RULES - NATIONAL COMPETITION RULES - PREPPED CATEGORY
These are the vehicle classing and preparation rules for the Prepped Category of SCCA National Time Trials Competition. The intent of Prepped Category is that these are street cars - or close to street cars. We do not guarantee the competitiveness of every car, as it would be nearly impossible and certainly overly complicated. Once you find where your car may fit within the classing divisions, make sure it fits in Prepped Category by scrolling down to see what modifications you're allowed to do.
Prepped Category Classing
This is where we're going to class cars that might not quite meet the rules, but we think they can go in this category anyway.
1. Cars listed as eligible in and prepared to the SCCA Road Race Improved Touring National Rules are permitted to compete in their respective Time Trials Prepped Class, provided they run on tires legal for Time Trials. Vehicles with this allowance are not permitted to interchange preparation rules otherwise.
A. Improved Touring cars are not limited to the spec wheel sizes.
B. Regional-only Improved Touring cars—e.g., "ITE"—do not fall under this allowance.
Prepped 1 (P1) eligible vehicles include:
1. Naturally-aspirated vehicles with an engine displacement of no more than 6.5L, not weighing less than 3,000 lbs. (with driver).
2. Forced-induction vehicles with an engine displacement of no more than 4.334L, not weighing less than 3,000 lbs. (with driver).
3. Naturally-aspirated vehicles with an engine displacement between 2.995 and 3.9L which weigh less than 2,600 lbs. (with driver).
4. Forced-induction vehicles with an engine displacement between 1.997 and 2.6L which weigh less than 2,600 lbs. (with driver).
Prepped 2 (P2) eligible vehicles include:
1. Vehicles with a real or corrected displacement of no more than 3.9L, not weighing less than 2,600 lbs. (with driver).
2. Vehicles with a real or corrected displacement between 1.995 and 2.995L which weigh less than 2,200 lbs. (with driver).
Prepped 3 (P3) eligible vehicles include:
1. Vehicles with a real or corrected displacement of no more than 2.995L, not weighing less than 2,200 lbs. (with driver).
2. Vehicles with a real or corrected displacement of 1.995L or less which weigh less than 1,900 lbs. (with driver).
Prepped 4 (P4) eligible vehicles include:
1. Vehicles with a real or corrected displacement of no more than 1.995L, not weighing less than 1,900 lbs. (with driver).
To determine the corrected displacement for classing purposes, the following formulas will be used:
1. Rotary: Actual displacement X 2.0
2. 2-Cycle Engines: Actual displacement X 2.0
3. Forced induction: Actual or corrected displacement X 1.5
A. For each additional forced induction unit 0.5 should be added to the forced induction displacement modifier (e.g., twin charged, twin turbo: Actual corrected displacement X 2. Quad turbo: Actual displacement X 3).
Prepped Category Authorized Modifications
These are the Authorized Modifications for Prepped Category vehicles (i.e., what you can do to your car and have it stay in Prepped Category). They are broken down into an Overview and then the "Authorized Modifications" (i.e., what you can do to your car and have it stay in Prepped Category). Prepped Category, along with Sport, Tuner and Max are restricted rulesets. If a modification is not specifically authorized in these Rules, it is not allowed. (If it doesn't say you can, you can’t.)
The Authorized Modifications are broken down into two (2) parts, the first of which are the "Layman's Terms." These are a basic way to describe the intent and allowance. For the rules nerds in our midst—or those who think their modification might be close to OK but not quite sure—there will be a link to the full rules which fully explains what is allowed.
Prepped Category is meant for street-drivable vehicles between Tuner and Max categories, with common OE engine swaps or aftermarket forced induction or camshafts. Vehicles in this Category may also install mild aero modifications and simple engine bolt-on parts.
1. Vehicles running in Sport, Tuner, Prepped and Max Categories must meet Safety Level 1 Standards.
A. Roll bars, cages, racing harnesses and other safety equipment may be added, and must meet manufacturers' guidelines for installation. It is highly recommended that they at least meet the minimum for Safety Level 2 or Safety Level 3 Standards.
B. Nothing in the rules prevents you from adding safety equipment; the minimum amount of modification to install safety equipment is allowed.
C. To facilitate safety, vehicles that have an added roll bar may remove carpet, seats and trim (including convertible tops) behind the front seats. Vehicles that have an added roll cage may remove carpet, seats and trim (including convertible tops) other than the dash.
2. Fuel cells may be used in cars with the following restrictions and allowances:
A. OE lines may be replaced in conjunction with a fuel cell provided they are shielded.
B. Any fuel lines—including gauge and vent lines—that pass into or through the driver/passenger compartment, shall be of steel tube or metal braided hoses or bulkheaded.
C. Drivers of cars with modified or replaced OE fuel lines or tanks must wear a suit, shoes, gloves and underwear as specified in SCCA Time Trials Safety Level 2 Standards.
D. Vehicles with modified or replaced OE fuel lines or tanks must have an on-board fire suppression (fire bottle or system) meeting SCCA Time Trials Safety Level 2 Standards.
E. Participants are cautioned that this is not an allowance to maximize fuel delivery by installing higher-performance parts than authorized by category rules. (E.g., installing an upgraded fuel pump if it's not otherwise allowed.)
1. To be eligible for Prepped Category:
A. A minimum of 1,000 of that model must have been produced that model year for road use.
B. The vehicle must be capable of being licensed for normal road use in and delivered through the manufacturer's retail sales outlets.
The following items are guidelines for modifications in Prepped Category:
A. Prepped Category builds on Sport and Tuner Rules—all of the general modification rules of Sport and Tuner Categories are allowed in Prepped Category.
B. Prepped Category vehicles are likely to be street-driven cars, and SCCA does not encourage or condone the breaking of laws governing pollution control systems or the alteration of street-driven vehicles contrary to state and federal laws regarding their use. It continues to be the responsibility of the individual to comply with such state and federal laws.
