wordingGT3U wheel and tire requirements reorganized; 15×7 225 section at GT3 weight plus 275 lbs; 15×9 245 section at plus 275 lbs plus 1.5%; 16–18×9 245 section at plus 275 lbs plus 3.0%.
As printed in Fastrack
In STU Spec Lines, Table B: Alternate Vehicle and Engine Allowances, STU-GT3U, change Notes as follows: "All GT3U (Majors and Runoffs) cars using up to 15”x7” wheels limited to 225 section width tires shall run at current GT3 race weight plus 275lbs. All Gt3U cars shall run a DOT approved tire with a maximum section width of 245. GT3U cars are allowed optional 15”x9” wheels with a 1.5% weight addition or up to 18”x9” wheels with a 3.0% weight addition to the total weight including the 275 lbs Increase the minimum weight of all GT3/GT3U 2.0 liter unrestricted engines to +75 lbs. All GT3 cars running in STU must meet the minimum ride height of 3.0” for the main frame rails not including rub blocks and a 2” minimum for the front spoiler and splitter. 1. Wheel and tire requirements for GT3U
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a. Cars using up to 15”x7” wheels and up to a 225 section width DOT approved tires shall run at current GT3 race weight plus 275lbs. b. Cars using 15”x9” wheels and 245 section width DOT approved tires shall run at current GT3 race weight plus 275 lbs plus 1.5%. c. Cars using 16, 17, 18” x9” wheels and 245 section width DOT approved tires shall run at current GT3 race weight plus 275 lbs plus 3.0%. 2. The minimum weight of all GT3/GT3U 2.0 liter unrestricted engines plus 275lbs, plus 75lbs. 3. All GT3 cars running in STU must meet the minimum ride height of 3.0” for the main frame rails not including rub blocks and a 2” minimum for the front spoiler and splitter."
A specification table follows in the original; it is not shown here.
slowerSTU cars at or below 2,825 lbs minimum weight limited to 8-inch wheels; over 2,825 lbs limited to 9-inch wheels.
As printed in Fastrack
In GCR, Section 9.1.4.1.F.1., change as follows: "Wheels may not exceed 18 inches in diameter. Cars equal to or less than 2,850 2,825 lbs. minimum allowed race weight may not use wheels wider than 8 inches. Cars greater than 2,850 2,825 lbs. minimum allowed race weight may not use wheels wider than 9 inches."
slowerSTU GT3U minimum weight increases from GT3 race weight plus 225 lbs to plus 275 lbs; 2.0L unrestricted engines add 75 lbs.
As printed in Fastrack
In STU Spec Lines, STU-GT3U, GT3U, change Minimum Weight as follows: "Current GT3 race weight plus 225 275 pounds" In STU Spec Lines, STU-GT3U, GT3U, change Notes as follows: "All GT3U (Majors and Runoffs) cars using up to 15”x7” wheels limited to 225 section width tires shall run at current GT3 race weight plus 225 275lbs. All Gt3U cars shall run a DOT approved tire with a maximum section width of 245. GT3U cars are allowed optional 15”x9” wheels with a 1.5% weight addition or up to 18”x9” wheels with a 3.0% weight addition to the total weight including the 225 275lbs Increase the minimum weight of all GT3/GT3U 2.0 liter unrestricted engines to +75 lbs. All GT3 cars running in STU must meet the minimum ride height of 3.0” for the main frame rails not including rub blocks and a 2” minimum
cars addedSTU BMW M50B20TU engine 1991cc added, minimum weight per chart, must meet all STU engine regulations.
As printed in Fastrack
In STU Spec Lines, Table B: Alternate Vehicle and Engine Requirements, classify the following: Make: "BMW M50B20TU" Maximum Displacement: "1991" Minimum Weight: "Chart" Notes: "Must meet all STU engine regulations."
wordingSTL and STU weight calculation wording clarified; percentage adjustments combined before applying fixed weight adjustments.
As printed in Fastrack
In GCR, Section 9.1.4.1.H.6., change as follows: "The minimum weight is determined by the installed engine displacement, TIR or table spec line. It is to be used as the base weight for any chassis weight related adjustments. Chassis related All positive adjustments that are percentage based are performed by adding the total of all specified percentages first and subtracting the total of all negative specified percentages second if necessar y. Final step is addition or subtraction of specified weight in pounds." In GCR, Section 9.1.4.2.H.4., change as follows: "The minimum weight is determined by the installed engine displacement or table spec line. It is to be used as the base weight for any chassis weight related adjustments. Chassis related All positive adjustments that are percentage based are performed by
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adding the total of all specified percentages first and subtracting the total of all negative specified percentages second if necessary. Final step is addition or subtraction of specified weight in pounds."
wordingSTU GT86 Cups Car must meet 2022 Toyota GR Cup rules, including DOT tires with maximum section width of 245.
As printed in Fastrack
In STU Spec Lines, Table B: Alternate Vehicle and Engine Allowances, change Notes as follows: "Must meet all 2022 Toyota GR Cup rules, including tires or DOT tires conforming to section 9.1.4.O with a maximum section
A specification table follows in the original; it is not shown here.
cars addedSTU Mazda Renesis Street Port added to Table B with 2450 lbs minimum weight, street porting allowed.
As printed in Fastrack
In STU Table B: Alternate Vehicle and Engine Allowances, add the following: Model: "Mazda Renesis Street Port" Maximum Displacement (cc's): "N/A" Minimum Weight: "2450" Notes: "Street porting allowed. Alternate 70mm choke throttle body from the following list allowed: OE from 1996- 2004 Mustang 4.6 liter V8; BBK #1700 (e.g., Summit #BBK-1700); Summit #227204; Trickflow #24070 1” thickness max manifold adapter allowed."
wordingSTU Mazda MZR (LF, L3, L5) adds Fab 9 Elite NC MX5 Performance Intake manifold as approved option.
As printed in Fastrack
In STU Spec Lines, Table A: Alternate Vehicle and Engine Requirements, Mazda MZR (LF, L3, L5), add to Notes as follows: "Short blocks, heads, and intakes may be freely swapped within these engine designations. May use Goodwin Part # 61-2510, Gato Performance Part #31972, or Jack Spania Racing 70 mm sheet-metal aluminum or Fab 9 Elite NC MX5 Performance Intake manifold. Must use stock throttle body or Acura part number 16400-PND-A17."
Request for Permission on Aftermarket Turbo Kit and Intake
fasterSTU Mazda MZR (LF, L3, L5) Turbo classified; Jack Spania Racing 70 mm intake manifold and Fab9 Tuning bottom-mount turbo kit approved.
