compression test is good or bad
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From: Cnetreville, FL, QA
compression test is good or bad
I did a compression test on my stock 92 prelude h23si just intake and exhaust and each cylinder was reading at like 230-245.. i was wondering if thats good or not. any help will be great. Thanks.
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From: Biloxi, MS, USA
Re: compression test is good or bad
They say that you want them all to be within 10 points of each other, but with your compression that high, I'm not sure. I'd personally be very comfortable with those numbers. Those are impressive numbers for an 18 year old h23. I bet that motor runs strong.
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From: Long Point Beach, ontario, canada
Re: compression test is good or bad
Its higer or lower as per elevation. Those numbers are okay. 15psi isn't a huge difference. At my elevation my h23a was 183 +/- 3 .
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From: Cnetreville, FL, QA
Re: compression test is good or bad
okay so it sounds like its good... what do you think of running 8psi of boost? it should be good with a tune and everything right. Yea it runs great me and my buddy race all the time and he has a K20 2007 civic hatch..(i think its 2007) but yea he always gets me on the pull but not at the top end we are completely even...pretty great for a 92.
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Re: compression test is good or bad
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From: Madison, MS., U.S.
Re: compression test is good or bad
230-245 psi sounds awfully high for a stock H23 compression check. I'm pretty sure that the H22 is like 10.5-1 - 11.0-1compression. Somewhere in there, and i don't think you'd see that high of psi numbers on that motor, either. I could be wrong.
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From: Long Point Beach, ontario, canada
Re: compression test is good or bad
Being he's in florida I believe he's at sea level almost. Lower altitude higher compression results.
ie.
http://forums.audiworld.com/showthread.php?p=18934858
ie.
I find myself agreeing with Dave again.
Its the same reason why 1 bar of boost at sea level is different (in psi) than 1 bar of boost at altitude.
atmospheric pressure at sea level = 14.7 psi
9.3:1 compression at sea level = (9.3 * 14.7) =~ 137psi
atmospheric pressure at 5500 ft = 12psi
9.3:1 compression at 5500ft = (9.3 * 12) =~ 111.6 psi
If you want constant numbers you could speak in terms of bar. EG
atmospheric pressure at sea level = 1 bar
Its the same reason why 1 bar of boost at sea level is different (in psi) than 1 bar of boost at altitude.
atmospheric pressure at sea level = 14.7 psi
9.3:1 compression at sea level = (9.3 * 14.7) =~ 137psi
atmospheric pressure at 5500 ft = 12psi
9.3:1 compression at 5500ft = (9.3 * 12) =~ 111.6 psi
If you want constant numbers you could speak in terms of bar. EG
atmospheric pressure at sea level = 1 bar
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From: Cnetreville, FL, QA
Re: compression test is good or bad
Ha sorry guys thats wrong lol im from maryland...ive been wanting to change that. I was wondering if that was wrong because i thought like around 230 was the cut off for pump gas...i could be wrong.
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From: WA
Re: compression test is good or bad
Keep in mind an older engine with high mileage may have carbon build-up on top of the pistons, which can easily cause the compression to increase. Same reason why older cars tend to knock more and requires the use of slightly higher octance fuel (higher than what the manufacture originally recommended).
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From: Further down the spiral, TX, usa
Re: compression test is good or bad
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From: Independence, KS, USA
Re: compression test is good or bad
No they aren't confusing them- it is the same thing. Compression ratio x air pressure = PSI.
230 is pretty high. 240/14.7 = 16:1.
There is pretty much no way that thing will run on pump gas. I would double check with and tester. You should be much closed to 130-140 psi. Definitely below 10:1 = 147 psi unless the engine has been modded.
230 is pretty high. 240/14.7 = 16:1.
There is pretty much no way that thing will run on pump gas. I would double check with and tester. You should be much closed to 130-140 psi. Definitely below 10:1 = 147 psi unless the engine has been modded.
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From: Biloxi, MS, USA
Re: compression test is good or bad
When I did my compression test, I was between 228 and 242 with a JDM h22. I had no issues with mine. OP, I'd definitely run the highest octane pump gas you can with those numbers.
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From: Cnetreville, FL, QA
Re: compression test is good or bad
okay well people are telling me it will be fine and others are saying it wont. i was just going to run 7psi bec i thought that would be fine but then i did the comp test and i was like oh shiiit. ill do the test again on my car and another car and make sure its not fucckup.
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From: Further down the spiral, TX, usa
Re: compression test is good or bad
No they aren't confusing them- it is the same thing. Compression ratio x air pressure = PSI.
230 is pretty high. 240/14.7 = 16:1.
There is pretty much no way that thing will run on pump gas. I would double check with and tester. You should be much closed to 130-140 psi. Definitely below 10:1 = 147 psi unless the engine has been modded.
230 is pretty high. 240/14.7 = 16:1.
There is pretty much no way that thing will run on pump gas. I would double check with and tester. You should be much closed to 130-140 psi. Definitely below 10:1 = 147 psi unless the engine has been modded.
Where did you get 14.7 from? That's stoich air/fuel ratio....
Prelude engines regularly provide compression test numbers in the 200s and have no trouble running normally (as I'm sure many other engines do as well).
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From: Biloxi, MS, USA
Re: compression test is good or bad
14.7 is 1 atm, but I'm not sure if he's using the correction way to find your compression. I'm too lazy to find out, though. My setup is supposed to be 10.6/1 compression. I had compression numbers around 240, and I had a clean block. I think OPs numbers are high but not unreasonable. I just think he needs to do some research to see how other people with similar numbers did with 7-8psi.
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From: Further down the spiral, TX, usa
Re: compression test is good or bad
I am very skeptical about those calculations also, but who knows.Guess we all agree that OP's compression numbers look good.
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