Compression Question

[DCGuerrette89]

ok when i bought my car the guy told me alot of BS he said it was cammed had a 3000gt fuel pump and injectors and some other stuff. now i did a comprestion test at my school alldata said it should be 114psi. i read 150(1) 170(2) 150(3) 170(4). why would it have higher compretion pistons in it when its turbo? i thought turbos use lower compretion because the turbo makes up for it? any help would be great.

 

[ChiTownHussla]

you numbers are ok. compression numbers be about the same for NA cars and our turbo cars. 150-165 is good for your car. I think spec is no more than 15 in difference but you are good man. do boost leak test now.

 

[1GenDSM]

150 is right where it should be. Id be more concerned with a difference of 20 psi from cyl to cyl.

 

[Bo0sTdTsI]

It should be ok but make sure you try your best at inspectingeverythng else. My last build i had 180-185 across all 4 running 10:1 wisecos and my car ran fine for a pretty good while. So idk everyones car is different and everyone said id have issues with that compression and i ended up not having issues at all.

 

[95AWD6Bolt]

ok when i bought my car the guy told me alot of BS he said it was cammed had a 3000gt fuel pump and injectors and some other stuff. now i did a comprestion test at my school alldata said it should be 114psi. i read 150(1) 170(2) 150(3) 170(4). why would it have higher compretion pistons in it when its turbo? i thought turbos use lower compretion because the turbo makes up for it? any help would be great.

114 is the service limit. If it is lower than that, you most likely need to rebuild.

Always, always always check a car thoroughly before purchasing, especially a modified one.

Lastly, please reread rule number 5 (Grammar, Punctuation and spelling).

 

[GIRman67]

I do know that perfect compression in 2nd gen cars is supposed to be 178 with serviceable limit being around 133. It was in the Mitsubishi tech manual for second generation dsms IIRC. After my head gasket job of was getting right around 178 +/-

Take my post with a grain of salt. I haven't looked up much on 6 bolt motors, other than the knowledge that 1st gen motors had lower compression pistons (7.8:1) than the 2nd gen motors which have 8.5:1.