XTSM 2012 Final Rules

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The true 8 Second 109!
XTSM - Extreme Turbo Street Modified is a class based off of the earlier TSM class. To allow more participation the rules will be opened up to allow more combinations of engines. Now 109, Stage I & II, & aftermarket blocks will be able to race together in heads up class like never before.

2012 RULES

MAIN RULE:*** All rules subject to change due to fairness ***

3250 lbs - Iron Production "8445" casting head / 109 / 71mm

3450 lbs - Aluminum (Champion Style) head / 109 & Series II / 71mm

3650 lbs - Any other block (Stage I & II on/off center, etc) / any style head / 71mm

-100 lbs for 67 3-bolt turbo from any combo
+100 lbs for Alcohol injection

*Safety requirments per track tech
*Factory Stock Appearing External Body must have headlights/tailights (81-87 Regal)
*FSA glass windows
*One 3 bolt turbo up to 71.5mm inducer/103mm exducer in factory stock location (No V-band downpipes)
*No Nitrous Oxide injection
*Iron heads must be production "8445" heads
*Stock suspension/mounting points (no wheelie bars)
*No mini tubs, notched frame ok.
*Any Exhaust: must exit in stock location
*Wastegate must plumb back into downpipe
*Gasoline fuel only (includes E85, Sunoco, VP, etc)
*Alcohol Injection +100 lbs
*70mm Throttle body/cast intake manifold
*Tires - 15" wheel Front must be 3.5" wide footprint. Rear tires up to 29.5" x 10.5"(Slick), 29.5" x 12.5" DOT (ET-Street), or up to 295 series (Drag radial)
*Any GM automatic transmission
*Any GM differential, Dana 60, or Ford 9"

Ultimate Goal
-The 71 turbo would limit the overall power potential to keep class ET close
-The 109 weights would improve 109 longevity
-Stage rules would allow more cars to join in with minimal changes
-Allows for many different combos to be competitive



• Heads-up, 4-tenths Pro tree start and Pro ladder (1vs.16, 2 vs.15, etc.)
• All safety rules are dictated by track personnel.
• All participants are subject to re-weigh and re-tech immediately after final round or at any other time and must pass weight check during qualifying and eliminations.
A courtesy weigh-in is available during class tech inspection.
• There is no fee required for a visual turbo peer tech before qualifying. A $250.00 fee must accompany a turbo protest. If the protested turbo is found to be legal, the protested racer shall receive the protest fee for his trouble. If the protested racer’s turbo is found to be illegal, the protest fee will be returned to the individual(s) that filed the protest. Tech Inspectors may protest a turbo at no cost.
• There is no fee required for a visual peer tech before qualifying. A $500.00 fee must accompany other mechanical protest. If the protested car is found to be legal, the protested racer shall receive the protest fee for his trouble. If the protested racer’s car is found to be illegal, the protest fee will be returned to the individual(s) that filed the protest.
• Any entrant caught trying to deliberately break the rules will be disqualified from the xTSM class and/or the point series for the remainder of the season if registered.

• To compete in this class the car must be Factory Stock Appearing with the following exceptions and/or clarifications:

Definition of "Factory Stock Appearing (FSA)

A factory stock appearing part is a GM part originally delivered on a 1981 to 1987 Buick Regal, GNX, Grand National, T-Type or Turbo Regal from Buick Motor Division and is externally stock in appearance. No external welding, cold weld epoxy, puttying, etc. may be done on any FSA part unless specifically stated.


• Minimum car weight w/driver must be at least:
•3250 lbs - Iron GM production "8445" casting head / 109 Block / 71mm Turbo
•3450 lbs - Aluminum (Champion Style) head / 109 & Series II block / 71mm Turbo
•3650 lbs - Any other block (Stage I & II on/off center, etc) / any style head / 71mm Turbo
•67mm and smaller turbo deduct 100lbs from minimum weights.
• Stock operating glass windows and windshield required. No lexan.
• Engine/firewall must be in stock location.
• Stock wheelbase required (108.0" measured).
• FSA inner front wheel wells required. Trimming allowed for downpipe clearance.
• FSA front suspension components and mounting locations required w/any type stock location shocks. Tubular front A-Arms allowed.
• Factory stock rear suspension locations required w/any type stock location shocks.
• Any suspension stabilizer/reinforcement bars or traction enhancing devices are allowed. No ladder bars, wheelie bars, or coil over equipped rear suspensions.
• Swaybars may be removed.
• No ladder bars or coil over equipped rear suspensions.
• No quarter panel modifications except rolled inner lip.
• Minor modifications to stock rear wheel wells (no mini-tubs).
• Outer frame rail notching allowed. Inner frame rails remain stock.
• Parachutes allowed if required for speeds attained.
• Brake system may be power assisted or manual.
• Brake system line locks allowed.
• Driver's name and club/sponsor decals on side/rear/quarter windows allowed.