Competitors may do anything allowed in Sport and Tuner, which includes things like aftermarket seats, shift knobs and steering wheels. Additionally, in Prepped Category, the interior styling isn't limited to North American markets, so it's possible to see a right-side drive conversion or other alternate-market customization.
Everything legal in Sport and Tuner Categories, plus the items below.
1. Interior parts may be swapped with alternate market parts (JDM, EDM, etc.).
1. A hole may be added through the bodywork to route a remote reservoir for shocks/struts and hose to a remote mounting location. Such holes may serve no other purpose.
2. Any steering wheel may be used. An alternate steering wheel assembly—including all mounting hardware—which replaces an airbag-equipped wheel is not required to have an airbag. An alternate wheel is not required to have a horn button.
3. Any shift linkage may be used.
1. Accessories, gauges, indicators, lights and other appearance, comfort and convenience modifications including pedal cover kits, alternate shift knobs and paddles which have little or no effect on performance and/or handling and do not materially reduce the weight of the car are permitted. Delayed shutdown devices such as a “turbo timer,” which perform no function while the car is in motion, are permitted. This does permit the installation of an additional mirror (e.g., Wink®). The addition of small holes for attachment hardware for cosmetic modifications is implicit (e.g., holes for fasteners to mount additional gauges).
2. The driver and front passenger seats may be replaced with the following restrictions.
A. The seating surface must be fully upholstered.
B. The top of the seat, or an attached headrest, may not be below the center of the driver’s head.
C. The seat shall be securely mounted, so as to provide fore/aft and lateral support.
D. Passenger seat must be either OE or match the requirements for the driver’s seat.
3. Alternate steering wheels are allowed, provided the outside diameter is not changed by more than 1-inch from the standard size. Steering wheels with an integral airbag may not be changed unless Safety Levels 2 or 3 Standards are met.
4. Short shift kits which only change the length of the shift rod attached to the gear shift knob may be installed. Kits which change other linkage, mounting brackets and/or tension through springs are expressly disallowed.
5. A hole may be added to interior body panels, the engine compartment, the trunk, and/or a strut bar to provide access to the adjustment mechanism on a shock absorber. The hole may serve no other purpose and may not be added through the exterior body panels.
6. Any item that cannot be held permanently in place by factory-installed fasteners may be removed.
7. Spare tires, tools and jacks may be removed. Any fastening hardware and/or other pieces that can no longer be firmly secured in the absence of the spare tire may be removed, if necessary, to ensure compliance with safety inspection requirements.
8. Data acquisition systems (including video cameras) and the accompanying sensors are allowed but may serve no other purpose during a run than real-time display and data recording.
9. The removal of interior carpet, trim and seats is allowed in conjunction with the addition of safety equipment, with the following restrictions.
A. Rear seats, carpet and trim behind the front seats may be removed if the vehicle is equipped with a 4-point roll bar, driver’s seat, and restraints meeting SCCA Time Trials Safety Level 2 Standards.
B. All interior carpet, trim and passenger seats other than the factory dash may be removed if the vehicle is equipped with a minimum 6-point roll cage, driver’s seat and restraints meeting SCCA Time Trials Safety Level 3 Standards.
C. Airbags may be removed if either of the above safety levels are met.
D. Airbag-equipped steering wheels may be replaced or have the airbag removed if either of the above safety levels are met.
E. Convertible soft tops and related structure and brackets may be removed as part of this allowance.
Because this Category of classes will allow engine swaps, competitors are allowed to do the minimum amount necessary to the chassis of the car—including subframes—to make those swaps possible. This doesn't allow changing suspension mounting points or other significant changes; those modifications put you in Max Category.
1. Subframes may be modified the minimum amount to enable legal modifications in this section. Competitors are cautioned that modification is not replacement, and suspension geometry should not be modified beyond what is listed in this section.
This is the first Category that allows a lot of bodywork mods, including alternate-market items like JDM parts. Hoods and decklids and hardtops can be replicas made of alternate material—like a carbon hood—but they need to be able to use all the stock latches and hinges. You can also install vents for cooling purposes here; however, there is a limit on how much you can remove, so read up on the rules. Prepped Category also allows things like cutting holes in bumpers, and flaring or adding fender flares.
Everything legal in Sport and Tuner Categories, plus the items below:
1. Hoods, fenders and bumpers may be replaced with OE parts and exact replicas from markets other than North America (E.g., JDM, Euro-spec parts).
2. Hoods and decklids may be replaced with replicas including those made of alternate material. Replacement pieces must retain any OEM lights and must be able to use OEM hinges and latching mechanisms as standard.
3. Hoods may have vents installed for cooling purposes. The maximum combined total area of all vents (including OEM) shall not exceed 200 square inches. The 200 square inches includes any area that deviates from the factory hood profile.
4. Hardtops may be replaced with replicas of alternate material. Replacement pieces must be able to use OEM hinges and latching mechanisms as standard.
5. Bumpers may be trimmed or cut for fitment or aerodynamics.
6. Fenders may be flared, or cosmetic over-fender flares may be added. OE fenders may be trimmed or cut to facilitate the additions. Flared fenders may not be trimmed or cut for drag reduction. Fenders must taper into the OE bodywork.
1. Front hoods, engine covers, trunk lids and hatches not containing glass, front fenders, rear fenders not part of chassis structure (unibody), front and rear bodywork, and side skirts may be replaced with factory parts or exact duplicates in order to facilitate allowed modifications.
2. Factory rub strips may be removed.
3. OE “pop-up” headlights may be replaced with static headlights, provided the replacement units are intended for automobile use on public roads as a primary means of illumination, and retain high and low beams as originally provided by the manufacturer. Minor repositioning of the headlights can accommodate the alternate headlight, but the unit may not be relocated, and the repositioning may serve no other purpose. All associated hardware may be removed, replaced or modified.
4. Bolt-on tow hooks and tie downs may be modified or replaced. Addition of tow hooks and tie downs are permitted, and location is unrestricted. Non-standard tow hooks shall serve no other function.
