[BLACK SUNSHINE]

I currently have an edelbrock performer intake on my 400 and was wondering if there would be any noticable difference in performance if I put an RPM intake on it?
My current engine combo is this:
400ci Y4 block bored .030 over
6X #8 non-ported heads (about 8:1 CR)
Mild cam (believe its the edelbrock performer cam)
600CFM edelbrock carb
3 tube headmand headers

I know the RPM is supposed to produce more power in the upper RPM range but I am wondering if putting on the RPM intake will hurt or help, or will any change be noticable to me?

[Larry Navarro]

No.
For your engine combination the RPM would not be worth using.
Its more in tune with a modified engine.

[grandville455]

For your set up stay with the performer!! if u like try a 1" spacer on it .. but ur combo is very mild wont benefit from the rpm!!!

[BLACK SUNSHINE]

Ive got a polished RPM and was wondering if there would be a negative performance impact if I put it on?

[b-man]

Originally Posted by BLACK SUNSHINE

Ive got a polished RPM and was wondering if there would be a negative performance impact if I put it on?

It won't help your performance, and will likely hurt it. Save it for a more performance-oriented build.

But hey, if you want the polished intake on your engine just for looks then do it. But don't expect a performance improvement.

[givver 1]

I just finished some updates on my 400and I debated between RPM and the performer.I went with the perfomer and glad I did.My carb. was getting hot from the alum. intake so I put on a 1"resin spacer.Carb.is now cool,Engine hauls and I didn't run out of hood clearence.They are also cheeper to buy used than RPM's

[BLACK SUNSHINE]

Yeah, I would like to have the flash of the polished intake but not at the price of performance. With my combo I need all I can get
I went off the advice of someone and shouldnt have without researching it some more. One more lesson learned.
I would put it on if there wasnt a noticable performance hit.
I bought it off ebay used so I didnt pay full price, but close, as it was almost new.
Well if you know of anyone that has a need for a polished like new RPM let me know. Appears I may be selling it
Thanks.

[74Grandville]

why not save it. maybe someday you can pick up some 6X-4's or even smaller chamber heads, change the cam, and there you go, you'll want to have the RPM.

[BLACK SUNSHINE]

Good point. I will see if I could sell it, if not; no big deal then.

[Ron H]

You could shave the heads and mild port them to increase the compression ,go to a flat top piston and with a cam change and 4 pipe headers and a bigger carb the rpm would be needed. Depends on if you want more power from what you have. The tests that Jim hand did show the rpm to perform the same as the stock intake but you have weight savings. The performer and all other aftermarket intakes showed less performance either in MPH or ET.

[JSchmitz]

Black Sunshine, I might be interested in your RPM. Do you have a picture? E-mail me if you want to sell it. jschmitz@charter.net

[uneasyrider]

Originally Posted by Larry Navarro

No.
For your engine combination the RPM would not be worth using.
Its more in tune with a modified engine.

Ditto, the runners are big enough on the RPM manifold that at the rpm your engine puts power out at the RPM manifold wont do a thing until you are at peak power and will hurt performance everywhere else more than likely. The RPM is good for 2,500-6,500rpm and the Performer is about 1,500-5,500rpm if I remember correctly.

[taalltheway]

Jim Hands tests showed, that ONLY the normal Performer did not lose against the stock manifold in a relatively stock engine. The big question is: How high do you want to rev your engine? A stock engine can only take about 5000-5500 rpm. In this area the Performer is the better choice. All "performance"-intakes bring their biggest gains between 4500-7000 rpms. But for that you need better rods, lighter pistons AND a radical cam.

Wich leads to the main point: Do you want a high revving screamer or a low revving locomitive? Since i guess most of us enjoy the low end torque of a classic american V8 i would say the Performer is the better choice for most of us. I bought the Performer because it fits under my shakerhood and i can report that it flows a bit better at higher RPMs (4000 up) than the stock manifold - at least that´s what it felt like.

[slowbird]

Since it isnt hard to change intakes why not try it? It might surprise you and then again it might not but it should only take about 2hrs to change so it isnt that much time lost.

[Cliff Ruggles]

For general interest, we just dyno'd a very "basic" 455 engine prepared here. We used "H" beam rods, Ross pistons, unported #46 heads (1974) with 2.11/1.77 Ferrea valves, Crower RAIV clone cam, 1.65 rockers, Performer intake, 900cfm custom q-jet. The engine made 431hp/520tq. It made over 500tq from 3000rpm's to 4600rpm's, then dropped to 487 at 4700rpm's. Peak hp was made at 4900rpm's.

We've dyno's several near identical engines with iron intakes, RPM's, and the Torker II intakes. They typically make peak HP at 5100-5300rpm and a bit more of it. My very similiar 6X headed 455 made 455.4hp/530tq, the only real difference was the intake (modified iron) and about 10 more cfm of cylinder head flow.

The sharp drop in power at 5000rpm's indicates the heads and intake were a tad restrictive for the big 455 engine. The Performer would fair better on the 400 engine with similiar parts....just my 02.....Cliff

[BLACK SUNSHINE]

I will most likely put the intake on to see if there is any noticable difference.
Does a new manifold require a re-tuning of the engine? I wouldnt want to put the manifold on without a tune if one was required.
I really just want to put the RPM on and see if there is a difference without a tune though.

[goatseeker]

Originally Posted by BLACK SUNSHINE

I will most likely put the intake on to see if there is any noticable difference.
Does a new manifold require a re-tuning of the engine? I wouldnt want to put the manifold on without a tune if one was required.
I really just want to put the RPM on and see if there is a difference without a tune though.

I would say go ahead and strap in on and try it. Try to gasket match if possible. The only basic tuning change you might need would be jets - but doubt you will appreciate any real difference except at the track. JMHO

[Geoff]

You can get a good compromise between the Performer [ or stock cast iron ] & the RPM by using the Performer manifold with a 1", 4 hole spacer. Leave the primary holes intact; with the secondaries, remove the section that connects the two secondary holes, so that you have an oval hole. The isolated primaries retain excellent low end response, while the top end is now improved with the cross connected secondaries.

[BLACK SUNSHINE]

When you say "gasket match" do you mean to make sure the gasket doesnt block off any of the intake openings? If not please explain. This would be my first manifold swap and want to make sure I do it correctly.
Any tips, tricks or watch out fors would be greatly appreciated.
Thanks.

[goatseeker]

Originally Posted by BLACK SUNSHINE

When you say "gasket match" do you mean to make sure the gasket doesnt block off any of the intake openings? If not please explain. This would be my first manifold swap and want to make sure I do it correctly.
Any tips, tricks or watch out fors would be greatly appreciated.
Thanks.

The ports on a brand new intake may not match up perfectly on heads that have been milled previously. Just because the bolts will thread doesn't mean that the ports will line up perfectly when the intake is torqued down. Try to line up the gaskets with the intake & head ports & the bolt holes and make sure the gaskets don't shift around when setting it onto the heads. Otherwise the gasket may protrude slightly into the port opening and cause turbulence. Cutting off the water crossover on intakes allows you to make finer adjustments to port alignment - in addition to making an intake swap easier. I wouldn't cut off the crossover on your new one if you're just planning to try it out though. A seemingly minor point but all the little things are what add up. I have just ordered a new RPM to change out the Performer on my 462 - will see what, if any difference it makes.