What is healthy comp reading for 4g63 ?

[BZY247]

Hey guys,

Did the comp reading on my 4g63 and got 167, 167, 165, 170

On a 6 cyl engine this would be good, not sure what is accepted on these 4g63 engines as an ok ?

 

[EVO-00X]

Which engine VR4 or EVO? is it stock internals? what compression ratio? different engine setups will give you different results.
No matter what the case, 165-170 is perfectly fine and the 3% variation between the lowest to highest reading in the cylinders indicates its still a very healthy engine.
It has a lot of life in it yet so dont worry. Start planning a rebuild when you get a large variation between your lowest and highest cylinders readings.
OEM specs I think say service limit is around 120psi or so from memory but thats a bit exaggerated IMO. Im sure theres been plenty of people over the years still driving around with much less than that lol.

 

[4piknup]

Those numbers look good and good on you for taking the time to do the test. They are like a history, if over a period of time they start moving (up or down) they indicate problems.

But, after the dry test, you should do the wet test with a teaspoon of oil in the cylinder. This will make the rings seal like a new engine and show how much ring wear there is.

Personally, I would just do 2 cylinder wet test (probably the lowest and maybe the highest)

You have shown that the motor is wearing evenly and head gasket is fine.
The wet test should raise the numbers 10% or less as well. So, the 170 can be 190 wet, and the 165 can be a 180. If more it indicates rings are worn out. I am confident yours will not come up that much. Just use whatever clean engine oil you have.

 

[Marc]

Looks good, almost a shame to remove it from its home.....

 

[caged]

Wet test on these are not accurate, the oil pools on the piston on your reading goes up regardless, unless you have a way to keep it out of the piston dish... My 9.0:1 measures up around 196.

 

[Hypo]

I would be rebuilding on those numbers. Not worth the effort to put it in the car and then have the safe boost of 2 bar running only for it to go pop on night one.

 

[caged]

I would be rebuilding on those numbers.

Even without knowing comp ratio and cams??

 

[brisvr4]

For the VR4 engine that you have those numbers are fine. Standard is 164 but you prob have some carbon in there bumping the figure a tiny bit.
Hypo, his comp ratio should only be 7.8:1 hence the lower figures.

 

[BZY247]

Thanks for all your help guys