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Old 01-09-2004, 08:25 PM
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Carbed "Ram Air Box"

How well do these work? How much of a Horsepower gain? How much will these effect detonation??

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Old 01-09-2004, 10:04 PM
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ram air is just another way for saying "cold air induction" or "fresh air induction" cold air is more dense than hot underhood air and results in better burn or the air/mixture, cool cans for fuel have a similiar effect, by it being denser, it can pack more in the cylinder, there`s also other reasons. it helps keep detonation at bay better than hot air, I`m sure there are articles on this on the web and possibly in the knowledge base of this site. horsepower gains will be margainal, but it will result in a slight gain. however, sometimes a real ram air system like came on the pontiacs in the 60`s can work against you, since it will knock off the air/fuel mixture since the ram effect overcomes the amount of air the engine can pull in, but with a box I wouldn`t worry about this.
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Old 01-10-2004, 01:11 AM
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Hey KeithB check this site out
Ram Air

They've got some great stuff, I wanted to use one but it won't fit on my setup

Hope it will work for you

Regards
Mark
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Old 01-10-2004, 08:04 AM
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Double Vision, you are correct about the cooler air, more density. Engines love that. Fuel injections love it also, particularly if they are 'speed density" systems. However, a good ram air system has the benefit of adding about 2 inches Mercury pressure at the mouth of the carb/air valve(at cruise speed), thus a higher flow/speed of air on the throat side,(or more vacuum). In theory, this results in better fuel air mixing. NASCAR Truck series use the Ram Air Box system for increased performance and on the big tracks, use smaller intake tubes to control HP/speeds, vice restricter plates on the Cup cars. I think the key to noticeable performance increase is to get the tubes/collector box at the front of the vehicle to get the benefits of the ram pressure and to run large enough tubes to get the flow volume. According to the Ram Air Box guys, a 4 inch tube, delivers 400cfm and a three inch tube delivers 300cfm. Any inlet tube installed in the wheel well, for example, looses the ram air effect and only has the increased density effect. So I say to KB, try to get your tubes in the frontal air stream if at all possible.

Trees
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Old 01-10-2004, 11:26 AM
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I currently run a Ram Air Systems set up on my Beaumont . I've used it for about 3 years and would not go back to just a plain open element air filter. The biggest difference I find is when the ambient air is hot the engine performance isn't affected as much as with a open element air filter. I did have to re jet as the original jetting I had before the ram air would lean out at high speeds. On a cool night I bet its worth 20 hp at least. I run the inlet tubes from the rad core. I did have to relocate the battery to the trunk to do this. Check my photo album for pics. Currently I am running the car without the hood due to clearance problems but I plan on welding up a cowl induction type set up on the hood to gain clearance.


http://hotrodders.com/gallery/showph...cat=500&page=1
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Old 01-11-2004, 06:13 PM
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Excellent replies!

Steve that looks tuff! That`s what I want to do but I have the ram air hood that I`ll hook the tubes up to the "Hood Nostrals"
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Old 01-12-2004, 07:54 PM
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OK so let's say I'm going to build an induction system for a carbed motor. Is there a formula that will let me calculate the tube diameters needed? If I have a 650 CFM carb on an intake doesn't the pipe need to be at least as big as all 4 barrels diameter, or will the induction effect allow for use of a smaller intake tube. Also as the air gets to the carb isn't the angle at which it enters important due to back pressure?

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Mark
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Old 01-12-2004, 10:58 PM
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Air direction is important. This is why most experts recommend an air filter (or at least a base) or a K & N Stub Stack. One of David Vizard's books says a straight pipe flows 115cfm per square inch of cross-sectional area (measured using inside diameter, subtract 1/8" from nominal size), I believe at 1-1/2" Hg pressure drop (20-1/2" water). Here's calculated flow for a few pipe sizes:

2".........317cfm
2-1/4"...384cfm
2-1/2"...509cfm
3"..........747cfm
3-1/2"...1029cfm
4"..........1356cfm

This is for smooth pipe, not the corrugated stuff. I imagine that stuff has serious turbulence issues anywhere near the walls. It seems to me that it would be a good thing if the intake piping were significantly less restrictive than the carb, but I'm just guessing.

