All this discussion aroused my curiosity about my TR4 race engine, so
I checked it out this afternoon.
Total Seal rings, micro honed bore, o-ringed liners, three angle
valve job, compression ratio 11.3:1, three race weekends on the engine.
I ran all these tests on two cylinders because I got tired of
screwing things in and out of spark plug holes.
Cyl #1 - Compression 190 dry, 220 wet, leakdown 5% dry, 5% wet
Cyl #4 - Compression 190 dry, 215 wet, leakdown 4% dry, 4% wet.
I'd never try this on my street TR6 because it runs great and I don't
want to know anything else.
The differences are tiny, but it might be interesting to try to
diagnose the little bit of leakage there is. To me, all this says
that cyl #4 is tighter than cyl #1, and the little bit of leakage
there is appears to be at the rings. Maybe. Or just maybe the
indexing of the camshaft lobes by the cam grinder is just a little
bit different for #1 and #4, because overlap also influences the
compression gauge reading, right? Unless somebody has a correct idea
instead of this one.
I'm going to watch this race-by-race to see what the rate of
deterioration is and where, just to satisfy my curiosity.
I guess I won't tear it down just yet.
uncle jack
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