Witch is better for top speed dual plane or single plane intake manifolds? I have a zz502 502hp and I'm not sure what to put on it.

Single plane .

what he said

Merlin Single plane.

but has anybody actually swaped a performer rpm air gap for a single with no other changes to see the real diff ??

6000 rpm and under the performer rpm air gap will out perform the single plane is for wot all day your lower rpm and idle will be like sh!!ty you want the engine to perform from idle to wot unless you are racing all day @ wot you will be loosing alot of performance every where else I run the performer rpm air gap on my 502 580 hp and I have the put you back in the seat performance all the way to wot.

thats what all the dyno intake shoot outs I've seen said to...just wondering if anybody actually flogged them on boat...now how about the diff from a stock merc alum high rise vs a rpm air gap ?? Rob

Air gap all the way the runners run cooler! The runners are not part of the valley cover they are a little higher and have longer runners than the stock manifold The stock one the runners are the cover for the valley and the runners will run alot hotter.

Hot Rod magazine does a lot of dyno testing and a recent article stated very plainly that an Edelbrock RPM Air-Gap was the best intake they've ever tested for engines smaller than 500ci turning less than 6,500rpm. It gave up only a few hp on the top end vs the single plane but retained the low end like we all know dual planes do.
http://www.carcraft.com/techarticles.../photo_16.html

http://www.carcraft.com/techarticles.../photo_15.html

Your head/cam combo (assuming it is 100% ZZ502 stuff) will be fine with the Air Gap RPM.

Now, for 502's with better heads (AFR/Dart/etc) and cam's utilizing the better heads (say .600" lift or bigger) the Air Gap RPm will step on the airflow the other parts will flow and engine would otherwise get. These will have much better top end with single plane intake like Edelbrock Vic Jr and really not much loss/if any at lower rpms.

Note: The Air Gap RPM's intake bolt holes inbetween the runner pairs will be exposed when the intake is put on must aftermarket aluminum heads since their port roofs are higher that the GM heads and thus the RMP Airgap.