I recently started down the path of something I've been wanting to do for fun, build an engine.
Not sure how to even do a compression test, but I am guessing if I could do one before I tear apart the motor that would be best. The motor came with out a car 
, it is a 1.8L miata motor. Items missing from this motor... no transmission, no fly wheel, no exhaust header and no intake manifold.
Can I do a compression test with out the motor in a car?
You'll need the tranny so you can use the starter to crank the engine.
if you can spin the crank you can do it. big bar or large air wrench...
you could concievably do a leak down test instead, but it would be tough w/o a fly wheel to secure to crank in a position during testing.
btw, a leak down test is when you use air from an air compressor and a pair of gauges connected in serries to fill the cyl (with piston set to tdc compression) with air at a set pressure, and then see how much it actuly holds and for how long. This is a usefull test when you have a compression loss but can't figure out wherre it is going, you can listen and check for whee the air is leaking to because you have a constant supply going into the cyl.
A leak down test would be much easier to do in this case than a compression test and will actually give more information as HA said.
ignorant wrote:if you can spin the crank you can do it. big bar or large air wrench...
I've tried that before, but could never get enough RPM to get a good reading. A leakdown test is more meaningful anyway.
I have done a compression test on a small block chevy on an engine stand, the starter bols to the block on those though.
Thanks for the education guys. I think I'm just going to tear into the engine (as soon as I get an engine stand).
