Compression/Leak Down numbers

#1

A car I am looking at has a relatively fresh engine and the compression/leak down numbers are as follows…

#1 162/1%
#2 145/4%
#3 149/7%
#4 153/8%
#5 148/5%
#6 155/1%

Are these numbers good, bad, or acceptable?

#2

On the surface, your numbers seem good on both counts. Factory compression is 149 and you don’t want significant variation between cylinders. On leakdown you’re looking ideally for less than 10% across the board. By chance did you run leakdown hot and cold to see the difference? If your numbers are cold, my take is that you’re fine. I’ll do the same on my 210K+ engine this weekend and will post my results as well.

For reference, here’s a good article on testing the engine including an altitude factoring chart for leakdown. That may explain why your compression #s are higher than factory.

http://www.pelicanparts.com/bmw/techarticles/Borrowed/mult_engine_rebuild-1.htm

#3

The test was done with a cold engine, and pretty close to sea level. The chassis has around 167k miles on it, but the engine was swapped out because of a blown headgasket and there was a 60k mile junked donor car with a good motor. New timing belt, water pump, valve adjustment, motor mounts and then dropped into this car.

#4

Greg, the numbers look good. Buy it, take it to the dyno and start a log of reference that attempts to correlate the static test to the dynamic test of a dyno.

Regards, Robert Patton