It is very difficult to put NA and Forced induction cars in the same pot and with the same set of rules. A NA car needs just the right amount of back pressure for peak performance. Without back pressure you lose bottom end torque. A turbo car needs no back pressure. Any exhaust restriction becomes an obstacle. Just by having an open exhaust rule, the turbos benefit way more than NA cars.
Certainly I've not seen everything but I've never heard of the boost spike throwing the car into limp mode.

Karl

If the dme puts the engine into limp mode then in fact it does control boost. And thats why having a telltale guage matters if a Turbo is allowed to change to an aftermarket chip which can remove or change the limit of the boost.

I agree with Dave. If the car overboosts either on purpose or by malfunction it's part of the game. As Dave has said in the past. Everyone should retain a bit of a safety cushion just in case certain circumstances can put you over the limit.

Karl

If the tell tale boost gauge actually works and doesn't end up recording inconsequential momentary overboost it is probably OK. I suggest we get some data from people actually using it. It might be interesting to see data from stock and non-stock dme chips to see how they compare. Since the idea is to get more participants I still think this idea doesn't make sense, in that it will drive some of the turbo guys away. PCA seems to be able to live with aftermarket DME chips. It would be nice to be able to run the same setup in PCA, 944Cup and NASA GTS. If people are gong to cheat it an amateur series, they will find a way to do it. Making life even a little more difficult for the vast majority of those who don't cheat is not a way to attract people to the series.

I will now go back to building my non-Turbo SuperCup car.

And this statement proves my point that stock chips work just fine, as the PCA Stock classes require a stock chip , including for Turbos.



And adding to the PCA comparison, they use their own boost guage, to test the boost being produced by a car, and if yur over, no matter how short the overboost, then u are DQed.



You can run the identical set up in PCA and NASA and 944 Cup . The Cup rule would allow you to run with a stock chip or an aftermarket chip, and PCA and NASA allows for both options too.

Steve,
If your open exhaust is causing your boost to hit too hard, why not go back to stock exhaust or something else? I know guys in the past ran different exhaust setups to move their cars from PCA stock class (no hp limit) to SuperCup (hp limit) . . .




It would be nice to race my car with a minimum of hassle. I don’t race a turbo because I think it is an overdog and is great for exploiting rules. I have had the car for almost 10 years now and I just like driving it. Maybe I should stick to winning Black group at DE’s. Seems like doubt will forever be cast over any future success I may have in racing by some of my competitors, no matter what controls DD puts in place.

PCA has the Turbo factory boost at 8.5 pounds and a limit for testing up to 9.5. For the Turbo S PCA has 11.5 for factory and their limit at 12.5 pounds. Regardless of the chip, we will use the same limits.

Where did you come up with those Boost #'s ?
Factory boost on a non S is more than 8.5 pounds

PCA Club Race Scrutineer.

The 951 was actually 8.82 lbs.

Source : Clarks Garage:

6.4 Turbo Overboosts
Problem statement: By far the biggest problem (at least so it seams) with my new 951 is that it cuts the fuel VERY abruptly during heavy acceleration. It is almost like someone is hitting the brakes! It usually happens around 4000rpm but will not occur if I just accelerate "normally". Also, my boost gauge is stuck at one when the engine is on (it returns to 0 when engine is turned off). I believe I can hear the turbo spinning during the acceleration so somehow the boost gauge must be connected wrong?

Second Problem statement: The car idles and runs fine, as long as you don't get on the boost hard. If you floor it, the boost gauge goes up to about 1.8, then, a couple of seconds later, the car jerks hard, and the boost goes away (fuel shut off??). I believe that either the cycling valve or the wastegate isn't working. Is there any way to check out which of these 2 items isn't working? Does anyone know of better designed parts to replace these?

Diagnosis 1: This is an overboost situation. One of the most common causes of overboost is the pressure line leading from the wastegate. A crack here will cause overboost for sure the DME then shuts off the fuel. This hose is rubber & can dry rot over time.

Diagnosis 2: You have a broken vacuum/boost line (hose) between the intake manifold between cylinders 3 and 4 and the KLR (Turbo control computer) box in the passenger footwell, or your KLR box is broken. If this hose is somehow cut or is leaking, the KLR will be reading atmospheric pressure, which will result in no real power for you. The KLR doesn't know how much boost, so goes into overboost protection mode (which is the abrupt cutoff of boost.)

Diagnosis 3: One possibility is that the connection to your air flow meter needs to be cleaned. The next is your wastegate is stuck. The next is that you have a leak in your lines going to the wastegate so that it doesn't measure the proper boost from the turbo and keeps letting boost build. Result: your DME/KLR will shut down the fuel so you don't blow your head gasket and you fly through the windshield. Inspect your hoses to and from the wastegate and cycling valve.