Im posting this for a buddy. He recently bought a pullout engine for use in a pre-runner project and asked about how to do a compression check. I am not familiar with blown engines and I have never done a compression check with the engine not installed in the vehicle. Any one have a "how to" for this? What would be considered good readings? Thanks in advance for input.

 

if the case is the engine is blown, check out vt competition engines. you could get a fully built shortblock for around $3000!!

 

Do a cylinder leak down test instead. It will show the mechanical condition of the motor.

 

I think he means that the engine isn't BLOWN kaboom but Blown WOOHOO. In which case he isn't to sure about the cylinder pressure readings. What psi should the cylinders be reading at when cranking over an engine with a supercharger?
as far as checking it without being in the truck, just put it on an engine stand, hook a starter on it and give it a crank.


am i right?

 

He shoulda been more specific then. Still a leak down test will tell more. Compression will be a lesser number for a forced induction engine if it was built right. This is because you should not use forced induction on a higher compression engine. I would worry if the highest and lowest reading were more than 15% apart. Do the leak down on the lowest cylinders first to determine what is bad.