BIG Changes to PCA Club Racing Rules

[304065]

The most interesting ones are a re-lettering of the class structure and a power-to-weight formula for the GT classes.

http://www.pca.org/clubrace/docs/2008%20Rules%20Adopted.pdf

Rules to be Adopted in 2008
The following rules will be adopted in the PCA Club Racing Rules for 2008. These rules proposals are sorted into two lists. The first list is those rule changes that will appear in the rule book. Please note that there have been modifications to some of these from the original proposal based on the comments received on the proposals. Some of the other rules proposals became unnecessary when these rules were adopted, and some rules proposals were considered to be allowed already under the current rules. In order to be clear that these are allowed, these items are in the second list.

A decision on one rule proposal (substitution of ABS control programming) is still pending while we continue to research the issue. This rule proposal is listed at the end. We will make a decision by the end of November on this proposal.

New Rules to be Included in the Rule Book

Stock/Prepared Classes

1. Allow ducting for fender-mounted oil coolers in stock class. Headlights must be retained; this is to allow small ducts mounted on the side above the bumper. Cutting of body panels is not allowed.

2. Add to Stock class rules: “Spacers to adjust the height of the steering rack and pinion are allowed.” This is allowed, but not currently published.

3. Add to Prepared class rules: “Spacers to adjust the height of the tie rod end at the steering arm are allowed.”

4. Change Stock rule 1.M. to read: “Any spark coil and CD unit is allowed, so long as it is not capable of changing ignition timing or offer any other performance advantage. The stock engine revolution limiter and function must be retained.”

5. Allow removal of the heater blower from air-cooled cars. Plates or ducts to close the openings for the heater flex ducts would be allowed.

6. Allow any limited slip differential in stock class; however no locked differentials will be permitted.

7. Allow replacement of toe links in stock class 993/986/987996. 993s may use aftermarket links if they are the same length as the OEM toe link when adjusted by the eccentric. 986/987/996 must use the GT3 adjustable inside rear toe links.

8. Add to stock class rules: “Non-stock factory shock housings with potentially adjustable spindle height are allowed if welded in the stock position and hub mounting matches factory dimensions”

9. Clarify the updating and backdating rule to explicitly state that the body must match the year and model for the vehicle to which it is converted.
911s updated or backdated across the ’73-’74 body style change will only be allowed if issued a logbook for the conversion before 2008.

10. Allow OEM two-piece lower control arms on stock class 986/987/996/997s.

11. Correct the horsepower of the 2005 Boxster to the factory specification of 240 hp, and reclassify the car in F (formerly E, see Rule 20 below) with the ’06-’07 Boxster.

12. Add 2008 Boxster in class F (formerly E, see Rule 20 below) at 245 HP and 3027 lbs (with driver) per published specifications.

13. Stock Rule 3. A.: Delete “No ‘autocross spec’ tires are allowed.” Tires still must have DOT approval and appropriate speed rating.

14. Allow deletion of AC or AC condenser as a prepared change.

15. Allow any dual-mass flywheel to be replaced with a single-mass, ferrous material flywheel. The clutch disk must be the stock diameter.

16. Allow removal of the headliners in stock class cars for the installation of roll cages.

17. Allow removal of all carpeting that is not glued or screwed to the car as delivered from the factory - (allows the removal of trunk carpeting, loose floor carpeting in 911s and the hatch carpeting in 924/928/944/968s)

18. Add to “Prepared” modifications: If there is no alternate ring and pinion available for the car model, an entire gear set for all forward gears may be substituted if the resulting gear ratios are equivalent to a ring and pinion change.

19. Clarify that radiators are “free” in water-cooled cars. Radiators must be installed in the stock locations.

20. Reverse the stock class numbering system to start at A for the slowest class. (Note: yes, we are really looking forward to Sebring for this one!)

