Offshoreonly.com - Selecting a manifold for AFR 265's - single versus dual plane

Quote:

Originally Posted by SB (Post 4081146)

I don't get it. Looks like you ported the heads to a standard intake manifold - ie: one with intake to head bolts between each set of runners. Where these bolts are, but your heads don't have them, is a very high flow area. Thus, why most aftmkt heads don't have this bolt hole.

In fact, on intakes that do, you need to tap and plug that holse so it won't be open to the runner.

Anyway, as far as dual planes go, 70% of the power to be gained by these are in the plenum - mostly transition from plenum to runners. Yeh, hard to get to on lower plane. And in the more pronounced curves on the runners. Sometime you have to whole saw these areas open to access this. Kinda overkill for most I/O builds, but atleast most 496+cid engines better utilize a smaller (Vic Jr/ Dart 4150, or etc) single pane intake anyway. Many 540+'s can utilize a 'medium' size single plane like a Victor 454R or etc.

Yes, I did not see the need to open up the runners any larger..... I just wanted a smooth transition from the rectangle port intake to heads as there was a huge mismatch....... Original port volume was 320 cc so they are at least 325/330 now and larger than I need on my 509....... If I ever decide to get a set of CMI's and a bigger cam, I may consider additional porting and go with a victor JR...... But for now, my combo was built to maximize torque with my current cam/ exhaust using the dual plane intake...... TBF