Compression test #'s to CR?

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Aug 31, 2002 | 02:40 PM

ShootingStar

Thread Starter

Junior Member

Joined: Aug 2002

Posts: 3

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From: Florida, Bahamas, Caribbean

Compression test #'s to CR?

I just bought a compression tester and got these numbers:
#1 270
#2 265
#3 270
#4 272
This was with a warm engine, WOT & fuel pump disabled. When I bought the car I was told that the CR was 11.1:1 but have had no way to verify it. The motor has about 24k miles and is a B18C1 bottom end from a '96 GS-R with B16A pistons & new OEM rings, a B16A head with CTR cams, Portflow inner & ITR outer springs, OEM head gasket. The question is: Can the ACTUAL compression ratio be calculated from these compression numbers? Anybody got a GUESS?

Sep 1, 2002 | 01:11 AM

dubcac

Joined: Jan 2001

Posts: 56,525

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From: Westside til I die

No it can't. Compression test results tell you the condition of the motor, not compression ratio. You will get higher numbers on the test with a higher compression motor, but there's no way to calculate that.

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Sep 1, 2002 | 11:13 AM

-KangaRod-

Captain

Joined: Jun 2002

Posts: 340

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From: Winnipeg, MB

those numbers look really high though...which is a good thing (I think)

Sep 1, 2002 | 11:18 AM

Luis

Civic1.6VTEC

Joined: Mar 2002

Posts: 1,036

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From: Miami, FL

as long as the numbers aren't more than 20 or 25 apart from each other. the motor is good.

Sep 1, 2002 | 10:11 PM

93si4ws

ChinoRN

Joined: Aug 2002

Posts: 171

Likes: 0

From: philadelphia/camden

how about calculating the CR for a ls/vtec, crvtec, or 2.3vtec? i'm building the last one. 2.3 crank/rods with 2.2 11:1 pistons with .25mm/.010" OS. any help...thanks
v