21. Combine classes J and K into a single stock class (which will be new class “A”).

22. Allow welding of additional flat metal to reinforce suspension mounting points or suspension pieces. Added material may not connect with roll cage components or otherwise significantly stiffen the chassis.

23. In “Prepared” Rule 2, change “Slotting to achieve suspension settings is allowed” to “Slotting or camber plates used to achieve suspension settings is allowed.”

24. Expand the number of classes for the cars currently in A-D. The final classification is attached at the end of this document. Rules 25-33 are incorporated into this table. Please note that there are 6 new classes, designated G-L in the table (under the new lettering scheme), to replace the current A-D.

25. Correct the weight of the '03-'06 GT3 to the factory-published value of 3042 lbs (w/o driver), which is 3192 lbs for the rule book.

26. Correct the weight of the MKI ’99-‘00 GT3 to the factory-published value of 2933 lbs (w/o driver), which is 3083 lbs for the rule book (adopted Clubsport weight).

27. Add 964RS, 3.6L to the rules in Class H at 260 hp and the published weight of 2684 lbs (w/o driver), which is 2834 for the rule book. (This is the only published weight found for the car and it may include a full tank of gas, but it is consistent with Porsche’s other published weights for models at that time.)

28. Change the weight of the U.S. Carrera Cups to the 964RS weight of 2684 lbs (w/o driver), 2834 lbs for the rule book, correct the horsepower to 265 and class with the 964RS.

29. Add ’74-’75 911 Carrera RS 3.0 to Class H at 230 hp and 2311 lbs (with driver).

30. Correct weight of 996 Turbo to 3546 lbs with driver, based on published weight of 3396 lbs.

31. Add 997 GT2 at 530 HP and 3325 lbs with driver to class L.

32. Add 2008 Boxster S at 295 HP and 3137 lbs with driver to Class G.

33. Correct the weight of the 997GT3/GT3RS to the RS weight of 3031 lbs (w/o driver) and 3181 lbs with driver.

Spec Classes
1. SP1, SP2, and SP3 rules are not part of the PCA rules process and will follow the rules adopted for their series of origin in 2008, including any changes in 2007 that are retained by those series in 2008.

GTC Classes
1. Allow the use of Lexan front windows in GTC Cup cars.

2. Allow any 2-way adjustable shock in GTC3 and GTC4.

GTC1-Specific Proposed Changes
The general reason for these is either difficulty with parts availability or issues of consistency because the U.S. Cups and Euro Cups differ.

1. After the stock heat exchangers, exhaust is free, except it must be a single outlet exiting in the stock location.

2. Factory aluminum hood may be replaced with factory steel or aftermarket foam core fiberglass or carbon fiber hood. Hood must have provision for hinges, with only two hood pins allowed. The hood should be indistinguishable from the factory hood in form and function.

3. Allow updating to the 993 solid shift rod part # 964.424.020.35. This part differs in that the universal joint is metal rather than a plastic bushing.

4. Allow the replacement of the magnesium engine mount with solid aluminum mounts of the same height.

GT Classes
[rule change omitted as it makes the post too long, see PDF]

[jase007]

John:

New rules let me run 2.27L air cooled 4 cylinder in GT6 ... in my 356 [keeping weight the same

Can you imagine a 205+ hp motor my #1700 car ...?

Won't be making any changes to our cars b/c of HSR / SVRA, etc.. rules but could if only ran PCA CR.

I'll be interested to see if the 914-4 GT cars come back with a vengence to romp on larger displacement classes

Cheers.

[304065]

Hey there Jason!

To stay in GT6 you must have a max power-to-weight of 9.76 pounds per horsepower.

Ok, let's figure your CAR is #1700 and you and all your stuff (helmet, HANS, cool suit, iPod, etc) weigh 175, and let's throw in a 4 gallon fuel reserve (25 pounds. So all-up you and the car tip the scales at #1900.

