Here is a slight variation. The plenum and snorkel are fixed
and the U tubes move in and out. A 3 inch movement of the U
tubes is an over all change in length of six inches. About 15
or 16 inches to 21 or 22 inches overall. A little more thought
needs to be given on how the force is applied to the U tubes
to prevent them from cocking in the bores.
I think Bill Jepson came up with this idea a year or so ago
(May 2003) but we never developed it to this stage. Bill
called it the Trombone intake as I recall. Are you planing to
build one Bill? Here is Bill's 3D as well.
When we get further info on the RV10 I will do a layout for
the three rotor p-port version. It is a bit much to ask to
have six tubes slide in and out rather than only three.
This could be applicable to a 3 rotor street car as it is
almost impossible to do a dynamic chamber 3 rotor engine. I
think that was a factor in the demise of the 3 rotor Cosmo
affecting both low speed torque and BSFC.
Paul Lamar
Paul, I have been considering PP on the 20B due to the much
simpler
plumbing. I agree that the Trombone slide would be almost
impossible on the 6 runner intake. 3 tubes would be much simpler.
The interesting part for the 20B was Francois comments on best
BSFC. Injecting full charge unto the large side port. The ports on
the 20B are set up for this from the factory, I'm not sure which
set are the primary injectors. There is a set of the two per rotor
shooting directly into the larger ports. The 20B is a 6 port (like
a 13B 4 port engine). I plan a full engine check out, (disassembly)
prior to running. Bill Jepson
I realize I'm pointing out the obvious here but the trombone slide
version lengthens the intake tube with half as much movement as the
"moving the plenum" version because you get lengthening on both ends
of the tube. Should be easier to fit inside the cowling and to work
up
a mechanism. Also a mechanism that involves half the movement should
be less prone to cocking in the tubes. Finally, because the trombone
slide part is not exposed to the wind, the mechanism won't have the
lateral force on it and therefore is more likely to work.
My question is whether you'd have this slide mechanism on a manual
control like mixture or cowl flaps (i.e., tweaked by the pilot, with
perhaps three settings: climb, best power, best economy) or whether
you'd try to rig up something that automatically advances it
connected
to throttle position (or more challlenging, rpm).
Barry Gardner
Wheaton, IL
Good points there Barry. I would start out with manual. I get bored on
long cross countries and I need something to do. I can fiddle with
this
and watch the fuel burn.
Paul Lamar
It seems like the slide might be difficult to seal. Vacuum leaks
are annoying.
Regards,
Matt-
That is the beauty of Tracy'w EFI system. Vacuum leaks don't count.
mixture is controlled by intake man pressure, air temp and RPM and
that is it. This means it automatically adjusts for vacuum leaks.
Not to say there are many vacuums in an AC engine at WOT in the first
place :)
Merry Christmas, may Santa bring you all an RX8 :)
Paul Lamar
In Response - Same to all!
George (down under)
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