Air flow through hood scoop
 

a427sc,
Your car looks very good and much better than the one behind!
With my choice of Yates headed race engine, manifold height dictates scoop height and I am another inch of so higher than your car! I could go EFI but I cant really afford that and dont see it as being any great improvement on the track, but it would solve some scoop height and fuel economy!

This is a most interesting thread for me. I presently have the 9" air cleaner 2 3/4 k+n filter element, turkey pan set up. I love the way it looks. I have found out that this filter is only capable of flowing 470 cfm, clearly not enought for a 428 with a big Holley DP. So I am looking for a way to get a lot more air and keeps the traditional look under the hood and on top of the hood
More research the other day, I found out that the long oval cobra air cleaner flows no better than the little one I have on there now(reduced height for hood clearance). I am shocked no one has designed a drop down base for the big oval air cleaner, I called k+n and the have a 3" filter element for this, it measures 20.81Lx9.5Wx 3H, it will flow 950 cfm, this to me would be perfect! Now, to make it perfect, would be to design a turkey pan to mount to the intake manifold flange(like the present Turkey pan), only shaped to accomadate the long oval filter.
Now, as far as providing air for this much increased cfm potential, I know under the hood air availability is a real question mark, especially at speed. Dyno guys have told me they have much increased numbers just taking the hood off and doing nothing else. I was thinking of a RAM AIR setup coming from the two 7x3 holes in the front, ducting it outside the wheel well and then entering it into the engine compartment thru the wheelwell housing. Location would be about 1/3 of the way back on the valve cover.
Mount a flanged adapter on each side of the new tukey pan that would accomodate a 3 inch brake ducting hose.
I think this could be a real clean, very effective and very good looking set up.
Pegusus has ducting and adapters, I am sure there are more sites that have more choices, this is as far as I have gotten so far.
Has anybody attempted anything like this yet, I don't want to recreate the wheel if has been done already.
To compliment this I would opt for new sidepipes with the spiral core option that I talked to Maurice at Unique about, to free it up so I can take advantage of all that available intake air I would now have. Then of course it would be off to a dyno to dial it all in.
Related Thread On Unique forum
http://www.uniquecobra.com/forums/showthread.php?t=5525
Any input would be appreciated!
Thank You....Dave

Take a look in my gallery. I started with a Summit oval aircleaner with a filter top and dropped the base. I still run a turkey pan. The exhaust no longer has that unburnt gasoline smell, so that tells me the aircleaner flows better than the S&H that it replaced.

Dave....You are on the right path my friend. Simple evaluation of basic airflow is something most Snake owners don't ever consider. They are so obsessed with being "original" that any change is considered heresy. You might install a set of air/fuel ratio gauges in your pipes to start with. A simple change you might try is to reverse the direction of the hood scoop. There's more air pressure at the base of the windscreen than out on the middle of the hood's surface. (a simple manometer test will prove that) Don't be afraid to go against the majority's opinions....there's little knowledge there..only monkey see monkey do. Badger

Nice car Lew, yes I saw that aircleaner in Summitt, I think it was an Edelbrock actually. Does it have a drop down base, I did NOT think it did, but you say it does?
I have heard of spurttering issues with the open top air cleaners with our cobras and the scoops we have on our cars affecting the airflow.

It does not come with a dropped base. The entire base sits above the carb. However, the flat base on it can be modified so that it drops. I think mine is dropped about 3/4". I have no sputtering issues.

Thanks Badger, but I probably fall into the same crowd, sort of anyway!
I still want it to look very Cobra-ish, I have no interest in turning the scoop around, and I am a working JOE so everything needs to be cost effective.
I figure, if I can at least supply lots of air availability(ducts), CFM availability( much bigger air cleaner), Looks( ducting, cobra oval AC dropped down to accept a 3" element, modified turkey pan or airbox).../then I will have a much improved performing car, and still look great at the car shows and for my own eye!

Hi Lew!
Your car is Sweet!

