What should my compression be?

[runmy6]

My car has about 60,000 miles on it and before i spend another $1000 on my nitrous setup i want to do a compression test to see how healthy my engine is. I was just wondering if anyone had an idea on about how much the compression should be around when the motor was new and about how much compression a 3.8 with a hard 60,000 miles should have on it to still be considered healthy.
I tried a search did not find much, thanks.

[Dominic]

With only 60,000 miles, the compression should be identical or slightly higher (due to carbon buildup) than when it was new.

I will try to lookup the value for our engines in a minute. Stock CR is of course 9.4:1, and total displacement per cyl is 631.88cc when brand new.

A rule of thumb is that there should be no more than 10% to 15% variance from the cylinder with the highest compression reading to the cylinder with the lowest reading.

Since our CR is 9.4:1, and atmospheric is 14.7psi, you should register readings ~138psi per cyl.

Hopefully then they'll be between 132-140psi.

[ May 26, 2003: Message edited by: Dominic ]</p>