View Full Version : compression VS. leakdown

10-18-2011, 11:50 PM
Have a question about a leakdown test. Say, I did a compression test and got 150 psi. on a cylinder. In a leakdown test, would it also show 150 psi as initial compression, or how do you compare readings?

10-19-2011, 01:26 AM
On a standard road car, you want to have less than 20% difference between the input pressure and the leakdown pressure before it's time for a rebuild. On a race car, I shoot for under 5% but less than 10% is acceptable.

Your compression test readings have nothing to do with a leakdown test.

10-19-2011, 10:11 AM
20%. I'll remember that, thanks. Now that i read a little, it makes sense. An air compressor is on my tomorrow forever list.