Ford Mechanic
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Couple pics of it mocked up.
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4" Ram Air Scoop for deuce
- Thread starter Repo3004
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Vintage iron
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WOW! Didn't expect that at all!
Ford Mechanic
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Got mine painted last night but it'll be a little while longer before I can test it, I have my truck still tore apart at this point.
ducer
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While that is a beautiful looking scoop I think you will find it is more of a restriction than the mushroom cap.
Now before you all line me up against the wall for the firing squad and start taking shots at me please here me out. First off I come bearing some experience. In the 80's & 90's my buddies and I dragraced one had access to Chrysler engineers and me GM. They both gave us copys of wind tunnel data and results the factorys used for their race teams. Basicly you want flow through the scoop to be = to or greater than flow through the carbureter. If the carb flows 800 cfm inorder to not hurt performance the scoop and air filter must not flow less than 800 cfm. To be on the safe side all engineers agreed the scoop opening must be at least 2x the carb opening and 4x with filters as a safe baseline, (example: if you have a carb with 2"x2"square throttle blades x 4 barrels = 8 square inches of opening non filtered). This means there must be a totaly unobstructed opening of 8 square inches no screens or anything, nothing! I see that scoop has a pretty
screen in there with some rather large and flat webbing inbetween the openings. NOT GOOD FOR AIR FLOW! With that type of screen it will actualy be a restriction at higher speeds due to the air getting deflected from the flat areas. Remember this is just baseline stuff and not final formulas. Our cars ran in the 130-155 mph range in the 1/4 mile only above 85-90 mph did we ever see any type of ram air effect and never more than 1/2-2 psi depending on opening size.
These were all naturaly aspirated engines and all scoops were sealed to carb openings.
The main reason to add a scoop is to get cooler air from outside the engine compartment, which our trucks all ready get by design. All engineers agreed the 2 best scoops ever designed from the factorys were #1 the Chrysler hemi s/s scoop and at #2 Chevrolets NASCAR cowl induction. The Chry because of it's large size, and the Chevy because of using the high pressure area at the base of the windshield. If we factor in vehicle aerodynamics that will be an even longer and more boring discussion.
There are many more variables that could be talked about here but this post would end up being 200 pages long and I type by hunt and peck. So go ahead and 
fire when ready.
Denny
Now before you all line me up against the wall for the firing squad and start taking shots at me please here me out. First off I come bearing some experience. In the 80's & 90's my buddies and I dragraced one had access to Chrysler engineers and me GM. They both gave us copys of wind tunnel data and results the factorys used for their race teams. Basicly you want flow through the scoop to be = to or greater than flow through the carbureter. If the carb flows 800 cfm inorder to not hurt performance the scoop and air filter must not flow less than 800 cfm. To be on the safe side all engineers agreed the scoop opening must be at least 2x the carb opening and 4x with filters as a safe baseline, (example: if you have a carb with 2"x2"square throttle blades x 4 barrels = 8 square inches of opening non filtered). This means there must be a totaly unobstructed opening of 8 square inches no screens or anything, nothing! I see that scoop has a prettyscreen in there with some rather large and flat webbing inbetween the openings. NOT GOOD FOR AIR FLOW! With that type of screen it will actualy be a restriction at higher speeds due to the air getting deflected from the flat areas. Remember this is just baseline stuff and not final formulas. Our cars ran in the 130-155 mph range in the 1/4 mile only above 85-90 mph did we ever see any type of ram air effect and never more than 1/2-2 psi depending on opening size.
These were all naturaly aspirated engines and all scoops were sealed to carb openings.
The main reason to add a scoop is to get cooler air from outside the engine compartment, which our trucks all ready get by design. All engineers agreed the 2 best scoops ever designed from the factorys were #1 the Chrysler hemi s/s scoop and at #2 Chevrolets NASCAR cowl induction. The Chry because of it's large size, and the Chevy because of using the high pressure area at the base of the windshield. If we factor in vehicle aerodynamics that will be an even longer and more boring discussion.
