M42club.com - Home of the BMW E30/E36 318i/iS

DISCUSSION => Engine + Driveline => Topic started by: PaulC on August 14, 2008, 02:58:38 AM

Title: cyl comp #'s
Post by: PaulC on August 14, 2008, 02:58:38 AM

Tried the search. I'm wondering about some of the numbers on M42's running around. Mine are 247, 243, 250, 249. Looks like the head was cut.

Title: cyl comp #'s
Post by: Jimmy Lewis on August 14, 2008, 09:06:47 AM

That sounds right for a test with 10 turns of the starter, the numbers are high and very close. You seem to have a very healthy engine with close to no blow-by. I don't think compression ratio effects the outcome of a compression test, it measures how tight the tolerances are between the rings and cylinder walls rather than the ratio. Though, with numbers that good on such an old motor it is possible it has seen a rebuild.

Title: cyl comp #'s
Post by: KenC on August 14, 2008, 09:14:09 AM

How many turns of the starter are you doing?  That's really high for even a healthy stock engine.

Title: cyl comp #'s
Post by: PaulC on August 14, 2008, 11:42:41 AM

The car has 92K and I don't know the history other than that. Did the test with around 10 turns. The head looks like it has been off before and probably cut, the upper tc cover doesn't line up. And thanks, it feels really healthy.

Title: cyl comp #'s
Post by: PaulC on August 15, 2008, 03:31:38 PM

Is there a thread I missed where people posted their #'s?