1940 fan shroud

[Kube]

Originally Posted by 19Fordy

Philip: I used a little sabre saw to cut the thin hardboard and then glued it in place. No bending required. I didn't have the heart to drill holes in top OEM grille bracket to secure the stainless piece.

Actually, if you do decide to use the panel, make one out of thin sheet metal like the stainless piece, paint it the color of your car so it doesn't look like an obvious add on. It looks better when you open your hood and don't see that stainless piece on top of your grille. You want it to blend in.
But, that's just my thinking.
I never did any before and after temp checks regarding the panel I made.

It would be neat to see a wind smoke tunnel test showing how the air coming thru the front grille circulates and flows through the radiator under the hood and then exits for new incoming fresh air. Wonder if anyone knows?

I did see a number of authentic (Ford archives) still photographs that depicted the air flow beneath the hood of a '40 deluxe passenger car.
It was very interesting.
The openings were engineered in to the air flow.
Makes me wonder if the pans some have installed in the front - hood actually hinder cooling.

[fortyfords]

My 40 coupe doesn't have any of the add on panels and it runs a cool 180 all the time even in traffic on a very hot day. The panels by the engine sides are not installed; previous owner told me that they wouldn't fit with the dropped axle but I haven't looked into that but maybe now I will.

[JayChicago]

Over heating usually occurs at low speed stop-and-go driving, when the fan is the only thing moving air through the heat exchanger. I don’t see how that aftermarket stainless deflector can do anything to help the fan do its job.

[G.M.]

Originally Posted by JayChicago

Over heating usually occurs at low speed stop-and-go driving, when the fan is the only thing moving air through the heat exchanger. I don’t see how that aftermarket stainless deflector can do anything to help the fan do its job.

Jay that deflector is not going to help. The only thing that helps is more
air flow. A fan blade with more blades at a steeper pitch really improve cooling at idle and stop and go speeds. These improvements along with a shrowd and water pumps that move more coolant through the system. With this you need
170 or 180 degree stats to adjust the temp. My 39 P/U with these improvements will run at a fast idle all day in above 100 degree outside
temperatures. Several people that are on this site were there when we
did the test. G.M. 39 generator with 2 heavy duty bearings.

[V8COOPMAN]

Originally Posted by JayChicago

I don’t see how that aftermarket stainless deflector can do anything to help the fan do its job.

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" way that works!

DD

[glennpm]

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I agree, you want all the maximum amount of air coming in the front side of the radiator.


Glenn

Originally Posted by V8COOPMAN

That deflector performs a function that is not obvious unless you think about it. ... That deflector prevents the fan from sucking already-heated air in the hood back across the top of, and back through the radiator again.
DD

[JayChicago]

Originally Posted by V8COOPMAN

That deflector performs a function that is not obvious unless you think about it. That deflector prevents the fan from sucking already-heated air in the hood back across the top of, and back through the radiator again.

I never thought of that. Makes sense to me. So I guess the deflector could be of some help at low speed and idle.

[19Fordy]

V8: Thanks for explaining the "Deflector Air Flow Theory". Makes sense to me. It would be neat to put experimental heat sensors in various locations under the hood to get readings at specific locations.

Under hood temperature sure is hot with car sitting in traffic.