Ask them to do a pressure leak test. It does require some special equipment but any dealer service center should have what they need. If they have a electric smoker they can add to the system once pressurized it is very easy to find leaks. Shouldnt cost you more than 1 hour to do test.

Small leaks frequently do not give CELs.

 

Typically the reason for not getting full boost is leaks, plugs, coils, wastegates (assuming the car is not in limp). It is quite possible the car has codes (not all codes trigger a CEL).

Do you have Stock DVs?

 

I'll definitely ask them to perform it if they hadn't been planning to. I appreciate the info - I was wondering how much time this might take to diagnose.

 

I'll have them check for any codes to be sure (if they weren't already planning on it). I'm assuming the car is not in limp mode, though I'm not knowledgeable about said condition. The name suggests very substandard performance, which I'm not seeing - just a slight drop in boost.

I'll hopefully have more info from the dealer in about twelve hours and will update this thread once they let me know.

Thanks for the insight.

 

anyone know how much whp does the K24 w/ GIAC & BPU's (intake/header/exhuast/5bar/plenum/gt2ic's) should put up on a tip? and the max boost of that on the K24?

 

I took my car in this morning and the tech found no boost leak and that no codes had been logged. Unfortunately the tech did not run a leak test, though the SA had told me that would be done. I specifically had asked them about it before they did their investigation and they indicated they would perform a leak test. But when all was said and done, all they did was to drive it (getting a 0.7 bar reading), check the boost pipe connections for proper fit, and check the fault memory for fault codes. They also noted on my receipt: "To avoid knock during high ambient temp, boost pressure will be limited."

Also, according to the service tech, the only information they have from Porsche for 996 Turbos is that there should be up to 0.75 bar. I asked him whether this was for an X-50 and he said that they (Porsche) didn't give any information on the expected boost for an X-50.

It wasn't my typical experience at the dealer.

Because of this I then ran over to the indy shop that did my PPI and talked to them about the situation. Unfortunately, their turbo expert was out so I couldn't pick his brain. The guy who was there suggested that one way to see what's happening is to get the car on a dyno, though I haven't decided if that's what I want to do. I'm going to call their turbo expert tomorrow morning.

The good news is that the dealer didn't charge me anything for the work they did.

 

Any updates here on the decreased boost and the causation? I'm curious to see if you got this sorted and what the issue was..

 

I only see .7 max as well on my x50...love to see what's happening if the x50s should be seeing .8 or .9...

 

.7 - .8 is the norm for non-modified K24 cars. Sometimes spikes to .9, but not sustained.

 

That is not an easy question!!

Close as I can tell, this setup is like an old EVOMS stage 4 with a plenum. As I recall, a 6 speed stage 4 put out ~460-530 whp depending on the dyno and conditions. The tip has greater drivetrain losses and plenum wont help much so I will guess 450-475 WHP.
I dont know what the max boost of a standard K-24 is but I dont think they will support more than 600-625 crank hp on the 996TT platform without modification.
Go easy on me, these are just estimates from memory.

 

The other day I found an opportunity to see max boost - I did get to 0.9 boost almost easily/after a few secs.
Now I can't help but watch the gauge like it's the news..

 

I spoke to Chris, the Turbo expert at the indy shop (www.chrisgerman.com) that did the PPI on my car. He suggested the same thing his colleague did earlier, that the dyno would tell me if I'm getting the expected output from my X50.

I then called Alex at MAXRPM (www.maxrpmmotorsports.com), a tuner on the other side of the Puget Sound from Seattle. He owns an X50 and he said one of the first things he would check is to see if the wastegates were set properly. He knows Chris and agreed that a dyno run might be a good idea. He did say that he would check the wastegates first though.

The dealership service manager sent me a document from Porsche that has further information but I haven't read it yet. I'm going to do that in the next day or so.

Bottom line: the boost issue is still unresolved, and I'm considering driving over to have Alex look at my car. I don't know if I want to spend the $300 - $400 on a dyno run yet.

I want to be sure that the issue isn't a degenerative condition that worsens over time. Thus far the max boost is consistently reaching 0.7 bar when I test it. I think I got a Type 1 overrev the other day during one test. I gotta monitor the tach more closely next time.

 

As I said in my first post the statistics say: 0.8 +/- 0.1 is normal. Recognize variation is everywhere...this includes supplied parts, and Porsche manufacturing....so no two cars are exactly the same...your values may differ and there still be no issue. Of course checking for leaks, wastegate adjustments, etc. is always a good idea, but I wouldn't sweat it. If you want more boost, flash the ECU.