Thread: compression ?
View Single Post
Noah930 Noah930 is offline
Noah930's Avatar
Join Date: May 2005
Location: Los Angeles
Posts: 15,011
Funny. We all look for these numbers in a PPI, but I've never seen anyone really publish what the factory would consider "good" numbers.

I wonder if that's partially due to the fact that not all mechanics really know how to do a proper compression check (motor should be warm, for example). Temp will alter the values.

I've heard mechanics/shops say that numbers in the 90s-120s are OK. But, again, this seems to be more hearsay than actual figures someone looked up in a shop manual. Obviously, the values that you would get in a normally-aspirated motor (somewhere in the 160-180 range will be much higher than what you would expect in a turbo motor, with it's lower static compression. Everyone also seems to agree that the clustering of the numbers is important (most important?). As long as all 6 cylinders are within a few psi from each other, most likely the motor will be healthy.

If someone actually has seen officially published compression values for a 930 motor, I'd like to see them.
1987 Venetian Blue (looks like grey) 930 Coupe
1990 Black 964 C2 Targa
Old 02-08-2009, 05:51 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #5 (permalink)