There are many more variables that could be talked about here but this post would end up being 200 pages long and I type by hunt and peck. So go ahead and fire when ready.Denny
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Yeah some one earlier made that point, but I'm fixing to find out for sure, call me hard headed. After talking with my father in-law about trying to measure the possibility of vacuum or pressure in the air box we came up with a no cost solution. He has a set of R22 a/c guages that he can adapt to 1/8th pipe thread and has all the stuff already due to normally needing it adapted to 1/4 pipe thread. So I'm going to remove the air filter minder from the top of the air box and plug it in there to get my readings and retest with the mushroom cap also. Now just to get my grill sand blasted and painted this week and I'll be ready for some testing!
Vintage iron
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I always appreciate good sound info. You do raise some good questions. I guess we will see when Ford Mechanic gets his scoop operating.
Vintage iron
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I can't wait to see the real test results! You need to drive the same road at the same speed at the same sections to get true readings.
Ford Mechanic
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Didn't Repo buy one too? Haven't heard from him lately... I need to post some pics of my scoop after paint. It took to paint like a nun to church!! Looks great!
Vintage iron
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Repo3004 did buy one too. He was putting it on a m809 series truck I believe. It would be good to hear his input too.
ducer
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The easiest way to check for a restriction would be to hook a regular old vaccume gauge up and see if you have positive or negative pressure. Positive pressure = no restriction, negative pressure means restriction. Of course remember to plug all openings in airfilter housing first. Horsepower has nothing to do with air flow, however airflow and restrictions/turbulance have everything to do with horsepower. RPM and cubic inches are just 2 of the many things to be concidered when dealing with cfm requirements of an engine. Example: You have 2 engines one is 400 cubic inches and makes 400 hp at 5,000 rpm. The other one is 800 cubic inches and makes 400 hp at 2,500 rpm assuming cfm flow to cubic inch ratio flows are the same between engines the 800 incher will need more air flow to match the 400 incher due to the differences in port diameter and air speed requirements. This may be hard to get your head around without visual aides but if you think about a 2 buckets one twice the size of the other, with holes in them. the 10 gallon bucket has a 1" hole in it and the 5 gallon one has a 1/2" hole in it. If you timed them on how fast they emptied the larger one would empty first.
Then there are boundry layers and turbulence to concider. All I can say about that are put that sucker up high in clean air (no turbulance). That would almost be imposible for me to explain typing. By all means experiment I wish to encourage that. That is how my friends and I learned and at times it was the most aggrivating and irritating yet rewarding. You would be suprised at the amount of things that you would think would work well don't work at all and the ones you say no way will that work that work great.
Denny
Then there are boundry layers and turbulence to concider. All I can say about that are put that sucker up high in clean air (no turbulance). That would almost be imposible for me to explain typing. By all means experiment I wish to encourage that. That is how my friends and I learned and at times it was the most aggrivating and irritating yet rewarding. You would be suprised at the amount of things that you would think would work well don't work at all and the ones you say no way will that work that work great.
Denny
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My vacuum guage only goes negitive pressure (hand pump with guage), thus why I was looking into using A/C guages. The low side goes positive and negitive. I plan on eventually mounting it higher like a snorkle kit but $$$ is preventing it right now, then it'll get lots of nice clean air hopefully with no turbulance like you said. And mabey go to a 5 in feed pipe. I'm trying to get her good and sound at the moment to take her to the beach for Memorial Day weekend!
Since the pressure of vacuum you are measuring is in the inches-of-water range, you can make a gauge out of a section of clear plastic tubing shaped into a "U" and partially filled with colored water (no kinks). You can hang this from the windshield or top support rods. One end of the tube goes attached to where you want to measure and the other is vented to atmosphere. If the vent side water level is higher, you have pressure and if lower it is vacuum. The measured difference in levels is inches of water column.
Vintage iron
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That method looks good on paper, but not sure how it would work going down the road or up a hill? 
HP / VE is directly related to CFM - I've actually never seen someone make your claim before, physics is against you.
