Giantman

Just curious as to what the factory set the boost at in the Turbo S and later cars?

Thanks.

JDeitz951

Was there anythiing later than the turbo S? I think all 951s were 14.5 psi stock.

streckfu's

.8 bar peak or about 12psi.

skene

14.5? I'm pretty sure stock is around 10-11 psi. Aftermarket chips usualy say to set it somewhere between 14.5 and 16.

hosrom_951

From the manual:

JDeitz951

My bad

streckfu's

+/- 10% ....I didn't know that.

UK952

It was higher on the turbo S and later cars but i forget exactly, 0.8 or 0.85
Tony

JDeitz951

Uhmm... see reply no. 5, regarding the M44.52 engine, where it states it's the same boost but holds steady to 5800 rpm. Isn't that the K26/8 (S) engine?

UK952

Well then I am probably wrong, is the overboost threshold the same in chips for 220 and 250 cars?
Tony

tommye

0.75 Bar = 10.9 PSI

RK951

1 Bar = 14.7 PSI
0.75 Bar = 11.025 PSI

lart951

10.1 psi

tommye

Not at all - you're probably talking about atm (athmosphere).
If you substitute Bar with atm in your statement above - then it is not too far off.
1 atm = 1.013 Bar
I think the Porsche workshop manual (as posted by Hosrom) is to be taken as reference. They state the level at 0.75 and the unit as Bar:s.

0.75 Bar = 10.878 PSI

hosrom_951

The numbers are not exact, it's a range. Hence the manual stating 0.75 +/- 10%, some cars would be boosting 0.675bar (9.79psi) and still considered normal.

Boost drops to 0.52bar +/- 0.03bar, which is as low as 7.1psi at higher rpms is also normal. Remember, this is for a fresh engine with a fresh K26, age and wear and tear definately brings down the numbers, considering the cars are now hitting 20 years (1986 models).