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Lynn,
I was all over the shop before, but now I think
I've got it all sorted. I was trying to see the differences the PP gave in
overlap and open ( intake) time.
I was confusing myself yet again, until I realised
I was looking at the degrees of crank, when I should have been looking at
the degrees of the rotor.
With IO @ 32 degrees ATDC
and IC @ 40 degrees ABDC (12A engine)
or IC @ 310 degrees ATDC = 278 degrees/3 = 93
degrees of the rotor
I did the same for Exhaust = 415 degrees/3 =131
degrees.
Overlap ( standard) =25 degrees/3 = 8
degrees.
Overlap PP = 144 degrees/3 = 48
degrees.
PP inlet = 430/3 =143 degrees.
Inlet time with the PP is an additional 50 degrees
(very good) but with a penalty of 40 extra degrees of overlap (bad) but only bad
at low RPM's.
Interestingly the overlap is 6 times the original -
this all varies accordingly with the different models.
While doing this exercise it is interesting to see
the RX8 port and why it's placed where it is to eliminate overlap. While it
might be nice to have say 180 degree of rotor ( or more) for complete burn of
the fuel, realistically the power derived from this exercise would be marginal
at best. The power from combustion would (I believe) be totally converted to
mechanical power ( to the rotor) by the time it reaches the existing
exhaust opening.
George ( down under)
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