5. Fenders may be rolled, but no material may be added or removed.
1. Addition or removal of spoilers, splitters, rear wings, bumper covers, valances, side skirts, convertible hard tops and scoops/vents is allowed provided that:
A. The removal of parts matches a production model of that generation. (eg., You may not remove parts unless a model of that vehicle was available without the part or parts.)
B. It is a production part which is standard or optional equipment of a model of the vehicle.
C. It is listed in the vehicle manufacturer’s accessory catalog for that vehicle for normal highway use. This may not allow for parts sold through a manufacturer’s performance catalog (e.g., Ford Racing, HPD, Mazdaspeed, Mopar Performance, Mugen, NISMO, SPT, TRD, etc.).
D. All allowed parts must be installed as directed by the manufacturer. Exact replicas, including weight, from alternate sources are also permitted.
E. Updated parts, replacement parts, or any other changes by the manufacturer documented in the parts catalog or other manufacturer documentation as superseding the original part number used when manufactured are considered to be standard parts.
2. Factory emblems, mud flaps, bolt-on front valance lips/spoilers and fog lights (except those integral to a headlight or turn signal) may be removed. Rear wings may be removed so long as the vehicle retains any federally-mandated third brake light.
3. Hood straps or fasteners may be added.
4. Cars may add one (1) rear trailer hitch. The resulting weight addition is allowed. The hitch may serve no other purpose. Factory tie downs and cosmetic pieces (e.g., diffusers) may be modified or removed to facilitate hitch installation. Complete or partial removal of the hitch is allowed for competition, provided it does not result in a reduction in weight compared to the unmodified standard configuration.
5. Tow bar brackets may be installed but may serve no other purpose.
This is the first Category which allows aftermarket items like wings, spoilers and splitters—but there are some limits, so read up on exactly what you can do and how big the items can be.
Wings, spoilers, splitters and air-dams may be added, removed, or modified with the following restrictions:
1. Non-OE wings have the following restrictions:
A. May not be added in addition to an OE wing.
B. Only one wing may be added.
C. May only be attached behind the centerline of the rear axle and may not attach to suspension components.
D. The total combined surface area of all wings shall not exceed 5.75 square feet (0.5341 m2) as calculated.
E. The number of wing elements is limited to one (1).
F. Wings designed to be adjustable while the car is in motion must be locked in a single position.
G. Wings—and any component thereof—may not extend beyond the vehicle width as defined by the outermost portion of the bodywork including OE mirrors, door handles, rub strips and trim.
H. No portion of the wing or its components (including end plates and mounts) may be more than 6 inches (15.24 cm) forward of the rear axle, more than 6 inches (152.4 mm) beyond the rearmost portion of the bodywork, or more than 6 inches (15.24 cm) above the roofline of the vehicle, regardless of body style.
I. Reinforcements to the wing mounting area may be used but may serve no other purpose.
J. Wing endplate surface area is limited to 165 square inches (1064.51 cm2) each and the number of endplates is limited to a maximum of two (2).
K. For convertibles/roadsters with no roof, and targa tops with no rear window, no portion of the wing may be higher than 12 inches (30.48 cm) above the wing’s point of attachment to the body of the vehicle.
L. For convertibles/roadsters with no roof and targa tops with no rear window that retain the OE windshield frame, a windshield of any material that meets the top of the windshield frame shall be considered the top of the roofline, and the car may use the wing mounting rules for a closed car.
M. Spoilers and rear wings are mutually exclusive such that a builder may use one or the other, but not both.
2. A spoiler may be added to the rear of the car provided it complies with the following:
A. It is a production rear spoiler which is standard or optional equipment of a US model of the vehicle or an exact replica in an alternate material.
B. It is a non-production rear spoiler which is mounted to the rearmost portion of the rear hatch, deck or trunk lid. The spoiler may extend no more than 8 inches (203.2 mm) from the original bodywork in any direction. Alternatively, on a hatchback, the spoiler may be mounted to the rear hatch lid at or near the top of the hatch; however, in such a configuration the spoiler may not extend more than the original bodywork in any direction. The spoiler shall not protrude beyond the perimeter of the original bodywork as viewed from above. The use of endplates is prohibited. The angle of attack is free. The spoiler may not function as a wing.
C. Spoilers and rear wings are mutually exclusive such that a builder may use one or the other, but not both.
3. A front spoiler/splitter is permitted, with the following restrictions.
A. Splitter blade shall be installed parallel to the ground (within ±3° fore and aft) and may extend a maximum of 3 inches (7.62 cm) forward of the front bodywork/fascia as viewed from above.
B. No part of the front spoiler shall be lower than 3 inches from the ground.
C. Splitters may not extend rearward past the vertical centerline of the front wheels.
D. No portion of the splitter may extend beyond the widest part of the front bodywork including the top of the wheel arch or further than 3 inches from the edge of the bumper—whichever is less.
E. Openings in the front spoiler are permitted for the purposes of ducting air to the brakes, cooler, and radiator.
F. OE (factory) front spoiler/air dam systems are permitted, and if mounted in the stock location, have no height restrictions.
As with Tuner Category, any wheel may be used provided it complies with some safety rules. There are allowances for things like spacers, converting lug bolts to lug nuts and removing tire pressure monitoring systems.
Any width or diameter wheel and wheel spacers may be used provided it complies with the following:
1. Non-metallic wheels must be certified/approved from an appropriate, recognized standards organization. (E.g., FIA, SFI, SAE, TUV, etc.)
2. Wheel spacers are permitted.
3. Wheel studs, lug nuts, valve stems (including pressure-relief types) and/or bolt length may be changed. Wheel bolts may be replaced with studs and nuts, but the number of fasteners may not be changed.
4. Tire pressure monitoring sensors may be removed.
5. Centerlock/spline drive/knock-off type hubs may be converted to lug-type hubs.
Prepped Category vehicles must be on tires that are DOT-Approved, 200 treadwear or more and made in enough sizes and enough tread depth to be eligible. (The same rules as Sport and Tuner, but no limits on tread width.)
