FE Power Forums
FE Power Forums => Non-FE Discussion Forum => Topic started by: KMcCullah on January 31, 2020, 12:01:19 AM
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I'm working on ram air ducting for the F100 right now. This is something that I've read quite a bit on but never tried. Most guys report it's worth a few tenths in the quarter mile. Hoping for some advice from the braintrust. :)
The opening of the duct will pass approx. 6800 cfm at 120 mph. Ducted from the cowl. This air will be funneled down to a 1050 Dominator. One of my questions is, is it possible to have too much air? Also..... What happens to A/F ratio with ram air? Before I get too carried away with hours of TIG welding, I figured I should ask. I might be overkilling it again. Lol thanks guys.
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It's not possible to have too much air as far as I know. As far as A/F, the big change will be from a lower inlet air temperature, as compared to the truck without a fresh air induction package. If you are adding the fresh air package, you may need to jet up a step, but I think I'd try it back to back at the track to see. It may not be necessary, depending on how hot it was under the hood without the ram air.
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I've seen a tenth or so difference in a few cars using ram air. I tried it one day, 20 yrs ago with my car and saw no big change but I didn't change the tune up to see what it actually needed. I've contemplated trying again since I still have the tubes, but need to build a bonnet for the carbs.
I know they used the cowl on many cars, but is it better then in the front? Worse? I've only see it used up front.
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Even though the cowl area is a somewhat higher pressure area, I'd bet the ram effect would be much greater in the front. Still, any outside air is going to be better than under hood air.
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I've noted .2~.3 in the 1/8 in back-to-back testing of a tear drop open to the engine compartment vs air cleaner sealed to the scoop. So yea, IMHO it's worth the effort and no, you can't get too much air in there.
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I agree on th 2 or 3 tenths. In my case I got almost three tenths( front hood scoop with tray and foam seal on bottom of hood. But I know that at the time the tune was alittle on the fat side, maybe if it was leaner i might not have gotten as much.
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All these results are cars tho.
My 76 pickup had a huge frontal area and a good bit of flow through.
Sure it’ll help, sure it’s a good idea. But I dunno if you’ll have the drastic results like you would from a car.
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Our '64 went from a 11.40 to an 11.20 by just hooking up the headlight snorkels. We didn't re-jet, may have been closer to 3 tenths off with a re-jet.
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Thanks for the input fellers.
One of my reasons for trying this is the fact that my local air is so thin. Typically 8k+ DA. So...maybe if I can stuff more of this crappy air down the carb, I can shave a tenth or two. We'll see how it goes. I'm planning on welding in a bung to hook a manometer up to. Maybe we'll see a 1/4lb of boost. Lol Kidding aside, what I do know is, at 120 mph, there's one hell of a breeze coming out of the factory vents. I figure it must be something to do with the angle of the windshield. It sits up pretty good.
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The cowl is just a natural high pressure area on all vehicles. Nascar teams did it clear back to the '50s I think, and Chevy had their cowl scoop, which is actually much better than Fords "ram air", although I'm not sure about the hood leading 427 Fairlane/Comet scoop, so it's a good place to grab that outside air.
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The cool/cold air may be the biggest benefit .
My car,Mustang, is FI so I can monitor inlet air temp.
180-200 v. Ambient plus 10deg or so.
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Consider wrapping the bonnet and duck with a heat barrier. It should get you a few more degrees drop in air temp.
Thermo-tech 13575 works well on bends. Summit carries it.
It ain't pretty exposed under the hood, but it works .
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What the hell is a "Bonnet"!? Do you mean a hood? ;D ;D ;D Damn Limies! ;D
-Keith
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Everything's better with a blue bonnet on it.
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It turned out to be a silver bonnet. :) I tacked some 1/16 aluminum together last weekend. It came out looking like a gigantic vacuum cleaner attachment. Dad figures "we're gonna suck our way into the 10's with this baby!" Lol He's always the optimist.
(https://i.postimg.cc/Pq4yv2rP/B626-D838-634-D-4043-A488-0-F2741760-AF4.jpg) (https://postimg.cc/xkXMWGm2)
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I think it looks good, and I'll bet it will really work...
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The work looks great. I hope it meets expectations!
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I know how much truck chassis' and cabs flex, so hopefully that has enough give to move with everything. I think it looks good and will probably work great.
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Solid motor mounts?
If not, I would add some flex somewhere, maybe a rubber boot between the bonnet and the cowl face?
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What the hell is a "Bonnet"!? Do you mean a hood? ;D ;D ;D Damn Limies! ;D
-Keith
Tequila and limies. Party time !
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I agree on th 2 or 3 tenths. In my case I got almost three tenths( front hood scoop with tray and foam seal on bottom of hood. But I know that at the time the tune was alittle on the fat side, maybe if it was leaner i might not have gotten as much.
I had a real nice plate made for my 2x4 setup with a good foam seal to the hood. Gained ZERO even though I tried it numerous times on 3 different engines. Thought I'd find the magical 2 tenths but all that happen is it looked like the hood was going to come off. Entirely possible there's not enough air going into the B-9 scoop to matter so even if with under hood air my numbers were a wash.
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I think the fact the B9 scoop is not tall enough to grab air is the problem at high speed. The brick nose of a Mustang certainly pushes the air up high enough to clear a 2-3" tall scoop. It would need a pro stock style scoop to make much difference. My .02.
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I agree for especially the '69-'70 Stangs the B-9 was designed for. The shark-nosed (see side view of any '69-'70 Stang) front of these 'Stangs does pretty much defeat the short 3" hood scoop at high speeds. Yet, at low(er) speeds IMO and by pulling in cooler outside air, the scoop is worth adding even if the gains are small. Besides, it's a killer look!
