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Director
Moderator
Joined: Nov 05, 2009
Posts: 1634
Location: Isle of Palms, SC
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Provost wrote: It will be interesting to see what they come up with for checking "CR". Be it the whistler or a compression test. What's a bigger shame is that they have to do this at all. I will be at Sebring doing track support for my customers and will watch PCA very close when sp2 cars get pulled in for tech. Robbie: can you come up with the measurement for the cylinder head for the factory limit for all 4 factory pistons: 9.5, 9.7, 10.2 and the 10.6 using a maximum 10.7 cr? and using the thinner factory gasket _________________Dave Derecola National Director 944 Cup cup944@aol.com
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| Thu Dec 20, 2012 7:58 am |
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Director
Moderator
Joined: Nov 05, 2009
Posts: 1634
Location: Isle of Palms, SC
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bobster4 wrote: Director wrote: This could get complicated. And while reading understand we are trying to establish some limits and means to limit power a car is producing. Up to this point we have used a dyno. Dynos have not be available or affordable. So what do we do as an alternative. Nothing full proof, but we do what we can do utilizing PCA techs.
We started out with set minimum limits on milling the head and the thickness of the gasket with the idea of setting limits for CRs, along with factory spec pistons. That in conjunction with using a device to measure CRs. The device would identify motors over the limit which would then be used to do further inspections for stroke, piston examining with borscope, and measuring the head. This types of limits aare set and to be used in SP1.
However, one of the difficulties in measuring a head and the gasket is one needs to know which of the four factory 944 pistons in use, as the measurement of CR will vary which in turn can change the allowed measurment of the head in producing a legal CR. This complication has led to us just going back to using a device to measure CR.
How will a driver know the exact CR their car is producing in advance of a race? Not sure other than finding a device, such as a Whistler, to take a measurement. If you are using legal pistons, legal stroke, have not milled the block, and are not using a head gasket thinner than stock,and have not milled the head beyond just truing, you will be fine. If you have done any or all of the above, you get into no man's land and you may be at risk.
Without the regular use of a dyno, we needed to come up with some type of limits to attempt to keep a level or at least defined field of play when it comes to power output. Just to be clear, I'm definitely ok with using an alternative to verify power compliance. My concerns are like I said, verifying my compliance (which based on what you said above, I should be good and I know my dyno numbers are good) and also how this will be done at the track. Just hoping that it's done in a manner that is relatively quick and painless so we are not in the impound area for hours on end. Post-race tech with a big field, a la Watkins Glen last year, takes forever. As I understand, the device, a whistler, would be used which is fairly quick. Only need to pull a spark plug. and would be done when enhgne is could first thing in the morning. _________________Dave Derecola National Director 944 Cup cup944@aol.com
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| Thu Dec 20, 2012 8:01 am |
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Director
Moderator
Joined: Nov 05, 2009
Posts: 1634
Location: Isle of Palms, SC
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ps. while we are late into the rule making process, if anyone has a better way to measure or limit power for these engines, please email with your solutions. It would need to bevery quick and very detailed. Thanks
_________________Dave Derecola National Director 944 Cup cup944@aol.com
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| Thu Dec 20, 2012 8:02 am |
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NATAL AUTO
Rookie Driver
Joined: Mar 12, 2010
Posts: 27
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I for one applaud this move. The Dyno is great but reality is we cant have one at all these events. Let us all not forget that this is a SPEC class. I came to cup from GT class for that very reason. Its not supposed to be a spending race. Everyone is worried that there in compliance. If you have stock pistons and havent milled a pound of aluminum of your head, your not going to have a problem. Trust me the ones that will have a problem already know!!! The more people see that to race with us means a fair shot to compete the more entries we will have. This is a win win situation PS happy holidays to all 
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| Thu Dec 20, 2012 8:03 am |
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cris.brady
Rookie Driver
Joined: Nov 09, 2009
Posts: 84
Location: Landenberg, PA
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I"m on the same page as you Dave. I'm all for making it a level playing field. I want to know when I go racing and get beat, it's by somebody doing a better job of racing than me, not just because they have another 20 hp in their motor. When I get beat by a superior driver, it makes me want to improve. When I get beat by illegal cars and there are no rules compliance, it makes me want to go elsewhere.
_________________- Cris
#88 1989 944 NA
Tales from the Dark Side of Racing
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| Thu Dec 20, 2012 8:06 am |
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DrFranz
Driver
Joined: Nov 23, 2009
Posts: 204
Location: New York, NY
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Director wrote: ps. while we are late into the rule making process, if anyone has a better way to measure or limit power for these engines, please email with your solutions. It would need to bevery quick and very detailed. Thanks We could just say that any car that is faster than mine down the straight is illegal. 
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SuperCup #57, National Champion 2011 and 2012
www.frankcelenza.com/racing.php
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| Thu Dec 20, 2012 8:22 am |
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Provost
Rookie Driver
Joined: Nov 15, 2011
Posts: 51
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When looking into a cylinder with a bore scope the 9.5 pistons are flat and the 10.5 are not. As far as the after market dished ones I have no quick way of telling. So is there going to be a prevision in the rule's(PCA) for aftermarket pistons?
This is so complicated and should not be.....open for suggestions.
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Robbie
Provostmotorsports.com
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| Thu Dec 20, 2012 10:18 am |
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NATAL AUTO
Rookie Driver
Joined: Mar 12, 2010
Posts: 27
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Hey Rob, we should be looking at max CR only and that will simplify things. So bottom line if your above max CR for the series thats it! It will get crazy if we are going to try to ploice this as per all different engine config. Yes guys with the high compression engines may have a little extra but we all have the option to go that route. There is always going to be slight veriation in our set ups. Just my thoughts
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| Thu Dec 20, 2012 11:52 am |
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wormhole
Rookie Driver
Joined: Mar 08, 2010
Posts: 10
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Checking the head surface limit is a nice start in terms of a compliance measure, but there is no way to verify the piston cc other than to use a bore scope. At one of the NJ race's they simply asked me which pistons I was using before they took the measurements. Measuring the wear limit is very simple, even Al Cohen can do it for those concerned. Below is straight from the Porsche manual. Using the whistler approach is a much more complete way to verify CR IMO, and is a no brainer. Get herr doneee….. http://store.katechengines.com/whistler ... -p174.aspx
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| Thu Dec 20, 2012 4:49 pm |
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Provost
Rookie Driver
Joined: Nov 15, 2011
Posts: 51
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Problem with the wistler is atmospheric pressure. Compresion readings will change at different altitudes. There is a chart for this but we are getting way complicated....
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Robbie
Provostmotorsports.com
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| Thu Dec 20, 2012 7:49 pm |
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