Can someone tell me what psi ranges indicate acceptable compression on a 13B-rew when the engine is COLD?
The Hayes manual for the second gen says 85 is the minimum, but that is with a fully warmed up engine....

Any help is appreciated!
Best,
John

 

One test I know of where cold/hot tests were done almost back to back (within a week) showed the cold test resulted in numbers almost exactly 1.0kg/cm^2 or 15psi higher than the hot test. So, using that as a basis, if the manual says 85psi is the minimum hot, then 100psi is the minimum cold.

 

rp

 

That's interesting. I always thought it would be the other way around... hmmmm.
Best,
John

 

The numbers are usually higher when the engine is warm.

 

Where did you hear this? Mazdatrix told me the opposite (which seems to concur with that one case), but thats all I have. The only other piece of imperical evidence I have is that when compression starts to get critically low, cars tend to develop "hot start" problems before cold start problems (see factory manual in the troubleshooting section). I'm also not sure if this applies only to low compression turbo motors or to n/a motors as well. Ideas anyone?

 

I always heard better when warm too because everything expands and seals up. Interesting.

 

Those are some of my observations using my rotary engine compression tester...

Brian