As printed in Fastrack
In STU Spec Lines, Table A: Alternate Vehicle and Engine Allowances, Mazda MZR (LF, L3, L5), change Notes as follows: "Short blocks, heads, and intakes may be freely swapped within these engine designations. May use Goodwin Part # 61- 2510 or, Gato Performance Part #31972 or Jack Spania Racing 70 mm sheet-metal aluminum Intake manifold. Must use stock throttle body or Acura part number 16400-PND-A17." In STU Spec Lines, Table A: Alternate Vehicle and Engine Allowances, classify Mazda MZR (LF, L3, L5) Turbo as follows: STU Maximum Displacement (cc's) Minimum Weight Notes Mazda MZR (LF, L3, L5) Turbo
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Varies Chart Short blocks, heads, and intakes may be freely swapped within these engine designations. May use Jack Spania Racing 70 mm sheet-metal aluminum Intake manifold. Must use stock throttle body or Acura part number 16400-PND- A17. Fab9 Tuning bottom-mount turbo kit approved with one of the STU approved Turbos.
slowerSTU cars over 3150 lbs lose 275-tire option with 2% weight adder.
As printed in Fastrack
In GCR, Section 9.1.4.G.1., change as follows: "A maximum section width of 245 is permitted. Cars over 3150 lbs. may run a 275 tire with a 2% weight adder."
slowerSTU-TCR tire width increases to 275 with weight adder raised from 100 to 150 pounds.
As printed in Fastrack
In STU Spec Lines, Table C: STU-GT3U, GT3-TCR, change as follows: Remove the current TCR spec line and add the TCR spec lines from GT3 that are being removed, adding the below to the notes. "DOT approved tire with maximum section width of 245. May run DOT approved tire with maximum section width of 275 with 100 150 pound weight adder. May not run A-compound with 275. STU-TCR spitters and side valance must comply with 9.1.4.D.3.f. STU-TCR chassis ride height must comply with 9.1.4.1.A.1."
unclearSTU 2.8-3.2L N/A engines now allow 245 max tire width; over 3150 lbs may run 275 with 2% weight penalty.
As printed in Fastrack
In GCR, Section 9.1.4.G.1, add the following: "A maximum section width of 245 is permitted. Cars over 3150 lbs. may run a 275 tire with a 2% weight adder."
cars addedSTU Honda JDM H23a added, 2259cc displacement, minimum weight per Chart, must meet ST engine regulations.
As printed in Fastrack
In STU, Table B, classify Honda JDM H23a as follows: STU Maximum Displacement (cc's) Minimum Weight Notes Honda JDM H23a 2259 Chart Must meet all ST engine regulations.
wordingSTU wheel width rules clarified: cars ≤2,850 lbs max 8 inches, cars >2,850 lbs max 9 inches.
As printed in Fastrack
In GCR, Section 9.1.4.1.F.1., change as follows: "Wheels may not exceed 18 inches in diameter. or 8.0 inches in width for vehicles 2950 lbs. and under minimum allowed race weight. Vehicles over 2850 minimum allowed race weight may use a 9 inch wide wheel. Cars equal to or less than 2,850 lbs. minimum allowed race weight may not use wheels wider than 8 inches. Cars greater than 2,850 lbs. minimum allowed race weight may not use wheels wider than 9 inches."
fasterSTU Spec Line GT3U minimum weight reduced from plus 250 to plus 225 pounds; wheel and tire options clarified with weight adjustments.
As printed in Fastrack
In STU Spec Line, Table C: STU-GT3U, change as follows: Minimum Weight: “Current GT3 race weight plus 250 225 pounds” Notes: "DOT approved tire with maximum section width of 245. GT3 cars base wheel is a maximum of 15”x9”. 18”x9” wheels allowd with a 3% weight addition. GT3 cars utilizing 15”x7” wheels are limited to a maximum section width of 225 with a 25 pound weight reduction" "All GT3U (Majors and Runoffs) cars using up to 15"x7" wheels limited to 225 section width tires shall run at current GT3 race weight plus 225lbs. All Gt3U cars shall run a DOT approved tire with a maximum section width of 245. GT3U cars are allowed optional 15"x9" wheels with a 1.5% weight addition or up to 18"x9" wheels with a 3.0% weight addition to the total weight
engineSTU BMW N54/N55 3.0L classified at Chart +3% minimum weight; N54 twin turbo not allowed.
As printed in Fastrack
In STU Spec Lines, Table A, classify BMW N54/N55 as follows: STU Maximum Displacement (cc's) Minimum Weight Notes BMW N54/N55 3.0 Chart +3% (DI) Short blocks, heads, and intakes may be freely swapped within these engine designations. N54 twin turbo not allowed
STU Mini Cooper pulley size clarification re: letter #36980
slowerSTU GT3 TCR gains 275-width tire option with 100 lb weight penalty, but not in A compound.
As printed in Fastrack
In STU, Table C, GT3 TCR, add to Notes the following: "May run DOT approved tire with maximum section width of 275 with 100 pound weight adder. May not run A compound with 275."
Request to Remove Miata Hubs from General category
wordingSTL/STU: 90-05 Mazda Miata alternate front wheel hubs moved from General to specific part approval.
As printed in Fastrack
In GCR, Section 9.1.4.M.18., change as follows: "18. Allow alternate front wheel front hubs, Mazda Motorsports Development Part #0000-04-5HUB-S1, for the 90-05 Mazda Miata: Mazda Motorsports Development Part #0000-04-5HUB-S1."
slowerSTU BMW N54/N55 turbo inlet restrictors now required per GCR definition; turbo swapping prohibited.
As printed in Fastrack
"Turbo inlet restrictors designed per GCR Appendix F Technical Glossary definition of “Turbo Inlet Restrictor” may be required; see table 9.1.4.1.H.h.2 3. Swapping of turbochargers between engine makes and models is prohibited. Supercharged cars may be approved on a case-by-case basis; twin turbo engines are allowed on a case-by-case basis only. Contact the Road Racing Technical Office for details. Twin turbo engines may be converted to single turbo using one of the allowed alternate turbos (see 9.1.4.1.H.3 2). Aftermarket turbocharger and supercharger kits will be allowed on a case-by-case basis.
slowerSTU Mini Cooper S SC 1900 restricts to 2.565 diameter pulley; 2100 allows 2.285 diameter pulley.
As printed in Fastrack
In STU Spec Lines, Mini Cooper S SC, add to notes: 1900: "Stock supercharger pulley. 2.565 diameter." 2100: "JCW Pulley permitted. May run a 2.285 diameter pulley."
fasterSTU RWD turbo cars no longer required to reduce restrictor by 1 mm from table.
As printed in Fastrack
In GCR, Section 9.1.4.1.H.3 - Inlet Restrictor (mm) Minimum Weight (lbs) table, change as follows: "RWD cars must reduce restrictor 1 mm from this table"
wordingSTU Mini Cooper S SC: alternate LEAP OMICRON hood scoop LEP-OMICRON3 permitted.
As printed in Fastrack
In STU Spec Lines, Mini Cooper S SC with Minimum Weight 1900 and 2100, add to Notes: "Alternate LEAP OMICRON hood scoop part # LEP-OMICRON3 is permitted."
wordingSTL and STU power steering rules clarified to permit electric-assisted and hydraulic-assisted steering systems.