Just an afterthought, Vizard says for exhaust, you need at least 2.2cfm per horsepower to avoid significant loss from back pressure. Divide above figures by 2.2 for HP capability of your exhaust pipe.
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Old 01-12-2004, 11:12 PM
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I had heard somewhere that there is a layer of dead air along the sides of the pipe, if thats true then the diameter of the pipe is effectively reduced isn't it? I have a snorkel built onto my Jag, but I think the opening is far to small for a V8. The snorkel at the back is about 3 inches but it has a 90 degree angle and then tapers down to about a 1 inch inlet. I was thinking of cutting it out and then re-piping with a cold air system. I'm just not sure the gains are worth the effort. I have an Edlebrock 14 inch air cleaner on the car now.

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Mark
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Old 01-13-2004, 04:06 AM
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That's the boundary layer. Smoother walls give more flow due to less turbulence at the boundary layer.

http://www.grc.nasa.gov/WWW/K-12/airplane/boundlay.html
http://www.bankspower.com/tech_howairflows.cfm

Vizard's carb/intake book has a chart showing how much various pipe-end shapes affect the flow of air into that pipe. A straight cutoff is quite restrictive.
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Old 01-13-2004, 03:34 PM
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That's interesting stuff Jim, thanks for the info. I'm wondering if a 45 degree angle in the pipe will cause a heavy turbulence spot at the small side of the bend. Any box at the end of the pipe in my case will have to be about 4 inches tall for hood clearance.

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Mark
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Old 01-14-2004, 02:56 AM
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I read in a couple of places that air flow sees anything less than a 15* angle the same as a curve, which is supposedly why valve seats don't really need a radius, just a series of 15* angle changes. I'd try to use good smooth mandrel bends if possible. I may try to use a couple of 3" steel pipes to run from my air cleaner housing to my upper firewall/cowl area for cool air intake, but I've got room for an air filter where you might not. I've seen pictures of carbs with cast aluminum 90* inlets (looks kinda like a big baseball cap with a pipe where the bill goes) that didn't look more than about 4" tall, but I've never seen one in person. Might work with a remote filter if you're creative.

Something along this line, but bigger:

http://www.knfilters.com/Racing/plenum.htm
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Old 01-14-2004, 11:53 AM
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Funny you found that link I was looking at that last night but the C.I. ratings were much to small for my use. I like to make something along the lines of Turbo S10s hookup or Dragon J's but I'm no welder. That was my Dad's forte. I wish I would have learned it now.

I was thinking there may be a way to modify an air cleaner to work

Regards
Mark
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Old 01-14-2004, 08:21 PM
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I agree that Chris really did do a nice job on his truck, and I too wish I could weld like that! In the meantime I hoping to at least come up with something to duct in a little cooler air. The rig I have now effectively takes it off the top of the exhaust manifold, and inlet temps usually run over 100 degrees.

Where do you find the basics...like say 3"-4" aluminum or steel tube stock?

By the way Mark, how are you managing smog? Your Jag looks too young to get the exemption (unless you have a secret you'd rather not tell ).

Dave
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Old 03-18-2004, 06:19 PM
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box?

hi,

i saw flexible 4inch aluminum hosing (for dryers) at home depot and thought about using that (costs about $8 for 4 feet long tube). They also have really heavier duty flexible aluminum 4inch tubing in the toliet/plumbing section too (costs $15 for 4 feet tube).

What about the box to fit around the carb or air filter? Is there a cheap thing to buy (a metal lunch box? hehe) or how to make it? SHould u leave the airfilter on top or get 2 separate K&N filters and shove them in the front of the 2 tubes. I plan to make a setup through my headlights like a fairlane thunderbolt.

doh!..is this reply too late for a old stream?
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