Air flow through hood scoop

maxrpm · #1 (**permalink**) 03-12-2004, 11:54 AM

I also didn't think that the little opening on the scoop would really pull much air but back to back runs at the dragstrip proved me wrong. I was thinking that I would actually hinder performance by restricting the engine to scoop only air.

Ant · #2 (**permalink**) 03-04-2007, 03:41 AM

This is an area that I havent really sorted yet, and due to having a high hp Nascar based engine with an Edelbrock 2961 inlet, I have bonnet clearance issues, and am using what Richard calls an ugly scoop, plus I have had to modify it another 3/4" higher to give approx 2.25" clearance above carb, plus I will have to angle and cut the breather tubes down somewhat, and on my car the air cleaner is tilted down at the front, which looks about the same as the JBL!
I am going to have to make a dropped base of almost 1.75" for my 14" X 3.5"High, K&N race filter, my engine isnt running the large rpms of the Nascar engines but will still see between 7000-7500rpm, going by the K&N calculation formula I have 32.5cfm additional capacity for dirt etc!

With this air filter I will have about 1/4" clearance above the filter top, and have considered an X stream top for it, but K&N recommend 1" clearance above the carb, plus I have read where these top filter systems dont actually do much for HP, well I went to the motoracing yesterday and see these V8 Falcons etc with the X stream and air boxes integrated with the hood, but these were reverse cowl induction. So some Cobra owners maybe using the X stream with little improvement in power, due to being to close to the hood?

I might be better to make an airbox around the carb, and have filters elsewhere away from any heat sources, but thats going to get messy for maybe little gain......!?!?

Morris · #3 (**permalink**) 03-04-2007, 08:02 AM

Ant

We are using a Dominator Carb.....and had to build the air cleaner just for the Dominator..... Here's the base we made to get the proper air flow into the carb....

Morris · #4 (**permalink**) 03-04-2007, 08:05 AM

Then we built the top of the air cleaner to contain the filter and use the Extreme Flow top.

It has a 2" drop with a 4" Air cleaner it's also a 16" air filter.....

Morris · #5 (**permalink**) 03-04-2007, 08:07 AM

The Dominator will pass over 1000 CFM's...... so we paid special attention to how we built this air cleaner.....

Morris · #6 (**permalink**) 03-04-2007, 08:09 AM

And of course when it's installed we had to modify the Hood ....

But it all worked very good on the high end.....and when a FE is pulling 7000 rpm's...... it's using a lot of air.....

Anthony · #7 (**permalink**) 03-04-2007, 08:24 AM

Quote:

Originally Posted by maxrpm

I also didn't think that the little opening on the scoop would really pull much air but back to back runs at the dragstrip proved me wrong. I was thinking that I would actually hinder performance by restricting the engine to scoop only air.

What someone could calculate is the scoop frontal opening area, and compare it to the total venturi area of the carburetor to get a ratio for comparison of air flow velocity, considfering you have a sealed system.

I don't think air via scoop is highly pressurized ( ram effect), but I think the main benefit for sealing the scoop to the carb is colder air, denser air, for more power.

David Kirkham · #8 (**permalink**) 05-07-2007, 07:41 PM

Badger,

Glad to see you are up and "hobbling" around! Better than the alternative of pushing daisies.

This thread reminds me of a joke my guys played on me. A couple of years ago, my guys got together on one of the SEMA cars and put the hood scoop on backwards. You work long, long, hard nights to get a SEMA car done and you loose track of time and your mind starts playing tricks on you. The stress is unbelievable. We had a zillion hours in the car and it had to be PERFECT!

Anyway, they were wondering how long it was going to take me to realize what was going on with the hood scoop backwards. Finally, when I saw it, I thought the guys just set the hood scoop on backwards just to lay it down somewhere--until I looked really closely at the hood scoop. I almost died--the hood scoop was riveted in! It would have taken hours to fix all the 21 holes in the hood and the scoop and we were already pushing the dead line.

Anyway after I had a heart attack, everyone started laughing. They had taken the shanks out of the rivets and placed them back in the holes so the hood scoop only appeared to be riveted on. They had even lined up two holes somehow and actually riveted the hood scoop on backwards in those two holes to make the effect complete. I think I aged 2 years that night.

As you can see, Kirkham Motorsports is actually a pretty cool place to work. They got me good--fair and square...of course, I did get them back!

David

ps. Peter, nice to see you on the boards! Get well soon! Anyway, you have to come by and try our new Rush. The car is phenomenal to drive. It is like driving a full sized go cart. We had it up at Miller's track last week. Everyone who drove it just giggled. It will run circles around a Cobra.