Sure my manifold will work and that throttle body will work.
My guess is you will get about 175 to 185 at 6300 RPM depending on the
prop.
You will need to fab a sheet metal plenum on the other end
of the manifold. Make it strong as suddenly closing the throttle will
apply about 15 psi to the outside of the plenum. Weld up a rectangular
box just big enough to take the TB on
one end. My guess is about 7 x 3 x 10 inches out of .093 thick
6061 T6. You can rivet it up with angle and plate if you seal
it well. Here are shots of what Chuck Dunlap is using.
If you sell the TWM TB you can make it smaller 3 x 3 x 10
and use a simple butterfly as you don't need the TWM throttle
position sensor if you are using Tracy's EFI.
BTW Hi Chuck. It never occurred to me until recently and I did not
put two and two together until just now.
You are using a dynamic chamber hidden in the plenum correct? If so I
think your runners are twice as long as they should be. IMHO a dynamic
chamber doubles the effective runner length. I have
been real slow in realizing this. It has been festering in my
subconscious for the last four or five years. Mazda was never
very clear in their tech papers just exactly how the dynamic
chamber really worked and I think I finally have it figured out.
They are tuned at two RPM's. The fundamental length and double the
fundamental length. We don't need double the fundamental length. That is
for cars that need the torque down low. IMHO the fundamental (short)
length tuning is compromised for the
double length tuning.
The weird takeoff RPM characteristics of your engine gave me a bit of a
clue. Sad that I did not put all this together three or
four years ago. Won't take much work to convert it to a simple plenum
and tuned runners with your monster TB :-) Make sure you have bell
mouths on the ends of the runners as they are worth 5% HP. IMHO you will
gain HP at 6000 RPM.
Paul Lamar
I have not experienced the weird takeoff RPM with the new engine. It
may have been from the toasted rotor in the old engine.
I started out with nothing inside the plenum except some small bell
mouths turned from blocks of nylon attached at the end of the runners
inside the plenum. At one time I bolted in an assembly made from the
elbows tied together as shown in this photo. I was trying to emulate
Tracy's dynamic chamber. They produced slightly less power so I took
them back out and put the bell mouths back in.
BTW I am taking a trip to Olympia, WA this weekend, about 9 hours each
way. Will report on anything unusual.
Chuck
You are way ahead of me. Taking them out resulting in more power
confirms my suspicions.
Paul Lamar
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