Below are the rules change proposals submitted by drivers and other interested parties for which the Rules Committee would like to receive comment.  Listing does not indicate that the Committee favors any of these changes. From time to time comments received on proposals have helped us avoid mistakes, especially those based on an incorrect understanding of the performance factors or terminology involved, helped us word rules better, modify proposals, and given us more confidence that changes adopted are likely to be improvements overall.

The reasons proponents gave for these proposals are state briefly where they may not be obvious.

Comments may be submitted until August 26th using the  contact form on this page or an e-mail to  It helps if comments in any single e-mail are limited to one class.  Racers may comment on rules for more than one class, of course, but please do so in separate e-mails.  This helps the rules chair a great deal when collating them for committee review.

Rule Book

Download your copy of the existing rule book to check out the general sections as well as those that apply to your specific class.


Contact the Committee

Rules Proposals for Comment – 2019

Download a copy of the 2019 Rule Proposals here (and the addendum).

Rules Proposals for Comment – 2019

Download a copy of the 2019 Rule Proposals here (and the addendum).


Interior: Boxsters and Caymans may duct air from the quarter windows (where ducting from that window is allowed) or from the passenger compartment in tubes to the far rear corners of the rear trunk to cool supplementary fluid radiators installed below. Fans may be used to force air through these allowed openings for this purpose also.

Allowing firewall penetration this far to the rear should be far enough from sources of flammable liquids or fire that driver safety will not be affected should an engine or transmission fire occur.  Note that ducting through other parts of the firewall (such as the engine top cover) is not allowed.


Every ABS whose PWIS programming includes an option for a PCCB flash may use that flash.  Doing this seems to help with “ice” pedal and is inexpensive.

Stock (Air Cooled 911s) – Serpentine Fan/Alternator Belts:

Modifying pulley ratios is a Prepared modification. Several air cooled cars were found with a serpentine system. These systems, and all available such systems, lower the fan and alternator speed. Converting dual pulley systems to single pulley systems will lower one or both of rotational speed of these systems. It appears that it is not feasible to make a serpentine system which would replicate the stock ratio for the Carrera 3.2s and earlier. And reducing the speed of the fan and alternator is the equivalent of an increase in horsepower (it reduces the power required to move the air and generate electricity). As an accommodation to those drivers and shops who have had cars which they believed would throw belts or otherwise fail without the use of a serpentine belt, or by converting a dual to a single pulley system, an interim rule was announced allowing, for 2018, the use of such belts (and by extension, altering the fan/pulley ratios) or conversions, but that a 25 pound increase in minimum weight would be required for this modification.

Please comment on the following approaches to this issue:

  1. Require cars with this modification to run in Prepared as before; or
  2. Keep the allowance and the weight penalty; and if so,
  3. Is 25 pounds the proper offset for the modification?

E Stock:

  1. Allow replacing the Boxster 2.7L 5-speed transmission with the 00-04 Boxster S 6 speed.
  2. Lower the minimum weight for the Stock E Boxsters from 2929 to2829 (100 lbs.).

This is proposed to balance performance for a readily available model in this class. Please comment on both.

H Stock:

Allow all H 997s, 996s, Boxsters, and Caymans in H to run the “S” model brakes on their cars.

This is proposed because the H 997 appears to overdrive the brakes in enduros despite all of the usual cooling and fluid options and driver skill and making it applicable to all the cars currently racing in this class ought not to upset performance parity.


Allow block to be sleeved to the original 2.5L spec.

This is allowed in Stock and SP2/3.


Allow the Bilstein PSS9 as an option. Less expensive.


  1. Allow a up to 1/4th inch spacer for the rear wheels.
  2. Allow a square spring setup with any allowed spring (i.e., 450/500, 500/450, 400/400, 500/500, plus stock)
  3. Allow a bolt-on cross tie bar connecting the rear suspension sub-frame sides.

Proposals to allow later model engine covers and plastic floor pan undertrays are not being presented because there is no evidence that the SPB parts are inadequate, the later covers are lighter, and the undertray parts were introduced by Porsche to improve the aero. PCA Club Racing is pursuing options to deal with the reduced availability of the allowed stock rims, and it is hoped that an alternative may be announced by the end of the year.

