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CVR Autocross - Index of Modification Definitions
 
2-4.2 "Free" Engine Modifications
 
  1. Ignition System - Any modifications is allowed, provided an original type mechanical distributor is used.


  2. Air Cleaner - May be removed.


  3. Carburetors - Any car originally equipped with a carburetor may have any carburetor, provided the throttle body and venturi dimensions are not changed from original specs. Jet sizes may be changed.


  4. Fuel pump - An electric pump may be fitted.
  5. Sump - Any wet sump lubrication system may be modified to ensure a constant source of engine lubrication at the oil pick-up point. If the car has a dry sump system, no modifications are allowed.


  6. Oil Cooler - Any addition of cooler/filter is allowed.


  7. Roller Bearing Crank - Any roller bearing crank may be used. Plain bearing cranks can be substituted for roller bearing cranks. Counterbalanced cranks may be used.


  8. Internal Engine Parts - May be balanced/blueprinted.


  9. Chain Tensioners/Guards - Any are allowed.


  10. Exhaust - Any modifications after the head is permitted, provided the car still complies to emissions/noise restrictions.


  11. Turbochargers - "Free" on cars with stock turbochargers. The boost pressure may not be increased by any means.


  12. EPROM Chips - Any chip may be used, except for those altering boost pressure.


2-4.3 Handicapped Engine Modifications
 
  1. Flywheel - May be lightened.


  2. Venturis - May be removed or modified.


  3. Velocity Stacks - May be added or modified.


  4. Displacement - May be increased. The amount of the increase determines the weight of the points assigned.


  5. Increase up to 1.2 millimeter in the bore. This is "free" for all categories. Many four-cylinder cars - Increase the displacement up to the limit or above that specified by the classification chart. This automatically places the car in the Modified category.

    If the compression ratio increases due to displacement increase, then additional points must be taken under "Compression Ratio."


  6. Compression Ratio - May be increased by any method, including turbo boost.


  7. Fuel System - Modifications to fuel injection systems or carburetion systems that are not allowed "free" are handicapped. This causes a jump to Improved.

  8. Turbocharger/Supercharger - May be used. All cars, except factory-equipped models, will compete in Modified.


2-4.4 "Free" Suspension Modifications
 
  1. Adjustments - Any adjustment to standard suspension components is permitted, providing no machining is required.


  2. Removal of Hydopneumatic Suspension - This modification is not only allowed, suggested.


  3. Springs/Torsion Bars - Any may be used (except one may not be substituted for another).


  4. Shocks - Any may be used.


  5. Sway Bars - Any may be installed.


  6. Camber Compensation - Any rear camber compensation device may be used.


  7. Bushings - Non-standard may be used, including shock tower mono-balls.


  8. Springplates - Adjustable springplates may be used.


2-4.5 Handicapped Suspension Modifications
 
  1. Machined Suspension - Any adjustment may be made and machining is allowed.


  2. Front Shock Tower Brace - May be used provided that it can be quickly removed (bolted, not welded in) and that all attachment points are within three inches of a vertical plane passing through the top center of the shock absorber.


2-4.6 "Free" Wheel, Brake, Tire and Fender Modifications
 
  1. Offset Rims, Tires, or Spacers - Permitted provided no modification to the car, other than increasing the wheel stud length.


  2. Brakes - Any pads, linings, and brake lines may be used. A "safety braker" device may be used. Any type of brake cooling may be used. Rotors may be slotted or drilled.


  3. Fenders - May be modified provided the tire-wheel-spacer combination and ride-height setting used could be used without the fender modification. Entrant should be prepared to provide compliance with this rule.


  4. Tire and Wheels - The wheel diameters permitted in Street and Prepared are listed in the wheel chart. Recapped or regrooved tires are not allowed. All tires must be DOT approved and must not rub against any surface on the car during driving events. Tires must be marketed nationally and generally available. They must have an unloaded circumference not smaller than the minimum listed for the car. Measurement is made by jacking the wheel up, adjusting the pressure to 30psi and measuring around the center of the tread with a non-expandable tape. The cord must not be visible during or after runs. Tires must be properly inflated; 30psi minimum is recommended for street tires. No tires with a wear rating of less than 140, shaved high-performance DOT (such are B.F. Goodrich Comp T/A, Pirelli P-Zero, or Goodyear GS-GC), recapped or race tires are allowed in Street.


2-4.7 Handicapped Wheel, Brake, Tire, and Fender Modifications
 
  1. Wheels - The rim width may be increased. The handicap corresponds to the widest rim used on the car in question. The use of any wheel smaller in diameter than allowed will be handicapped and the car will automatically be placed in Improved.

  2. Track - May be increased up to two inches over stock. This automatically places a car in the Improved category.


  3. Fenders - Any modifications not allowed under "free" receives points and automatically places a car in the Improved category.


  4. Tires - Use of DOT-approved tires that have an unloaded circumference less than allowed under the wheel chart will be permitted with points. If the circumference is less than the chart, then the car is automatically placed in the Improved category. The use of non-DOT, recapped, wheels +1" or more over the largest diameter over than model year, or racing tires will also automatically place the car in the Improved category. Racing tires must have visible tread depth indicators. Tires that run slightly under driving conditions will be permitted in the Improved and Modified categories, provided such rubbing is not a safety hazard in the opinion of the safety personnel.


  5. Brakes - Any component not allowed "free" may be used. This modification automatically places the car in the Improved category.


2-4.8 Other "Free" Modifications
 
  1. Fuel/Additives - Any grade of automotive gasoline available to the general public through normal retail service stations is allowed. The only additives that are "free" are those for upper lubrication, which must be added directly into the gas tank, and those which only improve the octane rating.


  2. Spoilers - Any may be fitted.


  3. Interior Modifications - Any accessory, gauge, or indicator may be fitted if its purpose is to improve driver or passenger comfort or convenience or safety, providing such items no effect whatsoever on mechanical performance. Alternate seats may be used. Floor mats may be removed, and it is suggested that they be removed. However, removal or substitution of any component that might be considered LIGHTENING of the car IS NOT A "FREE" MODIFICATION (see Other Items/Modifications).


  4. Roll Bars - Safety devices consisting of lateral members and longitudinal braces, all attached within the passenger compartment, are permitted.

  5. Gear Shift Linkages - May be modified or exchanged.


  6. Seam Reinforcement - Kits are allowed "free" on 914s, provided each reinforcement is limited to a single seam and that all reinforcements combined do not substantially increase the rigidity and stiffness of the chassis.


  7. Spare Tire - May be removed.


2-4.9 Other Handicapped Modifications
 
  1. Windshields - May be removed from cars that have bolt-on windshield frames.


  2. Bumpers - May be removed on 356 series cars.


  3. Removable Tops - Tops do not have to be carried on or with Speedsters or Roadsters, or Cabriolets. Removal is not permitted on any other model.

  4. Limited Slip Differential - Even if this is a factory option rather than a change, it is handicapped.

  5. Non-Standard Gears - Any gear that does not fit the car's model range specifications is handicapped. Street and Prepared cars will jump into the Improved category.


2-4.10 Other Items/Modifications
 
Any equipment, component, part or modification which is performance-affecting and which is not specifically defined in Class Progression rules will be handicapped under "Modifications Not Listed Above" and will automatically place a car on the Modified category.

"Engine Swaps" for engine modifications not allowed in any class, "Changes Outside the Model Range," "Displacement," and "Interior Modifications" are all examples that would fall into this range.
 
  
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