Compression Test Values - Factory Specifications?
 

Hi Guys,

I just got my car compression tested because I saw white smoke coming out the exhaust once or twice, issue seems to be resolved but I got a compression and leak test anyway.

Compression test came back 193, 197, 208, 198 (PSI)

Leak down returned less than <5% across all cylinders..

Just wondering if anyone knows what are the factory specified compression values?

E.g. New from factory = 210-230 PSI range,
Engine in serviceable condition = ... 170PSI+?

Thanks in advance guys
Rob

Previous engines I have had at 12.3:1 were around 210-215 and that was after 60k Miles. I would expect some issues at sub 200 on an engine with less mileage.

Funny that atmospheric pressure at sea level is ~15 PSI.
CR of 12.5 means 15 X 12.5 = 187.5 PSI.

That should be the highest static pressure you can get unless cranking the engine with the starter gives you a dynamic CR higher than 12.5 (not likely).
:iono:

Or my $15 compression gauge from Autozone is not accurate :(

When I compression tested an s2000 my buddy was buying it came out around 220.

When you compress the air, it heats up, which further increases the pressure even more than just mechanically reducing the volume. The higher the compression ratio, the more heat adding to the pressure.

[Pedantic]Sea level 14.7. And TDC pressure equation is 14.7X(12.5^1.3x).
Although, since throttle bodies are closed and Engine is running at ~200RPM on the starter, it is tough to know the manifold absolute pressure without logging.[/Pedantic]

I also compression tested my engine at Operating temp could also be a factor.

Totally unrelated but i cant pass it up, lol

[ame="http://m.youtube.com/watch?v=yetwdpsiM8Q"]http://m.youtube.com/watch?v=yetwdpsiM8Q[/ame]

Thanks, had a look at the engine manual couldn't find any references to comp test values.. I guess around 200psi is from factory new..

So does anyone know what the values should be, with sources? Or is the 200 psi just from filtering the forum?

Two posts above yours is a link to the FSM.

Is that what the service manual calls for during the test on the twins? When I turned a wrench for a living back in the 1980s, the throttle was always set at wide-open during a compression test.

Not in the FSM, that's basically what Kharn was saying in the post above. He looked thru it already.