Dan951

Well I sold my 87 951 with 194k on it, and purchased a 87 951 with only 44k on it. Beautiful car! Anyways my previous car had a HR Stage 3 MAF, Chips, and Manual boost controller. I ran the old car at 14.5psi and the head gasket blew, what could have caused this? Also what is the stock boost pressure on a 951, is it 9psi? Should I install a widefire and get my head o-ringed before i put all these items on my new car?
Thanks
Dan

IceShark

While I have seen various numbers tossed around, I believe the 951 stock was .65 bar, so 9.56 psi. The S was .75 bar.

Plenty of people, myself included, are running close to 1 bar, like .95, with no head gasket upgrade and no problems. I would say to leave your new car's head as is if you are going to stay under 14.7 psi.

BJCamp

I just asked this question at PCA and the answer is:

.75 bar max declining to .55 bar at redline. I think .75 bar is about 12 psi and .55 is about 8.5 psi

Luke

Head gasket failures are, unfortunatey, a result of a mixture problem, not a pressure problem

I know a guy that runs 23lbs of boost on an OE style gasket. As long as he keeps it close to that magical 12.5:1, he wont have a problem

Danno

Didn't your MAF-3 kit include the ARC2 fuel-adjuster so you can adjust the fuel curve?

lou951

I agree w/ Luke, it's a mixture problem. Currently I run 18 psi, but have sometimes dialed up 20 psi. All this on a stock block w/ stock head gasket. I keep an eye on my A/F mixture and it's always safe. My car is set up w/ the Autothority MAF which includes their chips. They are know to run on the rich side anyway.