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Quote:

Originally Posted by iceblue

Exactly and optimal flow into them would not be on the side like an SRT-4.
Well designed runner to plenum stack will show great improvements in flow return velocity. So the positing can play a roll. I prefer keeping a dedicated plenum to stage centered input. "Or you could put one of the air spin tornados in your intake ;-)"

Thinking about this last night I realized the possible reason that most throttle bodies are off to one side...If you intend to tune runner length vs. plenum volume, adding a cavity for the throttle body changes the plenum size around the runners directly in front of it. So those runners must be retuned to avoid this effect. With the rotary it's probably not a huge deal since 9 times out of 10 the runners in line with the throttle body are for the primary ports and Mazda has generally not tuned them in the same way as they work on the secondaries.

Quote:

Most OEM cars are that way because of cost benefit. Well the intake pulse tuning will be in the runner design shape wall thickness material used and so on but that’s another discussion, however the plenum just needs to be large enough to hold the amount of volume needed for the return pulse. 4 paragraphs lol and I doubt either of us got anything useful from these two posts :ugh2:

I think you'll find that 90% of aftermarket manifolds don't use a centered throttle body.

Quote:

Originally Posted by Aaron Cake

Yes I see your point, perhaps that is why the OEM setup has a shroud around the P ports in the plenum.

Quote:

Originally Posted by Aaron Cake

I think you'll find that 90% of aftermarket manifolds don't use a centered throttle body.

I think that 90% of the aftermarket comunity is not for fully custom level fabrication styles. They are main stream make things bolt on without modifying areas for fitment or drastic retune. The other 10% is the stuff you never see on a kids car and rarely on the street.