Did a compression test #'s a little low?
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From: Tustin, CA, USA
Did a compression test #'s a little low?
I did a compression test on my car with a warm engine and cranked it 7 revolutions and ended up getting 180-185 across the board. I was informed that gsr motors are suppose to get 210 compression. I dont know why my compression is so low. Comments?
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From: Tustin, CA, USA
Re: Did a compression test #'s a little low? (95GS-Racin)
My motor only has 16,000 miles on it also. Im not sure, but could it be from the turbo wearing out my engine. Maybe I have bad piston rings? BTW I did a compression test on my friends car which is a prelude with 30k and he was getting 205 across the board. So I know its not the guage.
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From: San Diego, Ca, USA
Re: Did a compression test #'s a little low? (NHB Fighter)
did u do while the engine was warm? and did u crank it with the gas down?
my first time i did the test i got 115 across, then the next day i warmed up my car and cranked it at WOT i got 250 across.
if you think your piston rings are bad use oil as a temporary seal. put oil in cyclinder. if your compression goes up alot, then your rings r bad, if it doesnt its your valves or headgasket
[Modified by gsrstyle, 5:32 AM 10/1/2002]
my first time i did the test i got 115 across, then the next day i warmed up my car and cranked it at WOT i got 250 across.
if you think your piston rings are bad use oil as a temporary seal. put oil in cyclinder. if your compression goes up alot, then your rings r bad, if it doesnt its your valves or headgasket
[Modified by gsrstyle, 5:32 AM 10/1/2002]
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Re: Did a compression test #'s a little low? (NHB Fighter)
You shouldn't worry about the actual #s. Me and a buddy got about 240 in all four with our GSRs; it doesn't necessarily mean we were pushing more air than you, it was probably the gauge.
You dont want large variation between the numbers though. Within 10% in all 4 is pretty good.
You dont want large variation between the numbers though. Within 10% in all 4 is pretty good.
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Re: Did a compression test #'s a little low? (Lee Chun)
Those are great numbers; The manual says it should be like between 130 or something all the way up to 200=normal reading. The variation is what's important but 180-185 is cool; the manual says shouldn't vary no more than 25 psi
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Re: Did a compression test #'s a little low? (NHB Fighter)
but what makes me confused is how did his friends prelude get a 205 reading(10:1 compression h22a or something like that) and he got 180 on his 10.4:1 compression b18c5)??
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From: San francisco, ca, USA
Re: Did a compression test #'s a little low? (NHB Fighter)
your numbers aren't bad. numbers should be at least within 10% of each other. as for going turbo . be aware that boosting will eventually wear the rings down but that's the trade off. stock motors are good but weren't built for forced induction.
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From: QC, Canada
Re: Did a compression test #'s a little low? (NHB Fighter)
I did a compression test on my car with a warm engine and cranked it 7 revolutions and ended up getting 180-185 across the board. I was informed that gsr motors are suppose to get 210 compression. I dont know why my compression is so low. Comments?
Regards,
Oz
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From: Tustin, CA, USA
Re: Did a compression test #'s a little low? (The_Oz)
yea i lowered my compression recently with thicker headgasket (compression should be around 9.0:1 now) and the numbers went down to 168-175 across the board. When I poured some oil into the cylinder, compession jumped up to 210 in all of them except cylinder one which went up to 190. Car runs fine, but I'm just wondering if my piston rings are worn and if I need to replace them.
[Modified by NHB Fighter, 8:35 PM 10/15/2002]
[Modified by NHB Fighter, 8:35 PM 10/15/2002]
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From: QC, Canada
Re: Did a compression test #'s a little low? (NHB Fighter)
yea i lowered my compression recently with thicker headgasket (compression should be around 9.0:1 now) and the numbers went down to 168-175 across the board. When I poured some oil into the cylinder, compession jumped up to 210 in all of them except cylinder one which went up to 190. Car runs fine, but I'm just wondering if my piston rings are worn and if I need to replace them.
Regards,
Oz
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From: California
Re: Did a compression test #'s a little low? (The_Oz)
I did a compression test on my car with a warm engine and cranked it 7 revolutions and ended up getting 180-185 across the board. I was informed that gsr motors are suppose to get 210 compression. I dont know why my compression is so low. Comments?
Your numbers are showing roughly 9.0:1 - 9.25:1 respectively. Normally, I'd say it's fairly bad, but you do have a turbo in there after all, do you not? If so, did you lower your compression ratio?
Regards,
Oz
Your numbers are showing roughly 9.0:1 - 9.25:1 respectively. Normally, I'd say it's fairly bad, but you do have a turbo in there after all, do you not? If so, did you lower your compression ratio?
Regards,
Oz
. You can have 120psi in all four cylinders and his CR can still be 12:1.
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From: QC, Canada
Re: Did a compression test #'s a little low? (3rdGteg)
You cannot tell what his dynamic compression is with static compression numbers . You can have 120psi in all four cylinders and his CR can still be 12:1.
. You can have 120psi in all four cylinders and his CR can still be 12:1.
Regards,
Oz
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From: QC, Canada
Re: Did a compression test #'s a little low? (NHB Fighter)
yea its 168-175 now with the 3mm head gasket. But when I first started this thread, my engine was still stock and it was 180-185.
Regards,
Oz
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