23-07-20, 01:39 PM
(23-07-20, 01:09 PM)red98 link Wrote: going back to my "stuttering thread" a while after lapping the valves and doing a compression test (135 psi ) i had it on the dyno, 1 or 2 bhp down on claimed power when new...makes me question Haynes figures...Just a thought of mine. If you are using a screw in tester with an adapter between the compression tester (where the non-return valve is) and the plug hole, then the extra volume of air space in the adapter effectively lowers the compression ratio and thus the gauge shows a lower reading. I can't remember how much it was with the adapter I was using but it was significant.
If you felt so inclined you could do the calculation using Boyle's Law of P1 x V1 = P2 x V2 to see the theoretical difference between with and without the adapter. Unusually for me I didn't record the figures when I did the test but I remember the calculation put my mind at rest.