Custom 16V NA intake manifolds

[ValveFloat]

Why is that?

I'm honestly curious, I don't know much about intake manifold design. This manifold concept looks like a tube version of the Ottengier 16V mani.

I am not going to pretend to know a lot about intake design, but I can't think of a OEM single TB manifold that doesn't have a plenum of some sort. My guess is that the plenum volume is needed to keep the cylinder that is on the intake stroke from pulling air from the runners that have closed intake valves. There is a science to intake manifold design, and the main factors that I am aware of are runner length, runner diameter, and plenum volume. My guess is that that header looking manifold will only make good torque over a very limited RPM range, and will probably not have very good throttle response.
I don't understand why people ditch the OEM manifold unless they are going FI, or looking for really big top end power, at the expense of low end power. The OEM manifold is designed to give a nice torque curve.
That Oettinger manifold does have a plenum of decent volume. I have always wondered though what the advantage of it is over the OEM manifold.

[PoorHouse]

So, on the Ottenger manifold the plenum area is where it is stamped "Ottenger"?

Runner length and diameter I've heard about. My understanding is that they are designed with air velocity and volume in mind. A long narrow track with increase velocity and low end torque, but will hinder maximum volume and higher RPM power.

[ValveFloat]

So, on the Ottenger manifold the plenum area is where it is stamped "Ottenger"?

Oettinger
Yes from there to the throttle body is plenum.

[PoorHouse]

Thanks