As printed in Fastrack
In GCR, Section 9.1.4.M.16., change as follows: "Power steering may be modified in any of the following ways: a. disconnected , pump, belt, pulley, and hoses may be removed. Hoses may also be looped. Steering rack or box may be modified internally to work without pump. b. an OEM manual steering rack for that model may be fitted c. an electric power steering pump may be fitted d. an OEM electric-assisted steering system may be used or any column mounted electric steering assist may be used e. an OEM hydraulic-assisted steering system may be used"
wordingSTU Mazda BP5A classified at 1839 cc maximum displacement, 2023-04-01.
As printed in Fastrack
In STU Spec lines, classify Mazda BP5A as follows: STU Maximum Displacement (cc's) Minimum Weight Notes Mazda BP5A 1839 Chart May use engine in its entirety or specific components from the engine.
In STU Spec Lines, Table B: Alternate Vehicle and Engine Allowance, classify Mazda 13 B Turbo as follows: STU Maximum Displacement (cc's) Minimum Weight Notes Mazda 13B Turbo N/A Chart Limited to Streetport only. Stock turbos are not allowed; only alternative turbos listed in the STU rules are allowed.
fasterSTU OEM louver vents now exempt from vent count and 200 square inch allowance.
As printed in Fastrack
In STU, GCR section 9.1.4.1.A.2., add as follows: "Louver vents that are OEM do not count in the number of vents allowed or 200 square inch allowance."
fasterSTU 2400cc non-4-valve engines gain 9% base weight reduction; DI turbo prep limits removed.
As printed in Fastrack
In STU Specifications, GCR Section 9.1.4.1.H.1., change Chart as follows: "Factory Engine Displacement (cc) - 2400 Minimum Weight (lbs) - 2596 2595" In STU Specifications, GCR Section 9.1.4.1.H.1., add the following: "Normally-aspirated engines of fewer than 4 valves per cylinder may reduce base engine weight 9%." In STU Specifications, GCR Section 9.1.4.1.H., remove the following and renumber: "4. All Direct Injected (DI) Turbocharged engines will be limited in preparation. DI Turbo engines must use OEM compression ratios, OEM camshaft lift, and may not port the cylinder head."
Error in new minimum weight table when combined with other text
slowerSTU normally-aspirated 2976–3200 cc single-throttle engines lose 10% base engine weight reduction.
As printed in Fastrack
In STU Specifications, GCR Section 9.1.4.1.H., eliminate the following in its entirety and renumber: "2. Normally-aspirated engines with stock displacement 2976cc-3200cc that breathe through a single throttle body may reduce base engine weight 10%."
wordingST redundant language removed from balance shaft and pulley modification rules.
As printed in Fastrack
In ST, GCR Section 9.1.4.G.29, change as follows: "Any engine balance shafts and associated gears or pulleys may be removed and the resulting openings plugged (including those in oil passages). Alternate pulleys or gears, of the same number as stock, may be installed in the location of the balance shaft pulleys or gears if required for timing belt or chain operation; they must serve no other purpose. Any engine balance shafts and associated gears or pulleys may be removed and the resulting openings plugged (including those in oil passages). Alternate pulleys or gears, of the same number as stock, may be installed in the location of the balance shaft pulleys or gears if required for timing belt or chain operation; they must serve no other purpose."
wordingSTU cars that qualified for 9 inch wheels in 2021 may continue through 2022 only.
As printed in Fastrack
In STU, GCR Section 9.1.4.1.H, add the following after weight chart: "Any STU car that qualified to run 9 inch wheels in 2021, may continue to run 9 inch wheels thru 2022 only."
Clarification request for GCR 9.1.4.D.3.a Splitter Definition
wordingSTU splitter definition clarified: must be single-plane with no vertical deviations, attached to lowest front point.
As printed in Fastrack
In ST Category Specifications, GCR Section 9.1.4.D.3.a, change as follows: "Definition: A horizontal, single-plane aerodynamic device attached to the lower est point of the front of the vehicle, protruding forward. It is intended to divert air and produce downforce through vertical pressure differential. A splitter shall have no vertical deviations."
Request Adjustment to Min Weight for STU BMW E36 M3 (95-99)
fasterSTU BMW S52B32 minimum weight drops 90 lbs to 3110; max displacement cut to 3152 cc.
As printed in Fastrack
In STU Spec Lines, BMW E36 M3 (95-99), change as follows: Car: "BMW E36 M3 (95-99) S52B32" Maximum Displacement: "3200 3152" Weight: "3200 3110" Notes: "Engines are permitted 0.040 overbore, 0.5 point increase in compression. Engines must use the OEM camshaft lift and stock intake plenum. "
BMW E36 M3 Canadian (North American) S50B32 engine
cars addedSTU BMW S50B32 Euro classified at 3201 cc displacement, 3300 lbs minimum weight.
As printed in Fastrack
In STU Spec Lines, BMW S50B32 Euro, classify as follows: STU Maximum Displacement (cc's) Minimum Weight Notes BMW S50B32 Euro 3201 3300 Engines are permitted 0.040 overbore, 0.5 point increase in compression. Engines must use the OEM camshaft. Engine must use stock intake plenum.
wordingST engine swap origin country requirement changes from North America to the United States for case-by-case approval.
As printed in Fastrack
In ST, GCR Section 9.1.41.G.2., change as follows: Engines from vehicles not available in a car delivered in North America the United States will be considered and approved on a case-by-case basis for use in ST. For an engine to be considered, a member must submit a classification request to the CRB with the following information:
slowerSTU Honda CRX (84-91) and Civic Del Sol (93-97) ineligible for front wheel drive weight reductions.
As printed in Fastrack
In STU, classify Honda CRX (84-91) as follows: STU Maximum Displacement (cc's) Minimum Weight Notes Honda CRX (84-91) Chart Ineligible for front wheel drive weight reductions. In STU, classify Honda Civic Del Sol (93-97) as follows: STU Maximum Displacement (cc's) Minimum Weight Notes Honda Civic Del Sol (93-97)
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Chart Ineligible for front wheel drive weight reductions.
fasterSTU vehicles at or over 2950 lbs base weight may use 9 inch wide wheels instead of 8.0 inch maximum.
As printed in Fastrack
In STU, GCR Section 9.1.4.1.F.1, change as follows: "Wheels may not exceed 18 inches in diameter and 8.0 inches in width for vehicles under 2950 lbs. base weight. Vehicles over 2951 with base weight equal to or over 2950 may use a 9 inch wide wheel."
fasterSTU normally aspirated engines: minimum weights reduced up to 310 lbs; single throttle body weight reduction removed.
As printed in Fastrack
Effective 5.1.2022 In STU, GCR Section 9.1.4.H.1., change as follows: "1. Minimum weights for cars with normally aspirated piston engines will be determined by 1.1 lbs/cc displacement for the installed engine (see following table) the following table. Displacement is the stock displacement for the installed engine. For the purpose of weight assignment, engine displacement will be rounded to the nearest 50cc (e.g., 2176cc = 2200cc and 2175cc = 2150cc)." Factory Engine Displacement (cc) Minimum Weight (lbs)
A specification table follows in the original; it is not shown here.
Request to Remove A4 1.8t from STU Spec Line Tables
tyres & wheelsSTL and STU Improved Touring vehicles must conform to 9.1.4 Tires & Wheels requirements.
