Daemorok

Does anyone know how much taller the permer RPM is vs the perfromer ?

I am getting a cam put in next weekened, and I am debating wether or not to put a performer RPM on, the engine has a performer on it already, but im sure i can sell it.

Sitting Bull

Read through the next posting.

RB83L69

All those dimensions are on Edelbrock's web site, along with instructions on how to measure them.

Most of these cars will not tolerate a RPM under the stock hood, esp. Birds. And even some of the various Camaro versions of taller hoods sometimes have to use "drop-base" air cleaners, which defeats the purpose of a more open intake anyway: if you imagine the air cleaner lid remaining in a constant location (up against the bottom of the hood) and mentally put a taller intake under it, what happens? The carb moves up along with the intake, and the air horn gets closer to the air cleaner lid, of course. It doesn't matter what you do to the base, the lid is still too close to the top of the carb. Basically you just move the restriction from immediately underneath the carb, to immediately above it. About 90% of the people with big intakes and "drop-base" air cleaners are kidding themselves.

I have the plastic hood.... very lightweight, but it might be the lowest one of all the Camaro hoods though... I am hosed when it comes to intakes.

Daemorok

Hmm, crap

Well right now i have the performer, and a plastic spacer on the carb so the air cleaner will fit, i still have about 1" or maybe 1.5" of clearance between the top of the air cleaner and the hood, ill have to check the measurements

thanks

Daemorok

This is the intake i have right now, and I think I have at least an inch of clearance left.

performer- A:3.50" B:4.60"

This is how edlebrock says to measure the intake clearance
http://www.edelbrock.com/automotive/index.html

I was looking at these 2 intakes neither of which is even an inch taller at the highest point

performer RPM- A:4.00" B:5.30"
difference from performer- A:0.5" B:0.7"

performer RPM Air Gap- A:4.20" B:5.25"
difference from performer- A:0.7" B:0.65"

I have to measure my clearance when i get home, maybe ill get lucky.

jasonbennett

The part about the drop base air cleaner is crap. Chevy High Performance just did a test on that very subject. The 7/8'' drop base with the 2 1/4'' filter outflowed and put out more horse than a non-drop base by 10 horse. All you need before you start restricting a carb is 3/8'' on the highest point. I swapped my flat base air cleaner for a drop-base and picked up more horse in the process, and I still have 1'' before I get into restrictions. I'm not meaning to flame, but it's not all true about drop-base air cleaners restricting airflow.

SSC

Ah No!

The drop base air cleaner will limit the air intake quite a bit, almost to the point where a single snorkle will outflow it. Think about it, A drop base air cleaner with a 14x3 eliment only allows about an inch of clearance from the base to the top above the air cleaner for the carb to suck air. A standard 14x3 allows a full 3in's of space in that area.

On the subject here, screw the edelcrap and get a Stealth. They fit, outflow the edelcrap RPM did I mention out flow????

Ray87Z

I have a RPM under the stock hood on my 87Z with a drop base cleaner, no problems.

I also don't buy the drop base limiting junk either, CHP did that test on a 400+ hp engine (I think it was a bigblock) and the drop base (along with a small 2 something inch tall filter element, so even less room between the airhorn and top cover) did not lose any power over the flat base units. They played it up about actually doing better than some of the other setups but it was all within norms for variation from one dyno run to another.

Not to mention the fact that I've run with the whole filter setup off the car and picked up no time in the 1/4 (should have given an extra inch or so of space over the carb w/filter setup once you figure in the wingnut, top cover thickess 1/4-1/2 inch clearance between top of wingnut and underside of hood, etc)...

But anyway, the RPM fits on my Z, performs well. If you have a 'Bird you're out of luck though from what I've read/heard.

RB83L69

i don't read magazine articles too much, I get my info from the experience of actually doing things myself and seeing them done by others, and observing the results... and I don't believe what you are quoting that magazine article as saying. Way too much real-world fact to fall for what to me looks like an apology for excessive marketing.

Daemorok

SSC: Is this the intake you are talking about ?

http://www.jegs.com/cgi-bin/ncommerc...18&prmenbr=361

Guest

I've seen any number of magazine articles over the years from one to another that say the same thing about drop base aircleaners, they all made more power than a regular 'tall' aircleaner base.

Either they are all lying, or there is some truth in it.

RB83L69

The key to power is not the "drop" base or the "tall" base, that's a red herring. It's the shape of the base itself. If you look at a regular cheap (but not necessarily inexpensive, such as Edelbrock) "tall air cleaner, most of them have an absolutely flat base. On the other hand, a "drop" base air cleaner usually has some degree of curvature to the base, that helps direct the air in the proper direction as it flows through the element and has to make the 90° to go down. So, the thing that they are actually measuring, is not "drop base" vs. "tall"; it's "curved base" vs. "flat base".

