9.1.5.B.5, which allows Improved Touring cars (a non-Runoffs eligible category) to compete in the Production class in which the same make and model car is classified, but wholly under the preparation, modification, and classification of their Improved Touring spec line and the Improved Touring rules.
Request to Allow Removal of Control Arms Rendered Obsolete
Thank you for your letter. There is not a significant advantage to allowing this, yet there's certainly some unintended consequence that could arise from it. Therefore, this is not recommended.
Thank you for your letter. This allowance is not recommended at this time, because it is outside of the scope of Limited Prep. Also note that pistons are already unrestricted.
Changes for DT L1/L2 Engine Builds Due to Re-Write Omissions
Thank you for your letter. After further review of this vehicles specs, and on-track results and data, no adjustments are recommended at this time. However, additional data on this classification is desired, and current competitors are encouraged to continue developing and campaigning their cars, so that more data can be gathered for any future adjustment consideration.
Thank you for your letter. The requested allowance is against the class philosophy, and adequate spring and ride height adjusting options are available for the rear of the BMW E36 chassis.
Allow Replacement of Rear Window Glass in Closed Cars
Thank you for your letter. Per rule 9.1.5.E.9.a.8.C, closed top cars are already allowed to replace their rear glass with polycarbonate material: “Rear, door, vent, and quarter window glass can be replaced with a clear polycarbonate material having a minimum thickness of 3mm.” Allowance of any holes in the rear window is still not recommended.
Thank you for your follow up letter. This request is still not recommended. There is too much difference between the two plates being compared in terms of port timing and porting potential. An alternative allowance is already given to update to the entire 13B engine.
Request to allow replacement of rear window glass in closed cars
Thank you for your letter. The Club Racing Board does not recommend this change. Openings in the rear window of closed roof cars could potentially weaken the window or allow exhaust fumes inside the vehicle.
Request for Better Rotors and Venting Restrictions
Thank you for your letter. The Club Racing Board does not recommend this change. Finding quality OE-style brake rotors has not been a known issue to date, but the PAC will continue to monitor parts availability across the category.
Thank you for your letter. This weight reduction is not recommended at this time, but the PAC encourages the letter writer to continue to develop and campaign this vehicle, as the performance parity across all of EP is continually monitored.
Supports Letter # 25426 Allow Drivers Seat Floor Pan
The end plates of the 12a and the 13b are too different to be considered interchangeable without impacting performance, and it is not an allowance that would be considered at this time. The allowance would modify the port timing and create a hybrid combination that never existed as an OEM assembly.