what I'm trying to do is figure out how to set up my racing beat intake without the intake tubes going over the top. the (bearded one) says it will work but is only for engines in the 10,000 RPM range and it's not good for 6500 -7000. does anyone. have any other suggestions. I will use four injectors but what I want to do is keep the profile as low as possible.

 

Tony;

 

What works and what is optimum are two different things.  And what is optimum depends on what your criteria are. You'll not know what is optimum without putting it on a dyno and trying a lot of different things.

 

My first impression looking at that intake is that it appears rather massive.  That's OK for a road vehicle, but not 'optimum' for an airplane.

 

Lynn says: Short systems tend to have very well defined RPM peaks where long systems tend to null out well defined peaks, and are thus a bit easier to tune.

 

I won’t argue with that, yet I have a short manifold (see photo) and the torque curve, measured on the dyno, that varies only 10% from 2500 rpm to 7000 rpm, and is very constant (varies only about 2%) from 4800 to 7000.  When torque is flat, hp is going linear upward with rpm.  Nothing wrong with that. 

 

My conclusion is that if I used a longer ‘tuned’ induction, I could get a bit more power over a particular range near the tuned point.  But for me, optimum also meant a compact installation, and light weight.  My manifold for a three rotor weighs 2 ½ lbs, the installation fits well, and power is good.  I suppose that one can argue that although the manifold is short (4.5” flange to flange), the TB barrels add anther 5.5” and the fiberglass air plenum maybe adds some more.  Maybe it just involves some luck.

 

Al