[glenn911]

Like the title says. I have read SO much info on the stock iron vs everything. I want a performer RPM but everyone says it will not fit under a standard 2nd gen fbody hood. I read that the stock iron will flow damn near as good. But what about the standard performer intake? I have one now, it is worth swapping it for the earlier factory intake? This is a 6x-4 head 400 now with Q jet. Will be stroking it in the future.

[Steve C.]

If interested...

Drop Base Shaker Hood Assembly for use with Edelbrock RPM Intake for Trans Am to Locate Shaker Hood Scoop back to Stock Height

http://www.jbp-pontiac.com/products/...s/dropBase.htm


.

[glenn911]

I am running the standard firebird hood.

[grandville455]

Stay with the stock intake, make sure ports line up well by removing water cross over. If this isn't a high power thing don't worry about changing intakes til down the road.

[PunchT37]

The Performer will work fine with the lo po 350 or 400. Little to be gained trying to find an early stock intake. The stock will flow better though. It`s also heavy vs. the Performer. Higher perf.? Larger cubes? Then, the Performer will choke the engine vs. stock, or the RPM or single plane manifolds.

[Cliff R]

The Performer intake will cost you close to 15 HP on a 455 making right at 1hp/cid.

I don't know where the "crossover" point would be with one, but I'll bet it's close to a stock intake on any 350 or 400 build to at least 1hp/cid.

A stock Performer would NOT support my last 455 engine at 514hp/587tq. That engine absolutely HATED it. Installed one on two different occasions to test it, and both times the engine stumbled, hesitated, bogged and wouldn't pull well past about 4500rpms. Re-installing the stock or RPM intake with no other changes and the engine would tear your head off from idle to at least 5800rpm's.

The stock intake with the plenum opened up is good to at least 500hp. We actually made 7 MORE hp than an RPM on back to back dyno testing on a 428 engine.

If I had to guess, I'd say a stone stock iron intake is just as good as the RPM to about 500hp. It will fair a tad better if port matched and plenum opened up to about the same size/shape as the RPM. On big CID engines even a modified stock intake will start to take a back seat to the RPM by 550hp, per the testing Dave at SD did with them a few years back.....Cliff

[PONTIAC DUDE]

Originally Posted by Cliff R

The Performer intake will cost you close to 15 HP on a 455 making right at 1hp/cid.

I don't know where the "crossover" point would be with one, but I'll bet it's close to a stock intake on any 350 or 400 build to at least 1hp/cid.

A stock Performer would NOT support my last 455 engine at 514hp/587tq. That engine absolutely HATED it. Installed one on two different occasions to test it, and both times the engine stumbled, hesitated, bogged and wouldn't pull well past about 4500rpms. Re-installing the stock or RPM intake with no other changes and the engine would tear your head off from idle to at least 5800rpm's.

The stock intake with the plenum opened up is good to at least 500hp. We actually made 7 MORE hp than an RPM on back to back dyno testing on a 428 engine.

If I had to guess, I'd say a stone stock iron intake is just as good as the RPM to about 500hp. It will fair a tad better if port matched and plenum opened up to about the same size/shape as the RPM. On big CID engines even a modified stock intake will start to take a back seat to the RPM by 550hp, per the testing Dave at SD did with them a few years back.....Cliff

X 2 on the performer not keeping up with the earlier iron intake. Ported it can then keep up.

[glenn911]

Anyone offering port work on the performer? I know I saw somewhere that someone was offering ported Early iron intakes.

Another update.....I run a 3" tall AC and have another 1" from top of AC to bottom of hood.....The RPM is 7/8" taller than a performer so it should fit....eh? Even if I had to run a 2" element...............

[b-man]

The RPM is 1.25" taller than a stock intake or a Performer, so be sure to check your measurements.

[Half-Inch Stud]

Originally Posted by grandville455

Stay with the stock intake, make sure ports line up well by removing water cross over. If this isn't a high power thing don't worry about changing intakes til down the road.

Such fine advice. LIKE

[67GTO4SPEED]

Originally Posted by glenn911

Like the title says. I have read SO much info on the stock iron vs everything. I want a performer RPM but everyone says it will not fit under a standard 2nd gen fbody hood. I read that the stock iron will flow damn near as good. But what about the standard performer intake? I have one now, it is worth swapping it for the earlier factory intake? This is a 6x-4 head 400 now with Q jet. Will be stroking it in the future.

This pic is a side by side comparision of the stock iron vs a Performer (that has has the numbers ground off and painted blue to appear stock). You can tell by the runner shape and design why the iron flows better.

Judging by the actually size of the runners, it does appear that there is a lot of material there to correct the problem.

[grandville455]

lets here what your whole combo is , car. motor, trans, gear etc ,and go from there, Just cause the RPM is taller doesn't mean squat if u don't need it, u will end up with a slower car and less money unless u can utilize it.

[glenn911]

1.25" taller....yea that could be a problem under a standard firebird hood. My current combo is a '79 espirit, 400 (1970 block), 4spd, 3.73, 6x-4 heads, logs, old 280 mag comp cam, performer. Near changes will be tri y headers, and a cam swap to a modern XE 268 grind. Far changes (2015) Butler balanced stroker kit, alum D ports, and a roller cam. Car runs mid 14's. Would like low 13's eventually.

[Overkillphil]

With good tuning your existing combo (maybe sans the logs for the headers) should be easily into the 13's. With your future changes in mind, the target should be much faster.

[glenn911]

Yea, I got a real soft low end due to the cam, poor vacume, etc. I have to leave the line with the rpms up to prevent bog, then I have to deal with lack of traction. Hoping that for this motor that a change to a modern cam designed to work with low compression will bring give me a smoother idle, more vac, and more off idle power.

[Lee]

In the early 90's, I had a fully-loaded daily-driver '79 T/A, originally a 301 car. It had a LOW-$ 455, unported 6X heads, fairly small cam (ran best when shifted at 4600rpm), Brad Urban Q-jet, 2.73 gears, a nearly stock torque converter, and a non-EGR iron intake. I raced most Wednesday nights, and had a BUNCH of runs with it, with a best of 13.27.

I later swapped to a Performer intake. Both intakes were TOTALLY stock. The best it ever ran with the Performer was 13.33.

[unruhjonny]

great thread!!

My brother* seems to have been bent on wanting to run a Performer intake with one of the strongest areguments "for", was the weight savings;
I have tried to tell him not to, but maybe this will make him reconsider.

- I've forwarded a link to this thread to him. Thanks!!

(* = to whom I recently gave back the '73 Formula to; it was his first car)

[A.W.Dille]

I can verify the performance of the iron vs. the Performer. In my GTO, 71 GTO, 400 (stock) with unported 670 heads, HEI Lunati BMII cam, 800 spreadbore Holley with a 4 speed and 3.55's on slicks. Best with the Performer in the 1/8th was an 8.72 with 60ft's in the 2.11 range. Iron intake, 60ft 1.806, e.t of an 8.46. The Performer will not keep up on my higher compression 400, may work fine on a 350 but the iron will outshine the others in my opinion.

[Tim Corcoran]

Another option would be the Tomahawk intake. It would fit under all stock hoods, is a great performing manifold and flows enough air to support 455+ cubes.

[phil400]

Is it possible to modify the runners of the performer to perform as well as the cast iron intake?