Rear Downforce Wing

[Alky V6]

I've been doing some research, and found that our notch back bodies don't do much for making wings mounted on the deck lid very effective. There's a lot of turbulence that gets created after the rear window, and wings don't like turbulence. The best way to have an effective wing on a notch back car is to raise the location of the wing off the rear deck lid until the wing is in 'clean air'.
I'm thinking I may video tape some tape and ribbon testing on the car before I decide on a wing design and placement.
I'm also starting to understand better why nascar changed their aero package on the cup cars. Very interesting stuff.

 

[Turbo1dr]

Maybe you need one of these...

 

[Mac in SD]

A GN Aero Coupe. Innnnterrrresting.

 

[Alky V6]

Yes. Very interesting. Do you have any more pictures? Different angles? Is there a company that makes that or is it home made?

 

[Turbo1dr]

Yes. Very interesting. Do you have any more pictures? Different angles? Is there a company that makes that or is it home made?

I found a Monte SS Aero in the salvage yard and got the rear window and all related hardware. What you see in the picture is the glass sitting on the trunk lid of the GN. That's just a "photochopped" of what I'm planning to do with my GN as my next project.

Here are some more photochopped pictures of the GN...

Here are some pictures of the window on my Turbo T. These pictures are not modified at all.

In this .zip file, are all the angles you'll probably want to see.

I'm confident it can be done without ruining the car. I think fitting the package shelf to the Regal will be the easy part.....the "1 of 1" trunk lid might be the problem.

 

[Alky V6]

I would figure a person could make the same sort of shape out of sheet metal with a plexiglass insert if desired.
Very interesting project. Keep us updated.

 

[Turbo1dr]

Making one and bolting it to the existing trunk and roof would be much easier on a race car than doing a complete swap like I want to do. I'll probably be starting on that project within the next 4-6 months.

 

[Dusty Bradford]

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

Don. I feel here is your issue. This should not be out of the question. You should be looking more into the proper rear tire and wheel arrangement which will allow lowering the car to a better handling set-up. Get the center of gravity lower to the ground. Use a stiffer sidewall tire and more air pressure. If your using low air pressure in the tire due to traction issues at launch, it goes back to the suspension being wrong.

I see cars go 1.21-1.23 60's on a 275/60 radial and stock suspension. I watched a G-body with no rear wing go 170mph to the 1/8th. 1.3g's at the finish line. No other g-body anywhere is accelerating that quickly on your size tire than this car. I don't think a wing will do anything for your issue. Getting the proper ride height and center of gravity will.

Ted also hit on a great point. What is the track prep like where you race? Once you hit a point where your trapping 150 or more at the 1/4, not all tracks are capable of letting you put that kind of power down. There are numerous tracks around my house that I will not attempt to go down.

 

[turbobuick]

Don. I feel here is your issue. This should not be out of the question. You should be looking more into the proper rear tire and wheel arrangement which will allow lowering the car to a better handling set-up. Get the center of gravity lower to the ground. Use a stiffer sidewall tire and more air pressure. If your using low air pressure in the tire due to traction issues at launch, it goes back to the suspension being wrong.

I see cars go 1.21-1.23 60's on a 275/60 radial and stock suspension. I watched a G-body with no rear wing go 170mph to the 1/8th. 1.3g's at the finish line. No other g-body anywhere is accelerating that quickly on your size tire than this car. I don't think a wing will do anything for your issue. Getting the proper ride height and center of gravity will.

Ted also hit on a great point. What is the track prep like where you race? Once you hit a point where your trapping 150 or more at the 1/4, not all tracks are capable of letting you put that kind of power down. There are numerous tracks around my house that I will not attempt to go down.

Good points.

I ditched the 29.5 tires 3 years ago and went back to a simple 28x10.5 stiff sidewall tire (with tubes) just to get the ride ht and COG correct and EVERYTHING worked better. Drag radials even worked better due to the increased sidewall stiffness but I don't think I would start with them in sorting out the suspension. You really need to move the tire in board and hack up the inner wheel wells to get the 29.5 tire to fit right.

I stopped going to local TT and started going to some local Outlaw Drag Radial events JUST for the track prep and tuning. It is MUCH easier to sort things out with a well prepped track as it takes out a significant part of the equation. If you want the best track your local track has try going during a points meet for the bracket classes. My local track is notoriously horrible but has decent prep on points days and I can still get 3-4 TT passes.

 

[Dusty Bradford]

On the powerglide discussion. It would absolutely kill Don's combo.

But can they work behind a low torque V6 in a heavy car??????? How about a 1.27 60' on a 28 inch radial tire in a 3450# car Went 5.42 to the 1/8th on it's 5th pass.