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I agree on th 2 or 3 tenths. In my case I got almost three tenths( front hood scoop with tray and foam seal on bottom of hood. But I know that at the time the tune was alittle on the fat side, maybe if it was leaner i might not have gotten as much.
I had a real nice plate made for my 2x4 setup with a good foam seal to the hood. Gained ZERO even though I tried it numerous times on 3 different engines. Thought I'd find the magical 2 tenths but all that happen is it looked like the hood was going to come off. Entirely possible there's not enough air going into the B-9 scoop to matter so even if with under hood air my numbers were a wash.
I don't doubt your testing experience yet need to ask why. Was this in 1/4 racing? No MPH increase either? I ask as most actual racers (or hot streeter in the 1/4 mile) do gain something, even if a small gain, in a lower e.t. or higher mph.
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I agree on th 2 or 3 tenths. In my case I got almost three tenths( front hood scoop with tray and foam seal on bottom of hood. But I know that at the time the tune was alittle on the fat side, maybe if it was leaner i might not have gotten as much.
I had a real nice plate made for my 2x4 setup with a good foam seal to the hood. Gained ZERO even though I tried it numerous times on 3 different engines. Thought I'd find the magical 2 tenths but all that happen is it looked like the hood was going to come off. Entirely possible there's not enough air going into the B-9 scoop to matter so even if with under hood air my numbers were a wash.
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I don't doubt your testing experience yet need to ask why. Was this in 1/4 racing? No MPH increase either? I ask as most actual racers (or hot streeter in the 1/4 mile) do gain something, even if a small gain, in a lower e.t. or higher mph.
Hey guys my scoop wasnt a B9 scoop it was a real hood scoop about a foot high. I dont know if that makes a difference. I still have that hood with scoop, would love to sell it maybe I will bring to the reunion.
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Bob.. it was 1/4 mile and back to back runs showed nothing to speak of. That said, my car isn't deadly consistent and maybe with some jet changes I might have picked up a little but nothing close to a tenth or two. As for the MPH, nothing there either however my MPH is RPM limited so it's not fair to say the hood seal wouldn't have helped on the top end. Less rear gear would be the tell tale. My 427 went 137, the 428 won't go over 135 and all the 390 has is 132.
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And before the blatant thread hijack... I like what the original poster has done there but also agree with the comment that some type of flexible seal might be needed for cab flexing and engine movement. Nice work though.
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My experiances with hood scoops pretty much mirrors Dales. My Fairmont has an old style 5 inch Harwood "snorkle" scoop, that was common in the 70s and early 80s Pro Stockers, Modified Production & Comp Eliminator cars. I have ran the car with the hood scoop sealed to a plate on the carb, and left the plate off, letting the air run "free range", never seen any difference on a ET slip. I have even ran the car with the scoop opening cover on, with no plate, same numbers. One thing I can confirm, if the scoop is sealed to the carb, and no air cleaner is used, the chance of the guy doing his burnout in front of you , and having a rock finds its way into your scoop, and onto the sealing plate, greatly increases your odds of having said rock find its way inside you engine! As for the foreward facing scoop vs cowl induction, I have several Chevy friends (sorry!) who have raced factory Cowl Induction equipped Chevelles and Camaros, as well as aftermarket cowl hoods , and none have been able to document any performace gain on the time slips either. A Buddy took his old "Grump Lump" cowl scoop, and reinstalled the factory flat steel hood on his 76 Camaro, and it runs the exact same numbers. Considering how the air has to hit the windshield, do a 180 degree turn and downwards into the cowl area, then move foreward, and then do a 90 degree turn into the carb, I would have to wonder about the efficency of the whole cowl theory. But the only way to know for certain is to test it and see. Years ago, I tried a homemade ram air setup on my street strip 12 second Fairmont. I mounted 2 furnace floor outlet ducts under the front bumper, and rsan 3" flexible dryer duct hoses to a dual snorkle air cleaner housing. Again, no noticeable dragstrip improvement, but I did find a wide array of dead bugs, pebbles and chunks of tire rubber in the air cleaner housing.
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I think it's interesting that Dale and Rory haven't seen an improvement in ET with a fresh air setup, and I wonder if it has something to do with the fact that they race at a sea level track? For my part, I have never NOT seen an improvement with a fresh air package. The biggest improvement I saw was on my 69 Galaxie, which is admittedly a very slow car, but it went from 15 flat to 14.7 with the addition of a Torino Cobra shaker hood scoop. I guess all you can do is try the system and see if it helps...
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Sea level in the morning or less early season but generally can go over 2000 feet on a warm day. Not saying our combinations have been maxed out but much like a person trying to lose weight... the first few pounds are the easiest. Gains (or losses) after that are hard to come by. A shaker scoop does provide some intake and maybe with the longer hood on a 69 Galaxie that's a benefit. Don't know unless you try is a truism for sure.
And while we're on this subject.... I hate an otherwise good looking cars/truck with a monster scoop that are no where near being fast enough to even need a scoop. I might get mad some day and put my original flat hood on for a weekend just to see if the car slows down. My guess is it won't be by much.
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Sea level in the morning or less early season but generally can go over 2000 feet on a warm day. Not saying our combinations have been maxed out but much like a person trying to lose weight... the first few pounds are the easiest. Gains (or losses) after that are hard to come by. A shaker scoop does provide some intake and maybe with the longer hood on a 69 Galaxie that's a benefit. Don't know unless you try is a truism for sure.
And while we're on this subject.... I hate an otherwise good looking cars/truck with a monster scoop that are no where near being fast enough to even need a scoop. I might get mad some day and put my original flat hood on for a weekend just to see if the car slows down. My guess is it won't be by much.
Hah! You think that's bad? How about 4-door, 4-cylinder ricers running around with trunk-mounted wings that would put any Formula One racecar to shame!