Downforce / Aero question

[Jamesbe]

I have an FX Ireland which is basically an FE before FE existed. The chassis is virtually identical except for one body piece.

The sidepod floor is different. I've attached a photo of the side of my car. As you can see the sidepod floor has a "triangle" that comes out about 2 feet from the back of the pod close to the rear wheels.

So I'm wondering if those smarter than I think this adds downforce or reduces it? Or perhaps adds some drag or what.

My first thought is it adds a slight amount of downforce as it increases the flat area under the car and it may even create a slight vortex in front of the rear wheels which could reduce drag.

Thoughts?

[Jamesbe]

To be clear. This piece

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[phantomjock]

Aren't "Tire Shelves" like this one suppose to be "winners" in the downforce arena?

I think if the curve of the side pod is too quick (steep) you might get some separation and lose effectiveness -- at least in this picture.

A Gurney flap or VGs might get some back. Short of a tunnel test - some tufts, or pressure taps might help answer the question. Don't know if I helped - bet others might.

Oh, looking again does that pod flow straight through? More details please. Internal radiators?

At the least I'd think it is a PLUS as you'd get some downforce as it would act like a "shelf."

Cheers - Jim

[Jamesbe]

Pods do not flow straight through. There is a rad in each pod yes.



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[Purple Frog]

Since you are not running it in SCCA as a FE class car..... Put a diffuser on that car!
Increase the downforce with less drag than the rear wing, which you would be able to trim out.
I'm guessing a late model VD diffuser or one off a Firman with bolt right up with a little modification.

Always thought the FE needed a proper diffuser. But i understand its a spec class and they wanted to eliminate that cost.
They just look like they lost their bloody diffusers somewhere out on the track.

[problemchild]

Aren't "Tire Shelves" like this one suppose to be "winners" in the downforce arena?

That treatment is reducing drag by managing the airflow that is being backed up by the tire. The shelf is trying to reduce that air trying to get under the car and mess up airflow under the car.

Undertrays/diffusers are consumable items that need continual maintenance and are a PITA for any other service work. I would never add one to a track day car unless I had a problem that absolutely required it, and I would attempt to solve that problem by adding more wing instead.

[Jamesbe]

I would like to add a diffuser it is on the list. Thanks for the info, maybe I can find a used VD one.

This part doesn't really get in the way of any maintenance, it's the side pod floor just extended.

Here it is broken, I'm currently repairing it.

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