As a general rule of thumb, CFM x .069 = estimated lbs./min lbs./min x 10 = estimated HP
port size only determines air velocity at the ports not the intake, runner diameter and length will determine air speed in the runners. CFM and intake diameter determine air speed. But displacement/rpm/valve overlap determine total SCFM, and since we are talking about a turbo SCFM gets difficult to determine without also knowing your PSI. thus HP is the best method for easily determining the air volume requirements of the engine.
saying that a 800 cubic inch engine would need more air for the same hp as a 400 cu in because it is bigger is just plain wrong. Port size will determine the air speed in the runner and at the port but have zero effect on the primary intake, the same as it will have zero effect on the required exhaust tube (it will only effect the exhaust runners diameter and length for tuning)
it starts getting more complicated when you bring virtual displacement (boost) into the equation because then you have displacement, intake pressure, intake air temperature, volumetric efficiency, valve overlap, and rpm to deal with. HP is about as close as you can get to that number without having extensive engineering data and readings.
for this design the face opening has a larger cross section than the pipe, the mesh screen could induce some turbulence, however what will likely have the greatest determination on the air flow is how the pipe enters the box.
if the pipe goes straight in and stops at the box it will generate a lot of turbulence at the hard edge of the pipe. if the pipe extends into the box that will help some, and if the pipe flares or trumpets out into the box that will have the best flow.
some handy math info onthe topic:
http://www.ajdesigner.com/phpengine/engine_equations_volumetric_efficiency.php
http://classicinlines.com/cfmcalc.asp
something like this can have a surprising effect on airflow
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Repo3004
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I actually just had mine delivered to me up here in North Dakota, to the rig I'm on. It'll be awhile before I can leave the rig to get to a town to track down an adapter to make it fit the deuce. The quality is excellent, can't wait to get it home to powder coat it.
The tube portions where the liquid level is can be touching each other. Truck movement or inclination would have a minimal, if any, effect. I would tape the tubing to a ruler so you see the inch differences. Additionally, I would think the absolute reading is not as important as a relative indication of improvement, or lack thereof.That method looks good on paper, but not sure how it would work going down the road or up a hill?
ducer
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Kohburn you need to read more carefuly. The point I was trying to make, all though clumsily is, without any airflow you don't have any horse power. And yes in my experience on the engine dyno a larger cubic inch engine will need more air. I genericly attribute this to differences in volumetric efficiency brought on by a hole bunch of outher factors. Port design,intake manifolds, runner legnth, valve sizes, cam lift, cam duration and overlap, vehicle weight and aerodynamics, gear ratios and barametric pressure are just some of the things I did not want to bring into this discussion because this is a discussion on air scoops and not engines. I just used that as an example. It was not my intention to muddy up this thread with that kind of stuff. I am just relaying what I have found to be true through testing and experience. At this time I would like to say I'm sorry if you think I lead this thread astray.
Vped you are 100% correct in the way you described checking for restriction and should work well in our trucks. Your method would be most accurate. We could not use this method though we wanted to in our cars for many reasons, not enough room, no place to secure it and on acceleration the water would go everywhere. All testing should be done on the same road, in the same direction, at the same speed for the results to be meaningful. Going to 5" would probably only be most helpful if you could continue to the turbo inlet without having to neck down at all.
Denny
Vped you are 100% correct in the way you described checking for restriction and should work well in our trucks. Your method would be most accurate. We could not use this method though we wanted to in our cars for many reasons, not enough room, no place to secure it and on acceleration the water would go everywhere.
All testing should be done on the same road, in the same direction, at the same speed for the results to be meaningful. Going to 5" would probably only be most helpful if you could continue to the turbo inlet without having to neck down at all.Denny
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Pics of the freshly painted scoop and progress of my truck! Also my less than $10 horn upgrade!
ducer
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Wow! FM your mushroom cap has a different screen than mine. That thing has to be restrictive as all He11. Mine looks like a heavier wire gauge window screen. I wonder if mine was off of some other piece of equiptment or was yours? I would have to say that the scoop is bound to help compared to that restrictive screen and will help more once you move it up.
Denny
Denny