333pg333

Nice work! So you are thinking that by not having the open header panel that the air coming in from the underneath and ducted / vented upwards, will then move more easily through the vent in the hood? I'm inclined to think that having the open header slot is too good to not take advantage of being so close to the i/c or radiator (depending on setup)?

reno808

DUDE U DID THAT IN MS PAINT???????????????

NeoRules

What the heck is air stall? and why does the angled IC cool better than the flat one?
I am out of my league here I know....
JC

x944turbo

There is a article in September 2007 issue of Racecar Engineering That explains Effective ducting to a racecars cooling system that makes the efficiency of the radiator greater and at the same time having little to no drag caused by the mass of the cooling system.

Its says the fresh cool air that flows into the inlet is heated by the core of the cooling system (radiator). Once the air exits the outlet, which there must be an outlet by the way, it is charged energy created by the rise in heat. This heated air exiting back into the slipstream was considered thrust. Not thrust as in pushing the car forward but thrust as in change in temprature reducing drag.

So the question " Does heating air with a convetional radiator matrix offset drag?" Keep in mind that most if not all production cars arnt really designed with an outlet for the radiator, so the article was mainly using a well designed racecar as an example (i.e. indy, F1, cart), Although it does show an example of the Prodrive Ferrari F550 GT for its cooling system.

The design looks somthing like this

x944turbo

Ill see if i can scan the pages an post them on here. Its a very interesting article.

And i think some the ideas will be usefull in the ventilation we are looking for. "Can anyone spare a windtunnel"

Spidey944

On the DP, we used a nose inlet for the radiator, and had an opening right after the radiator that followed the contours of the hood right before it reached the cockpit/windscreen area where the driver sits. We only used the noses with the opening on the high downforce tracks because of it's ability to do what was stated above. On the low downforce tracks, we used a nose with no opening. If you want to see what I mean, go to www.grandamerican.com and look at the race pics from a track like Daytona, and the pics from a course like Mid-Ohio. The nose sections on the cars are different.

sweanders

Air stall can be found on almost all cars very easy. Drive in light rain and at certain speeds you can get the water drops to stand still on the windscreen.

333pg333

Thanks for your input here X944turbo, although I'm a bit puzzled by the illustration . It says above view, but I don't quite get it? Is it a cross section view? I imagine that the thing in the front is the radiator? Sorry, a bit lost.

Trucho-951

Looks like only the passanger side of a car, and "the thing in the front" is the front axle, with only the passenger front wheel attached.

333pg333

Ah, so they are side mount radiators on an open wheeler?

Guns951

Right Patrick, its the top/angled view of a Formula car showing entry and exit of the side pod radiators.

Guns951

One more thing is that, if you notice in the illustration that the radiator is angled inward. This is done because back in the day, when they tried the whole ram air effect and found it was causing cooling problems and bad flow through.

With tilting the radiators inwards they found that the flow rate was increased significantly and drag was also reduced. Also the exit ducting on the radiator is what aids in "pulling" the air through the cooler.

That's what I think Patrick is trying to do, is not force air through but rather create a low preassure zone behind it so that the radiator or IC will have air pulled through it.

Great example of air stall: have a buddy drive a car at 25 mph, stick your head out the window with your mouth wide open in the air stream and try to breathe...notice how difficult it is? Sometimes the air stalls in your mouth and will cause you to feel like you can't breath.

If you close your lips more and just have a small opening you can allow the air to enter your mouth and you won't have trouble getting the air down your throat because it has a place to expand, slow down, and the air will have a chance to straighten out a bit so the flow rate can be increased.

azmi951

Great explanation Guns.

Fluid dynamics is a nonlinear science, meaning it is not a logical progression from one concept to the next. This makes it EXTREMELY difficult to just make something that works without testing. I think the best bet is to get book devoted to calculating this type of flow in these conditions. The name of an outlet like on the 968 T RS is either a parallel flow diffuser or a parallel plate diffuser with tripped flow. It will have to be a very specific book to be of any use. I do also believe that there is a lot of potential to increase the efficiency of the heat exchangers and I also think the right place to start is on the outlet side, not the inlet since the inlet is pretty well optimized from the factory.

I need to pick up that Racecar Engineering rag, I love reading that stuff.

billthe3

Why not do something to the extent of the C6R/ALMS GTS cars with the large duct behind the radiator to create the low pressure spot? It obviously won't work nearly as well on ours cars since our motor isn't as low as possible and 6" into the firewall, but the basic idea would seem doable (if you aren't running a stock airbox).

Guns951

Bill, that's basically the setup I'm working towards as it is pretty much ideal - however to get the room required to do this successfully, you need a partial tube frame/the ability to slant the radiator forward and a hood & header panel combo that's one piece as that vent needs to go right where the hood/header panel seam is.