BigBillyStyler

What is the max PSI for a stock '88 TII? And about how far up is that on the stock boost gauge?

Turbonut

iTrader: (1)

Hope this helps-
Quote from ScottT2:
You won't get full boost till probably atleast 3000rpm. which is 5.5 psi. what that is on the stock gauge I can't remember. probably 3/4s up.

BigBillyStyler

it dosent sound like he is completely sure, that is why I asked again.

gsracer

Scott is right. Stock boost for a s4 turbo II is indeed 5.5psi although that can fluctaute a bit depending on ambient air temp and the barometric pressure.

Stock boost guage goes up to 400 mm of hg. That is just under 9 pounds, stock boost cut occurrs at 8.6psi. So about 3/4 up is exactly where you should be.

NZConvertible

What is posted above is incorrect. The facts are:

Max boost on a totally stock 88 is 6.56psi, not 5.5psi, as per the FSM. This boost is reached at ~3500rpm and held until ~5500rpm, where it starts to drops off because of the stock compressor and the various restrictions. At redline you see ~5.5psi, which I think is where the misunderstanding comes from.

6.56psi is 340mmHg and the boost gauge reads to 400mmHg, so it should go to about 7/8 of the way between the zero and 40 marks.

gsracer

my my aren't we picky. FWIW with clogging cats and turbos that have spun over 100k miles now, it wouldn't suprise me to see max boost of 5 pounds

NZConvertible

He asked for the facts.

You're right about the clogged cats, etc. A better exhaust and a rebuilt turbo will give you more than stock boost anyway, so those figures aren't really relevant unless you plan on keeping your car in completely mint, stock condition. And who does that?