Tires must meet the following requirements to be eligible for use in Prepped Category. No tire model will be eligible for Time Trials competition until it meets all requirements of this section. Tire models not meeting the requirements by April 30 are not eligible for Time Trials competition until after the Time Trials Nationals of the year.
A. Minimum UTQG Treadwear Grade of 200.
B. Minimum molded tread depth of 7/32 inch as specified by the manufacturer.
C. Listed in a current year or prior two years of the “Tire Guide®” and/or the “Tread Design Guide®” (www.tireguides.com).
D. US Department of Transportation (DOT) approval.
E. Tires must be designed for highway use on passenger cars.
2. Eligibility Requirements:
The following are prerequisites before a tire can be used in competition at Time Trials Events.
A. Tire availability: Tires are considered available when competitors can take possession through retail channels. Pre-orders are not considered available.
B. Tires must be equally available to all competitors. Tires that are in short supply do not specifically violate this section. Extensive shortages may result in the tire being placed on the exclusion list until supply is replenished. Tire variations differing from standard specification, delivered only on a limited basis, or only to selected competitors may not be used.
C. Tire models must have tires available in at least four (4) rim diameters and in at least six (6) sizes which meet these requirements.
D. Material Change: Tires which previously met the eligibility requirements that undergo a significant compound change, tread pattern change, or other significant redesign reset the requirement for eligibility described in this section.
E. A tire model which was previously allowed by these rules continues to be eligible for competition until specifically disallowed.
F. Reintroduction: Models that were once discontinued will be considered a new model once reintroduced and must meet all the requirements of this section.
3. Tire Use
Unless a “wet session” is declared by event officials, vehicles must run on the same set of tires for all competition rounds, and the tires should be marked with a stamp on grid of the first competition. Tires may also be replaced at the discretion of the Technical Chief in cases of safety issues such as damage or excessive wear. (Entrants are warned that damage caused by deliberate abusive handling or deliberate shaving should not be given a replacement allowance.)
A. Tires may be shaved evenly and parallel to the axis of rotation, but may not otherwise be siped, grooved or modified.
B. Tires must have a minimum tread depth of 2/32nds at two (2) points 180 degrees apart.
C. No recap and/or retread tires may be used.
D. Excluded tires: Tires may be excluded for, but not limited to, low volume production, extensive availability limitations and specialty design.
E. The tire must not appear on the following exclusion list, which may be altered at any time by the Time Trials Board (TTB) upon notification of membership.
- Kumho V720 ACR (less than minimum molded tread depth)
Competitors can do all of the same things with brakes that are allowed in Sport and Tuner Categories, which means swapping for factory brake options and aftermarket big brake kits are allowed. In addition to those, competitors can now add a brake proportioning valve.
Brakes may be modified or changed within the guidelines of Sport and Tuner Categories, plus the allowances below:
1. Proportioning valves may be added.
1. Non-standard brake rotors may be used provided they are of equal or larger dimensions.
2. Aluminum rotor hats are allowed.
3. Cars originally equipped with solid (non-vented) rotors may utilize vented rotors.
4. Brake calipers and mounting brackets may be replaced provided they bolt to the standard locations and the number of pistons is equal to or greater than standard. A functioning emergency brake of the same type, operation, and actuation as OE must be present. Drum brakes may be replaced with disc brakes of a diameter equal to or greater than the inside diameter of the standard drum. Such conversions must be bolted, not welded, to the axle/trailing arm/upright and must include an integral, redundant emergency brake. Changes to backing plates/dust shields/brake lines to accommodate these changes are permitted but may serve no other purpose.
5. Air ducts may be fitted to the brakes and changes may be made made in the body/structure for their use. Ducts or holes may serve no other purpose. Backing plates and dirt shields may be modified or removed.
1. The make and material of brake pad/shoe linings (friction material) may be changed.
2. Non-standard brake rotors may be used provided they are of equal or larger dimensions (diameter and thickness) and match the OE design and are constructed of the OE or heavier materials. Thickness includes the individual plates of a vented rotor, as well as the overall dimension. The diameter for replacement rotors is measured at the minimum outside dimension. Cross-drilled and/or slotted brake rotors may be fitted provided all such voids are within the disc area and comprise no more than 10% of that area.
3. Brake lines may be substituted with alternate DOT-approved flexible brake lines.
4. Alternate brake bleeder fittings (e.g., Speedbleeders®) are permitted. They may serve no other purpose.
5. Standard anti-lock braking systems (ABS) may be electrically disabled but may not be removed or altered in any other way.
6. Brake Rotors and Calipers may be swapped to OE option package configurations from the same model and generation of car, providing the rotor width and diameter are of equal or larger sizes and the number of caliper pistons is the equal or greater. The allowances from 1–5 also apply to option package swaps.
Prepped Category vehicles can do anything listed in Sport or Tuner Categories. Some things—like the steering wheel—is covered in the section on interior rules, but you can replace steering rack bushings in Tuner and here as well, as long as they stay the OE material (i.e., rubber).
Prepped Category also allows for right-side-drive conversions.
Proposed Category vehicles may have any modifications allowed in Sport or Tuner Categories, plus the allowances below:
1. Right-side-drive conversions to left-side-drive vehicles may be performed and vice-versa, provided that: the vehicle was delivered in retail sales locations, the converted configuration is OE, and the conversion is done with OE parts for the vehicle.
Prepped Category has the same rules for shocks and struts as Tuner. Competitors can replace stock shocks and struts with most shocks or struts that bolt to the stock locations and don't alter suspension geometry. (This means there are some allowances for converting to a spring/shock assembly for cars that had the spring separate from the shock, and threaded-body coilovers are OK, along with remote reservoirs and more than one adjustment.)
Because these rules are the same as Tuner, we have included the Tuner Category rules for shocks and struts below for those who want more details.
1. Shocks and Strut Replacement Allowances:
A. Any shock absorbers may be used.
B. Shock absorber mounting brackets which serve no other purpose may be altered, added, or replaced, provided that the attachment points on the body/frame/subframe/chassis/suspension member are not altered. This installation may incorporate an alternate upper spring perch/seat and/or mounting block (bearing mount). The system of attachment may be changed.
