question about drag racing

[BEEF]

I was wondering about some of the aero they use on drag cars and applying it to mine.

some drag cars (top fuel cars) have a parachute on the back. right above the parachute is a lip on the back of the car that extends a good 8-12 inches past the back of the car. is this protection for the parachute or is it aero?

I saw a while back where someone had added a piece of plexi-glass to the back of the car using really strong magnets and was getting better FE.

I was thinking that I could cover my entire trunk lid and leave enough material to over hang the trunk by about 8 or so inches. use maybe 1 or 2 screws to hold it down (along with double sided tape for the perimeter) paint it white and that way my trunk is still functional.

if this is stupid or won't work, someone let me know before I make my car look really funny for no reason. I don't know a lot about aerodynamics so I am really reaching out there with this one.

thanks

[RoadWarrior]

Should work to detach air cleanly from the rear of the car. Some might have it angled a touch if they need downforce on the back. Probably don't really need more than about 3 inches for it to be effective.

[bobc455]

I can't address the aerodynamics of this piece, but I suspect it is irrelevant. In drag racing, aerodynamic drag is essentially irrelevant anyhow. (Aerodynamics does play other roles, such as creating down force, but the aerodynamic drag from those items will not really affect ET or MPH - even over 200 MPH).

-BC

[BEEF]

roadwarrior,

I have a spoiler on the car now (factory) which houses the 3rd brake light. my trunk actually slopes down and the spoiler sits above it. I was thinkin that by puttin the plexi over the entire thing would make it sit almost completely level.

would you think that more length would be better/worse/not matter at all?

bob,

the fact that is in drag racing wasn't that important other than the fact that I could relatively easily depict it that way (didn't know how else to describe it). I had hear of people doing things for air separation. I thought about removing my spoiler and leaving it at that but that would leave my trunk with an easy slope downward to my bumper (which I have heard is bad). it was just a thought and I am playing around with the idea because it would be relatively inexpensive and simple to do.

[Curly1]

The spoilers and wings on Top Fuel and Funny Cars are not for aerodynamics they are fro down force. The wing on a Top fuel car is supposed to put 7000 lbs of downforce on the rear of the car to keep the tires from spinning. Even at 330 MPH and 7000 lbs of downforce they can still blow the tire off if the clutch comes in too much. They have some awaesome power.
Now Pro Stock spoilers may be more for aerodynamics?

[BEEF]

curly,

you're right. I got the cars wrong. I did mean the type on pro stock cars. that was what I was trying to portray, not the wings that give downforce.

they come straight and level out from the car about a foot, no angle to them (or at least not much of one).

[skale7]

It doesn't seem like it would create much downforce, I'm guessing it would help with aero a bit? I cannot say, I don't know enough about the subject to say for sure.

[theholycow]

A picture is worth a thousand worms...isn't that the saying? :D

http://images.mustang50magazine.com/featuredvehicles/p66050_large+1998_Ford_Mustang_GT_Pro_Stock+Rear_S poiler.jpg

[BEEF]

that is exactly what i am talking about though mine would be more flat and not with the upward turning lips on the sides of it.

thanks cow man

[BEEF]

this is the area in question. I have also been giving thought to a cam back for the back glass. the aero on my car is actually pretty good to start with

[Curly1]

Yes I think the rear spoiler on the Pro Stock cars is only for aerodynamics. On Pro Stock I do not think any down force is needed. Most of their traction problems is in the first 60 feet unless they get out of the "Groove".

I would like to know if the little flat spoiler on your car helps or hurts the aero on the car. I know it would not be a huge difference but many factory style spoilers actually hurt mileage and top speed. I am considering putting a similar one on my HHR but will not do anything that may hurt it even if it is only just a little. I would not want to spend $250 dollars to lose 1/2 MPG.
I like the way it looks so if it is better even marginally I would put one on.

[RoadWarrior]

On an HHR you probably need a "whale tail" halfway down the back and a deflector up top.

[BEEF]

test of pic
http://i38.tinypic.com/fbx6hj.jpg

bam, it works

[DRW]

Here's more pics showing a Ford Fusion going for a record top speed at the Bonneville salt flats. It also has a flat extension attached to the trunk.

www.autobloggreen.com/2007/08/16/ford-hydrogen-fusion-999-runs-207-3-mph-at-bonneville/

You could also do some tuft testing on your rear window to see if airflow remains attached all the way to the back, or if it separates before the spoiler. This would be easy to do since you could see the tufts in the rearview mirror while driving. Just use a few pieces of string 5 to 6" long, and duct tape them in various locations.

[BEEF]

yea, I kind of dropped the idea because I have no time.

I haven't even been able to stay on here as long as I would like. work is getting a little crazy so I don't see much daylight, especially with daylight savings time and all.

I may revisit this when I get more time but for now, I am just going to enjoy the relatively low gas prices and drive with what I have. it has still yielded me over 38 mpg for my best tank.

[VetteOwner]

just an FYI most stock spoilers are for purely looks (hence usually on sport/high up submodel list cars)

[BEEF]

my spoiler has the 3rd light in it and is very low profile and unlike most, there is no gap between the spoiler and the car.

I am not saying that it is any better because of it but it isn't the gargantuan thing that aftermarket people put on the mustangs and hondas.

also, it is a stock spoiler (and yes, it is probably just for looks)