Rear Downforce Wing

I've reached a point with the car where it's becoming obvious that I need a rear downforce wing. If I up the boost just one psi, the car fishtails across the finish line. Bring the boost back down that one psi and the car sticks and is a joy to drive. It's time to build a rear decklid wing.

Anyone out there have any experience with this, and can you add any design points to avoid? Any trick features to add? I want the wing to turn out bitchin. Any pictures of great spill plate designs that work with the body lines of our car welcome.

Just a quick note Don, RJ Racecars (Quartermax) sais the rear wing should be level and not kicked up as you would think. No longer than 14". Id get a pro stock style wing from them or from a few differant vendors in National Draster. I think that would look cool.

Craig

Thanks for the tips. Yes, I was thinking a Pro Stock style, hinged so that the wing could be fine tuned. I understand flat is the preferred position.

Don, if you are having issues at the point you are, your chassis is screwed up big time. We (as well as many others) have NO ISSUES with the car getting loose on the big end running WAY more MPH up top. My car is as stable as can be up top. I am not even considering a wing on the back of my car and with Dave F and Tony G going mid 170's just goes to prove this.

I would look into other things first.

Just my opinion.

I think my problem is that the car is starting out the first half a lot slower than what you guys are doing. The car isn't up to speed when the big numbers hit and the tires are slipping. If the car had a better first half and didn't have to make up as much on the second half, it might be a different story. What mph are you guys doing by the 330 mark? I'm at only 91 mph.

I thought about a rear diffuser that goes under the car. Something to block off all the air that gets caught in the truck area for cars without the stock fuel tank. .02

You bring up another interesting area. Ground effects. I suppose it would help a lot to extend the front air dam, and what about skirts along the rocker panels? The diffuser idea sounds real good too.

Due to my rear axle, wheel and tire arrangement lowering the car is out of the question.

Thinking about the diffuser idea. What about a triangular shaped diffuser set before the rear tires, directing the air out at the end of the rocker panels? The bottom of the triangle blocked off to simulate a solid and to prevent turbulence of any air that got under the front edge of it. I could mount it easily along the X frame member with the front point starting at about the end of the transmission.

You could try making the whole bottom of the car flat. I think Saab does that and they also incorperate "dimples" so the air moves across the bottom of the car easier resulting in a vacuum effect. I have the plans in my head, its just a matter of finding time to get a car on a lift and doing it.

Donnie, do you have a FG rear bumper? Next question would you mind cutting it up

The rear bumper is FG. What idea do you have?

I'm going to try and draw something up Donnie, I'll post it up when I get done (hopefully sooner than later, it sucks trying to draw with a laptop touch pad )

Ok Donnie here is a quick sketch I made. This is not drawn to scale first and formost . The light blue line would be the trunk pan, the dark blue would be the airflow, and the red is obviously the diffuser :biggrin:. The solid red peice would be a vertical diffuser (kindda like the rear of a Ferrari).

That would work good on a car that's lowered, but what about a car that's not lowered. Controlling the air would have to start much farther forward.

You could bring it lower to the ground. Like I said "Not to scale". Just an idea Donnie. I know you think outside the box, so I figured i'd toss one out there for you :biggrin:

So then what do you do with the air that is coming through the engine
compartment via the grill?

I'm thinking of partially blocking off the grill. Block it off from behind the grill with a flat black paint to make it a stealth block off. Leave a small opening so the air filter can pickup fresh air.

Any air that does collect in the engine bay will travel down around the transmission. There it would get caught up by the triangular air dam and be directed out the sides of the car before the rear tires. An air dam could extend down along the rockers starting behind the front tires and ending about midway back to leave an opening for the air that would be directed out the sides of the car by the triangular air dam.

I appreciate the help. Believe me, all ideas help out a lot.

With the pointed air dam directing undercar air out the sides of the car in front of the rear tires, I wonder how much it would help to blow loose dirt off the track surface for better contact?