• Any V6 Buick block allowed including 109, Stage I & II, Series II, or TA Block allowed. (See minimum weights above)
• Any valve covers and oil pan allowed.
• Buick V6 cast iron (8445) or aluminum production style cylinder heads.
• Any cylinder heads are allowed.
• No dry sump-oiling systems allowed.
• No aftermarket sheet metal intake manifolds of any kind allowed.
• Any cast aluminum intake and cast intake plenum allowed. (ie Stock GM, Champion Racing, and BGC cast aluminum lower intakes)
• Single modified stock or aftermarket throttle body up to 70mm allowed. Single throttle plate only.
• Any type stock location exhaust headers are allowed. Welded in EGT gauge probe bungs are allowed.
• Any size single or dual exhaust system and downpipe allowed. Exhaust must muffle and exit in stock location. Downpipe must be routed down through the stock location, no flex pipe allowed.


• Single 3-bolt turbo only.
• Maximum size compressor wheel inducer size is less than 71.5mm. Inlet bore cannot exceed 72mm to allow for machining tolerances. Maximum compressor wheel exducer size is less than 103mm.
• No sleeves, welding or cold weld epoxy on any exterior surface of the turbo compressor housing to allow a larger than legal “70mm” compressor wheel to be installed is allowed.
• One of the following turbine exhaust housings is allowed: A Garrett P/N's 430832-4 and 430832-5, PT&E P/N's THB376, THB380, THB576 and THB580, Turbonetics P/N's 20240-63 and 30340-82 3 bolt turbine housings that were available November 1 of the previous year. The FSA turbine exhaust-to-downpipe flange connection must be used. (no “V-Band” flanges)
• Any air intake to turbo allowed.
• Any wastegate configuration acceptable, external wastegate(s) must be plumbed back into the exhaust system, no external dumps allowed.
• CO2 allowed for wastegate actuator.


• Any stock location or front mount air to air intercooler is allowed. No part of a stock location intercooler (not the shroud) may extend down more than 11.5” below the centerline of the crankshaft.
A front mount intercooler, except for the piping, may not extend down below the bottom of the stock located radiator support.
• No liquid intercoolers, intercooler external spray cooling, or add-on cold boxes allowed.

Engine Management & Fuel System

• Stock, modified stock ECM or aftermarket fuel management systems allowed.
• Stock (Type I) or Type II DIS, aftermarket Distributor, or aftermarket COP ignition systems are allowed.
• MAF optional.
• Thumbwheel chips allowed.
• No Delay boxes, Throttle stops or crossover boxes allowed. Throttle blade must be foot operated.
• Any air induction system allowed.
• Any fuel pump(s) configuration/location allowed.
• Voltage increasing and fuel pump hot wiring devices are allowed.
• Any fuel lines allowed.
• Aftermarket fuel rail(s) allowed.
• Any type fuel pressure regulator allowed.
• Any fuel injectors allowed.
• Factory stock fuel tank w/sump addition is allowed. Fuel cells allowed.
• Gasoline fuel only (includes E85, Sunoco, VP, etc), no additives, or nitrous oxide injection allowed.
•Alcohol injection allowed with 100# weight penalty.

Engine Compartment

• A/C and heating equipment may be removed.
• Power steering, Manual Steering, and aftermarket rack and pinion steering allowed.
• Stock alternator operational w/belt in stock location. Relocation brackets allowed as long as alternator is still on driver's side, front of engine.
• Stock water pump or Electric water pump allowed.
• Any engine compartment dress up allowed, subject to requirements noted in these rules.
• Battery may be in any location.
• Any stock type/location electric engine cooling fan(s) allowed.
• Any stock or replacement radiator in stock location allowed.


• Any GM automatic transmission allowed. (TH200-4R, TH400, etc.)
• Any size torque converter allowed.
• Any transmission oil cooler and pan allowed.
• Transmission brake allowed.
• No aftermarket automated shift actuation of shift lever, linkage or linkage components. Linkage must be manually shifted.


• FSA GM differential housing, a Dana-60 style or the 9" Ford style differential housing required.
• Limited slip differential or spool allowed with any gear ratio.
• FSA or aftermarket differential cover allowed.

Tires & Wheels

• Any 15” diameter wheels allowed.
• Rear drag slicks w/sidewall designation up to and including 29.5” x 10.5” - 15” (ie Slicks). No "W" tires allowed. Rear DOT street tires w/sidewall designation up to and including a 29.5” x 12.5” - 15” (ie ET Street) and up to and including 295 series Drag Radial tires are allowed (ie ET Radial 295/55R15). Rear tire footprint when installed on a rim and mounted on the car can not exceed a maximum of 10.6” slicks & 10.9" Drag Radial width at 10 psig checking pressure. Tires may not be shaved at the tread edge to meet the maximum tread width rule.
• Front tire footprint must be at least 3.5" wide.


• Full FSA interior required.
• Race seats allowed only if seats are attached to rear crossbar of roll bar/cage and seats are painted or upholstered to match factory interior.
• Any transmission shifter allowed. Linkage must be moved manually.
• Any additional aftermarket gauges allowed
• Roll Bar/Cage and Window nets allowed.
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