compression numbers

[sfron03]

so i got a compression test on my three week old gsx. so my dipstick kept popping out, i thought it was the dipstick, which it was, but i went ahead with a compression check. these are my numbers

#1-190
#2-160
#3-175
#4-180

number two is way low, so im guessing this motor is done for. is this car ok enough to daily drive? i think il need this till the end of summer. no boosting for sure

 

[Area51Workshop]

I thought 150 was the number you wanted for a dsm? Or is that just for 1g's?

Did you try and put some oil in the low cylinder to see if the compression would come up? If it does maybe bad rings.

 

[tom04841]

150 is for the 1g for sure...not sure about 2g

 

[GSX20]

Standard 2G compression #'s are 178psi. Service limit is 133psi.

 

[Stangmurdera]

Don't worry about your low number on cylinder 2. 160 is only 18 below the recommended compression for your car. It will run forever at that compression. I would only worry when it falls below 150. Your engine is not shot by any means.

 

[sfron03]

would it be safe to push this motor?

 

[sfron03]

i also took a look at the sparkplugs, they're WHITE. meaning im running lean. any ideas why im running lean?

 

[diablos991]

There is only supposed to be a 15PSI difference between cylenders. I would be concerned why 1 is so high and 2 is 30PSI lower. Are you burning oil, leaking oil into coolant, burning/ losing coolant?

 

[sfron03]

i dont really know, but im probably burning oil. ill check the coolant today to see whats up.

 

[LaN-]

you could run a wet compression test to see if the rings are causing the compression difference. if your burning oil it could be a few different things.

If the compression doesnt shoot up with the wet compression test your head or headgasket could be bad.

All else fails do a leak down test to figure it out.


either way those numbers arent bad at all, only thing bad is the burning oil.

 

[sfron03]

how do you do a leakdown test?

 

[LaN-]

http://www.dsmgrrrl.com/FAQs/leakdown.htm

 

[DGajre777]

http://www.dsmtuners.com/forums/showthread.php?t=227313

You should not have more than 14psi difference between cylinders, which you don't.
The standard compression is 178psi.
The service limit is 133psi.

You shouldn't have more than 14psi difference between cylinders because it could mean that you need a new head gasket.

 

[LaN-]

http://www.dsmtuners.com/forums/showthread.php?t=227313



You shouldn't have more than 14psi difference between cylinders because it could mean that you need a new head gasket.

this is correct but if its more then 14psi its not the end of the world. A buddy of mine ran low 12's and his compression was 165 165 165 130. In no way am i telling you runing your engine like this will not cause problems. I just hope you get the idea.