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Discussion Starter #1
My brother-in-law is a certified mechanic and when checking my plugs, we did a compression test. Here are the results:

Front bank from left to right
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221 psi
219 psi
217 psi

Rear bank from left to right
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210 psi
219 psi
221 psi

He said my compression was good and holding on all cylinders. Knowing these numbers....What would my compression ratio be? I need to know for some upcoming mods. Thanks!
 

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Aghhhh
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9,731 Posts
As far as I know there's no good way to get compression ratio from a compression test. There may be some formula for it, but I don't know what it is. In any case, your car has 10.0:1 compression unless someone changed the pistons or did some serious headwork.
 

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McStealthless
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1,456 Posts
O.k.

I'm going to be changing the plugs/wires next week and will be checking compression while I'm at it. What is the "normal" range (in PSI) for a DOHC N/A?
 

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1,933 Posts
Mine was 150-160 on all 6 and the "Mitsubishi Certified Gold Mechanic" :) Said "Ohh yeah thats fine" I dont know I guess thats in Spec for a dohc stealth
 

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Retired
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12,235 Posts
i think the n/a's should be around 200psi
 

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Senior Member
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i believe it is ~180psi for the n/a dohc... so that compression is way high...

i just got the manual: @250-400rpm standard value
turbo: 156 psi
dohc: 185 psi
sohc: 171psi

limit: @ 250-400rpm
turbo: 115psi
dohc : 139psi
sohc: 127psi

compression pressure difference limit between cylinders: 14psi
 

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West Side!
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1,201 Posts
If there was a good layer of carbon build up it would increase compression. I know when I took the pistons out of mine there was at least 1/16 to 1/8 in. of carbon build up on the piston crown.
laters,
Gene Crumpler
1992 Stealth ES
 

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Discussion Starter #12
Thanks for the response guys...getting ready to have the heads on my car worked on. When we take it apart, I'll check and see if there is a lot of carbon buildup.
 

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221 Posts
what's up,,, i am from mission actually... lookin to check out the car scene some time soon again...
by the way,,, when i got my car for those glorious 70 some miles after my last overhaul,,, i was able to show off my engine to some chevy and ford fanatics guys i know and they just wet their pants to look at the engine... so damn cool..
all i got is the polished dn y-pipe, polished plenum, and polished valve cover, along with the polished plug cover that says "STEALTH" and the K&N aircharger, plus some cosmetic blue vacuum hoses and the ngk blue wires...
i want the DN Pipe kit,,, but... well let me just get this car to run for a while 1st.... haha...
 
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