944TurboStar

Picked up my car from the Bauer (porsche shop) yesterday and was explaining that I was thinking of putting in a manual boost controller and custom chips. I was saying that I wanted to increase the boost to about 18PSI.........both mechanics said not to do it and that any 951 running more than 14 PSI is a hand grenade just waiting to explode. They told me that even on engines they build for racing they never go more than 15PSI. They recommended I only put on a MAF and thats it.

Any commensts from the Turbo crowd?

Porsche-O-Phile

I personally run stock-only boost because I hate manual boost controllers and don't feel like blowing $500 on an EBC right now. There are plenty of people running 18 psi though and little or no problems. The engines are plenty strong IF they're tuned properly. Think of it this way: there are Jap cars out there with 10:1-ish stock compression ratios running boost of 20, 25, even 30 or more pounds of boost. How? It's in the tuning. As long as the mixtures are controlled well and kept on stoich and not run too lean or rich, you should be fine.

That said, FWIW I HAVE heard of several cylinder walls cracking recently (usually the #4) but I beleive the concensus on that is that the #4 intake runner tends to skew the air-fuel ratio a bit higher for whatever reason. Based on this, I'd either dial in a slightly richer mixture or run any AFM metering off the #4 exhaust runner. Just my $0.02.

WesM951

I agree with P-O-P, as long as its turned right, there is no problems running higer boost.

Bill

I run 22psi of boost.

Tuning is the number one important factor. Under any boost, if you do not have the proper air/fuel ratio the engine will not last. PERIOD.

But useage is almost as important as tuning. A race car with a boost level of 22psi is definately a hand grenade. On a track, the car is under full boost/full load 95% percent of the time. Full boost for hours at a time is brutal at almost any boost level. Under those conditions, heat gets harder and harder to remove. Heat is a major enemy of an engine. But on a street car like mine, I may see full boost a couple of times per hour for just a couple of seconds each time (say a nice vacant windy road, a mustang cobra, or a ricer on the freeway). Then it is back to cruzing. The heat load generated at full boost has plenty of time to disipate. As long as the mechanicals are sound (head torque correct, wide fire head gasket, bearings good, clean oil, cooling system up to snuff, etc), the 944 engine is quite strong.

But to qualify my statements above, I have only 4,000 miles on my car, since I made all the modifications to be able to boost to 22psi and 335rwhp. So time has not yet proven if my beliefs are true. I also do not drive my car daily, and as such, do not care to have a safety margin. If it breaks, I put it back in the garage and have fun repairing it. If it were a daily driver, I would definately require a safety margin. Perhaps the 15psi your mechanics recomended, would not be out of line at that point.

RKD in OKC

I had a Turbo S 7 years ago. The common concensus back then was to just put a conservative chip in and leave it. Even then there were a lot of blown head gaskets. Back then you really had to be careful what you did or even which chip you got.

Today with the aftermarket wideband sensors and fuel tuning electronics capability overboosting lean and head gaskets are no longer the issue they once were.

A lot of mechanics just don't trust the new technology yet.

Also

#4 cylinder problems are not the intake runner as much as the coolant passage design, and there is a fix for it.

special tool

Time to find new mechanics, dude. They are retards trapped in 1981.


Besides, if you are going to buy a turbocharged Porsche, are you really a conservative person??????

sweanders

944TurboStar

Ha ha....maybe you are right......but I notice you are only running 1 bar of boost.....why not 22 psi like Bill?

OriginalSterm

he's not running 1 bar, that is when he GETS 1 bar!

944TurboStar

well DAM.....impressive.......

WesM951

Yea jim is a crazy *****.. he runs like 25-26psi.

special tool

Did a couple of 32 psi pulls last week.
Walk in the park.

WesM951

bwahaha.. open mouth insert foot wes. d'oh.

I wasn't joking when i said you're crazy. (BTW, Where is the video of this!!)

David Floyd

Man has ***** of steel !

944TurboStar

OK but honestly.....without having to spend some serious $$$ on engine upgrades (wide fire, O rings.....etc) how much PSI should I run on a daily driver 2.8L engine that hasnt been built up?