Opinions on cold air intake setup

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71swing

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Hello guys. I need some help and your opinions on what to do. I have 71 dart with a brand new 408 topped off with a FAST EFI. I been wanting to build a cold air intake for it. My plan is to use a single plenum connected to some 4" piping that I already have and run it to the passenger fender where the air filter will be located. But Im have a clearance problem with the plenum.

I purchased a single Spectre plenum it required 3.5" of clearance. which just about all I have at the top of the thottle body. So I had the lower lip milled off about 1/4" or so. I asked them to take of as much as they could without opening the radius more. You can see the clearance to the hood from the putty I used to gauge the clearance. (see picture). Thought that was all I was going to need. But now that Im clearing the hood its hitting the bracing. (see picture) So do you guys think I should just cut out the brace. I will need to cut where the electrical tape is on the hood to clear the plenum. (see picture)

Or they also offer a low profile plenum that only requires 2.5" thats an inch more clearance. Now for the down side. It is only listed to flow 675cfm as versus the one I currently have that flow 900 cfms. Will the 675cfm plenum kill the performace of my 408? Is 675 cfms enough?

http://www.summitracing.com/parts/spe-98499

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Well I want to thanks all of you for your opinions and ideas. Your input is greatly appeciated. I have gone ahead and purchased the Low-profile version that only requires 2.5" of clearance. Its only rated for 675cfms, but I used a Wallace Racing Calculator for the required cfms and It should be just enough. I guess Ill have to dyno it with and without to see if there are any restrictions.

http://www.wallaceracing.com/intakecfm.php
 
71swing said:
Well I want to thanks all of you for your opinions and ideas. Your input is greatly appeciated.
Click to expand...

LOL, it's not a question that just anyone can answer. Sometimes it takes a day or two for the right person to see it.

If I had seen it I would have suggested getting a dual inlet, low profile if they make such a critter. I am considering a cold air intake on my car.
 
I never seen this post before. My carb 406 has a drop base air cleaner with dual 4" inlets. Allows extra clearance. Then I ran flex tubing to radiator support.
 
Well I dropped another $99 on the low profile version. It clears no problem. I just need to trim up my 4" tubing I'm running to the inner fender were I will mount the filter. will post up finished pictures when I get that installed.
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Injected engines usually require more fuel when you introduce more air to keep the air fuel ratio correct. That means reprogramming the computer to maximize incoming fuel. Maybe T/B injected engines are more forgiving, I don't know. But in general, air and fuel work hand in hand together. You cannot just introduce more of one and expect more power.
 
UPDATE:

Finally got the tubing mocked up. Still need to take it back apart and clean it of any loose shavings. The only other thing is I need to hunt the hardware store for a good thick strip of weather stripping that I can use on the rim of the hole in the fender instead of the temporary vacuum hose I'm using for the moment that I cut a slit in. Something with enough volume to take up the extra space and prevent the intake from bouncing around too much.
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the filter on the inside the fender
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Wow, this is the first I've seen this

Are you sure you have the correct engine insulators? Why do you have so little engine to hood clearance? that throttle body appears to be pretty short. I do understand the intake is fairly tall, but still.......................

"I'd bet money" that there's a chance all that plumbing will lose, even though "cold," compared to an open air filter which would actually flow enough air.
 
Looks good.

Cold air intakes make an engine work better and more efficient because the mixture is more dense.

I think you could have cut part of the bracing in the hood and reweld a piece of 1/16" flatstock back in there to maintain rigidity.

Are you also going to make a splashshield for the airfilter?
There's a lot of dirty water being flung into that area when driving in the rain or through puddles.
 
Not sure about the mounts. The car was originally a /6 car. So it has convertion mounts. Maybe that the difference? Before I had a nitrous plate and had to run a drop filter base to clear the hood. They say the throttle body is the same height as a standard holly or demon carb (I didn't measure) Without the nitrous plate I gained a lot more room just not enough to fit the taller hat.

Yes my plan is to get a thin aluminum sheet from the store and fit it in and mount with rivets to block the dirt.
 
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