Compression testing

4.6_crossbolt · Post by **4.6_crossbolt** » Sun Dec 22, 2013 12:32 pm

While hunting for the cause of a non-firing cylinder on my Scimitar's Rover V8 (prefix 11A - cr 9.35:1), I did a set of dry compression tests - the results of all eight were between 140-150 psi.

Is that figure reasonable? I know a difference of about 10 psi is nothing to worry about, but I was curious as to what figure I should expect.

Incidentally, the non-firing turned out to be a sooted-up plug which occurred during setting up a four SU installation on a Boxer manifold - a somewhat tedious and complex procedure.

SimpleSimon · Post by **SimpleSimon** » Sun Dec 22, 2013 1:07 pm

They are similar to what I got with a serp 3.9 with the same CR with a spikey cam I backed this up with a leak down test which gave very good results for a high mileage RV8

ChrisJC · Post by **ChrisJC** » Sun Dec 22, 2013 5:25 pm

I tend to concern myself with all readings being similar, rather than what the readings actually are.

Chris.

4.6_crossbolt · Post by **4.6_crossbolt** » Sun Dec 22, 2013 6:30 pm

Thanks for the information - I have no idea of the engine's history, so can only guess at the mileage, but I imagine it's fairly high. The results seem reasonably encouraging that I'm not facing a rebuild just yet.

SimpleSimon · Post by **SimpleSimon** » Sun Dec 22, 2013 7:00 pm

ChrisJC wrote:I tend to concern myself with all readings being similar, rather than what the readings actually are.

Chris.

+1