Pancake Fan on Rear Clip

Ron Earp · 06-01-05, 11:38 AM

Anyone run a slim line 1" thick 12" diameter pancake fan on the inside of the rear clip blowing out through the metal grill? Seems this might help with heat build up, especially for those cars with the AC condensor in the rear comparment. Some cars have little space to make this happen, but some do have space. If anyone has photos of rear clip ventalation I'd like to have a look.

Ron

BenL · 06-01-05, 12:58 PM

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Anyone run a slim line 1" thick 12" diameter pancake fan on the inside of the rear clip blowing out through the metal grill? Seems this might help with heat build up

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Didn't Jim Hall do something like that in the 60s with his Chaparrals? I think he claimed that the fans were there to cool the engine. [img]/ubbthreads/images/graemlins/smile.gif[/img]

You can see a couple pictures of what the fans looked like on his 2J cars at:
http://www.autoweek.com/files/specia...parral-130.htm

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A few years ago, I encouraged my father to put a pair of small 12V "muffin" fans from a PC on the intake of his Lotus Mk IX to provide cooling at low speeds. They're nice because you can get a really quiet ones and you can locate them so they're not easily visible.

Would it be possible to hide muffin fans in the ducts by the rear wheels?

Ian Anderson · 06-01-05, 01:22 PM

Ben / Ron

How about fitting the fan/s on the rear of the clip either side of the exhaust on those outlets?

My theory is thet they could be fans between 6 and 8 inch and not be so space restricted.

Also to put a fan directly above the exhaust would put the plastic bits in a pretty extreme heat area - unless the fan will run on after the engine is turned off. Yes it's possible but more wiring and electronics!

Just my 2c worth

Ian

Bill Musarra · 06-01-05, 03:04 PM

I am planning to add 2 small fans on the two rear screen areas for cooling of the oil and the trans fluid. I haven't reached that stage yet but I do have the hardware for it. If you look at the MDA cars you will see one on the left rear and its long support bracket. I plan also to have an oil accumulator wich will be mounted on the rear clip support on the left. It will be kind of crowded with all the lines and equipment, but I have a lot of requirements for my car. When I get the rear clip back from the painters(repainters) I will mock it up for pics.

Bill

Mike · 06-01-05, 09:02 PM

I have 2 Derale 7"/400cfm fans for the vents beside the exhausts. They're 2.55" thick and fit perfectly. They're available from Summit (at least) part#DER16507, list $67.88.

Howard Jones · 06-02-05, 10:30 PM

In order for a fan to draw air ACROSS the area to be cooled the inlet zone must be on the other side of the heat sorce so that the cool air flows across the heat sorce and out thru the fan. In the case of the engine room the air inlet is the entire bottom of the car along with the "airbox" side vents behind the doors and any other leaks at the front of the engine.

The problem is the fans will draw air from the closest sorce and the air flow will be the shortest distance possible. This will be the area directly in front of the fan. The resulting air flow path would be up from under the car directly in front of the fan, thru the fan, and out of the car.

This would not be of much help cooling the top of the engine room in the area of the top heat vent where all the heat is comming off the headers.

Drawing a large volume of hot air out of the top of the engine room, with the resulting air flow comming from the bottom of the car, across the headers and out the top might be a better solution. To do so would require mounting a fan over the rear clip top vent.

The fan and the fan motor would need to be able to stand very high temps in this location.

The Hall CANAM cars had the bottom of the car sealed with skirts. This caused an low pressure area to be developed below the car with the resulting down force.

A better example would be the Lauda Grand prix car that was run in Belgium in 1979. This car ran a huge fan off the back of the gearbox. The airflow was down thru water radiators above the motor from vents in the bodywork above the Flat 12 that alfa was using it that car. Then out the back thur a big hole behind the gearbox. The bottom of the car was sealed with skirts. The big lie was this wasn't a moveabe aerodynamic device, but was a engine cooling fan!

If I remember right it ran at engine speed and was about 24inchs in diameter!
I bet that fan had to consume 50hp!. As the revs went up the car was sucked down to the ground so much so that when he hit it in the pit lane other teams began to complain about violating the min ground clearance rule. Nicky didn't like the fact that he had to put the car in neutral, break the car, and hold the revs up at the same time into and thru a corner or all downforce was lost at just the time he needed it. The other drivers didn't like the setup because it tended to pick up EVERYTHING off the track and shoot it out the back at about a millon miles an hour right into their faces if they tried to pass him.

Mario hated it because it was FAST and he lost the poll and the race to lauda.

Oh and after Lauda won that race, the car was banned for the next race, and Mario went on the win the title.

Bill Musarra · 06-03-05, 07:21 AM

You could always do what the Lotus Turbo Esprit does and put a fan above the exhaust and blow the exhaust heat out the stainless cover on the rear clip. All you need is a thermostaticly contolled switch. Since it is covered with stainless, you wouldn't have the problem that Lotus had with the fiberglass showing fine stress cracks.It doesn't have to be a high volume fan, just one that keeps the air moving. With ceramic coatings or stainless, the heat would be disapated quickly and would not be a big drain on the battery.

Bill