Roof Scoop Options

I guess I should also add that this is only currently for when I run the car extremely hard or when the weather is very hot. When I first had the windshield done it would overheat very quickly under normal cool, average pace dune conditions so we added pusher fans to the front of the radiator also and that has worked good until i really push the car hard. 

So as of right now the car has 2 sets of 16" fans on the radiator that are set to come on at different temperatures.

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HydroPower said:
I guess I should also add that this is only currently for when I run the car extremely hard or when the weather is very hot. When I first had the windshield done it would overheat very quickly under normal cool, average pace dune conditions so we added pusher fans to the front of the radiator also and that has worked good until i really push the car hard. 

So as of right now the car has 2 sets of 16" fans on the radiator that are set to come on at different temperatures
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Can you get a picture of the part number on the fan sets?

 
Kraut_n_Rice said:
This.  Highly unlikely the most powerful fan in that particular size was used.
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This ... and how old is the radiator.  They tend to get less efficient over time due to corrosion and build up.  Its work, but often you can flow check and flush the radiator or replace it and see huge improvements, they always look good from the outside but not so good in the middle

Also Coolant wears out - you should change it every two years.  If iys not that cold (no freezing nights in the dunes), dump it, fiush it  and try water with water wetter for a trip. If that does not drop the temps by 15-20 degrees  you have a radiator of fan issue (bad thermo conduction)

Thats a way easier and better fit than trying to add scoops that may or likely may not work

 
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HydroPower said:
I guess I should also add that this is only currently for when I run the car extremely hard or when the weather is very hot. When I first had the windshield done it would overheat very quickly under normal cool, average pace dune conditions so we added pusher fans to the front of the radiator also and that has worked good until i really push the car hard. 

So as of right now the car has 2 sets of 16" fans on the radiator that are set to come on at different temperatures.

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Are they specifically pushers or universal pull/push?  If universal, did you reverse it to a pusher?

 
Airflow issues can be a bit unintuitive. I found my issue with streamers and a GoPro... poor mans wind tunnel. Don't assume it's lack of cool air. It's probably backpressure from turbulence. See what the air is doing at 40mph.

 
Goatpoker said:
Airflow issues can be a bit unintuitive. I found my issue with streamers and a GoPro... poor mans wind tunnel. Don't assume it's lack of cool air. It's probably backpressure from turbulence. See what the air is doing at 40mph.
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This is SO very true.

I learned that trick years ago when building Cobra replicas after meeting Carroll Shelby,  and have used it ever since.  Carroll Shelby and Pete Brock  tested the famous Cobra Daytona Coupe using Yarn and masking tape and watching the car go around Riverside speedway. People thought he was crazy, then he won the 1965 world manufacturers Championship with that car  - handing Ferrari his A$$   In 1999 they put his #98 car in the Wind tunnel at Northrop and found they could not really improve on the deign Pete Brock did in 1964 ,,,,  Hot Rod enginuity

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a drag race buddy taught me about the yarn trick.  K.I.S.S.

 
Something most people don’t know or understand. You can try to push as much air as you want, but if it has no place to go, it actually reverses and causes another negative pressure bubble and can try to push air back out. 

I learned allot about this after talking to Robby Gordon after he built the Dakar  Hummer/buggy and then the Gordini. What was learned on the Hummer did not translate fully to the Gordini. The windshield was laid back more on the Gordini and this causes a different pressure zone at the bottom of the windshield. They thought they needed to move the roof scoop closer to the windshield to grab the air going up the windshield. It was actually wrong, it actually needed to be moved back farther on the roof. 
 

Next issue was they had multiple ducts on the side back window panels, but these side ducts were not letting the air in to the radiator area like expected, even with the roof scoop pushed back. What was found after the first year at Dakar with the Gordini , was they did not have enough exit ducting to allow the air to get sucked out. Once they figured out what and where they needed the exit ducting, it became like a vacuum and was pulling air in much more efficiently. To the point they were not dependent on just the fans to pull the air through the radiator. 

Years ago I did a whole house fan in my house. The shutter door would only open 1/2 way. My issue was not enough attic vents to get the air out. Air was buffering in the attic. I added two whirly bird roof vents. As soon as I did that the shutters opened strait up and the air pulling into the house was insanely strong that it would slam doors. 

So back to your car. See how much room is behind the radiator & fans? How close are they to your fuel tank etc? Can you improve the air flow behind the radiator? 

Then fIrst test I would take some cardboard and make a 2 -3 inch lip around the front of the radiator. Just tape it on your aluminum body panels and see if that helps direct more air through the radiator, and not let it push away as air is going to find the least resistance. 
 

Just for kicks leave the windshield on, but remove your roof panel. See what happens? If you see a dramatic temp drop, then maybe some sort of roof scoop or deflector might be a way to go? It’s also interesting how air flow changes when going strait at 40mph or slightly turning at 40mph. 

 
Fullthrottleguy said:
This is SO very true.

I learned that trick years ago when building Cobra replicas after meeting Carroll Shelby,  and have used it ever since.  Carroll Shelby and Pete Brock  tested the famous Cobra Daytona Coupe using Yarn and masking tape and watching the car go around Riverside speedway. People thought he was crazy, then he won the 1965 world manufacturers Championship with that car  - handing Ferrari his A$$   In 1999 they put his #98 car in the Wind tunnel at Northrop and found they could not really improve on the deign Pete Brock did in 1964 ,,,,  Hot Rod enginuity

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Yes i think i will try the yarn and take the car for a ride on the street this weekend and see what the airflow is doing on the back of the car 

 
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