RPM manifold

[MeanMofakee]

jayb, Did they show the same low end torque issue as the RPM on those couple of engines.

[jayb]

I only tested that intake on the 425HP 428CJ, but it did not have the same low speed issues; it started off with 400 ft-lbs right at 2500 RPM.

[CaptCobrajet]

I have used one of those per the customer's request.  It showed me about 40 less hp than the same build with a Ford 2x4 MR.  After that, I never tried it again.  Some of that was the carbs, I feel sure, but my assessment was that it was not on the same planet with a MR 2x4 with two good Holleys.

[jayb]

My guess is that at least half of that difference was the carbs.  Here's a little data from my dyno testing:

427 Sideoiler dyno mule:

Ford MR 2X4 Peak HP - 577.8
Ford MR 2X4 Peak Torque - 526.6

Edelbrock Air Gap 2X4 Peak HP - 566.7
Edelbrock Air Gap 2X4 Peak Torque - 504.2

The Ford intake was run with Holley 660 center squirter carbs, and the Edelbrock manifold was run with Edelbrock 1405 carbs.  For power production I think the Holleys are head and shoulders above the Edelbrocks.  I'll bet that Edelbrock manifold would work just as well as the Ford intake if it was fitted with some decent carbs...

[Joe-JDC]

All I will say about the Edelbrock RPM Air Gap  8V is that it does out flow the MR intake both in unported and after porting condition.  It was possible to balance the runners to within a couple of cfm each.  I personally would like to see a well ported MR vs RPM AG comparison on the same engine at 482 CI or larger.  I think folks would be surprised.  I agree, most folks use the small Edelbrock carbs, and there are two large Edelbrock carbs available that are rated at 750, 850 cfm.  I have not seen anyone compare those carbs to the 660 Holleys.  The ported BT MR was within a few horsepower of the Tunnel Wedge in  your testing.  Personally, I don't think anyone has spent the time to try to get the maximum out of the RPM AG because of the carb spacing.  Until someone does a maximum effort on the intake for testing, it will always get a bad rating.   Joe-JDC

[MeanMofakee]

I was hoping to find an aftermarket 8V intake to use with a dual efi setup. There aren't many options. How much time was spent working on the ed ag to get the flow right. As far as carb spacing, to get the looks of the traditional oval filter could a custom base be made?