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Message
It would be interesting
to know what the MAP reading is near the intake port in a setup like
Tracy’s.
Hi Al, I would love to
see someone like Ed or Tracy give a MAP reading for the plenum, and also the
runner near the port. My thought was that their MAP would be low,
like mine near the port. Unfortunately, if Bill and Bernie can get near
Sea Level MAP readings measured in their runners, then mine must
be restrictive.
Whether the MAP reading at the TWM ports
is accurate or not, I don’t know.
I'm thinking of drilling
and tapping a port in the current intake, near the port, just to see if it
reads near the same as the TWM port. I have to bet that it will,
since there's no reason the TWM port should be
wrong.
My 44mm diameter barrels (1 per rotor) may
be a bit smaller than I’d like; but I don’t think they are causing a significant
performance penalty. The MAP reading is, of course, not the full measure
of the charge into the chamber. There are the pulses and momentum
(velocity) to consider.
I agree, but with only
40mm barrels, and my desire to run 7500+ rpm, I think I'm going to have to
upgrade. I may find out that I get a better MAP reading,
but no more power, due to losing the velocity, but I have to find
out.
It might be good to
have the TB barrel x-section area roughly matched to the port area. I
can’t find my calcs now, but I think the combined primary and secondary ports on
my engine is over 3 sq. in., like maybe 3.5; and the TB barrel is 2.34 sq.
in. So maybe a 20% larger diameter would give better high end performance,
at some expense to throttle response.
You've got to be way below the port
size with a 20B for sure. Even my 4-port primary and secondary adds
up to 1.77 sq in, which equates to a 45mm barrel.
I am anxiously awaiting
your definitive data on performance vs TB barrel diameter. J
Yeah, I bet you are. About the only thing
I've proven definitively, is that you shouldn't use an evap core for an oil
cooler :-)
Cheers,
Rusty (providing my part of the education
and entertainment)
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