How much HP will a RPM Airgap support

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How much HP will a RPM Airgap support

Postby Prostreetbike » Sun Sep 03, 2017 5:22 pm

Hey guys, I have seen builders advertise that they made 530 to 550HP with engines that have a RPM Air gap intakes on them. Do you think they did port and plenum work to the intake to get that kind of power ? or could you get there with an out of the box intake ?
Just wondering because I had seen a stock air gap flowed by a shop and they advertised it to flow about 210 cfm out of the box. I do not know how accurate that number is but if you put an intake on an head that flows 270 cfm isn't that going to kill some HP at the 550 HP level ? I understand that an engine is only going to use what it needs but Can you even make 550 hp with 210 cfm of flow with SBC or is there something more to the dual plane design than just the cfm flow ?

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Re: How much HP will a RPM Airgap support

Postby bigjoe1 » Sun Sep 03, 2017 6:08 pm

I have made 615 HP with an RPM Air Gap, But I had a much better AFR head ( 310 CFM ) on a 383 engine





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Re: How much HP will a RPM Airgap support

Postby Erland Cox » Sun Sep 03, 2017 6:23 pm

What did you do with that manifold Joe?
It is hard to believe that is was box stock.

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Re: How much HP will a RPM Airgap support

Postby bigjoe1 » Sun Sep 03, 2017 6:56 pm

I do a very light clean up and port match- and I play with carb spacers- I also like BIG carbs ( CFM )





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Re: How much HP will a RPM Airgap support

Postby Erland Cox » Sun Sep 03, 2017 6:59 pm

Amazing that the port area didn´t strangle the engine more.
What would that engine have given with a single plane with proper port size?

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Re: How much HP will a RPM Airgap support

Postby bigjoe1 » Sun Sep 03, 2017 8:14 pm

A reworked super victor is about 20 HP better at 7000 RPM





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Re: How much HP will a RPM Airgap support

Postby F-BIRD'88 » Sun Sep 03, 2017 8:30 pm

On that same very capable 615 HP 383 what is the power potential of a 2x4 RPM air gap Dual Quad intake on it?
Will it make a bit more power than the single RPM intake? Will it match the Super VIC.?

Does it respond to a bit of "cleanup" too.? Spacers?

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Re: How much HP will a RPM Airgap support

Postby bigjoe1 » Sun Sep 03, 2017 9:01 pm

I have done several dual quads setups, and with fine tuning, they can be about as good as a super victor. I always run 750 carbs, not the little 500 Edelbrock wants you to run. The out of the box jetting is very close with them too.




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Re: How much HP will a RPM Airgap support

Postby Prostreetbike » Sun Sep 03, 2017 10:04 pm

Hey Joe, thanks for your reply. Have you ever compared one of your cleaned up RPM air gaps to the AFR Titon DPR dual plane intake? or even just an out of the box RPM air gap at the 550 to 600 HP level ? Wondering if the AFR DPR has bigger as molded runners than the RPM for use with 406, 415, or 421 size SBC ? Have you tried on out yet ?

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Re: How much HP will a RPM Airgap support

Postby bigjoe1 » Sun Sep 03, 2017 11:14 pm

YES--- I have tested the AFR plastic manifolds. On my Son,s 434 drag race engine, The AFR plastic manifold with the Dominator top, was almost exactly the same as a fully ported Super Victor- It made 833 HP with one 1100 CFM Demon - but we were getting 890 HP with two 850 Demon carbs on a reworked Edelbrock Victor Ram ( tunnel ram ) The AFR single carb ( 4150 type ) is just as good as a fully ported Super victor on a 700 HP 434. They seemed to be very good for the money if you were going to have your regular manifold ported. - I have not used one on a street engine ( 550 HP) They do not need it. I have heard that some people have problems with cracking the plastic manifold.




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Re: How much HP will a RPM Airgap support

Postby mag2555 » Mon Sep 04, 2017 5:34 am

That shop with there 210 cfm claim are blowing smoke up your Butt!

The stock bottom of the heap Edelbrock Perfromer flows way more then 210 cfm@28"!

If that Manifolds port area at the flange says basically constant up to the Plenum then there is no way it could not flow atleast 250 cfm@28", and 250 cfm can make you a tad over 500 hp!

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Re: How much HP will a RPM Airgap support

Postby mtrhead » Mon Sep 04, 2017 10:50 am

I didn't dyno my combo but I ported my AirGap to 1206 size to match my 210 Speier Profilers. Runs good on my 410" with Jones Cam. You can only get up so far into the AirGap intake runners. It did run better ported!

I just bought at Weiand 8016 to port and try.

I wish someone would make a new dual plane designed for today's sbc heads that have 1206 intake entrances and 195-230cc's

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Re: How much HP will a RPM Airgap support

Postby Erland Cox » Mon Sep 04, 2017 11:00 am

Joe, how does the power curves compare between the performer RPM and Super Victor manifolds?
Does the RPM gain in the bottom what it looses on top?

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Re: How much HP will a RPM Airgap support

Postby bigjoe1 » Mon Sep 04, 2017 11:20 am

Pretty much so--- RPM is 20 better say down at 4000, both are the same at about 5800, then the Super vic is 20 better at 7000- - at 7500, it is even better- like 35 over the RPM





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Re: How much HP will a RPM Airgap support

Postby Erland Cox » Mon Sep 04, 2017 11:26 am

OK, thank you.
I would never had believed that a dual plane could be so close to a single plane manifold in such an high hp application.
We have made almost 700 hp on a big block with the stock aluminium dual plane.
But only on the forst pull.
Power drops up to 50 hp because of heat soking at the second pull and then stays the same.
Despite a valley tray to keep hot oil off the bottom of the manifold

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