Upper air deflector installation

JayChicago said:
Don't most overheating problems show up in stop-and-go driving, not at highway speed? Isn't this deflector going to be effective only at speed? I don't see how this deflector can help the fan pull more air thru the radiator when idling at a stop light.
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Below is a COPY/PASTE of a dissertation that I put up here on the forum in August of last year, describing what the "Front of Hood" deflector does to aid cooling on a '40 Ford. In fact, it was in reply to a post by "JayChicago".
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That deflector performs a function that is not obvious unless you think about it. The fan pulls air through the radiator which hopefully carries heated air out through the two openings at lower rear of engine compartment. Air is just like electricity in that it is 'moved-around' via high and low pressures, and air also takes the path of least resistance. The fan creates a low pressure situation to draw COOL air in through the radiator, which of course absorbs heat from the water. The back side of the fan pressurizes that air, forcing it across a hot engine which must heat the already warm air to SOME further degree, and on toward the rear of the engine compartment looking for a way to escape.....the path of least resistance. Some of that air hits the firewall and bounces upward and forward up into the hood cavity. That big hood cavity is full of hot air that moves forward, because it is also being affected by the vacuum of the fan sucking air from the grill area, as well as HEATED air that can come forward OVER the top of the radiator, and back down into the airstream being sucked through the radiator. That deflector prevents the fan from sucking already-heated air in the hood back across the top of, and back through the radiator again.

Of course, there's one guy who figures that deflector doesn't do 'squat', and that HIS way, as usual, is "THE ONLY Way" that works! Click the link BELOW to find out what this 'nay-sayer' had to say about MY theory. DD


https://www.fordbarn.com/forum/showpost.php?p=1922505&postcount=24

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V8COOPMAN said:
Below is a COPY/PASTE of a dissertation that I put up here on the forum in August of last year, describing what the "Front of Hood" deflector does to aid cooling on a '40 Ford. In fact, it was in reply to a post by "JayChicago".
___________________________________________________________


That deflector performs a function that is not obvious unless you think about it. The fan pulls air through the radiator which hopefully carries heated air out through the two openings at lower rear of engine compartment. Air is just like electricity in that it is 'moved-around' via high and low pressures, and air also takes the path of least resistance. The fan creates a low pressure situation to draw COOL air in through the radiator, which of course absorbs heat from the water. The back side of the fan pressurizes that air, forcing it across a hot engine which must heat the already warm air to SOME further degree, and on toward the rear of the engine compartment looking for a way to escape.....the path of least resistance. Some of that air hits the firewall and bounces upward and forward up into the hood cavity. That big hood cavity is full of hot air that moves forward, because it is also being affected by the vacuum of the fan sucking air from the grill area, as well as HEATED air that can come forward OVER the top of the radiator, and back down into the airstream being sucked through the radiator. That deflector prevents the fan from sucking already-heated air in the hood back across the top of, and back through the radiator again.

Of course, there's one guy who figures that deflector doesn't do 'squat', and that HIS way, as usual, is "THE ONLY Way" that works! Click the link BELOW to find out what this 'nay-sayer' had to say about MY theory. DD


https://www.fordbarn.com/forum/showpost.php?p=1922505&postcount=24

.
Click to expand...
great theory and explanation !
 
V8 Coopman
I had forgotten about that interchange a year ago. What you are describing seems to make sense. (at least it seems logical) I can see how the big hood on a 39 or 40 could allow recirculated engine compartment hot air to get in front of the radiator, and that aftermarket deflector could prevent it.
 
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