As printed in Fastrack
In STU Table B, Improved Touring Vehicles (1985-), change Notes as follows: "Must completely conform to ITCS requirements. Tires must conform to 9.1.4, Tires & Wheels" In STL Table B, ITA-spec and ITS-spec RX7, change Notes as follows: "Must completely conform to ITCS requirements. Tires must conform to 9.1.4, Tires & Wheels" In STL Table B, ITS, ITA, ITB, or ITC vehicles (1985- ), change Notes as follows: "Must completely conform to ITCS requirements. Tires must conform to 9.1.4, Tires & Wheels"
fasterSTU engines may delete balance shafts and plug openings; alternate pulleys allowed for timing belt or chain operation only.
As printed in Fastrack
In GCR, Section 9.1.4.G., add as follows" "29. Any engine balance shafts and associated gears or pulleys may be removed and the resulting openings plugged (including those in oil passages). Alternate pulleys or gears, of the same number as stock, may be installed in the location of the balance shaft pulleys or gears if required for timing belt or chain operation; they must serve no other purpose. Any engine balance shafts and associated gears or pulleys may be removed and the resulting openings plugged (including those in oil passages). Alternate pulleys or gears, of the same number as stock, may be installed in the location of the balance shaft pulleys or gears if required for timing belt or chain operation; they must serve no other purpose."
cars addedSTU adds Honda K23 with 2354cc displacement and minimum weight per chart, K24 block allowed with K23 internals and head.
As printed in Fastrack
In STU, classify Honda K23 as follows, effective 1/1/2022: STU Maximum Displacement (cc's) Minimum Weight Notes Honda K23 2354 Chart May use K24 block. Must maintain all K23 internals. Must use K23 cylinder head. Maximum bore of 87mm.
wordingSTL and STU piston engines clarified: intake manifold and cylinder head porting remains free.
As printed in Fastrack
In GCR, Section 9.1.4.1.B.4., change as follows: "The intake and exhaust porting on piston engines is free. Porting of intake manifolds and cylinder heads is free on piston engines."
wordingSTU fender flare wording clarified: exterior contour of any wheel opening may not change opening size, location or shape from side view.
As printed in Fastrack
In STU, Section 9.1.4.1.A.4., change as follows: "The flaring e of the exterior contour of any wheel openings may not change the wheel opening size, location or shape when viewed from the side. The overall vehicle width may not exceed the manufacture's published width, plus 4"."
Request weight reduction for 12A bridgeport motor in Miata
fasterSTU Mazda 12A Bridge Port Miata weight reduced from 2550 lbs to 2350 lbs.
As printed in Fastrack
In STU Spec Lines Table B, Mazda 12A Street Port, change Notes as follows "Induction: 1 Nikki 4 barrel carburetor with primary chokes bored to match secondary chokes on a stock manifold, or 1 Auto- type 2 barrel carburetor with 42mm chokes on a "dual-y" manifold." In STU Spec Lines Table B, Mazda 12A Bridge Port, change weight as follows: "2550 2350"
wordingSTU fender flare rules clarified: maximum 2 inches, must cover tire contact patch from above, cannot alter body configuration or wheel opening geometry.
As printed in Fastrack
In STU, section 9.1.4.1.A.4., change as follows: "The exterior contour of all wheel openings Fenders may be flared up to a maximum of 2” per corner with a total 1% weight penalty of 1%. The flare must maintain the OEM profile and appearance, seamlessly around the wheel arch. Material may be added or removed as necessary to create flare. The fender/wheel opening or any other part of the body forming the wheel opening, when viewed from the top perpendicular to the ground, must cover the portion of the tire that contacts the ground while the car is at rest. The flaring of the exterior contour of any wheel openings may not alter the basic body configuration or change the wheel opening size, location or shape when viewed from the side."
Provision for Interchangeable Engine Components Already Allowed
wordingST oil coolers and filters now explicitly allowed to be added or substituted; wording clarifies existing permissions.
As printed in Fastrack
In ST, section 9.1.4.G.14, change as follows: "Vents, breathers, and oil filters and oil coolers may be added, or substituted. All emission control devices may be removed and the resulting holes plugged."
wordingSTL/STU 90-05 Mazda Miata gains approval for Mazda Motorsports Development alternate front wheel hubs.
As printed in Fastrack
In ST, GCR section 9.1.4.M, add alternate front wheel hubs as follows: "18. Allow alternate front wheel front hubs for the 90-05 Mazda Miata: Mazda Motorsports Development Part #0000-04-5HUB-S1"
wordingSTU Porsche PDK automatic transmission limited to 8 forward speeds instead of torque converter restriction.
As printed in Fastrack
In STU, GCR Section 9.1.4.1.C.2., change as follows: "Transmission and ratios are free. Forward gears are limited to 6 speeds. Cars equipped with automatic transmissions using a torque converter a re limited to 8 forward speeds. Cars with sequential shift transmissions including factory DCT-type systems shall increase the required minimum weight by 3.5%."
Reference Letter #29333 Proposed STU 13B Spec Line Changes
fasterSTU Mazda 13B Street Port 2400 removes choke location restriction, allows auto-type 2bbl with dual-Y manifold.
As printed in Fastrack
In STU, Spec Lines, Mazda 13B Street Port 2400 Min Weight, change Notes as follows: "Allow any dual throttle body/bodies. Chokes must be located within 4” of the throttle butterfly. Auto-type 2bbl choke(s) with any dual-Y manifold. Unrestricted"
wordingSTU driveshaft and half-shaft materials change from OEM-type to steel or aluminum.
As printed in Fastrack
In GCR, Section 9.1.4.L.1., change as follows: "Alternate differential housings are permitted from the same model of vehicle. Differential may be open, locked, or of a limited- slip type. The internals of limited-slip type differentials may be modified to change the amount of slip limiting. Differentials with external, or electric, adjustability are prohibited. Driveshaft and half-shafts may be aftermarket, but shall be the OEM-type and use the same types of materials as stock steel or aluminum. Drive shafts may be replaced by one piece drive shafts, and conversely."
slowerSTU Mazda 13B Street Port classified at 2400 lbs minimum weight, replacing peripheral and bridge port variants.
As printed in Fastrack
In STU, remove Spec Line in entirety, Mazda 13B, weight 2300. In STU, remove Spec Line in entirety, Mazda 13B Bridge Port, weight 2600. In STU, classify Mazda 13B Street Port as follows: STU Maximum Displacement (cc's) Minimum Weight Notes Mazda 13B Street Port N/A 2400 Allow any dual throttle body/bodies. Chokes must be located within 4” of the throttle butterfly. Auto-type 2bbl choke(s)
aeroST aero devices and reference areas now include end plates but exclude fasteners protruding over 1/2 inch.
As printed in Fastrack
IN ST, GCR Section 9.1.4.D.4.e, add the following: "Unless otherwise specified in the applicable rules the measurement of aero dynamic devices and reference areas shall include end plates but not include fasteners as long as the fasteners serve no other purpose. Fasteners may protrude no more than 1/2” from the mounting surface."
