[BrandX]

I am doing some winter weight and aerodynamic upgrades. (mostly because they are cheap or free haha). And would like to know how bad off they are to start with.

[punisher#1]

they are just a little bit better than a "78 fairmont. hehehe

[adam woodmancy]

i remember hearing tony christian say that he though his "new at the time" 98-02 trans am body was worth .06-.08 over his 57 chevy at the same weight

[Brian Baker]

Look up a brick and you'll be close (LOL).

[77 TRASHCAN]

If there is any wind tunnel info. available for Chevelles around that year, you'd have some numbers, then where to find such info...???

I doubt you'd find any numbers for a Pontiac "A" body, I doubt anyone raced one in NASCAR back then.

Just a thought...

[bpenrod]

7 the answer is always 7

[Brian Baker]

Originally Posted by 77 TRASHCAN

If there is any wind tunnel info. available for Chevelles around that year, you'd have some numbers, then where to find such info...???

I doubt you'd find any numbers for a Pontiac "A" body, I doubt anyone raced one in NASCAR back then.

Just a thought...

Plenty of A-bodies in NASCAR in the early 70's. Remember David Pearson's?

[Tom Vaught]

Use .46 for your Cd. Just remember one thing, the frontal area of the car has a much bigger effect vs the Cd number.

If you have two perfectly round objects: One the size of a golf ball and one the size of a basket ball, they both will have exactly the same Cd number. The Frontal Area will be much larger on the larger round ball. The smaller frontal area makes it possible for the "golf ball" sized round object to travel much farther than the "basket ball" sized round object.

Food for thought.

Tom Vaught

[GOAT490]

If you pull BIG wheelies your frontal area is HUGE for the first 60ft!!!

PHILLYGOAT

[Jim Yanoski]

I don't think the the frontal area or the angle that most people make such a big deal about by changing the whole look of the front end is that important. Making a wedge out the front end has some advantages but to make a car look like a triangle and take a good looking body style and make it fugly is not worth it. I think the windshield angle, the back window angle, trunk overhang, and having the sides/rockers smooth and out past all of the tires is more important than the front end shape. ...........Jim

[Tom Vaught]

Originally Posted by Jim Yanoski

I think the windshield angle, the back window angle, trunk overhang, and having the sides/rockers smooth and out past all of the tires is more important than the front end shape. ...........Jim

All of those things were done to the R. Butler/ Travis Q. 63 Tempest.

You still need to keep the air out from under the car. Little things like a smooth surface change from the windshield to the windshield pillar/ roof will gain a few MPH.

My point is you can lower the Cd by 20 numbers (.20) and still take a hit if the Frontal Area goes up by 3 square feet.

Tom Vaught

[lust4speed]

Don't you include the area under the car in figuring frontal area? So if your car is 54" high and 74.4" wide, you have 4,018 square inches of area or about 28 square feet of frontal area. So lowering the car 4" would be worth 4x74.4" wide = 298" or a little over two square foot of area removed which is about 7-1/2% less frontal area.

[Tom Vaught]

Originally Posted by lust4speed

Don't you include the area under the car in figuring frontal area? So if your car is 54" high and 74.4" wide, you have 4,018 square inches of area or about 28 square feet of frontal area. So lowering the car 4" would be worth 4x74.4" wide = 298" or a little over two square foot of area removed which is about 7-1/2% less frontal area.

You can typically make the calculation you mentioned above to get a basic idea of the frontal area and the change in height.

A true Frontal Area Scan is done with a "Shadow Graph" machine that traces every "blockage" of the scanners light beam. "Blockage" would be things like the tire profile, suspension components hanging below the bumper, exhaust parts, etc that would impact on the air coming under the car and slow the vehicle down. Years ago Salt Flats Racers made belly pans to cover as much of the underside of the vehicle as possible and still have functional parts.

A Chin Spoiler, a couple of inches off the ground, does wonders for keeping the air out from under the vehicle.

Tom Vaught

[Gach]

Tom: great information, I remember seeing the front end of Marty's 70 GTO with the chin spoiler, always wanted to copy that...kept the pictures of it and now I'm finally getting to do just that. Love that car... the most beautiful
70 GTO I've ever seen.

[johnta1]

Try this calc:

HP to Run a Speed

Not much HP to run 150 MPH, but try 200 then 250/300 MPH.

[rustedgoat]

Smoothing out the front end by making the headlights and grills more flush with the bezels couldn't hurt. I don't know about an underbelly pan on a drag car seems like it could end up being a sail if the front end rises, kinda like those drag boats.

[Jim Yanoski]

Originally Posted by rustedgoat

Smoothing out the front end by making the headlights and grills more flush with the bezels couldn't hurt. I don't know about an underbelly pan on a drag car seems like it could end up being a sail if the front end rises, kinda like those drag boats.

Most Pro Mod cars have full belly pans from the front of the engine to the rear end and are in the 230 to 250 mph range.

[BrandX]

I want to make a front spoiler/air damn down low, what material should I use? Was thinking about maybe trying to make one fit from another vehicle also

[punisher#1]

Originally Posted by BrandX

I want to make a front spoiler/air damn down low, what material should I use? Was thinking about maybe trying to make one fit from another vehicle also

i have one off of a mid '80s s-10 on my car. it is about 5-6 inches tall and very simple square shape. go walk through the local wal-mart parking lot tomorrow with a tape measure and get some ideas.

[BrandX]

Good idea!!!! That's what I'm gonna do!!