C. The number of shock absorbers shall be the same as standard.
D. No shock absorber may be capable of adjustment while the car is in motion, unless fitted as original equipment.
E. MacPherson strut equipped cars may substitute struts and/or may use any insert. This does not allow unauthorized changes in suspension geometry or changes in attachment points (e.g., affecting the position of the lower ball joint or spindle). It is intended to allow the strut length changes needed to accommodate permitted modifications which affect ride height and suspension travel.
2. The following additional allowances apply to cars originally equipped with separate spring and shock absorber assemblies.
A. Coil springs may be relocated so they encircle the body of the shock absorber in a “coilover” configuration.
B. Coil spring perches may be modified, added, or replaced and their position may be adjustable.
C. Additional bolt holes may be drilled for coilover assembly mounting brackets. This does not permit any modifications to the frame or unibody beyond the allowed mounting holes.
Prepped Category has the same rules for springs as Tuner Category, so your Prepped Category vehicles may use any springs that fit the rules. There are no limits on where to get the spring.
Prepped Category also allows leaf spring cars to be converted to a coilover design—you can find that allowance in the rules section titled, "Suspension."
Because the rules are otherwise the same, we have included the full Tuner Category rules below.
Springs must be of the same type as the original (e.g., coil, leaf, torsion bar, bellows) and except as noted herein, must use the original spring attachment points. This permits multiple springs, if they use the original mount locations. Coil spring perches originally attached to struts or shock absorber bodies may be changed or altered and their position may be adjustable. Spacers are allowed above or below the spring. Coil springs may incorporate spring rubbers. Suspension bump stops may be altered or removed.
In Prepped Category, competitors can add a sway bar, including fancy splined ones that don't directly replace the OE sway bars.
Because the Prepped Category Rules for anti-roll (sway) bars are the same as Tuner Category, we have included those full rules below.
Substitution or removal of sway bars (at one or both ends of the car) and supporting hardware (brackets, end links, bushings, etc.) is permitted. Tow hooks may be removed for the instillation of sway bars.
Strut braces/bars—also known as "strut tower braces"—are allowed in Prepped Category. There are also allowances for strut braces on the underside of the car, and some attachment rules.
Strut bars are permitted with all types of suspension, subject to the following constraints:
1. Strut bars may be added, removed, modified or substituted.
2. Lower suspension braces must be attached to the lower suspension pickup point locations on the chassis within 2 inches (50.8mm) in any direction of the actual suspension attachment to the chassis.
3. Except for standard parts, no connections to other components are permitted. Additional holes may be drilled for mounting bolts. Only “bolt-on” attachment is permitted. Interior trim panels may be modified to allow installation of strut bars. Holes or slots may be no larger than necessary and may serve no other purpose. This does not permit any modifications to the frame or unibody beyond the allowed mounting holes.
Prepared Category builds on the Tuner Category allowances for adjustable suspension—and adds some more. You get shocks, bushings and some camber adjustment as with Tuner, but in Prepared you can also add a ball joint extender to control bump steer, and the Rules are opened up on control arms. Now you can replace all of the control arms, as long as: camber is only adjustable at one place, the aftermarket arms are the same length as stock, and they don't have spherical bushings in them.
Like Tuner, this Prepped Rules section has some complication to it. If you’re really getting crazy with suspension, it’ll pay to give the full rules a good look.
Prepped Category vehicles may have any modification allowed in Sport or Tuner Categories, plus the allowances below:
1. Ball Joint Extenders/Bump Steer Adjustment
A. Parts which bolt directly to OE parts may be installed.
2. Control Arms/Camber Adjustment
A. Control Arms
Control arms for vehicles that have integral bushing/arm assemblies may be replaced subject to the following restrictions:
i. The replacement arms must attach in the original standard mounting points. All bushings must meet the requirements of this section. Intermediate mounting points (e.g., shock/spring mounts) may not be moved or relocated on the arm. The knuckle/bearing housing/spindle assembly cannot be modified or replaced.
ii. The replacement arm length must be the same as OE.
iii. The replacement arm may not be adjustable unless it meets the restrictions for camber kits as outlined below.
iv. The bushings of the replacement arms may not be spherical.
B. Camber kits (also known as camber compensators) may be installed. These kits consist of either adjustable length arms or arm mounts (including ball joints) that provide a lateral adjustment to the effective length of a control arm. Alignment outside the factory specifications is allowed. The following restrictions apply:
i. On double/unequal arm (e.g., wishbone, multi-link) suspensions, only the upper arms OR lower arms may be adjustable, but not both. Non-integral longitudinal arms that primarily control fore/aft wheel movement (e.g., trailing arm(s) or link(s) of a multi-link suspension) may not be replaced, changed or modified.
ii. On arm-and-strut (MacPherson/Chapman) suspensions, the lower arms may be adjustable OR other methods of camber adjustment as allowed by the previous sections may be used, but NOT both.
C. Leaf spring cars may be converted to a coilover design.
1. Ride height may only be altered by suspension adjustments, the use of spacing blocks, leaf spring shackles, torsion bar levers, or change or modification of springs or coil spring perches. This does not allow the use of spacers that alter suspension geometry, such as those between the hub carrier and lower suspension arm.
2. Suspension bushings may be replaced with bushings of any materials (except metal) if they fit in the original location. Offset bushings may be used. In a replacement bushing, the amount of metal relative to the amount of non-metallic material may not be increased. This does not authorize a change in type of bushing (e.g., ball and socket replacing a cylindrical bushing) or use of a bushing with an angled hole whose direction differs from that of the original bushing. If the standard bushing accommodated multi-axis motion via compliance of the component material(s), the replacement bushing may not be changed to accommodate such motion via a change in bushing type, for example to a spherical bearing or similar component involving internal moving parts. Pins or keys may be used to prevent the rotation of alternate bushings but may serve no other purpose than that of retaining the bushing in the desired position.