Request for Advanced Aero Rule Wording Clarification.
wordingSTU fender flare rules reworded: up to 2" per corner allowed with 1% weight penalty total.
As printed in Fastrack
In GCR, Section 9.1.4.1., remove d.: "d. Each fender may be flared to allow for tire clearance up to 2” with a weight penalty of 1%. The flare must maintain the OEM profile and appearance, seamlessly around the wheel arch. Material may be added or removed as necessary to create flare." In GCR, Section 9.1.4.1., add 4. as follows: "4. Fender Flare Fenders may be flared up to 2" per corner with a total weight penalty of 1%. The flare must maintain the OEM profile and appearance, seamlessly around the wheel arch. Material may be added or removed as necessary to create flare."
wordingSTL and STU clarify weight adjustment calculation order: engine adjustments first, then chassis adjustments.
As printed in Fastrack
In STU, GCR section 9.1.4.10., add the following: "All weight adjustments for engines shall be applied first, then that total is to be used as the baseline for any chassis-related weight adjustments. Chassis related adjustment that are percentage based are performed by adding specified percent first and subtracting specified percentage second if necessary. Final step is addition or subtraction of specified weight in pounds." In STL, GCR Section 9.1.4.4., add the following: "All weight adjustments for engines shall be applied first, then that total is to be used as the baseline for any chassis-related weight adjustments. Chassis related adjustment that are percentage based are
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performed by adding specified percent first and subtracting specified percentage second if necessary. Final step is addition or subtraction of specified weight in pounds."
wordingSTL and STU rear wing rules clarify that wicker is a Gurney flap; no performance change.
As printed in Fastrack
In GCR section 9.1.4.D.4, clarify wording as follows: "d. Wings shall be a single element with a maximum chord length of 8.50 inches, including any wicker Gurney flap." "f. The entire rear wing assembly, including the end plates and any wicker Gurney flap, shall be mounted a minimum of 6.0 inches below the peak of the roof or roll cage main hoop whichever is higher, measured at the highest point. Cars with a wagonback/notchback/hatchback style body may have the rear wing assembly, including the end plates and any wicker Gurney flap, mounted a maximum of 4.0inches above the highest point of the roof."
wordingSTU large displacement turbo engines limited by GCR turbo list; non-turbo trim suggested as more competitive.
As printed in Fastrack
Thank you for the letter. Given the rule set for STU large displacement turbo engines are limited by the turbos allowed in the GCR. We are forced to adhere to this turbo list to maintain parody in the smaller displacement turbo engines. This engine may be more competitive prepared in non-turbo trim in STU or inquire with T1 committee about running turbo trim.
wordingSTU sequential shifters referred to Board of Directors for approval; no change implemented yet.
As printed in Fastrack
Thank you for your letter. The Club Racing Board is monitoring performance and adjusting as needed. Recommended Items The following subjects will be referred to the Board of Directors for approval. Address all comments, both for and against, to the Club Racing Board. It is the BoD’s policy to withhold voting on a rules change until there has been input from the membership on the presented rules. Member input is suggested and encouraged. Please send your comments via the form at www.clubracingboard.com.
fasterSTU Honda S2000 adds HKS Supercharger kits 12001-AH006 and 12001-AH010 as allowed.
As printed in Fastrack
In STU, Honda S2000 (2000 Maximum Displacement) Spec Lines, change notes as follows: "HKS Supercharger kit 12001-AH006 and 12001-AH010, allowed" In STU, Honda S2000 (2157 Maximum Displacement) Spec Lines, change notes as follows: "HKS Supercharger kit 12001-AH006 and 12001-AH010, allowed"
slowerSTU Volkswagen GTI/GLI MK5 and Jetta Mk4 may install turbo inlet restrictor in OEM turbo inlet housing.
As printed in Fastrack
In STU, classify the Volkswagen GTI/GLI MK5 as follows: "May install TIR in the OEM turbo inlet housing. Must comply with all TIR specification." In STU, Volkswagen Jetta Mk4 Spec Lines, add to Notes as follows: "May install TIR in the OEM turbo inlet housing. Must comply with all TIR specification." In STU, add Spec Line, Volkswagen GTI/GLI MK5: STU Maximum Displacement (cc's) Minimum Weight Notes Volkswagen
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GTI/GLI MK5 1984 Chart K04 turbocharger permitted. May install TIR in the OEM turbo inlet housing. Must comply with all alternate TIR location specification.
slowerSTU GM Ecotech LNF now allowed with turbo removed or with LE5 head and intake manifold, meeting STL specs.
As printed in Fastrack
In STU, GM Ecotech LNF Spec Lines, add to Notes as follows: “LNF Engine Permitted with turbocharger removed. LNF Engine short block with LE5 cylinder head and intake manifold permitted. Must meet all other STL specifications.”
fasterSTU vehicles over 2951 lbs base weight may use 9 inch wide wheels, up from 2950 lbs.
As printed in Fastrack
In STU, GCR section 9.1.4.1.F.1., change base weight as follows: "Vehicles over 2950 2951 base weight may use a 9 inch wide wheel." Note: Other requests in this letter are not recommended.
wordingSTU turbocharged engines now use base weight instead of minimum weight, with 3% DI increase applied to base weight.
As printed in Fastrack
In STU, GCR section 9.1.4.1.H.6., change as follows: "All turbocharged engines shall use a turbo inlet restrictor. Vehicle minimum base weight is determined by TIR size selected from the following table. Turbocharged engines of greater than 2.7L displacement shall use the weight either as listed in the lbs/cc or restrictor size/lbs charts, whichever is greater. Turbocharged engines utilizing Direct Fuel Injection (DI) shall increase their minimum base weight by 3%."
wordingSTU cars with manual OEM throttle bodies may convert to OEM electronic throttle body of same inner diameter.
As printed in Fastrack
In GCR section 9.1.4.G.8, make changes as follows: "Cars produced with an electronic throttle body may use the OEM electronic throttle body. The OEM electronic throttle body may be converted to manual actuation and the actuation cam on a manual throttle body may be changed to alter the opening/closing rate of the butterfly. Alternately actuated throttle bodies may be considered on a case by case basis. Vehicle/engine combinations with manual OEM throttle bodies may be converted to an OEM electronic throttle body of the same inner diameter as the original OEM throttle body."
wordingSTU wing assembly wording corrected: no part higher than roof height.
As printed in Fastrack
In STU, GCR section 9.1.4.1..A.3.b., make changes as follows: "A wing assembly no wider than the widest part of the body (Not including the mirrors), with a maximum cord length of 12”, and end plates that do not exceed 72.0 square inches each. No part of T the wing assembly may be no higher than roof height."
fasterSTU alternate intake manifolds now allowed case-by-case instead of prohibited.
As printed in Fastrack
In STU, GCR section 9.1.4.1.B.3, make changes as follows: "All cars shall use the installed engine’s or vehicle's stock air throttling device (e.g., throttle body, carburetor) and intake manifold, unless noted otherwise. Alternate intake manifolds will be permitted on a case-by-case basis."
