Comp. Ratio - 90 L98
Thread Starter
Le Mans Master
Joined: Apr 2002
Posts: 5,726
Likes: 46
From: Waukesha WI
St. Jude Donor '15
Comp. Ratio - 90 L98
I was doing some reading and came up with some differing info. According to my Owner's manual and a few websites the compression ratio of the 90 L98 is 9.5:1. However, according to the Service manual (Helm's book) the CR is 10.25:1.
Who's right? Is this one of the ole early/late model deals?
Thanks! :cheers:
Dale
Who's right? Is this one of the ole early/late model deals?
Thanks! :cheers:
Dale
Burning Brakes
Joined: Jan 2001
Posts: 1,169
Likes: 0
From: Manhattan
Re: Comp. Ratio - 90 L98 (Professor)
They switched from dished to flat top pistons in '90. I think it was Craig Marcho who took pictures of his engine with the heads off. I don't know if they switched during the model year or right at the cutoff of '89/'90.
Thread Starter
Le Mans Master
Joined: Apr 2002
Posts: 5,726
Likes: 46
From: Waukesha WI
St. Jude Donor '15
Thanks for the info guys!
This would definatly explain the poor performance when I accidentily filled up with regular gas. I wonder why there is difference in the sites tho? Hmm..
Dale
This would definatly explain the poor performance when I accidentily filled up with regular gas. I wonder why there is difference in the sites tho? Hmm..
Dale
