What should the compression be..?

A

Android

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Hi,
(07 CH Sedan, 4g69, 110,000km)
I replaced the plugs last night - and while I was at it, did a compression test.
Using a new compression tester, they all came in at about 142 PSI (+/-1), and looking at the factory manual it says it should be 1560kPa, and when converted should be 226 PSI.
Either the manual is wrong, the conversion is out, the gauge is wrong, I'm doing it wrong or, I have a serious issue.

Which one is it?



Compression.png
 
I'd assume the tester or book is wrong - an engine with 110k kms shouldnt lose that much compression from factory, and that fact that all cyl are within 0.5% of each other is perfect.
In fact, given that the difference is 1kpa+/-/0.5%for each cyl, thats almost too perfect, and something you'd see on a brand new just broken in engine, leading me to be a little suspicious of the testers accuracy more than anything else.

How does the engine perform? Feeling really sluggish or anything?
 
140 PSI sounds acceptable. Particularly if they are so similar across all 4.

I would double check your gauge - try a wet compression test, the reading should increase.
 
As a note, I probably should have mentioned it has an upgraded cam in it. Which, until now I didn't think should change any of the characteristics.
It appears as though I was wrong.
A reply from RPW,
"A larger camshaft with more duration will reduce the dynamic compression of the engine which would account for your lower values."

So, that in a nutshell explains it.
I'm not sure of the manufacturer of the cam, so I have no specs on it - but as mentioned they are all a very tight tolerance in values.

As for it feeling sluggish, not on your life! With a bit of 'stick', it has lifted the front off the ground taking off.
 
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