I have an new AA 96mm piston/cylinder kit that will convert my 1.7 to 1911cc, the heads have been opened up to 105mm, no other change.
After checking deck height and combustion chamber volume i realise that this engine will only get a CR of 7.4:1 (Im aiming for around 8.1-8.5, yes we have 99octane fuel over here).

However if I do not use any head gasket (which is 1.25mm) I will get a CR of about 8.2.

Has anybody successfully been running a longer period without any head gasket on a head that has not in any way been modified for non head gasket use?


/Lars S

I had a similar issue, same engine & cylinders. I lapped the cylinders to the head and did not use a gasket. 10K miles and no problems...yet. Recent leak down test was less than 10% on a cold engine.

No head gasket is the correct way to mate the head to the cylinder.

and I think between the cylinders and case, are shims.

"Correct" "IF" you have a late 2 liter VW T4 engine .................................. Others call for a head gasket. However, there is considerable anecdotal evidence that you can run without 'em.

The Cap'n

Awww Cap'n, not again. The VW bulletin (it's a VW engine) advising against using head gaskets was issued in 1990. By custom and law manufacturers go back ten years, in this case that means to 1980, when Porsche was out of that window but for some engines VW wasn't. So Porsche not issuing a bulletin is not really relevant, but VW issuing one for VW engines is, and that's the technical bottom line. But, as the Cap'n rightly notes, there is anecdotal evidence out there.