Request to clarify afterrmarket side skirts exhaust exit
wordingSTU aftermarket side skirts must meet 3-inch ride height, no openings except jacks or side exhaust, no wider than fascias, not higher than door bottom, no chassis reinforcement.
As printed in Fastrack
In GCR section 9.1.4.D.6, add as follows: "Aftermarket side skirts may be used provided they meet the minimum ride height rule of 3 inches, have no openings/ducts in them other than for jacking insert(s), or side exit exhaust, are no wider than the approved fascias, do not extend any higher than the bottom of the door and do not reinforce the chassis."
wordingSTU fender flare wording clarified: each fender may be flared up to 2" for tire clearance with 1% weight penalty.
As printed in Fastrack
In GCR section 9.1.4.1.A.3.d, make changes as follows "OEM base model body Each fender may be flared to allow for tire clearance up to 2” with a weight penalty of 1%. The flare must maintain the OEM profile and appearance, seamlessly around the wheel arch. Material may be added, or removed as necessary to create flare."
wordingSTL and STU ride height measurement clarified: without driver, at rocker panel lowest point, excluding pinch weld.
As printed in Fastrack
In GCR Appendix K.F.5, add as follows: “Ride height will be measured without driver at the lowest point of the rocker panel, not including the pinch weld.” In GCR section 9.1.4.F.5, add as follows: “Ride height will be measured without driver at the lowest point of the rocker panel, not including the pinch weld.”
fasterSTU Mazda 13B Bridge Port may use ELITE ROTARY SHOP FD V2.0 intake manifold instead of stock.
As printed in Fastrack
In GCR section 9.1.4.1 Table B, add to notes as follows: STU Maximum Displacement (cc’s) Minimum Weight Notes Mazda 13B NA 2300 Street porting allowed, contact SCCA Technical
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Services for details. Stock Fuel injection or 1 Auto- type 2 barrel carburetor with 42mm chokes on a “dual-y” manifold. May use ELITE ROTARY SHOP FD V2.0 INTAKE Mazda 13B Bridge Port NA 2600 Stock intake manifold & throttle body required, or automotive 2 barrel carb with 44 mm chokes. May use ELITE ROTARY SHOP FD V2.0 INTAKE
Request Alternate Intake for Mazda MZR In a Rear Wheel Drive App.
unclearSTU Mazda MZR LF/L3/L5 may use Goodwin Part #61-2510 intake manifold with stock or Acura throttle body.
As printed in Fastrack
In GCR section 9.1.4.1, Table A, Mazda MZR (LF, L3, L5), add to notes as follows: “May use Goodwin Part # 61-2510 Intake manifold. Must use stock throttle body or Acura part number 16400-PND-A17.”
wordingSTU suspension rules clarified: alternate components from same manufacturer moved from section E to section D.
As printed in Fastrack
In GCR section 9.1.4.1.E, remove wording as follows: “7. Alternate suspension components including spindle, knuckle, hubs, etc. sourced from the same manufacture are permitted.” In GCR section 9.1.4.1.D, add wording as follows: “7. Alternate suspension components including spindle, knuckle, hubs, etc. sourced from the same manufacture are permitted.”
fasterSTU Honda/Acura B20 classified at 1973 cc, now permits VTEC B16 or B18 cylinder head and intake manifold.
As printed in Fastrack
In STU, GCR section 9.1.4.1 Table B, classify the Honda/Acura B20 as follows: STU Maximum Displacement (cc’s) Minimum Weight Notes Honda/Acura B20 1973 Chart May use Cylinder Head and Intake Manifold from VTEC B16 or B18 engine. Manifold must be from same as the
aeroSTU flared fenders up to 2" with 1% weight penalty moved from base to Advanced Aero rules.
As printed in Fastrack
In GCR section 9.1.4.C.10, remove as follows: “OEM base model body fenders may be flared to allow for tire clearance up to 2” with a weight penalty of 1%. They must maintain the OEM profile and appearance, seamlessly around the wheel arch.” In GCR section 9.1.4.1.A.3, add as follows: “d. OEM base model body fenders may be flared to allow for tire clearance up to 2” with a weight penalty of 1%. They must maintain the OEM profile and appearance, seamlessly around the wheel arch.”
wordingSTU BMW S54B32 OEM reclassified from E46 designation, 3246 cc, 3300 lbs minimum weight.
As printed in Fastrack
In GCR section 9.1.4.1 Table B, BMW E46 S54 OEM, make changes to the spec line as follows: STU Maximum Displacement (cc’s) Minimum Weight Notes BMW E46 S54B32 OEM 3246 3300 Cannot use Super Touring engine allowances
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and must be OEM as delivered for sale in the U.S., including stock intake plenum, and camshafts. Engine cylinders may be over bored 1mm. Compression may increase .5. No porting allowed.
unclearSTU Mazda 13B and 13B Bridge Port may use RE or REW housings and intake with turbo removed.
As printed in Fastrack
In STU, table B, Mazda 13B, add to the notes as follows: “May use 13B RE or REW housings and intake with turbo removed.” In STU, table B, Mazda 13B Bridge Port, add to the notes as follows: “May use 13B RE or REW housings and intake with turbo removed.”
unclearSTU World Challenge car weight calculation method removed; new basis unclear from text provided.
As printed in Fastrack
In STU, GCR section 9.1.4.B.2.c, strike the wording as follows: “Weight will be set at the greater of the World Challenge weight plus 5% or the STU rules weight plus 5%.”
Request a phone call for discussion regarding weight
aeroSTU rear wing maximum cord length set to 12 inches, end plates to 72.0 square inches each.
As printed in Fastrack
In STU, 9.1.4.1.A.3.b., add the wording as follows: “A wing no wider than the widest part of the body (Not including the mirrors), with a maximum cord length of 12”, and end plates that do not exceed 72.0 square inches each. The wing may be no higher than roof height.”
You are correct that the 4% is applied at the end, after all other adders and subtractors. Consolidating the 4% into the weight table is currently under consideration.
Due to time restraints, it would not be practical to include every letter writer to the monthly zoom calls and manage bringing them in and removing them for just the discussion of their letter.
Suspension components in your request are currently legal in STU. Please see 9.1.4.1.D.7. If you are requesting a Diff, please submit a letter with that request.
In GCR, Section 9.1.4.E.6., change as follows: "Stock d Dash/instrument panel cover (dash pad) must be used which fully encloses instrument wiring and mechanical components. Original instruments/gauges may be replaced, or supplemented, with additional engine monitoring gauges. Accessories, lights and switches may be added or removed. Box-type extensions from the dash pad may be used to mount switches and controls, in the areas where the OEM insert panels were mounted, so that they more easily accessible to the driver. Audio and video systems may be removed. In GCR, Section 9.1.4.E.8., change as follows: "8. Dash pad modification – It is permitted to modify the dash pad in order to run the roll cage tubes through the dash area as
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long as the dash pad is modified only enough for roll cage fitment. If necessary, the dash pad may be parted to ease installation around roll cage. Any such parting shall be done in such a way as to minimize the appearance that they have been separated once pieces of dash pad are installed."
