Ducting the Engine Compartment

[Al Keller]

I've searched the Hybrid Z archives and am more confused than when I started. How do you get the hot air out of the engine compartment efficiently?

I'm trying to:

1. Keep the engine compartment cooler.

2. Keep the interior cooler.

3. Help reduce air build-up/lift under the front of the car.

The car will have a G-nose with air dam, ducting to funnel the air thru the radiator, 2-11"fans to pull air thru the radiator, an L-88 type air scoop to help feed air into the carb air box.

Would it help to remove some of the inner wheel well? Maybe C5 Corvette style side vents behind the wheel well?

HELP!!!

Thanks,

Al Keller

[johnc]

You have two things to think about when venting the engine compartment: Car stopped, car moving.

 

Car Stopped

 

Hot air rises. You need openings in the hood to let the hot air rise out of the engine compartment. If you can build chimneys from the exhaust header to a hood opening (a la Aston Martin Vanquish) that will really reduce compartment heat.

 

Car Moving

 

Generally you have a low pressure area under the vehicle so directing air in and then down behind the crossmember is effective. Move the air past the hottest parts of the engine (the exhaust header).

[Al Keller]

John,

Thanks for the reply.

1. At rest - were should the hood vents be located? In front, in back, half way, would it make any difference?

2. Moving - If I wanted to "pull" the air out of the engine compartment, how should I do it? What does pulling the hot air out of the compartment to the low pressure area under the car do for the aerodynamics of the car (i.e. lift)?

I just found some more threads in the "high tech" section. Maybe there will be some ideas there.

Thanks again,

Al

[Guest Carlissimo]

Look at the hood as a big wing flying thru the air. Because of its curved shape, it acually creates significant lift and thus low pressure on the top surface. The largest low pressure area should be forward of the halfway point, probably just forward of the front wheel axle. (The lowest pressure on a wing is around the 25% chord length)

 

If you look closer to the cowl at the base of the windshield you actually get into a high pressure area caused by the rake of the windshield. Because of this high pressure, air in this area will tend to flow the other way, down into the engine compartment.

 

In between you will probably get no flow at all.