 

[Alky V6]

Traction at the launch has never been an issue, regardless of what tire was on the car, 28 or 29.5. The reason I was trying the 9 1/4 air pressure was in an effort to get the sidewall to wrinkle more at the launch. I'm convinced that was the wrong tact to take. What the car needs is more power at the launch. Now that I'm comfortable with where the fuel map is with the new turbo, I'll be increasing the tire pressure in future TTs and tuning the launch attitude with the nitrous system jetting. The latest jetting change will have the car leaving the line at over 4350 rpm versus 4000-4100 with the past jetting level. There are plans to move the jetting up to where the engine pushes the stall to over 4500 rpm for the lauch, if needed. That should test the chassis setup at the line pretty well. At the past jetting level, the chassis was not getting a fair test at the line.

The 29.5s that I'm using are already stiff wall tires, and I've always used tubes.

I don't feel the ride height in the rear is hurting me that much. I've seen other G bodies do 7s in the quarter with a similar stance to my car. The IC is not as far off as you fellas may be thinking. I'm not using a stock rear axle housing with the stock control arm mounting points.

 

[Dusty Bradford]

The 29.5s that I'm using are already stiff wall tires, and I've always used tubes.

I don't feel the ride height in the rear is hurting me that much. I've seen other G bodies do 7s in the quarter with a similar stance to my car. The IC is not as far off as you fellas may be thinking. I'm not using a stock rear axle housing with the stock control arm mounting points.

You need to run as much air pressure as you can get away with.

How many G-bodies on stock suspension are even in the 7's??? I'm betting there isn't alot of them. The faster ones that I have seen with your ride height all seem to be weaving on the top end of the track. Alot of that is from the slicks causing the back of the car to move around. A radial tire won't do that. Some drivers tend to "overdrive" a car on slicks because they do move around somewhat.

Why not try a shorter tire like a 28x10.5 S? You could tuck it in and get the ride height lower. Cars are going 7.40's on the 28x10. If a higher ride height won't hurt, wonder why we don't see INDY car or NASCAR rasing their ride height 2"??

 

[lazaris]

Just curious, you said traction at launch was never an issue. So why would remove air from the slicks just to get more wrinkle?

 

[Alky V6]

You need to run as much air pressure as you can get away with.

How many G-bodies on stock suspension are even in the 7's??? I'm betting there isn't alot of them. The faster ones that I have seen with your ride height all seem to be weaving on the top end of the track. Alot of that is from the slicks causing the back of the car to move around. A radial tire won't do that. Some drivers tend to "overdrive" a car on slicks because they do move around somewhat.

Why not try a shorter tire like a 28x10.5 S? You could tuck it in and get the ride height lower. Cars are going 7.40's on the 28x10. If a higher ride height won't hurt, wonder why we don't see INDY car or NASCAR rasing their ride height 2"??

Let me simply explain the main reason why I can't go with a setup that will tuck the tires and allow me to drop the ride height.

MONEY.

 

[Alky V6]

Just curious, you said traction at launch was never an issue. So why would remove air from the slicks just to get more wrinkle?

To drop the effective overall ratio. Even with the lower pressure I found that it was difficult to wrinkle the slick. It just needs more power.

Keep in mind fellas that my main concern has been improving the launch. Top end has taken a back seat until lately. Recently, I have been looking at things that affect the top end more, but until I get the launch where I want it, I could be fighting problems that may be originating at the beginning of the run.

 

[lazaris]

"To drop the effective overall ratio"

 

[Alky V6]

The overall effective gear ratio that the car leaves the line with involves;
Transmission first gear ratio.
Rear axle final drive gear ratio.
Tire diameter, or more importantly, tire radius measurement to the ground.

Think of the tire radius to the ground as a variable gear ratio. First, you must have the power that will match the sidewall design to take advantage of that variable ratio. Lowering the tire pressure was an attempt to test how well the engine power was matched to the sidewall firmness. If I were to find that even at an extraordinarily low 9 1/4 psi, the sidewall would not wrinkle to my liking, that would simply be telling me that I need more power applied to the tire. With more power applied to the tire, I can now play with higher tire pressures. Tire pressure, to me, is just another tuning tool that can be used to test the limits of other tuning parameters. So guys,... let the tire pressure thing go.

 

[Dusty Bradford]

Let me simply explain the main reason why I can't go with a setup that will tuck the tires and allow me to drop the ride height.

MONEY.

Some 15x10 wheels with 5.5 backspacing should be easy to find on numerous sites for reasonable money. Maybe even find a local who would let you borrow a set to try.

 

[turbobuick]

But can they work behind a low torque V6 in a heavy car???????

I don't know anyone running one of those Nothing low TQ about a turbo V6 Buick.

 

[turbobuick]

Traction at the launch has never been an issue,

I don't feel the ride height in the rear is hurting me that much.

The IC is not as far off as you fellas may be thinking.

Donnie, no offense but that is all theory until you get up there and smack it with some power off the line and get to actually try to run a decent 60'.