In GCR, Section 9.1.4.1.E., add the following: "7. Delta Motorsports ABS system is allowed. Other aftermarket ABS systems will be considered on a case by case basis."
We appreciate your perspective and feedback. The TCR cars are no longer running with STU. The BoP between GT3U cars and STU cars will continue to be evaluated. Please continue to run your car so we can obtain data to include in our evaluation.
We appreciate your perspective and feedback. The TCR cars are no longer running with STU. The BoP between GT3U cars and STU cars will continue to be evaluated. Please continue to run your car so we can obtain data to include in our evaluation.
In GCR, Section 9.1.4.1.H.7., change as follows: "All current STU cars, except TCR car s, may reduce their weight by 4% after all other modifiers." In STU Spec Lines, remove Chart STU-TCR in its entirety. In T2 Spec Lines, classify T2-TCR Chart as follows:
Thank you for your letter. Without sufficient data we are not able to justify an adjustment. If the car comes, we would be happy to consider adjustments.
Thank you for your letter. The 4% modifier does apply to all STU cars, including Table B cars.
Alt differential housings
#37032 from Super Touring Committee · Recommended to the Board · Minutes (2025-05 Fastrack)
In GCR, Section 9.1.4.1.C. add the following: "(Effective 6/1/25) 3. Front engine rear drive cars may use a Ford 8.8 IRS differential housing in place of the original housing. Rear subframes may be modified or replaced for fitment but cannot alter the mounting points of the rear suspension greater than what is allowed in 9.1.4.1.D."
Thank you for your letter. As we work on the consolidation of these classes scheduled for 2026, we will evaluate aerodynamics as well as other performance parameters based on data we collect in 2025.
Classification Request - 1995-8 Eagle Talon Tsi AWD
Thank you for your letter. The 1995-1998 Eagle Talon Tsi AWD is eligible to run in STU without a spec line but must comply with all STU rules.
Body Parts Interchangeability
#37474 from Super Touring Committee · Recommended to the Board · Minutes (2025-04 Fastrack)
In GCR, Section 9.1.4.C.1., change as follows: "(Effective 6/1/2025) Unless otherwise allowed, standard body appearance must be strictly maintained. Different models of the same generation chassis may interchange body panels, trim and lights."
In GCR, Section 9.1.4.L., add the following: "5. Any final drive ratio is permitted provided it fits the differential/transaxle housing without modification to the housing. 6. Any limited-slip or locking differential is permitted." In GCR, Section 9.1.4.2.C., change as follows: "3. Any final drive ratio is permitted provided it fits the differential/transaxle housing without modification to the housing. 4. Any limited-slip or locking differential is permitted. 5 3. Short shift kits are allowed."
Gasoline Direct Injection (GDI) to Port Injection Conversion
In STU, Table C, create new STU-GT3 classification as follows: In GCR, Section 9.1.4.1.F,, change as follows: ”Vehicles over 2950 2850” In GCR, Section 9.1.4.1.H., add the following: "7. All current STU cars may reduce their weight by 4% after all other modifiers."
Thank you for your letter. Future changes are coming that may address this issue after the runoffs. If they do not address your specific request, please resubmit your letter.
Thank you for your letter. We have no data currently to support your request. Please provide us with JCW advertised power increases with the requested pulley. It would be helpful to have you participate at a HST event where data is frequently collected so we can obtain data on the car.
Thank you for your letter. At this time there is no evidence that this change is needed, however we will continue to monitor data from the class. The GR86 Cup is a Spec Car and cannot take advantage of the STU preparation potential.
Thank you for your letter. For consideration, please see GCR Section 9.1.4.G.2. for procedure to have the engine to be reviewed for classification. Please submit a new letter with required documentation.
Against Proposed Super Touring Light Changes in Feb Prelim TB
Thank you for your letter. This car exceeds the displacement limits and performance envelope of STU. The STAC would recommend the author investigate the Touring rule set to determine if Touring would be a better fit for this application.
Thank you for your letter. Please provide STAC the TCA ruleset that the car will be prepared to, specifics regarding the HKS Supercharger with model number and the pulley sizes and compressor map as we requested previously.
Request for Inclusion of Spoiler in Rules for Wings
Thank you for your letter. Please provide STAC the TCA ruleset that the car will be prepared to, specifics regarding the HKS Supercharger with model number and the pulley sizes and compressor map.
In GCR, STU Specific Technical Regulations, Section 9.1.4.1.A.2., add the following: "Hoods may have a maximum of 2 vents installed for cooling purposes. Cars with mid or rear engines may have a maximum of 2 vents located in the hood or fenders for cooling purposes. The maximum combined total area of the vents shall not exceed 200 square inches. The 200 Square inches includes any area that deviates from the factory hood or fender(s) profile. Louvers within the 200 sq. inch are allowed. Louver vents that are OEM do not count in the number of vents allowed or 200 square inch allowance.
Thank you for your letter. Data does not currently support BoP adjustments at this time. We will continue to watch the performance of this car through 2024.
H Pattern Dog Box Clarification
#34734 from Super Touring Committee · Recommended to the Board · Minutes (2023-09 Fastrack)
In GCR, Section 9.1.4.1.C.2., add the following: "(Effective 1/1/2024) Cars equipped with Alternate H-Pattern Transmission w/non-stock type syncros (dog-ring) will increase the required minimum weight by 1.25%."
Clarification on Dogbox Gears in H-Pattern Transmission
Thank you for your letter. We have found that 8” wheels are available for your car. Allowing 8.5” wheels would have a negative impact on other competitors in this class.
Thank you for your letter. The two lines of the GCR are found not to be redundant, as one allows for the existence of portioning valves and the other allows for driver adjustability of brake force balance.
In STU, GCR Section 9.1.4.1.B.3., change as follows: "3. All cars shall use the installed engine’s or vehicle’s stock air throttling device (e.g., throttle body, carburetor) and intake manifold, unless noted otherwise. Alternate intake manifolds will be permitted on a case-by-case basis."
Thank you for your letter. The change was made based on collected data and we will continue to monitor data and adjust as necessary.
STU wheel width rule
#32409 from Super Touring Committee · Recommended to the Board · Minutes (2022-04 Fastrack)
In STU, GCR Section 9.1.4.1.F., change as follows: "Wheels may not exceed 18 inches in diameter and or 8.0 inches in width for vehicles under 2950 lbs. and under base minimum allowed race weight. Vehicles over 2951 0 base minimum allowed race weight may use a 9 inch wide wheel."
Thank you for your letter. Power assisted brake systems and ABS systems are not the same. Currently there are no provisions for changing systems, even within same manufacturer.
In GCR, Section 901.4.H. change as follows: "1. Water Cooling Provided that the stock method of cooling is retained, the cooling system is free, including cooling fans, but. Water radiator(s) must remain in the approximate OEM location or removed. The mounting angle may be changed."
Thank you for your letter. This is a change from a single throttle body to individual throttle body, which does not meet class philosophy. Please refer to GCR section 9.1.4.1.B.3.
Request to add 2004 Mazda Protégé World Challenge Car
Thank you for your letter. At this time, we do not have enough information to classify the car in STU. If more information is available, we would be happy to review.