3. The following allowances apply to strut-type suspensions. Adjustable camber plates may be installed at the top of the strut and the original upper mounting holes may be slotted. The drilling of holes to perform the installation is permitted. The center clearance hole may not be modified. Any type of bearing or bushing may be used in the adjustable camber plate attachment to the strut. The installation may incorporate an alternate upper spring perch/seat and/or mounting block (bearing mount). Any ride height change resulting from installation of camber plates is allowed. Caster changes resulting from the use of camber plates are permitted.
4. Camber bolts may be installed providing these parts use the original, unmodified mounting points and meet the restrictions specified in Sport Category. Caster changes resulting from the use of camber bolts are permitted.
5. Camber kits (also known as camber compensators) may be installed. These kits consist of either adjustable length arms or arm mounts (including ball joints) that provide a lateral adjustment to the effective length of a control arm. Alignment outside the factory specifications is allowed. The following restrictions apply:
A. On double/unequal arm (e.g., wishbone, multi-link) suspensions, only the upper arms OR lower arms may be adjustable, but not both. Non-integral longitudinal arms that primarily control fore/aft wheel movement (e.g., trailing arm(s) or link(s) of a multi-link suspension) may not be replaced, changed, or modified.
B. On arm-and-strut (MacPherson/Chapman) suspensions, the lower arms may be adjustable OR other methods of camber adjustment as allowed by the previous sections may be used, but NOT both.
C. The non-adjusting control arms for vehicles having integral bushing/arm assemblies may be replaced subject to the following restrictions.
a. Arm length must remain the same as OE.
b. The part may not be adjustable.
c. The replacement arms must attach to the original standard mounting points. All bushings must meet the requirements of this section. Intermediate mounting points (e.g., shock/spring mounts) may not be moved or relocated on the arm. The knuckle/bearing housing/spindle assembly cannot be modified or replaced.
d. Any allowed arm must be commonly available (or have been available) at SCCA supporting partner Tire Rack, for regular retail sales and without custom order. Parts do not have to be sourced from Tire Rack, but they must be as they would have come off the shelf there, or the part must be on a specific approval list.
e. If you believe there is a commonly available retail unit which otherwise fits the intent of these Rules but is not available at Tire Rack you may write in for specific approval of that brand and model.
6. On swing or trailing arm suspensions, the main arms may not be modified or replaced, but lateral locating links/arms may be modified or replaced.
7. Front wheel drive (FWD) cars with rear beam axles may use shims between the rear axle and hubs.
8. The replacement arms or mounts must attach to the original standard mounting points. All bushings must meet the requirements of Tuner Category Rules. Intermediate mounting points (e.g., shock/spring mounts) may not be moved or relocated on the arm, except as incidental to the camber adjustment. The knuckle/bearing housing/spindle assembly cannot be modified or replaced.
9. Changes in suspension geometry are not allowed except as incidental to the effective arm length change.
Note: Many modern suspension designs known by other names, actually function as double A–arm designs. These include the rear suspensions on 1988-on Honda Civic/Integra, Chrysler/Plymouth/Dodge Neon, BMW E36, and most “multi-link” and are covered by the double/unequal arm rule.
10. On strut-equipped cars, the strut’s lower integral mounting bracket, for attachment to the upright or spindle, is unrestricted provided it attaches to the standard location. Any resulting change to the position of the strut centerline is allowed. Such brackets shall serve no other purpose. This does not allow for changes to the integral steering arm on cars that have the steering arm integrated with the strut body.
11. Changes in alignment parameters that result directly from the use of the allowed components are permitted. For example, the dimensional changes resulting from the use of a cylindrical offset bushing that meets the restrictions of Tuner Category Rules are allowed, including those resulting from a change in the pivoting action to:
A. About the mounting bolt, or
B. About the bushing itself.
12. Subframe mount bushings may be replaced but must attach in the standard location(s) without additional modification or changes. Subframe position may not be changed. The amount of metal in a replacement bushing may not be increased relative to the amount of metal found in a standard bushing for the particular application. Solid metal bushings are specifically prohibited.
Prepared has the same sub frame connector (SFCs) rules as Tuner, so competitors are allowed SFCs that run front-to-back, but there are some rules on installations. For instance, you can drill for mounting bolts, but you can't weld them in or cut subframes or unibody.
Because the rules are the same, the Tuner Category SFC full rules are below.
Longitudinal (fore-aft) subframe connectors (SFCs) are permitted with the following restrictions:
1. They must only connect previously unconnected boxed frame rails on unibody vehicles.
2. Each SFC must attach at no more than three (3) points on the unibody (e.g., front, rear, and one point in between such as a seat mount brace or rocker box brace).
3. SFCs must be bolted in place and not welded.
4. No cutting of OE subframes or floorpan stampings is permitted. Drilling is permitted for mounting bolts only.
5. No cross-car/lateral/triangulated connections directly between the driver’s side and passenger’s side SFCs are permitted. Connections to OE components such as tunnel braces or closure panels via bolts are allowed and count as the third point of attachment. No alteration to the OE components is permitted.
6. SFCs may not be used to attach other components (including but not limited to torque arm front mounts or driveshaft loops) and may serve no other purpose.
In Prepped Category, competitors may make all modifications allowed in Sport and Tuner Categories. This includes replacing the alternator, installing electric fans, replacing spark plugs, spark plug wires and grounding cables, and relocating and replacing your battery—even to a lightweight one—is allowed. Of course, this doesn't apply to electric or hybrid cars.
In addition, competitors may make any wiring harness modifications or coil pack swaps to make legal engine swaps work.
Prepped Category vehicles may have any modification allowed in Sport or Tuner, plus the allowances below:
1. Wiring harnesses may be replaced or modified in order to accommodate further allowances in these rules.
2. Coil packs and other engine electrical accessories (e.g., sensors) may be swapped to accommodate further allowances within these rules.
Except for those with electric and hybrid powertrains, Tuner Category vehicles may do everything allowed in Sport Category plus the list below.
