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Im going to be replacing most of the top end on this engine. Wondering if I should change this ram air out for an open air system. I have both so just wondering what u think the advantages or disadvantages of either would be?
Cooler, externally sourced air is almost always preferable as long as it is properly filtered from dust and dirt. How you go about that is largely determined by the degree of benefit you seek. If you are looking for a ram effect (performance), for example, it becomes a choice between some kind of hood scoop and a Thunderbolt type inlet. Given the fact that our favorite truck is something akin to a barn door aerodynamically speaking, I favor the Thunderbolt approach if only because it doesn't add to the total frontal area.
With the OEM intake, the air will be colder as long as it is all functioning properly. With the open air filter, you will have warmer air but there will be a lot less restriction. In my opinion, run the open air in the winter and the OEM in the summer. That's what I do.
99% of hood scoops are to far back on the hood to have "ram air".
Will it pull in cool air or just look good only testing will tell. The scoop could be in a low pressure area or worse a vacuum and cause other issues.
If you don't believe me look at what the bug shields did to air flow to keep the windshield clear. What kind of air flow would get to a scoop with the front hood lip only 6" lower
Dave ----
If you can find all the parts, Ford put factory hood scoops on their heavy trucks. I will warn you, these parts are hard to come by. I am literally in the middle of modifying and installing a set up.
Gotta attach this ducting to my air cleaner housing. Since the PO removed all the AC system, I might have to remove the evaporator housing to make it all fit.
Gotta make one of these to bolt under the hood. It will connect the scoop to the air filter housing.
Look how the scoop opening is placed, to the glass.
This is just like the Chevy cowl induction scoop.
They say the bottom of the glass is a high pressure area, air hits the glass and what can't go over the top of the glass & roof builds up there.
If it was turned forward it would not work as good because it is out of the air flow for the "ram air".
if you did not hook it up to the carb and just left it open it would let heat out went stopped, and maybe be pulled in through the cowl vent, or when moving push cool air into the engine bay.
Look at scoops on drag cars and see how high they are mounted to get ram air.
Dave ----
Ford started this scoop in 1958. This was the only year Ford had the scoop in the center of the hood facing forward. Too many complaints of snow clogging the scoop and rain water drowning the engine. In 1959, they turned it around and placed it on the passenger side. This fixed all the problems from 1958 and increased the air flow into the intake.
Im going to be replacing most of the top end on this engine. Wondering if I should change this ram air out for an open air system. I have both so just wondering what u think the advantages or disadvantages of either would be?
It seems like Ford was trying to anticipate both hot & cold environments by taking air from in front of the radiator and from around the exhaust manifold and then blending the two. My environment is such that, even in winter, the engine doesn't need any of the heated air. But it does benefit from the cooler air that avoids the radiator. This reduces the chances that the fuel in the carburetor will get too hot due to underhood temperature. Cooler air is denser than hotter air and should contain more oxidizer. My cool air intake remains intact. The heated air part is abandoned and blocked.
The blend of hot & cold was 2 fold.
1- the hot air when the motor is cold will help it run better till up to temp and keep the carb from icing.
2- see the vacuum hoses going to the factory lid? They are hooked to a temp switch.
This switch modulates the blend door to pull in the cold & hot air to maintain a steady temp.
It is easier to maintain smog levels when the temp is steady.
So unless you did something to the blend door to keep it from the N.O. to pull in hot air it is still pulling in some hot air when cold and modulating when motor is up to temp.
Dave ----
The factory setup is not that bad from a drivability longevity point. The warm air sped up warm up and the pcv received warm air instead of cold to dry out engine and kept carburetors from icing up.
I haven't yet seen anyone try to tap into the fresh air plenum to the rear of the hood and at the base of the windshield. I suppose that it could be blocked off from the cab so as to be for the exclusive use of the intake system.
Thank you all for your input. It has a slight overheating problem so I may just take off the hot air intake hose in the summer but use it in the winter.
I am switching to an aluminum intake to get rid of all that weight and have better flow. From my understanding, it should warm up faster but not get as hot on long trips. Should I use the hot air intake hose with that?
The performance gain you'll see by putting an aluminum intake on a low pro 351 will require a dyno with a micrometer on it to measure. if you think it sounds like fun go for it but if you're expected results spend the money on lottery tickets at least you have a chance there.
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