Alot of us have been saying the same thing for years, except about factory breathers. Take a typical "flat" base air cleaner, and measure the flow. Then take a factory base and lid that are cut to the same outer diameter and put the same element in it, the factory base will outflow the "flat" base every time, by 10% or more. But they don't tell you anywhere in the magazine articles that you don't need to spend $40 on some chrome POS and you can get far superior results with a hacksaw, now do they?

If they compared a correctly designed "tall" air cleaner with flow direction, against a "drop" base of similar design, the truth would come out.

The real truth about this is so obvious it hurts to look at it: Vic (and whoever else) wants your $40 for his 14x3 chrome thing and more importantly your $150 for that tall manifold, and tells you all about how good it flows, but then you make all that air have to pass through a slit 4½" in diameter and less than an inch tall, and make an immediate sharp 90° to go into the carb? And you need the 14x3 element, but the slit isn't a restriction? Come on.

In other words, the articles aren't lying, they're just not telling the truth.

jcb999

some are more of a compromise than others. YMMV

Guest

Yea RB, but do you have any proof on paper, like back to back dyno sheets? Could argue all day but the only hard results I have seen dont agree with what you are saying for the most part. And I am not talking about comparos of 'Brand-X' fancy dancy drop-base aircleaner vs. stock aircleaner or flat bottom 'tall' aircleaner just to sell a product, but rather both just off the shelf type aftermarket curved bottom and top (where the wingnut/bolt would go) aircleaners just to compare drop base to non drop base.

I've noticed you beating on this subject over and over again, and every time I have bitten my tongue because the information I have read doesnt agree. One article even had an in-depth explanation of the path of the airflow, and how the aicleaner lid and base should be shaped for optimal flow. Having a drop-base aircleaner wasnt an issue according to them. This agrees with other information I have seen on the subject.

And to clarify things, I had a Performer RPM with Carter carb and 1" drop base aircleaner with 3" filter under the hood of my 86 TA, cleared with room to spare. And the lid was not 1/4" above the carb. I'll go measure it when I get home for giggles, but if I had to guess it was around 1.5" or so. Plenty, I think.

Ray87Z

You mean kinda like going to the track and taking the entire cleaner assembly off as I did and not picking up time? Yeah, the drop base cleaner does not affect power enough to notice either way, and was not slowing me down. If it was such a big deal the inch+ of extra space added from not running the drop base setup at all would have done something, at least one would think... But maybe your back to back drop base testing has shown otherwise.

Face it, it's a track side rumor and known "fact" that drop bases are somehow bad, and dyno testing on numerous different occasions has proven this wrong, not unlike hundreds of other little "facts" people like to pass around...

jcb999

350ho motor. It was the first zzz I think. They baselined the motor with just the airmeter. 348hp at 5250 and 383ft/lbs.
They used a GM hiperf openelement 6423907 (which has a pretty big drop but was designed for max airflow with good hood clearance) and it made 343.2 and 380ft/lbs.

They tried taller ones (a K&N 14x6) and it went up to 349hp and 386ft/lbs .

They then rebaselined the motor and it made 350 and 387.

It appears that when combined with the correct base, there is no loss. But,, the base is not all there is too it.. the top is very important on drop bases.

SSC

Yes!


So Max, did you measure it yet?? When I get back home I'm going to break out the tape measure and see, I'm 99% sure it's a tad less than an inch.

jcb999

The one in the top pic is the old street dominator holley made.

F-BIRD'88

Study the pics.. One is a ColaNut the other is a Un-colaNut.
Notice how the ColaNut is much Larger, Juicer too.

GM makes the ColaNuts,,,,,,, The aftermarket sells the inferior UNColaNuts.

F-BIRD'88

....

F-BIRD'88

See how nice the Cola Nut fits....

F-BIRD'88

And how much higher the Uncola Nut is.... Ha Ha Ha Haah!!!....

Guest

Sorry, forgot about that.

13.5" diameter housing, 3" tall filter element, the base is a 1" drop base, have 2.5" clear from the lid to the base of the mounting flange. I know Holley's choke tower sits a little higher than a Carter does, but I cant imagine it cutting down the clearance a whole bunch. The Carter I have is around 1" from flange to top of carb, so there's still 1.5" clear. Good guesses off the top of my head huh? LOL I guess I'm not so forgetful after all.
IIRC I had like 3/4" to 1" clear of the hood on my TA. Too bad the manifold was machined wrong, or it'd be on my car right now.