Potomac-Greg

I had my first track day since fabricating my belly pan (from what may have been at one time a 30 MPH sign). I made it a solid sheet from radiator support to the aluminum subframe.

First session, first day (at New Jersey Motorsports Park, Thunderbolt track) I saw temps go up almost to the red line. I immediately suspected my belly pan and took it off. Temps were significantly lower after that.

I was able to check out a belly pan on a 944 Turbo that was at the event, and it had multiple vents cut out between the radiator and the engine, so that's going to be one of my weekend mods -- cut some vent holes.

Otherwise, it was a wonderful, trouble-free, two-day event where I was able to catch and pass some very powerful and pricey hardware.

m73m95

Not only are they holes, but the are angled to "suck" air out from the engine compartment.... louvered if you will.

racer

Why don't you just locate a stock one? Or run without one?

ritzblitz

Vent it and try again.

944CS

there is one in the front that is a scoop and not a louver

Potomac-Greg

I am running without one now (and did so for years). I assume they exist for a reason. But they are fairly hard to find.

FRporscheman

It's funny, most people that have one toss it aside. When someone doesn't have one at all, it's hard to find.

I think the vents are there to allow air to exit the radiator, otherwise there won't be a good flow of air through the radiator. But that's just my guess.

ZR8ED

The metal (ahemm...) that you are working with is a bit thick. Go pick up some thinner stuff. I think I used something in the range of 30 thou thick. Easier to cut, shape, bend etc. If you have a good picture of what a proper tray looks like, you could copy the slits in the pan to make vents that will draw out the air properly.
As for the forward pan directing air into the rad (I've never seen one, so I will take your word for it) Ducting the front of the car to direct air into the rad is a good idea. I have done extensive work like this on my 280Z with noticeable benefits in both cooling and handling

Potomac-Greg

The "municipal" metal is aluminum and while thick, still fairly easy to work. I'll cut some vents and even leave some louver material to draw air out. I agree that the radiator air flow would be greatly improved by some sort of deflector or scoop up front.

M758

When formed properly the under trays work really well. Less drag and better radiator cooling.

Here a photo of my stock on and you can see the louvers.

Campeck

Yeah. You want negative pressure behind the radiator in comparison to the front. Louvers help achieve this.