aeromodding del sol track car
 

Well this isn't exaclty the forum for talking about race cars, but at least my race car uses less gas in an 8-hour training day than a corvette uses in a 40-minute track session.

My Del Sol has some good mods, but none of them are power-mods. I have a high-gear ratio tranny that is crap for acceleration, and a small motor. D16Z6 for those of you that care. Due to lack of power, i figure .CdA is the place to tune this car.

The profile of a Del Sol is aerodynamic-vomit. So far I have used the advice of this forum to make a "garden edging air dam" that extends my bumper 6" closer to the ground and I've installed a coroplast partial undertray (from firewall back with a gap in the middle for exhaust). It also has a 1-piece fiberglass hood/fenders/bumper that is wonderfully smooth and has fender flares to reduce my wheel turbulence.

My next intended step is to turn the car into a fast-back with a piece of flexible lexan. I am hoping to create a profile that matches the curve of a NACA aerofoil as described in another thread about rear window curves.

After that, a rear diffuser to smooth the flow around the gas tank and my incomplete rear-end.

Also possibly garden-edge side-skirts.

Any suggestions re: fastback design?

Post up some pictures of the rear end so we can see exactly what you're talking about. Sounds like a good idea. I dunno how much it'll save you on the track though. What is your top speed?

This is not roundy-round racing, this is the kind where i turn both ways and have to use the brakes and shifter. :p (poke to all the rounders out there)

My MINIMUM speed at the next track I'm going to will be about 70-80km/h. Maximum, i'm not sure, but over 150km/h. I've never been there.

I'm trying to figure out how to add a picture right now...

ok, this is my best profile picture. I have an over-sized picture of a closeup of the back end. The back of this car is not stock, when i bought it, the front and back were sawwed off of it and it had to be custom built.

I think your best bet is to do what you said. Follow the standard teardrop shape and make a type of kamm back similar to what Metro is doing right now.

Would a curve from the roof line to the rear edge be too steep to promote attached flow? I'd try to come off the roof flush, rather than a sharp angle, then i'd curve it down to meet the rear edge.

I suppose if it is too sharp i'd have to have it raised from the rear edge and try to continue it farther back.

It does looks too steep. Overlay the teardrop on your car like was done in Metro's kamm back thread. That'll give you the profile you want.

I will see if i can get ahold of photoshop or something... unless some kind, bored, ecomodder would like to superimpose that for me :p

Was the shape from his thread considered the "maximum slope to allow attached flow"?

Well, I can't seem to get my Photoshop installed but I did some quick paint comparisons and it's pretty close, you might need to bring the back up an inch or so, I'd measure the height from the ground of the tail then the height from the ground of the roof line, measure the distance between them and do some trig to find the angle would be one of your best ways.