Performer RPM or Airgap manifold
 

I have a perfectly good Performer RPM manifold on my Gen V 502. Would I see any gains by going to an AirGap or something else? I want to stick with a dual plane for driveabilty and idle quality. Just wondering if I will get $250 worth of improvement or should I save my money and just buy gas. I am changing the cam anyway so now would be the time to do the manifold.

Thanks, Doug

Depending on your HP and weight you are probally looking a 5-10hp. IF your close to stock and your manifolds are in good shape use the money elsewhere...The RPM Air Gap is a great manifold though...

BH

Hey Macdad, long time no see! Give me a call and let me know when you're going to be in Zeeland. I'll buy lunch and we'll talk boat big-blocks. 616-403-3962 is my cel.

Doug I doubt you will see any differance unless you spin the crap out of it....5700+++

But it'll sound really cool spinning that fast.

No. "Performer RPM AirGap" is just an updated "Performer RPM" with incrementally better runner design (not significant enough to warrant replacing) and a designed-in hollow underneath the plenum to isolate the runners from the heat transferred from the engine oil splashing from the cam and lifters onto it (which is noteworthy, but a valley splash guard will give much of the same benefit).

If I were buying new, of course I would pay the $60 premium for the newer airgap, but if I already had a P-Rpm, I would block off the heat crossover and stick a splash guard in it ($25 total in parts to do both) and rock on.

Mac, you already have a pretty good manifold, so no I don't think you'll have $250 in improvement.

Thanks for the replies guys. I think the consensus is to stick with the RPM. My motor already has the valley splash guard so I should be OK there. I kinda wondered if there really was much difference other than the "airgap" under the plenum. I have one of the Comp Extreme Energy cams with 224/230 duration that Dennis Moore is always talking about that I bought a few years ago when I was thinking of hopping up the old 7.4L. I have to pull the engine anyway this winter to install a bigger oil cooler so while it is out I am going to change the cam, too. I need about 1.5 to 2 more mph out of the old Baja to hit 65. With any luck the cam will get me a couple of hundred more RPM. :rolleyes:

See ya, Doug

MACDAD260, is the cam you are talking about the Comp Cams Grind# CB XE268H-10? if so I am trying one in one of my engines also.....just wondering about any reversion issues.....what exhaust are you running?.....Fred

I also am running the air gap intakes but as others said the change wouldn't be noticed especially for the $ it will cost to make the change....Fred