Author Topic: Dual-plane intake manifold divider plate  (Read 5304 times)

Offline RLEBird

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Dual-plane intake manifold divider plate
« on: February 25, 2009, 04:28:35 PM »
What are your thoughts on notching the secondary divider on a Performer RPM manifold that's using a Q-Jet?  I know Jim Hand discusses the benefits in his book, and Crosswind manifolds actually come that way.  Also, I have a 1" spreadbore spacer, which I'm considering removing the material between the secondary openings.  What do you think would work best for the street?

Offline Cliff Ruggles

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Re: Dual-plane intake manifold divider plate
« Reply #1 on: February 26, 2009, 08:22:52 AM »
Use extreme cautioun with any modifications to the divider.  We have recorded some significant LOSSES in power taking out the divider or even modifying them.  A small notch or divit between the secondary throttle plates is fine, or use an open gasket.

The effectiveness of a spacer can only be measured with dyno and/or track testing.  I've done a lot of this here, and the only spacer I've tested which showed some improvments at the track was a semi-open spacer.

4 hole, fully open, and fully divider spacers ran SLOWER at the track on my 455 than no spacer at all.

The semi-open spacer still ran .02 seconds slower, but almost 2mph faster......Cliff