sweanders

You need to place the exit-air vent at a low pressure zone.

From Utzon.se:

333pg333

I very much like the look of Corleone's front as it offers max inlet for cooling, combined with the vents on that 924 should increase efficiency greatly.

333pg333

Yes some hood vents in that position, but I'm also thinking that they will mostly only help the i/c and radiator. Some more outlets further back as shown on other cars in this thread. In fact I wonder if another inlet before some more outlets wouldn't be better again. Bring some cool air into the hood and exit the hot air further back?

gt37vgt

confusing the low pressure areas seem to be marked with higher numbers so further back is better?
and no high pressure at the back of bonnet due to the racked back screen angle. a directional vent will work anywhere in the bonnet mine are like gills recessed in to the bonnet

pete95zhn

Numbers increasing from front to back are measuring points which correlate to the graph. Negative markings in the graph mean underpressure and positive overpressure. Cuttings feeding air into the engine bay should be in the positive pressure zone ( like from 2.5 to 10, except position 8 ), where air rams in and hot air vents in underpressure zone ( from 10 to 17 ), where underpressure sucks air out.

BTW, according to this graph nose panel vents are functional...

gt37vgt

cool thanks pete makes sense now so position 12 is the ideal point of hot air extraction witch is a handy spot relation to the back of your front heat exchangers

333pg333

Are these pressure points taken all from outside the car? In other words they don't necessarily have a 100% relevance once you start venting air out from under the hood. That may change those numbers?

x944turbo

This is the hood design i was thinking of going with.

It has inlet for intercooler through the nose panel with an exit through the front of the hood. Also the heat extracter luvers placed at the back of the hood but before the firewall. One set of luvers will be place over the headers and the other over the turbo.

Let me know what everyone thinks!!!

gt37vgt

well it appears there is a mild positive pressure zone at the rear of the hood as a wake of the windscreen so it would perhaps work against your louvers ..
these bonnet vents can often reduce the lift created by the bonnet for better front grip.

x944turbo

So in theory, If you create your inlet vents in the #9-14 pressure zones were the pressure is high, and the outlet vents in the #15-20 pressure zones were the pressure is low then you would create a more even "pressure vs. vacume curve" across the front of the car. This may create the flow of ventilation we are looking for. the hood design above kindof fits that theory.

reno808

x944turbo do you have a picture with the louvers on top of the turbo and headers added to your pic?

333pg333

Sorry to steal your picture and I do like it, but I am thinking why can't we have some dedicated air coming into the engine bay itself and then some exit's further back. Excuse the crap diagram, it's hard to draw with a mouse!
Also does anyone have any links to where you can buy aftermarket louvers and vents?

gt37vgt

please don't encourage him 6 holes in such a nice car is really out of control
yes you pat

333pg333

Heheh, I know it looks like a dog's breakfast, but I think it could be done pretty neatly and I still think it's a good idea Adam, don't you? I mean why shouldn't there be cool air coming into the engine bay itself. I can't see why not? Remember this would be on the c/f hood. If I want to I can switch that on and off for the road and track.

gt37vgt

well because it increases the engine bay pressure and therefor decreases the pressure differential across the heat exchangers in the front of the car .
it also promotes lift . and ruins the control the cooling system has on temp.