964 Top End and Compression Ratio
Racer
Joined: Jun 2001
Posts: 439
Likes: 3
From: West Coast
Came across a similar problem with my engine. Broken stud caused the head gasket to fail causing a leak. At the time, I was told the same, I might see a 1/4 point compression at most.
http://boards.rennlist.com/upload/Clossml.jpg
http://boards.rennlist.com/upload/Clossml.jpg
Thread Starter
Racer
Joined: Jun 2001
Posts: 491
Likes: 0
From: Carmichael, CA
Don't look now, but you're missing a set of spark plugs!
Originally posted by jeff91C2T:
<STRONG>Came across a similar problem with my engine. Broken stud caused the head gasket to fail causing a leak. At the time, I was told the same, I might see a 1/4 point compression at most.
http://boards.rennlist.com/upload/Clossml.jpg</STRONG>
<STRONG>Came across a similar problem with my engine. Broken stud caused the head gasket to fail causing a leak. At the time, I was told the same, I might see a 1/4 point compression at most.
http://boards.rennlist.com/upload/Clossml.jpg</STRONG>
Race Car
Joined: Jun 2001
Posts: 4,878
Likes: 62
From: TX
The quarter point will not cause a problem at all. The true compression of the 964 motor is around 10.5 to 1 (stated 11.3 in manual) Many of the very good engine builders will actually bring the heads down enough to get a true 11.3 to 1 in the RSA's that club race for example.That way they are still"stock" motors, but actually have a bit more oomph. I would actually ask him to bring the heads down a bit more so you can get that "true" 11.3 to 1 while you are there. Your builder can cc the heads to get the true compression currently and after the work. The knock sensor, (when working properly) can easily handle that even with the 91 octane. Just my thoughts, hope it helps.
