SCCA Stock Boxster SetupWhile it may sound like a boast, I now believe that very few unmodified "Stock Category" cars are faster in an autocross than the Boxster. Though some are, including Vipers, the '93-'95 Mazda RX-7 twin turbos and some late-model Corvettes. The Boxster's handling is that good! (OK, keep in mind that certain exotic cars, like many Ferraris, aren't allowed in SCCA's Stock Category, otherwise I might have to add a few cars to that list!
General Notes
The standard Boxsters all compete in SCCA's "BS" class, while the Boxster Ss all go in the "AS" class.
The SCCA Stock Category rules are pretty strict: Basically your car must run exactly as originally delivered from the factory to the dealer (dealer-installed options, like Tequipment are not allowed!), except for those changes specifically allowed by the rules. Consult your original window sticker... that's pretty much how you should run your car. When in doubt, it's not allowed.
For instance, you can't "update" or "backdate" between different model years. So, if you drive a '97 Boxster you may only run the wheels that were available as standard or optional from the factory on your '97 Boxster. Pretty much just the standard 16" or optional 17" wheels. No, you can't run the fronts in the rear or vice-versa. You must run the 6.5x16" in the front and 8x16"in the rear, or 7x17" in the front and 8.5x17" in the rear. But '98-'99 (and '00 it seems) models can also run those huge 7.5x18" front and 9x18" rear wheels.
You can, however, upgrade your car with factory optional equipment that it didn't come with, so long as it could have been ordered that way. So, for example, if your '99 Boxster doesn't have the optional M030 Sport Suspension you can add the correct parts on yourself (basically stiffer springs, shocks, and sway-bars). You must, however, use only the correct Porsche parts, and you must make the upgrade complete and identical to how it would have been installed on Porsche's assembly line if originally ordered with the car. Note: If you have a '97 or '98 Boxster, the P38 Sport Technic Package option was available instead of the M030 option. P38 included the same parts as M030, plus the 17" wheels and the P37 Traction Control, so you'd have to add those items too. You can't "mix and match."
Allowed Modifications
The rules change slightly every year, but the basics have been unchanged for many years. Visit the SFR SCCA website's Solo II Stock Class Rules page for details.
Below is a pretty good summary of what you can change on your car and still remain legal in Stock Category. I've highlighted the ones that are truly important... most are rather unhelpful.
- Option package conversions may be performed between specific vehicles of a particular make and model, but only between configurations from within a particular model year. Such conversions must be totally complete and the resultant car must meet all other requirements of the rules.
- Cosmetic changes that don't affect performance (paint, added gauges, trim, lights,etc.)
- You may remove the spare tire and tools, and any removable hardtops, floor mats, or similar items considered removable (like Boxster windstops).
- You can add a racing harness and roll bar or roll cage (so long as they're only bolted in).
- Any tire approved by the Department of Transportation may be installed (but must have measurable tread). Note: Some SCCA Regions have "Street Tire" classes which exclude soft-rubber tires.
- The wheels may be replaced with any wheel of the identical dimensions, except the offset may be changed by up to .25 inch. This just allows you to buy wheels that look different, but are the same size as whatever you got from Porsche (see above). So '97 models still can't install the 18" wheels.
- Shock absorbers and struts may be replaced by any others that fit and have exactly the same external dimensions. So they may not change the ride height, and "coilovers" are not allowed unless you weld the spring seat in place at exactly the stock position. Springs, and strut bushings, must remain the same, but shock bushings may be replaced with any bushings.
- Brake pads may be replaced with any that will fit without modifying the car.
- Any brake, coolant, and hydraulic fluids and lubricants may be used.
- The front sway bar may be changed. So even non-M030 and non-P38 cars can add the stiffer front sway bar that Porsche includes in those options, or whatever sway bar the aftermarket sells that will fit. Fordahl Motorsports in Bellevue, Wa. (425) 644-6020 makes a front bar, Gemballa makes a front/rear set.
- Both the front and rear suspension may be adjusted through their designed range of adjustment by use of factory adjustment arrangements or by taking advantage of inherent manufacturing tolerances.
- Spark plugs may be replaced with any make.
- The engine air filter element may be removed or replaced.
- Any part of the exhaust system beyond (downstream from) the header/manifold or catalytic converter, if so equipped, may be substituted. Modifications of any type, including additions to or removal of, the catalytic converters, thermal reactors, or any other pollution control devices in the exhaust system are not allowed and the system must be operable. Replacement catalytic converters must be OEM if the vehicle has not exceeded the 5-year/50,000 mile warranty period as mandated by the EPA. Converters must be of the same type and size and used in the same location as the original equipment converter(s). This does not allow for a high performance unit. If the vehicle has exceeded the 5 year/50,000 mile warranty period, replacement catalytic converters must be OEM-type.
- Any oil filter may be used.
Based on my own experience, and that of countless others, I can say that the tire allowance is easily the most important. Combine that with a high-performance wheel alignment and you'll cut a lot of time off of your runs (assuming your driving skills are good enough). The muffler and filter allowances help very little, but if you're in tight competition, you should take advantage of those rules too.
How to Make These Modifications
Most of them are discussed in detail elsewhere on this site. Click the links for more info:
Tires
Wheel Alignments
Mufflers
Air Filters
Wheels
But most importantly, don't forget that the driver is the ultimate factor! Sign up for a school if you can, or buy a copy of a high-performance driving book.
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