The San Francisco Bay Area based PRC is helping Porsche racing enthusiasts find a regular schedule of high quality racing events organized with local racing clubs such as NASA, POC, SCCA, etc. and to ensure that participants have a safe and enjoyable experience at each event. The PRC is not a sanctioning organization. We are simply individual Porsche racing enthusiasts acting in a collective manner to maximize our fun. The goal for the Club is to attend about one event per month run by well organized sanctioning organizations that set aside a group for Porsches only. Competitions between the Porsches use a very simple car classification system and class-based awards are presented after every race.

Spec911 is intended to be an entry level wheel-to-wheel racing class with an emphasis on fun, competitiveness, and cost containment. Below is a glimpse at some of the rules for Spec911:

(The full rules document can be viewed here.)

Appendix A: Porsche Racing Challenge 911 "Spec" Class

SP911 Class Rules and SP911 Eligible Models

This class is for 911s with air-cooled 2.7L, 3.0L and 3.2L engines. Modifications not specifically listed below are

prohibited. Where “stock” is specified, it means the components must remain stock. No material can be added or removed;

no re-allocation of weight or material can be performed. No material can be substituted for another material of similar

geometry. PCA will honor grandfathering of items not in compliance with the 2009 rules if the grandfathering has been

noted in a vehicle logbook.

1. Chassis, Body and Interior, Minimum Weights

A Any Porsche 911 chassis up to 1989 is allowed except for turbo or turbo-look body shell.

B. Minimum weight of cars with drivers is as follows:

• 2.7 engines: 2300lbs,

• 3.0 and 3.2 engines: 2350lbs

• 3.0 engines and 3.6 intake plenums: 2400lbs.

C. Bolt on fiberglass and composite replacements of front and rear bumpers, rear deck lids/tails, front fenders, and

front hood are allowed. Bonded or glued fiberglass or composite sunroof “plugs” and fender flares are allowed.

Substitution of other parts are not allowed. Fender flare configuration is free.

D. Cars must have a windshield, a rear window and rear quarter windows. Cabriolet bodies must have a stock size

windscreen and no other windows are required. Materials may be original equipment or equivalent glass,

polycarbonate, or other break-resistant plastic.

E. Rear wing choices include: ducktail, 911 whale tail, 930, IROC, large IROC, 911 3.6 RS wing, 3.8 RSR short

wing. Wicker bills up to 1” can be added to the ducktail, 911 whale tail, 930, IROC and large IROC tails.

F. Any front air dam may be used as long as it does not extend forward of the stock front bumper

(excluding bumperettes).

G. Interior modifications are free.

H. Electrical system and instrumentation is free.

2. Engine

A. All engines must run on standard pump gas with octane rating not to exceed 93.

B. Exhaust system may have any header system with a maximum primary tube size of 1.5” outside diameter.

C. Crankcase can be any 911 crankcase and machining of any kind is allowed.

D. Rods must be stock. Aftermarket rod bolts are allowed.

E. Valve springs & retainers are free.

F. Ignition system is free as long as it is single plug per cylinder.

G. Engine oil system and cooling is free.

H. 2.7 liter engine specs

• Allowable intake systems are: 40 or 46 mm Weber or PMO carbs, CIS from any year, Bosch MFI from

1969-1973, 3.2 intake manifold with any throttle body and airflow meter, “straight-through” fuel injection

systems with individual throttle bodies no larger than 46 mm, 3.6 intake manifold from 1989-1995 911

with any throttle body(s).

• Crankshaft: stock 70.4 mm stroke.

• Pistons and cylinders: maximum of 90mm bore and maximum compression ratio of 9.25:1.

• Cylinder Heads: stock, maximum port sizes of 39 mm intake, 36 mm exhaust and valve sizes of 46 mm

intake, 40 mm exhaust.

• Camshafts: 911S, Elgin mod-S, or GE60.

I. 3.0 liter engine specs

2009 18

Allowable intake systems are: 40 or 46mm Weber or PMO carbs, C • IS from any year, Bosch MFI

from 1969-1973, 3.2 intake manifold with any throttle body and airflow meter, “straight-through” fuel

injection systems with individual throttle bodies no larger than 46mm, 3.6 intake manifold from

1989-1995 911 with any throttle body(s).

• Crankshaft: stock 70.4mm stroke with 9 bolt flywheel configuration.

• Pistons and cylinders: any stock CIS 911 SC 95 mm bore.

• Cylinder Heads: maximum port sizes of 39 mm intake, 35 mm exhaust and valve sizes of 49 mm intake and

41.5 mm exhaust. Small intake port 3.0 liter heads may have cylinder head material removed to match the

port shape and dimensions of the large, stock 3.0 intake port.

• Camshafts: stock 911SC.

J. 3.2 liter engine specs

• Intake system must be stock from the air filter housing face of the air flow meter to the cylinder head. All

induction air must pass through this stock intake tract. Air filter assembly and fuel management system

are free. Forced induction is not permitted.

• Crankshaft: stock 74.4 mm stroke.

• Pistons and cylinders: any stock Motronic 911 3.2L, 95 mm bore.

• Cylinder Heads: stock, maximum port sizes of 40 mm intake, 38 mm exhaust and valve sizes of 49 mm

intake and 41.5 mm exhaust.

• Camshafts: stock 911 3.2L Carrera.

3. Transmission and Clutch

A. Models up through 1986 must have a Porsche 915. 1987-89 cars may use a Porsche G-50 transmission. The

transmission must use Porsche synchronizers.

B. Differential is free.

C. Clutch package is free except G-50 must use stock steel pressure plate. Stock flywheel must be used on all

transmissions. Flywheels must remain unmodified.

D. Transmission coolers, lubrication, and shift linkage are free.

E. 915 transmissions must use an 8:31 final drive ratio. G-50 transmissions must use the 9:31 final drive ratio.

F. The following gear ratios are acceptable in any combination:

915 Transmission G-50 Transmission

1st gear 11:35 12:42

2nd gear 18:33 or 18:32 17:35

3rd gear 23:29 22:31

4th gear 26:25 or 26:26 32:36

5th gear 28:23 36:32

4. Suspension

A. Stock suspension pivot axis must be maintained by all suspension components.

B. Front spindle height is free; struts must be O.E. components manufactured by Boge, Bilstein or Koni with the

location of the spindle as standard or relocated. The retaining system for the O.E. shock absorber insert must be

used. Custom fabricated strut housings are not permitted.

C. Front and rear shock absorbers must be the same configuration as stock, maximum 2-way adjustment.

D. Torsion bar suspension required, front and rear.

E. Suspension bushings are free. Front camber plate/caster plate design is free.

F. Stock 911 rear control arms only, 930 rear control arms are not allowed.

G. Adjustable rear spring plates are free.

H. Anti-roll bar (sway bar) systems are free.

I. Alignment settings are free, except track width can only be increased by .25” per side.

5. Tires, Wheels and Brakes

A. Wheels must be 7x16 front and 8x16 rear. Any aftermarket wheel is allowed.

B. Tires must be Toyo RA1 or R888 225/50-16 front and the 245/45-16.

C. Any brake caliper, pad and rotor combination is allowed as long as they fit inside the required wheel size

and the rotors are steel.

D. Brake lines, air ducting, master cylinder, brake balance control and fluid are free. Dust shields may be removed.

E. E-brake, parking brake or hand brake system may be removed.