924Board.org

[Lizard]

the variable boost controller just limits the amount of air between the charge tube and the wastegate by adding a piece in the control line which limits the amount of pressure that gets to the wastegate, you dont have to have a variable boost controller to do this you can make one from parts found at a regular hardware store, but that will be harder to tweek and another story altogether,

the euro models yes had .7 bar or 10PSI, the US models had .43 bar or 7 PSI springs, you can yes take a 930 wastegate spring and drop it in, but you need to find out what rate that spring is, I would say the max to go with w/o an intercooler (85% efficiency) is 1 bar or 14.5 PSI (ROUGHLY), w/ an intercooler you are safer to go higher, into the 17-20 PSI range (these # are derived from Corky bells boost theory for combustion temp b4 detonation/pinging) this is for the 79-82 US models, the 81 and on 931 in Europe used abit higher compression and less boost would want to be used, however with the CGT they used roughly 12 PSI of boost with only a top mounted air air intercooler, which is a much less efficient design to a front air air intercooler, or an air water IC,
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3 928s,

[exc911ence]

Thanks Lizard. Sorry to hear about your 928 by the way...
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1975 911S

[Tigger937]

Does anyone have experience running the Corky Bell boost levels (1.0 bar w/o intercooler, 1.2-1.4 bar w/ intercooler) on a stock 931 US motor, ie., w/o Raceware studs, improved head gasket, etc.? Can a stock US motor in good condition handle these levels?

[Zuffen]

Dennis Wilson has been daily driving one of my old cars. An 81 with a 1 bar spring, we should encourage him to give us a report. I think he added a boost gauge to the car.

When I had it ran pretty damn fast....I was working as a Porsche tech and was driving all kinds of things and as I recall it would smoke any 944 NA and was pretty impressive up against the early and up to mid 80s 911's. The late 928s, 944T and 930s still outdid it, but a 4K car against 20 to 40 K cars and still do well isn't too bad

But that was many moons back...

I can tell you that my 931 while running with a friends 951, well we would be about even on a rolling start, up till about 60 and then he would pull away, but not at any great rate.

I have a gt top mount IC and one of these days will get around to bumping the boost and going back up against him....of course he swaped an S motor into his 86.
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Bob Dodd - 924turbo@cox.net
931 1982, 944 1982 euro, 924S 1988SE, 93 968 tip 06 Silver Cayenne S, 06 Black Cayenne S

I have Way too many cars, parts for the 931,944 and 951

[J1NX3D]

[Racing]

A stock engine will NOT survive on stock timing with 20 psi and an intercooler.
Just forget it.
IF you however re evaluate timing a little it might live.
20psi=1,4 bar.
I´d play it safe and back off 3-4 degrees from stock.

If you go to far you´ll spot that easy as the car will be a sitting duck.
It´ll feel like it won´´t move if you so go out and threaten it.
The other way around,with to much timing you´re up for some new pistons.