1. OE traction control systems may be electrically disabled, but not removed or altered in any other way.
2. The make, model number and size of the battery may be changed, but not its voltage.
3. Relocation of the battery or batteries is permitted but not into the passenger compartment. If the battery is relocated and the original battery tray can be removed by simply unbolting it, the tray may be removed or relocated with the battery. Holes may be drilled for mounting or passage of cables. Longer or shorter cables may be substituted to permit relocation.
4. The number of battery or batteries may not be changed from standard. The area behind the rearmost seat is not considered to be within the passenger compartment. The area under the rearmost seat is within the passenger compartment.
5. Holes may be drilled in the firewall to permit passage of electrical wiring. It should be no larger than necessary to facilitate allowed modifications in this section and shall serve no other purpose.
6. Any starter, generator or alternator may be used in the original position. An alternator or generator must have an electrical output (including amperage) equal to or greater than the original equipment unit. Any generator or alternator pulley and belt of the same type as standard may be used.
7. Electrically driven fans are allowed. Flex fans are not allowed.
1. The make of spark plugs, points, ignition coil and high-tension wires is unrestricted including spark plug wires having an in-line capacitor. Substitution or addition of ignition coil mounting brackets is permitted, provided they affix to the original standard location and serve no other purpose. (Modification of the distributor cap for the purpose of installing allowed non-standard components is not permitted.)
2. On cars made prior to January 1, 1968, any ignition system using a standard distributor without modification may be used.
3. Ignition settings may not be mechanically adjusted outside factory specifications.
4. Additional battery hold-down hardware may be added to supplement the standard equipment in order to meet safety inspection requirements. It may serve no other purpose.
5. Tire pressure monitoring systems (TPMS) may be disabled. Altering the signal to the TPMS is permitted.
6. On cars without the ability to turn off anti-lock braking systems (ABS), electronic stability control and/or traction control (ESC/TC) from the manufacturer, modifications to defeat the ABS/ESC/TC are permitted. These modifications are limited to altering the inputs to the ABS/ESC/TC processor (e.g., removing fuses, unplugging yaw or steering angle sensors, altering signals, etc.) and may serve no other purpose. Any codes or error lights resulting from ABS/ESC/TC modifications are permitted.
7. On cars equipped with computer-aided gear selection or “skip-shift” features from the manufacturer, modifications to defeat the skip-shift feature are permitted any may serve no other purpose.
8. On cars with electronically-controlled exhaust pipe valving downstream of the catalytic converter, devices may be added to satisfy the PCM/ECU provided the OE component is still installed. Such devices shall perform no other function.
9. The addition of electrical grounding cables and associated distribution blocks/terminals is permitted. Holes may be drilled for mounting only. This does not permit the use of electrical enhancement components such as condensers, voltage controllers, etc.
The ECU and engine control units can be replaced without restriction in Prepped Category, and distributers may be swapped for alternate OE units.
1. Engine Control/ECU/Electronics
A. Engine Control/ECU may be replaced or modified without restriction.
B. Distributers may be replaced by alternate same-manufacturer OE units.
Competitors may perform any Sport- or Tuner-legal intake modification, but further allowances and restrictions on the intake are included in the “engine” section of these rules.
Competitors may perform any Sport- or Tuner-legal intake modification, plus the allowances or restrictions below, based on engine options listed further down.
1. Vehicles with their OE naturally-aspirated engines may have replaced or modified any part of the intake manifold and throttle body.
2. Vehicles with their OE force-induction engines must keep their OE intake manifold turbo and throttle body.
3. Vehicles with a swapped naturally-aspirated engine may use either the OE intake manifold and throttle body, or the intake manifold and throttle body from the donor engine.
A. Minor modifications for fitment are allowed, provided the modifications serve no other purpose.
4. Vehicles receiving a forced-induction engine must retain the OE intake manifold, turbo and throttle body from the donor engine.
5. Vehicles receiving a naturally-aspirated engine in place of a forced-induction engine must keep the intake manifold and throttle body from the donor engine.
For Prepped Category, the rules are the same as they are for Sport and Tuner—you can put in a larger radiator as long as it goes in the stock location, you can add water expansion tanks, and use whatever thermostat (in the stock housing) you want.
1. Engine cooling radiators may be replaced or added with alternate parts subject to the following restrictions:
A. Radiator core dimensions (width, height, thickness) cannot be smaller than the standard part.
B. Radiator must mount to OE radiator mounts.
C. Fluid capacity and dry weight of the radiator must be no less than that of the standard part. Installation of an alternate radiator may serve no other purpose (e.g., to allow a cold air intake passage).
D. The installation of water expansion tanks is allowed. A water expansion tank is the container which catches overflow coolant.
E. Thermostats may be added or substituted. A thermostat is a device which controls the passage of water.
F. Modifications necessary for additional radiators must be the minimum required for installation.
You can rebuild the engine, but you have to stay within tight factory service limits. If you're going to rebuild your engine, or your engine has been rebuilt, give the full Rules a look.
1. Engine Service Limits
A. Engines may be rebored to the manufacturer’s first standard overbore, not to exceed 0.020 inch (0.508 mm). Sleeving is allowed to repair to the standard bore. Only OE-type standard or first overbore pistons of the same configuration and of the same or greater weights are permitted. No interchange between cast and forged pistons is allowed.
B. Valve seats and guides in older engines originally designed for leaded fuel may be only substituted with alternate components if the dimensions are the same as those of the standard components.
Prepped Category is the first category which allows any internal engine modifications or engine swaps. While the details are specific, you can generally swap in any OE engine from the same manufacturer, including a forced-induction engine in place of a naturally-aspirated one, or a naturally-aspirated engine in place of forced induction. A swapped naturally-aspirated engine may use the intake manifold from either the donor or OE car, and a swapped forced-induction engine must keep the stock throttle body, intake manifold and forced-induction unit.
For naturally-aspirated vehicles without an engine swap, either forced induction may be added (as long as it feeds through the stock throttle body and intake manifold) or, if the stock engine stays naturally aspirated, the camshaft and intake manifold/throttle body can be changed.
