LSJ Compression Testing & Numbers Info
LSJ Compression Testing & Numbers Info
There has been some off and on information passed that compression number range between 180-220 on the LSJ engine. This is dependent upon whether or not you have done internals work but for the most part I believe compression testing on our cars is a great tool to use if you believe your engine has encountered a problem and have ruled out all other possible solutions or you just have beaten on your car alot and want to see how it has held up at xx,xxx+ amount of miles. I blew a head gasket and did not realize this until I compression tested and figured out what had happened. Since having one and modding other peoples cars, I have voluntarily asked them if I could test their cars compression to compare against others and mine. Well after doing 12 different LSJ cobalt's from the tri-state area I have some pretty definitive numbers I stand by. Only 1 car out of 12 had different numbers other than 215/220-220-220-220 compression. The other car had run 12 bottles of nitrous through the car and had compression numbers of 205-210-200-210. The cars tested had various miles on them and different mods (no internals work, stock longblock), but the results speak for itself and if you should find yourself looking for a benchmark use these numbers, if your number come out differently, its not necessarily bad if they are all with +/- 5-10% of each other.
Cliff notes: 11 out of 12 LSJ's compression tested at 220 across. Useful information on diagnosing engine internal wear/damage.
Cliff notes: 11 out of 12 LSJ's compression tested at 220 across. Useful information on diagnosing engine internal wear/damage.
Last edited by recklessactn; Jun 2, 2010 at 01:52 PM.
There has been some off and on information passed that compression number range between 180-220 on the LSJ engine. This is dependent upon whether or not you have done internals work but for the most part I believe compression testing on our cars is a great tool to use if you believe your engine has encountered a problem and have ruled out all other possible solutions or you just have beaten on your car alot and want to see how it has held up at xx,xxx+ amount of miles. I blew a head gasket and did not realize this until I compression tested and figured out what had happened. Since having one and modding other peoples cars, I have voluntarily asked them if I could test their cars compression to compare against others and mine. Well after doing 12 different LSJ cobalt's from the tri-state area I have some pretty definitive numbers I stand by. Only 1 car out of 12 had different numbers other than 215/220-220-220-220 compression. The other car had run 12 bottles of nitrous through the car and had compression numbers of 205-210-200-210. The cars tested had various miles on them and different mods (no internals work, stock longblock), but the results speak for itself and if you should find yourself looking for a benchmark use these numbers, if your number come out differently, its not necessarily bad if they are all with +/- 20 of each other.
Cliff notes: 11 out of 12 LSJ compression test at 220 across. Useful information on diagnosing engine internal wear/damage.
Cliff notes: 11 out of 12 LSJ compression test at 220 across. Useful information on diagnosing engine internal wear/damage.
where have u been? u going to Hooters 3
200 across the board =-D pulled the head off for the ported one and the number 4 had some carbon build up in the center, looked like detonation, took a scotch brite pad *whistle* all better
Ding ding ding. This topic is irrelevant if you aren't using the same gauge. I have used 2 different gauges and got 10psi difference between 1 gauge and the other. My car makes 190-195psi on my gauge between all 4 holes.
^^ good stuff and yes it was all done with the same gauge. Ill see if I can get another gauge to support your info. Would like to just see some consistency in the numbers.
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