Request to Classify the Hyundai Veloster Turbo TCA
Thank you for your letter. At this time, we do not have enough information to classify the car in STU. If more information is available, we would be happy to review.
Thank you for your letter. Request is not recommended due to being outside of class philosophy. Alternate material hubs are not an approved modification.
Thank you for your letter. We are taking your request under consideration. We would like to see the car race, requesting to collect data so that we can evaluate BoP adjustments.
Thank you for your letter. ABS systems may be added to cars not originally equipped. The ABS system must be of the same manufacturer as the car it is being added to and be a street car production system. Non ABS weight break does not apply.".
Adjust the Weight Reduction Percentage for the Larger Engines
The Club Racing Board requests class stakeholder input on considered throttle body changes in the ST class. Please reply via the CRB letter log system. 1. Should ST standardize a throttle body size per displacement? Or per class? 2. Should individual throttle bodies be allowed in all STU engines with a weight penalty?
Thank you for your letter. With the allowable STU suspension pick up point modifications, the CRB believes a front strut weight reduction is necessary. The CRB will continue to monitor performance.
Thank you for your letter. STU aftermarket intake manifolds are approved on a case by case basis. Aftermarket throttle bodies are not within the STU class philosophy.
In STU, GCR section 9.1.4.1.H., add DI section and renumber as follows: "7. All Direct Injected Turbocharged engines will be limited in preparation. DI Turbo engines must use OEM compression ratios, OEM camshaft lift, and may not port the cylinder head."
Request for Headlights Covers with Openings for Air Ducts
Thank you for your letter. The GCR already allows STU a non-ABS modifier. Please reference GCR Section 9.1.4.N.10 - Vehicles not equipped with ABS brakes may reduce their weight by 2%.
The Club Racing Board is requesting member input regarding freezing the rules in STU through the end of 2020. This would not include any prudent BOP changes including weight and restrictor.
Request to approve alternate turbocharger on Subaru WRX/STI
Thank you for your letter. This change is not recommended at this time. There is a list of approved alternate turbos for STU. Please choose either the stock turbo or one from the approved list.
Thank you for your letter. There is no requirement to class a car in STU if it is under 3.2L. You may compete with the TL as long as it meets all other STU regulations.
Thank you for your letter. Your request is not recommended at this time. Author is asking for more horsepower and it is not warranted. The Club Racing Board will continue to monitor performance.
NR: Thank you for your letter. BOM for S/C Kit was requested multiple times. Competitor nor Jackson provided requested information. S/C Kits will not be permitted without BOM for kit.
Request to add Rotrex s/c to supercharged S2000 list
Thank you for your letter. BOM for S/C Kit was requested multiple times. Competitor nor Jackson provided requested information. S/C Kits will not be permitted without BOM for kit.
Request Procedural feedback regarding category rule vs. spec line
Thank you for your letter. The Club Racing Board currently does not wish to classify this car for consistency. Currently the ST category has many hard lines regarding tire size, brake size, number of forward speeds. This car exceeds those hardlines. There are currently pending rules changes that may allow for this car in 2020. The Club Racing Board has chosen not to spec line the car due to lack of relative performance data.
Thank you for your letter. 9.1.4.G.1.e Is a general category rule and applies to both STL and STU. 9.1.4.1.B.3 is a STU specific rule applying only to STU and over riding 9.1.4.g.1.e.
Thank you for your letter. The Club Racing Board decided to remove the 1 mm of TIR from AWD due to driveline loss. The Club Racing Board decided that RWD will retain the -1mm of TIR from chart weight until further data supports its removal.
#26423 from Super Touring Committee · Recommended to the Board · Minutes (2019-04 Fastrack)
In GCR section 9.1.4.1.C.2, add as follows: “Transmission and ratios are free. Forward gears are limited to 6 speeds. Cars equipped with automatic transmissions using a torque converter are limited to 8 forward speeds. Cars with sequential shift transmissions including factory DCT-type systems shall increase the required minimum weight by 3.5%.”
Recommend 6 Piston Calipers for 2020
#26422 from Super Touring Committee · Recommended to the Board · Minutes (2019-04 Fastrack)
In GCR section 9.1.4.1.E.2, add as follows: “Calipers- The standard production calipers or any 4-piston or fewer calipers may be used. 6 piston calipers may be used with a 1% weight penalty.”
Thank you for your letter. There is no requirement to specifically class cars in STU. Your car can run freely per STU regulations. Please choose a TIR and appropriate weight from the STU chart.
Thank you for your letter. Starting in 2020, all Direct Injected Turbo engines will be limited in preparation. The new limits will include; stock compression, stock camshaft lift, and no porting.
Thank you for your letter. All turbo charged engines running either their stock or approved alternate turbo must run at chart weight for turbocharged engines. The weight is set based on turbo inlet size. You may choose a restrictor size and weight from the chart. GCR 9.1.4.1.H.6
Thank you for your letter. The Renesis engine already has ports larger than the street port template. There would be no reason to allow street porting specifically on a Renesis.
Thank you for your letter. Per your request regarding 9.1.4.1.B. The Club Racing Board does not recommend this option for DI turbo charged engines at this time. Per your request regarding 9.1.4.1.H.6 Please see response to letter #26398 Per your request regarding 9.1.4.1.H.5 The TD05HR-15GK2 turbocharger was specifically permitted on the Dodge SRT4 due to it being a factory available dealer installed part. This turbo would not fit any manifold other than the SRT4 Stage 3.
Thank you for your letter. Your response has been logged.
24504 Amendment
#25830 from Super Touring Committee · Recommended to the Board · Minutes (2019-01 Fastrack)
Effective 1/1/19: Add to 9.1.4.1.A.3.b.: The wing may be no higher than roof height. In 9.1.4.1.A.3.a.: Adjust weight penalty for advanced aero from 3% to 5%. Change: 9.1.4. Super Touring Category Specifications C. Bodywork… 10. Fenders and wheel openings shall remain unmodified. OEM base model body fenders may be flared to allow for tire clearance up to 2” with a weight penalty of 1%. They must maintain the OEM profile and appearance, seamlessly around the wheel arch. It is permitted
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to roll under or flatten any interior lip on the wheel opening for tire clearance. Cars with plastic/ composite fenders may remove any interior wheel opening lip, but the resulting material edge shall be no thinner than the basic fender material thickness. Non-metallic inner fender liners may be removed
STU Intake Manifolds
#25829 from Super Touring Committee · Recommended to the Board · Minutes (2019-01 Fastrack)
Effective 1/1/19: Add: 9.1.4.1 B. Engines 3. All cars shall use the installed engine’s stock air throttling device (e.g., throttle body, carburetor) and intake manifold, unless noted otherwise. Alternate intake manifolds will be permitted on a case-by-case basis.
Thank you for your request. All turbo cars in STU have a weight based on the inlet size of their turbo. If you would like to run without a TIR, your turbo inlet diameter must be equivalent to a size on the chart. The vehicle base weight would then be the chart weight. Otherwise you must choose a restrictor size from the chart.