The 944 Cup has always allowed aftermarket pistons. Too late to back up on this. Also, much more expensive to buy or build with factory pistons : viewtopic.php?f=10&t=2119

There are numerous factors that can effect the whistler. As I understand, PCA has a trained tech in charge of its use. But like the dyno, there just isnt any perfect solution. I am trying to write the rule so that half the field last year isnt illegal but still sets a reasonable limit attainable by all and that can be reasonably enforced. If you talk to 5 engine builders, you get 3 different answers, and the other two won't give you an answer. It's not an exact science.

Would it really? The tracks we run at all have to be within, say, 500' of each other in terms of altitude, I would think. Unless we're having an event at Mexico City, I don't think this would come into play, would it?
Just interested, and wondering.

You can use a car or seriers of cars as a baseline for environmental variables. If everyone is a tenth of a point over then it's a safe bet on the machine. If everyone is within range and one car is half a point over then there is a problem with that car.

John

I sent over to PCA what I hope to be the final version of the rule change covering compression ratios and the cylinder head. I accepted the PCA version, one that has been endorsed by some techs that I would have confidence in as valued members of the 944 Cup community, setting the CR limit of 10.6 for the 2.5L and 10.9 for the 2.7 L . Truing of cylinder heads with compensating head gasket is allowed, as long as the compression limit listed here is not exceeded. Aftermarket pistons will be allowed.

The CR values for SP3 were already included in the rules for 2012. Added was truing of cylinder heads with compensating head gasket is allowed, as long as the compression limit listed is not exceeded.

Sounds good Dave ..... I think it is important to allow aftermarket pistons...For those who think they are illegal we did the math and if you do a simple compression test and don't go over 197-199 psi you should be in the ball park for 10.6-1...... 200 plus your over. We have seen some heads come threw here cut so far down that they were around 13.5 to 1

Thanks for the info Robbie. That should help our drivers get some idea where their motors are.

I quick measurement of the head may also give them an idea how much the head has been milled, using the specs provided by Wormhole.

PCA has confirmed the changes we are making to the Cup rules. Hope to have the finals version posted in the next week or so.

Hey Robbie, what would be the compression numbers for a 2.7L?

2013 Rules are posted: http://www.44cup.com/official/944CupRules-2013.pdf