SPB Rules Clarifications:

The following clarifications of the SPB rules are effective immediately:

  1. Where “bumper” is used in 6.C. and 6.D., change to “bumper cover.”
  2. One or both side radiator fans may be removed.
  3. Electrical wiring for parts which may be deleted may be removed.
  4. Seam sealer, undercoating, weather stripping, and tubing for water drainage may be removed.
  5. The windshield washer tank and the washer mechanisms may be removed.
  6. The plastic fender liners may be removed, or holes cut in them.
  7. Thermal insulation and shielding may be removed.
  8. The clamshell piece over removed convertible top components may be attached to the body in any secure manner.


Cooling System additional allowances. The left and right stock radiators may be replaced with high efficiency front radiators provided they fit into the stock mounting points. Shrouding around the left and right radiators may be modified to allow for more efficient air flow to the radiators. A center radiator may be added and can be either a Tiptronic or GT3 type. The center radiator may be vented out either from the bottom, or through the top between the bumper and front deck lid equivalent to a 997 GT3.  Radiator fans may be direct wired with a switch, and one of them may be removed.


  1. Prohibit plastic door windows. The Cup doors with plastic windows only fit the 911s and are thus not allowed on Caymans. This would keep everyone the same, and avoid the inevitable corner worker confusion which can arise from not seeing a driver’s side window, or seeing either window is up.
  2. External door mounted mirrors are free. This arguably is part of the GT origins of this class.
  3. Allow the 2003-06 996 GT3s to run in GTB under the stock J class rules for this model, but with a 100 pound weight reduction (3192 to 3092) and with tires being free (DOT not required).  Some of these racers want to be in a more competitive class.

GTB1 Interim Rules Change:

The mandatory 50 pound ballast requirement for Gen1 Caymans using the throttle body and intake plenum option is deleted effective immediately. The minimum weight in the rule book table for cars with this option is not changed.

944 Turbos:

There is a continuing concern about the effectiveness of the 20+ year old boost control system. It is necessary to limit boost in these cars to a peak or spike pressure, to a steady state pressure, and to the length of time it takes a peak to decay to the steady state, but it appears that by now the
original systems don’t allow the original maximums (which can be measured with our data system) all to be met. As a result, 951s are being converted to normally aspirated motors, at least in SP3.  Devising more modern control systems involves considerable expertise, and cooperation with aftermarket manufacturers. Such systems would have to keep these turbocharged engines within their original capacities in order to be fair to other cars in their classes. The Club Race National Staff can’t devise such systems on its own. Two likely approaches which would allow boost
controlling to involve aftermarket parts (certainly not cockpit adjustable), and perhaps sealable at the track if adjustable, are:

  1. Specify not to exceed spike, decay, and steady state parameters, probably altitude corrected. If this is done, what should they be? How should the early turbo be differentiated from the S model?
  2. Adopt an altitude corrected system like IMSA uses for turbocharged cars in the Continental Tire Sportscar Challenge for Grand Touring Daytona:
    • A single maximum boost pressure.
    • No spike can exceed 125% of the maximum.
    • The maximum can be up to 7% higher for no more than 7% of the time for that lap.
    • The total time over 7% may not exceed 3% for that lap.
    • No single event over the maximum boost may exceed two seconds.
    • You can find the formula for altitude correction on the IMSA website.

What should the specified “maximum” boost be, and how should these differ between S and nonS?  Should any of the percentages be different, and if so, what should they be?

It would be helpful if any aftermarket systems had some built-in flexibility, so one or more parameters could be changed if experience showed that was needed.

Those interested in this approach are requested to e-mail We will put all those interested (and those with the special knowledge needed who may agree to help) in touch with each other, so a working group can be formed to see if something feasible can be done. The
951 is a terrific Porsche model, and its exit from Club Racing would be a shame.  But active involvement of racers, shops, and aftermarket parts manufacturers will be needed so a proposal can be put out for racer comment.

National Championship:

Should all races at an event, except the fun races, earn points towards the National Championship Points Series?