Big Ports and Little Motors

[roverman]

Offenhauser, as of late, has not been noted as "leading edge", in intake manifold designs, but I think, they were on something, or on to something, with the "Dual Port". Yes it was too low, except for engine swaps and the port divider needed to be rotated 90 deg. Think about that for a moment ? When you finally get a 2 valve head that will make "bucu" power, it's worthless for street use. You-know, that "under the curve", thing. The late, Chet Herbert, hemi head was reportedly flowing 550 cfm/28". Chet would say ,you would get your power spread ,with the right intake man. design,(cam not withstanding).That in mind, I think the divorced runner has potential, especially with port or direct injection.We're not talkin single plane, 4bbl here. As we know, cfm. works in concert with velocity and velocity aids drivability.I'm thinkin, that Stg.II Buick head, at 300 cfm. on the int. side, might benefit from velocity enhancement ? Your thoughts ? roverman.

[castlesid]

Art,

With late technology 4 valve engines it is not uncommon to have split runners to the 2 inlet valves the second controlled by an additional butterfly nwhich probably opens progressively above 3-3500 RPM thereby enhancing the torque characteristics of the engine.

Clearly this is not so relevant for an engine with only 1 inlet valve per cylinder, the offy JWR manifold does enhance torque but on the other hand does not flow paticularly well at higher RPM.

Kevin.

[roverman]

Kevin, I think the Dual Port was designed primarily for stock/mild engines. There was a problem of ,"dry port stumble", as secondary port was without fuel and started at zero velocity. Heads just didn't flow much either. My point is, vertically divided, Large inlet runners,such as for stage II V6 race head should benefit, with a broadened power range. Any 32 valve V8's using a controlled, second valve, runner system ?  roverman.

[castlesid]

Art,

Easier to respond here to your PM re the lotus bits.

Heres a company that does parts.

http://www.lotusbits.com/

Kevin.