dual plane manifold plenum notch

[Pete Munroe]

All,

About to install the Stealth dual plane intake manifold on my 347" engine rebuild.

Considering modifying the dual plane by adding a notch to the plenum wall like Performer RPM Air-Gap. About 4 inches long, ~ 1/2 inch deep.

Supposedly this will let the manifold behave a little more like a single plane at high RPM, but still retain a good amount of torque at lower RPM.

Not sure with my build mild build it is worth the trouble.

new CompCams 284RF retro-roller...224/224, 0.533/0.533, straight up
with 1.7 rockers.
TrickFlow heads, 2.02/1.90 with 170 cc runners.
headers 1-1/2 inch ID
compression static 10.7/1
carb currently a 750DP
rear end 3:55 with Tremec 3:27 first

Old cam had less intake duration @117 more exhaust @226. Would pull pretty well to 6500 in fourth.

Anything to be gained by notching the intake manifold plenum at this performance level? Goal is to shift the power band up a little.


The Edelbrock Air-Gap with plenum notch is now quite popular, and actual hp/torque numbers notched vs normal separated plenum would be interesting.
(odd that the Edelbrock add copy mentions the obvious air-gap and I think totally neglects to mention the plenum notch)

Pete