Proposed Rule Changes for 2022

From: PCA Club Racing Rules Committee

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. These are just proposals for comment. From time to time comments received on proposals have helped us avoid mistakes, especially those based on an incorrect understanding of the performance factors involved, helped us word rules better, modify proposals, and given us more confidence that changes adopted are likely to be improvements overall.

The wording (or the concept) of the proposed changes is in italics.  What follows for most proposals is an extremely brief statement of why the proponent felt the change would be beneficial.  These may not be entirely accurate but should help the reader understand the reasoning put forth.

Comments may be submitted to through October 25, 2021.  Please note that at this stage entirely new proposals for change are not appropriate.  Those should be submitted between February 1 and June 1, 2022.

It helps if comments in any single e-mail are limited to one numbered proposal.  Racers may comment on as many rules proposals as they wish, of course, but please do so in separate e-mails.  This helps the rules chair a great deal when collating comments for committee review.

Rule Book

Download your copy of the existing rule book — sans the proposed changes summarized here — for comparison purposes.  Use this link to download a PDF copy of the 2021 rule changes listed below.


Use these links to jump directly to specific changes:


     1-An FIA or equivalent rain light is required to be on track in conditions wet enough to reduce visibility.

Proponents believe one stock tail light is not adequate.  Note that this does not require that a car have rain lights, only that such cars can’t drive in conditions requiring a rain light.  Under this proposal, the previous compromise – one working stock tail light required in the rain – will be replaced with this wording.


        2-Air cooled 911s through the end of the Carrera 3.2 may extend two roll cage tubes through the rear firewall.

    1. These old cars are showing significant cracking where the shock mount cross member meets the side rails, where the center tunnel meets the firewall (impairing shifting), and in other areas. The ongoing development of DOT-labeled tires has greatly exacerbated the lateral loads on these areas, leading to more cracking.  Because these are torsion bar cars, there is no significant advantage in tying these bars to the shock mount area if the owner so desires.

    3. Comment is also solicited on whether an additional two bars should be allowed to pierce the front firewall and attach rearward of the center of the camber adjuster opening in the inner fender.

        3-Aftermarket starter motors are allowed.

    Geared starter motors are available at roughly the cost of a shop rebuild of the original Bosch starters.  Being smaller and lighter, they are easier to install and remove.  As all cars have to meet class weight, they don’t represent a distinct competitive advantage.


        4-The 2000-2004 2.7 Boxster transmission is allowed.

    The reliability problems (read breaking) of the ’97-99 transmissions for these cars are well known.  While this transmission may not be more robust, the ability to use it will increase the supply of used replacement transmissions.  Despite the 2.7’s shorter 4th and 5th, its taller ring and pinion means it is taller in every gear.


        5-The 318mm front rotors may be replaced with —mm Girodisk—mm two-piece rotors, along with any needed adapters.

    The idea here is that there is no reason to restrict rotor alternatives to one manufacturer if other disks of larger OD can be adapted.


    1. Some racers have reported boiling brake fluid, pads that last only one race weekend if that, one event rotors, and new rotors cracked after one event, despite providing as much cooling air as reasonably possible.  The larger diameter rotor provides more braking torque, has more thermal mass, and – perhaps most significantly – has a larger diameter central inside the open area to feed cooling air into the internal vane passages.  Other Porsche or Porsche aftermarket disks have the wrong offsets.  Some believe that the higher cost of the Girodisk is offset by a reduced pad and rotor replacement time.

    2. Comment is also solicited as to whether the rear rotors may be replaced with the Girodisk.
      The same brake issues have been reported for the rear brake rotors and pads.  A disk with the advantages for the fronts should resolve this.  However, it should be noted that many GTB1 Caymans, where brakes are free, use the same stock rear rotors and calipers as the SPCs,  Perhaps adding rear brake-directed cooling air could help here, or use of a less aggressive, higher temperature pad would help?

    3. As an alternative to A and B:
      Comment on whether any one or two piece steel brake disk, using any steel or aluminum hat, which will fit within the stock caliper, may be used.  Any spacer/adapter block to allow the caliper to be repositioned could be used.


    6-The 996 with X51 minimum weight is reduced from 3000 lbs to 2900.

    The proponent notes that the 996s in GTB1 are allowed a GT3 throttle body and plenum with no weight penalty, though it has been reported that these GT3 parts, without the X51 cam, do not improve performance in these engines.

     This is consistent with the 100 lb X51 “bonus” used to balance GTB3 performance.

     6A- Add 100 lbs to the GTB1 997 3.6 minimum weight.

     Analysis of lap times at various tracks for this model and other GTB1 models indicates that, taking account of the fact that various models are more or less suited to different track configurations, the platform has inherent advantages, especially when equipped with the PDK, in both top speed and corner exit speed.

     6B-Remove 100 lbs from the 996 GT3 minimum weight in GTB1.

    Analysis of lap times at various tracks for the 996 GT3, both when running in J, and this year in GTB1 (at J class specifications and weight), support this its GTB1 weight.  The analysis involves an estimation of driver skills.

    The goal of these GTB1 proposals is to produce a class where, subject to the strengths and weaknesses of the various models at different tracks, all cars have a shot at finishing first in a race against equally skilled competitors on some tracks.


    7-The GTC5 wheels need not be the originally specified part but must be 3-piece wheels of the same width, diameter, material, and offsets as specified for the class.


    1. This is the same allowance provided for the 997.1 and earlier GTC classes as the cars have aged.

    3. Comment is also requested on adopting this proposed rule for GTC6, and for GTC7.

    5. Comment is also requested on revising the wording for GTC3 and 4 allowance of aftermarket rims to add “same material” to the allowance, to avoid carbon fiber or magnesium rims, as it was never intended to allow lighter rims.

    SP911 and 911CUP

    8 -The Rules Committee has a proposal to join the SP911 class with the 911 Cup class.

    Race results indicate that the lap times of the quickest drivers in each class are basically equal.  The idea would be that, for 2022, drivers with cars configured for either class could declare whether they will race in SP911 or 911CUP as part of registration for any event.  The only modification to a car would be to put on class letters and numbers front and rear indicating the class for the event.  Championship points would accumulate in the class chosen for the event, and if the driver ran the car in the other class at a subsequent event, points would accumulate in that other class.


    A proposal will be formally submitted later to make certain changes to the Cup rules for 2022 along the lines indicated below.  Informed technical comment, however, would be welcome now.

    9- Impose maximum horsepower limits on the various models and require racers to have a Dyno-Pro dyno sheet in the logbook indicating compliance.

    Standardized chassis dyno results have been accepted in a number of racing series where performance must be balanced among different models.  The SP911 class already requires this.  The HP numbers need to be determined.

    10- Allow 9.8:1 CR Euro SCs to run a carburetor instead of CIS. 

    The idea here is to select a carburetor size and venturi size which will produce the same power as the CIS without the attendant tuning difficulties some have reported.  In short, not more power, but more reliable power.

    11 -If feasible, adopt an intake system for the 8.6:1 CR 1978-9 SCs which will allow them to be competitive with the Euros without requiring removing the heads. 

    These cars can already be converted to late Euro specs with a change of pistons and a Euro fuel distributor.  But is there a bolt-on solution beyond allowing an additional weight reduction.

     12If feasible, adopt an intake system for the 9.3:1 CR 1980-83 US SCs which will allow them to be competitive with the Euro.

    These cars are already allowed to run carburetors.  To date, no engine builder has asserted that any bolt-on engine modification (such as the intake) can make up for the small port heads to produce horsepower equivalent to that of the Euro SC.  Perhaps such a system exists.