Cylinder compression

[mrviper99]

What numbers should I get for compression test on my 1996 GTS, just turning it over with a remote starter?

 

[Marv S]

more than 100 psi

not more than 25% diff between cyls

 

[Newport Viper]

What should it be for a Gen 1?

 

[HP]

For Gen I - 155-170psi with no more than 25% variation
between cylinders

 

[Newport Viper]

Thanks Hugh,
Why the big dif from gen 1-2 in compression?

 

[Jack B]

I did a compression test on 94 and a 97, they were both 160 psi with no deviation between cylinders. A 25% diff would show a problem. If you want to go one step further, do a leak-down test.

 

[Newport Viper]

What is the difference between a compression and leak down test?

 

[mrviper99]

Thanks for the replys, I checked all cylinders on my 96 GTS and the results were between 160-169 so feel pretty good about those numbers. Spark plugs looked good only have about 500 miles on them, a little on the white side, must be running a little on the hot side. Thanks again

 

[HP]

A leak-down test-
is a more specific test done on a questionable cyclinder - performed by inflating the cyclinder with compressed air. This
takes away any other variables, such as cam or RPM that would
affect cylinder filling. Here you would look for how long the
cylinder would hold a certain pressure, or how much pressure is
lost over a certain time.