Turn the scoop around... Humm. I aam going to use the Classic Dynatek Direct induction system on my build. (mild 351W w/ 435 // 430 ft) The system would benifit from the reverse scoop with the use of a turkey pan. Hummmmm.
Mother

About the only thing my hood scoop does, that I can think of is: allow clearance, and let heat out when you turn off the car. I tried the yarn on the scoop trick, and the big opening in the front of the car was just forcing hot air out of the scoop while driving. LOL

Double Venum
Nice use of "Duponts Croman Illision" on the build. I have no concerns about changing the looks of the hood to an improved air flow question.

Has anyone tried adding vents to the hood? If the air coming through the radiator is causing air to flow out the scoop, what if we gave the air another place to go?

The Problem is the Turkey Pan, with it on, the scoop cant flow enough air for a 500CFM much less a 750 or 780CFM Carb! Do a full bore accceleration run and shut the key off at about 6000RPM and take a plug reading - They'll be black with the pan on. Take the Turkey pan off and do the run again - if the carb is jetted properly, the plugs will read perfectly! We proved this out while tuning for a Run & Gun many years ago.

Also, if the filter element can only flow 470 cfm(mine):CRY:

Take the Turkey pan off
 

So you're saying if I'm running an 850cfm holley on a 427 so I should take the turkey pan off.

dls141

notice this thread started in Feb 2004 and stayed active till 2008. Lots of good info in this thread.

The turkey pan is killing your hp.

I did the cal's on an 8" S&S air filter on a 351W with 400 flywheel hp. At 4000 rpms it was losing 97 hp because of the filter.

use this link to cal your air filter. You can not get the proper size filter in the turkey pan.

Second Strike Air Cleaner Calculator

Dwight

I read this thread from the first to the last post, what I see is a bunch of guys try to explain and calculate fluid dynamics.

What I don't see, are any real numbers - like dyno sheets. With or without turkey pan / larger or smaller filter.

To bust some of the bubbles here, the efficiency of an air filter is altered by 25% in the first 6 month (not in Nevada or West Texas - more like 35%).

Many numbers swirling around about CFM and RPM. All manufacture numbers are based on a stoichiometric air–fuel mixture. Well, most carburetor guys just can dream of it. So, take 25% of the number and let this the base of the calculations.

A good motor performance is not created on the internet nor just on paper. Many "internet engineers" don't realize that. They even believe Wikipedia is correct in all fields. :LOL:
Trial and error is the key, so if someone would provide some numbers here to make this thread more substantial.

Thanks

I agree with you to a point, but as a start in the right direction, the airflow is what it is. So if my K+N filter wont flow more than 450 cfm brand new(per K+N tech dept), and engine needs 750cfm to perform to its intended potential, at this point it is not rocket science!
I love the look of the turkey pan and I have the biggest filter (height and width) I could possibly run with the turkey pan. I will be going with the spiral flow exhaust this year which will flow much more than my present setup, this will further exaggerate the starving for air in high performance situations. I will most probably go to a cool looking ram-box setup and a dyno service to get it all perfect!
Dave

G-Pete, I thought I posted some "real-world" results on this thread early-on, but maybe not. Here you go:

I have a mild 2x4 sideoiler with 2 600 CFM Holleys. The guys in Houston all decide to do a "dyno day". I put mine on it, did two back-to-back pulls and got 394 RWHP with stock paper filters on the S&H housings, and 402 RWHP with just the base of the S&H housings on the carbs (I've been told that without the base of the housing the airflow into the carb gets disrupted).

That makes 7 RWHP difference between paper elements and no elements, up through 5500 RPM. The reason I run paper elements is because the K&N elements let way more fine particles through, and for 7 HP, it isn't worth it.

Now for the guys with one big carb, the single S&H filter seems way too small, but for me, it works. And FWIW, Double Venom's tuft work confirms what I had always suspected, the hood scoop is good looking, but fairly worthless, and any benefit you'd get from cool air by sealing your carb to the hood would be lost by starving the engine for air (at higher RPM). JMHO.

Thanks Dwight. I've seen the TP setup before on a small block but thought it looked odd - and constricting on the 427.

We'll be installing the new Holley next weekend and I'm dropping the turkey pan. It's great to live 30 minutes from Summitt too!