MarkRobinson

With the low boost, moderate compression we're running, & moderate power, our studded heads are still beyond what most mfgr's design into their engines. a 944t has a studded head as well, & can take well into the 500hp range (on 4 cylinders, ala, 10 head studs), w/o issues. Our 928's should be good for at least 1000hp with the stud design Porsche as allowed. Since most 928's are 1/3 of that, & most boosted 928's are 1/2 of this range, I think we're all safe enough.

Now if you're bulding an engine, no reason not to use ARP 944t rod bolts...probably cheaper than Porsche's OEM bolts. I did this on my black 928, easy swap via machine shop.

FWIW, Boostlogic (MFGR of my turbo kit), uses thicker headgaskets on their NA/turbo supra conversion (& SC300 turbo conversions). This works very well with factory pistons, & my buddy's car ran a 11.2 @ 129 last week in his SC300-turbo, with the thicker headgasket. Car puts down 561/490 to the wheels @ 30psi. They've been doing this for years without issues.

BC

I have ARP rod bolts and ARP head studs. The S4 engines and beyond head BOLTS, and there is the reason I upgraded to head STUDS.

I purchased them from motorsport, and will get the proper directions and proceedures for fitting them from Garrity or David. I'll take the cams out again after a heat cycle if I have to, but I'm not sure if they are stretch or not.

The 951 guys use head studs, whether they are porsche, raceware, or ARP.

The only reason porsche (that I am personally aware of) used BOLTS was for ease of removal of the heads with the engine in the car. 85/86 32V cars have studs.

MarkRobinson

Doh, forgot about that (bolts >87 plus). though, all 944's are on studs FWIW. Some change them out to Raceware, ARP, etc, but you only have head lift on a 951 if you're detonating. I ran my 440hp 2.5l 951 hard on pump gas (1.2 bar), never a detonation issue, never a headgasket issue.

BC

I just want the best longevity at about 13psi. Cometic HD, coated pistons, non-cast rings from the 951, S3 cams, Forged OEM 928 rods, and the ARP stuff. Should hold together for everyday use.

Its all on a learning curve

CMW

So sounds like Cometic is perfect for my intentions and insures that there will be a 5.4L engine arond for awhile