Here's the formula:
Weight in Pounds/[Displacement x specific output multipler] * 100 >= 976

For other classes:
<= 425 GT1

426 < GT2 < 550

551 < GT3 < 675

676 < GT4 < 825

826 < GT5 < 975

976 < = GT6

So the quick way to solve these is:

All-up weight divided by minimum power-to-weight divided by specific output for the engine type times 100.

1900 / 976 = 1.946 / 90 =.021630 *100 =2.1630

Or, with a 74mm stroke, a bore size of 96.5mm. Now practically I think the biggest cylinders for a 356 are 90mm. Do I see a VW type IV in the future?

In my own case, if I wanted to stay with my current car and race in GT5 without having to lighten everything with fiberglass, I could. . . .

Race weight without driver 2249
Driver and gear 210
All up weight 2459
2459/GT5 max power to weight of 826 =2.97 divided by aircooled six specific output of 110bhp/liter . . .2.7 liter engine!

2.7 liters at 110 BHP= 297HP in a 2459 pound car. WOW.

The real trick is how do you fit the car in more than one sanctioning body. e.g. HSR has a displacement limit of 2,5 for a certain class. That's the beauty of the rule, if you ran a 2,5 you could still fit in GT5 by making the car weigh 2238 pounds-- work the math operations backwards--

2464 cc "ST" motor= 2.464 liters divided by 100 =0.024640 times 110 BHP/liter times 826 max power-to-weight for GT5= 2238 pounds.

Fun with math!

[jase007]

Do I see a VW type IV in the future?

Hmmmm ... was my 1st thought but don't think PCA wants to see 200+ hp 356s running around.

I got the math and ran through the formulas when they were 1st released. Like you said ... PCA allows me to run 1750 cc now [before these '08 rules], I don't b/c HSR and others only allow 1600 cc [actually 1622cc]. Don't / won't build specific motor for PCA so ... point is kind of mute 4 me.

I do think with no limit on displacement .... [except as constrained by total weight and specific output by engine type] I think we'll see some interesting things.

FWIW our 3.4L GT-3R car .... can now keep the same weight [change nothing], use the specific output by engine type [110 for air cooled 6 cylinder] and can run a 3.7X L motor. WOW

PCA allows for this ... unfortunately, where we mainly run it's illegal. Still, 3.7L X 110 = 407 hp is pretty good numbers for a NA six cylinder ... LOL

Fun with numbers

[304065]

Jason, quite right. I don't think PCA is that concerned about guys building monster motors for comparatively high-weight cars: the cost of increasing horsepower is always higher than the cost of weight reduction, which pays dividends in handling and braking (at the expense of safety, e.g. steel doors are better than fiberglass.

Consider what it would take, for example, to build a 220 HP 2,0 liter engine. . . that's right up there with the original 911R. I have no doubt that today's engine builders can achieve that. . . but the cost goes exponential for the incremental power gains above that number.

Here are some "historical" power-to-weight ratios from my database. . . someone may correct the numbers a touch but it should give some perspective on the best the Factory could do "in the day!"

[mjshira]

interesting thread, no matter how I add it up, I end up in a class with a bunch of drivers that are WAY better than I will be for quite some time :-D

[jase007]

John: FWIW, the HSR / SVRA Klub sport racers are running 220+ hp 2.0L cars. Yes, $$ is no object for them and I saw an engine dyno sheet recently where a 2.0L motor was making ~230 HP. I don't think PCA is concerned about including these cars in GT as there are other sandboxes to play in for them.

It seems to me that the PCA GT toss-up is an attempt to get a handle on some of the GT classes and make it a "fairer" class for NA cars as compared to boosted. That said ... the 951s in GT3S or R are still going to crush 3.7L +/- 911s [if someone builds one] as they'll be still be making ~450 hp. Will be interesting to watch.

The stock / prepared class rule changes are going to equalize the field better in some classes and still leave others out to dry. Can't please everyone all the time and I give Donna A. et al a lot of credit for trying to make it work.

Now ... where can I get a big BIG block Type IV motor cheap... hmmmm LOL