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The Caterham CSRs and some of the Westfields (and probably others) have internal ductwork and exhaust the radiator air out a hole in the nose cone or hood, as opposed to out the bottom or sides.

Since the exit path for a 7's radiator air isn't noticeably obstructed, I was thinking it was mostly a styling thing.

I just realized that ducting out the top means less hot air against the firewall and down the tunnel, or underneath the car. Which would mean a cooler cockpit. (maybe not a good thing in England or Canada, but down here in Dixie, a big win) It also lets inboard shocks run cooler, for less change in damping rate from cold to hot.

If you have a cockpit heat problem in the summer, a radiator exit duct might help.

Another possibility might be a wedge shaped deflector behind the radiator to direct the radiator exhaust out the sides between the upper and lower A-arms. Lotus used a similar set up on the 25. IIRC, the wedge in that case was the oil tank for the dry-sump system.

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Mike - Read my story at http://twinlakesseven.blogspot.com/

Ducting rad air out the front of the hood is to reduce aero lift. A huge amount of the aero lift on most street cars comes from air piled up under the front of the hood and a lot of that comes through the radiator. Ducting it right out the top puts all that air on top of the hood and reduces front lift.

Almost all race cars and many street cars (I work at GM on the Corvette and it is a great example) do the same thing.

Alex

If you have a cockpit heat problem in the summer, I would suggest that you try house construction foam glued to the inside tunnel area and foot wells. It will reduce the surface temps by a good 25 degrees. DaveW

And speaking of which, are there foam sheets made out of something that doesn't emit all kinds of poisonous fumes when burned like home construction foam does?

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mobilito ergo sum
I drive therefore I am

I can explain it to you,
but I can't understand it for you.

I would think that the top radiator outlet on factory built Locosts, with modern engines of much greater high speed potential than the originals ever dreamed of, is at least partially to reduce lift on the front axle at speed.

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-Justin

"Orville Wright did not have a pilots license." - Gordon MacKenzie