Air extractor

[XJguy]

Free down-force (lift reduction), free drag reduction, as well as free increased engine cooling.

[Otto]

Sounds good, but how does it get reduced drag? Car rides lower at highway speed, so less frontal area?

Otherwise, I may put a hinged panel aft of the intercooler on my Porsche 944 Turbo, for the same reasons--extracts heat from engine bay and lets IC get more cooling air through its fins.

[Otto]

PS: You could use your cut out pieces and hinge them at the leading edges of those holes. Airflow over the nose + internal pressure beneath would lift them and extract air at highway speed, but lay down to keep rain out when parked. Radius the internal duct edges.

PPS: How'd you make a nice, clean and conformal cut into the sheet metal? Router + template?

[XJguy]

Originally Posted by Otto

Sounds good, but how does it get reduced drag? Car rides lower at highway speed, so less frontal area?

Otherwise, I may put a hinged panel aft of the intercooler on my Porsche 944 Turbo, for the same reasons--extracts heat from engine bay and lets IC get more cooling air through its fins.

Normally air entering the engine bay has to contend with working its way around the engine and its parts then hitting a firewall then going under the car.

By allowing the air to leave from the radiator out of the hood you reduce the amount that gets parachuted in the engine bay.

The pieces I cut were actually folded down to act as scoops/guides.

To optimize this design I would need to angle the radiator to a more horizontal position, and seal it off completely to those vents. Even so the amount of air that comes out from my vents even at idle is huge.

Most front engined enclosed wheel race cars have this setup in some form or other.

Flap would not work as well. Notice at the leading edge I incorporated a gurney flap, that further helps evacuate the hot air; creates a low pressure area behind it which helps suck the air out. It also prevents any air from coming in instead of out.

How: Lots of measuring, tape of areas, cut off wheel, touch up edges. But a reciprocating saw might work better.

[Bill in Houston]

under hood pics!! is the radiator somehow ducted to the vents? have you tested with yarn to make sure of the direction of the airflow at speed?

[euromodder]

Hucho has this sort of set-up in his books.
Grab air from the high pressure zone in front of the car, lead it hrough the radiator, and exhaust it on top of the hood.

If I'm not mistaken, Vekke built something similar on his Seat.

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