These rules don't allow for suspension geometry changes—no subframe swaps are allowed. It also doesn't allow for other internal engine modifications like internal machine work, aftermarket head gaskets or fuel pumps which flow more than stock.
There are three “either-or” options for engine modification. Engines may either be swapped or competitors may replace/modify items from the “ports out” plus replace the camshaft(s), or may add aftermarket forced induction, but may only pick one.
1. Option 1: Engines—including swapping OE Forced-induction engines for naturally aspirated and vice-versa—may be replaced with the following restrictions:
A. The engine must be from a production car of the same manufacturer, and that engine must have been produced and delivered in at least 2,500 vehicles per calendar year in any single market (USDM, JDM, EDM).
B. The “long block” (i.e., head and block) must be a matched OE pair.
C. Naturally-aspirated engines swapping for naturally-aspirated engines may use the intake manifold and throttle body from either the OE engine or the swapped engine. Minor modifications for fitment are allowed, provided the modifications serve no other purpose.
D. Vehicles receiving a forced-induction engine must retain the OE intake manifold, turbo and throttle body from the donor engine.
E. Vehicles receiving a naturally-aspirated engine in place of a forced-induction engine must retain the OE intake manifold from the donor engine.
F. An engine swap may not be performed on any vehicle taking advantage of Options 2 or 3, nor may items from Options 2 and 3 be performed on a swapped engine.
2. Option 2: Vehicles that keep their OE engine may take advantage of the following allowances:
A. On OE naturally-aspirated engines, items from the “ports out” plus camshafts may be replaced with the following restrictions:
1. Intake manifold, carburetors and throttle-bodies may be modified or replaced.
2. Camshafts may be replaced or modified, but cam gears may not be swapped.
B. On forced-Induction OE engines, components of the system may be modified or replaced with the following restrictions:
1. The OE intake manifold, throttle body, and supercharger or turbochargers may not be modified or replaced.
C. These allowances may not be performed on any vehicle taking advantage or Options 1 or 3.
3. Option 3: Aftermarket forced induction may be added and fuel injectors may be changed on an OE naturally-aspirated engine with the following restrictions:
A. Only a single unit may be added. (E.g., a single turbo or single supercharger; multi-turbo or twin-charged systems are prohibited.)
B. Aftermarket forced induction may not be added to any vehicle taking advantage of Option 1 or 2.
If you're doing an engine swap, the transmission/transfer case or rear end can either be from the OE vehicle or from the donor car. Clutches and flywheels can also be replaced here without the same restrictions as Tuner Category.
1. Transmissions and drive-gear may be replaced as part of an engine swap, with the
A. The transmission/differential/drivetrain components must meet category rules otherwise.
B. The transmission/differential/components of the drivetrain must have been packaged with the original car, or the car supplying the donor engine. Further mixing and matching of different models, option packages or trim level is prohibited.
2. Clutches may be replaced with those of different design.
3. Flywheels may be replaced with those of non-OE material.
In Prepped Category, exhaust manifolds, headers, downpipes, catalytic converters and any associated EGR tubes may be replaced, and the exhaust exit may be relocated provided it meets safety requirements. You can also move the oxygen sensor and remove/modify exhaust heat shields which only attach to legally replaced parts.
1. Exhaust manifolds, headers, downpipes, catalytic converters and any associated EGR tubes may be replaced with alternate units. Exhaust exit may be relocated provided it meets safety requirements. Relocation of the oxygen sensor is permitted. Exhaust heat shields which cover only, and attach solely to, these parts may also be replaced, removed or modified. All other exhaust heat shields may be modified the minimum amount necessary to accommodate allowed alternate exhaust components. Mounting brackets/hardware which serve no other purpose are considered part of the exhaust components.
Note: The SCCA does not encourage or condone the breaking of laws governing pollution control systems or the alteration of street-driven vehicles contrary to state and Federal laws regarding their use. It continues to be the responsibility of the individual to comply with such state and federal laws.
As with Tuner, oil pans may be replaced but, in Prepped Category, minor modifications to allow oil pan changes for swaps may be performed as long as the modification serves no other purpose (e.g., removing the balance shaft or swapping an oil pickup because it won’t clear the new pan).
1. Oil Pans may be replaced, and minor modifications to facilitate replacement may be performed as long as the modification serves no other purpose (e.g., removing the balance shaft or swapping an oil pickup because it won’t clear the new pan).
When a car is out of production, or parts are no longer available, you can use aftermarket parts as long as they are as close as possible to the original specs, and are not high-performance parts.
Where a car is out of production and the manufacturer is either out of business, stocks no parts or no longer has a required part, a part of any origin but as similar as possible to the original may be substituted.
1. The entrant must be prepared to show documentary evidence that one of the three circumstances above applies and that the substituted part is as similar as possible under the circumstances.
2. Substitute parts which provide improvements in performance (e.g., superior gearing, lighter weight, better camshaft profile, etc.) are not permitted under this allowance.
Prepped and Max Category vehicles must meet Sport and Tuner Category fuel rules, but the use of E85 is not restricted.
1. Prepped and Max Category vehicles will use fuel which is “Federally approved for use on public highways.” This does not allow racing-type fuels which are available at service station pumps.The use of E85 is not restricted.
2. Propane or Compressed Natural Gas (CNG) fuel may be used in any category provided that the following conditions are met:
A. The tank must be located in a safe location on the car and be firmly and securely mounted. This does not permit the cutting of vehicle sheet metal (e.g., the trunk floor) for tank installation.
B. The tank must conform to Federal and local container standards and have an emergency relief/cut-off control.
C. For use of propane or CNG as a fuel, no changes to the induction system of the engine may be made with the exception of the necessary fuel lines to the carburetor or fuel injection. There may also be no other engine parts changed.
D. The entire system must meet local ordinances covering the use and transmission of compressed gas.
E. Propane or CNG may not be used in combination with another fuel.