Adding a little down-force

[Flibbie]

Effects are questionable at my cruising speeds but I like the looks. Jim

[Spaz]

That looks very cool, but it you need mroe down force, just hook up the trailer

[Hank]

Oh come on, you can't just provide 1 picture! I want to see a lot more than that! Any pics showing how far you went in? What material? Any angle of attack from the start of the diffuser to the back of the car?

[Flibbie]

Hank, I'll try to get my son to get some better pics maybe with a flash. The diffusers start at the frame member that runs across behind the seats. I put a floor up under the rear and the diffusers are attached to it. Material is scraps of ali left over from other body mods. Anodized dark blue. Jim

[Flibbie]

Hank, The front of the diffusers extend about 3/4" below the floor pan in front. That leaves me about 5" of ground clearance. At the rear they extend 4" below the floor pan and leave about 6-7" of clearance. They are 2' long. The angle between the floor and the trunk floor is 10-12 degrees kick-up. These pics are on the right side. Jim

Edited May 13, 2009 by Flibbie

[Flibbie]

The left side is mirror image of right side. Jim

[Hank]

Beautiful job, Jim. If you are truly concerned with aerodynamics I'm told the proper angle is 5 degrees upward from the front of the diffuser to the rear. They mentioned the 5 degree angle is good until 175mph. Anything above that and the angle changes for the salt flat guys (typically the only people to take advantage of it). I hope to get around doing this soon.

[jlumba81]

Did you also make a undertray for the engine compartment or just the rear?

[Flibbie]

The floor of the trunk was covered to allow for future baggage area. The diffusers were added just for looks. I've seen 120mph once. As I use back roads, 55-65 is perfect for me. The front has undertrays on both sides of the engine. As the engine and bellhousing extend beneath the frame they are not covered. Jim

[rotus8guy]

Downforce, maybe? But who cares, they look great! Nice idea.

 

jb

[jlumba81]

Does the front undertray affect engine cooling? I was considering an undertray when I get my 7 build underway as to help get a some downforce and maybe help w/ the drag. Might help keep a cleaner engine bay too by keeping rocks from bouncing up. Is the driveshaft also covered up?

[Croc]

That really looks nicely done.

 

At what speed does a diffuser begin to have some effect? Have you noticed anything from your casual drives?

[Flibbie]

Jlumba81,

I don't know if the engine bay undertray sides effect cooling or not. I removed the side panels (the panels around the headers) when it got hot down here about a month ago.I had considered covering the driveshaft but decided against it. The problem I see is that dirt and water can still get in at the front of the transmission tunnel. I'll try to post pics to explain better.

Croc,

My guess is diffusers start to effect downforce around 90-100. However, to notice a difference, I'd bet 150+ in needed. I've read the Elise diffusers contribute 4lb downforce. However, they never mentioned at what speed. I never expect to see any effect. I just like the looks. Jim

[7evin]

Beautiful job.... Since most people will be looking at the back trying to keep up ..

 

Cheers

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