jollythought

After searching which is the most aerodynamic third gen, the common conclusion was the 83/84 trans am with gfx were the most aerodynamic.
I have an 83 trans am w/o gfx and I was going to adapt the 85-90 T/A gfx until I found out the aero package would be more aerodynamic.

My question is how much of difference would it make, in acceleration or mpg? Its not going to be a drag car, just a fun weekend car.
Opinions welcome

pound

iTrader: (7)

Unless you have access to a wind tunnel or something I doubt it will make any difference that you would be able to measure or perceive.

Damon

Wind resistance doesn't make all that much difference until you're up over 100 MPH. Now, I know that's not entirely true, but small things like adding GFX or a wing do basically nothing at street-legal speeds. The overall shape of the car from the factory is the primary determining factor (compared so, say, a Jeep Wrangler or a pickup). 3rd Gen Firebird/Trans Ams are VERY slippery from the factory. Just ask Gale Banks what body shell he preferred using to set land speed records back in the 80s!

BlackenedBird

iTrader: (5)

The 91/92 Trans Am is the most aerodynamic. cd of .29 iirc. and the earlier years were closer to .34 and a bit higher (like the early 3rd gens)

89rs454

What the real question should be is between 4th & 3rd gen aerodynamics? Lets keep it civil folks.

urbanhunter44

iTrader: (3)

As beautiful as the 4th gen 'birds are (LT1 and LS1) I doubt they're as aerodynamic as the 3rd gens. I bet the LT1 cars more so than the LS1s though.

jollythought

I was just wanting to make sure because I eventually want my car to be lightweight, as aerodynamic, and as efficient as possible. I'm not trying to really compare all third gens. mainly just 82-84 to 85-90 T/A (gfx included)

stealtht/a

iTrader: (1)

There seems to be some conflicting info on the different aero pkgs as far as which drag less, prob to do with comparisons of different wings and stuff. My feeling is the 85-90 gfx are prob less drag , esp on lowered cars, but they had the wrap wing which was designed (badly) for downforce, hence more drag. The flat wing was shown to decrease drag as it had minimal downforce effect but improved laminar flow and reduces low pressure areas behind the car. The 91-92 wing was designed to go back to this idea, with little or no downforce. I doubt the 91-92 gfx are more aerodynamic than 85-90, since they are obviously designed with looks ahead of function, but the nose might have less drag.
I also believe that the best thing you can do to improve drag Cx on TA s is to get rid of the plastic extractors on hood and fenders. I also think this is why 4th gens are less aerodynamic, way too many scoops and slots that were only put there for looks.

jollythought

Ok, thanks for all the quick responses guys. Helped a lot

58mark

iTrader: (3)

4 words.

bowling ball wheel covers

stealtht/a

iTrader: (1)

Correct, I remember the road and track article cited that these wheels and covers had a significant effect. That's why I'm using the 20 slot 16" aero wheels instead of the 16" "formula" wheels.

paul_huryk

84 is the most aerodynamic from the factory - never seen any data on the 91 and 92 cars to see what their numbers are. Hard to believe that the ones with the bird beak are better - they let a lot of air under the cars.

stealtht/a

iTrader: (1)

Hmm, didn't think about the under part, I was just thinking the rounded part might be better.

Has anyone seen a test result for the 85-90 with straight wing and gfx? The only one I remember from the 85-90 years used an 86 with the wrapwing and high third bklight. Iiirc that one was .36 Cx.

Jeffs82TA

iTrader: (1)

That is incorrect. The 83 daytona was the one that did .29

TTOP350

iTrader: (8)

Yeah, the early 82-84 T/As have the best cd of all the thirdgens.

BlackenedBird

iTrader: (5)

I suggest doing your research & trying again because they were not the lowest cd. In fact? I already answered it above.

58mark

iTrader: (3)

1984 Trans am (with optional W62 Aero Package and N89 Turbo Cast rims)

http://en.wikipedia.org/wiki/Automob...ag_coefficient

BlackenedBird

iTrader: (5)

Yep. Until 1985 that was. But that changed in 1991.

58mark

iTrader: (3)

you said the same thing in this thread and nobody listened to you either. I don't buy it. You're the only person I've ever seen make that claim, but I've read others disproving it

Saying the same thing over and over does make you right

https://www.thirdgen.org/forums/body...-firebird.html

BlackenedBird

iTrader: (5)

Show me a fact that disputes it. And BTW....We all know just how un-factual Wikipedia can be on things.

58mark

iTrader: (3)

I looked up several sources, and they all mentioned the 82-84 being the best. you're the ONLY person saying 91-92 were the best, not to mention that you said the DC on the early ones was 34, which is totally wrong.

Stephen you're wrong, and looking more than a little foolish right now.

neeb_usmc

iTrader: (2)

wikipedia? lol

BlackenedBird

iTrader: (5)

But in any case.....You will need to do a good deal to affect the mpg.

I have a fiberglass hood, fiberglass rear wing (weight reduction) but have a better flowing intake (more hp now), have heavier wheels and wider tires front & rear (over stock) & lowered the car about 2.5". My mpg still stays in the exact mpg average range as it did 6 years ago when it was bone stock (except for exhaust).

To really affect the mpg you'll get to really lighten things up, swap to skinny tires (less handling in an emergency maneuver), fine tuning of the PROM & develop a really light right foot.

TPI-Formula350-

Gale Banks had the land speed record in a production car- in a modified 1988 GTA with a record speed of 283 MPH
http://www.gtasourcepage.com/galebanksturbogta.html


The 300 MPH land speed record was not broken until 1999 by Joe Kugel. He broke the 300 MPH mark in his modified 1992 Firebird with the 1990 wrap around spoiler on it. He choose to use the older wrap around spoiler being it provided the best down force of any Pontiac spoiler. The later spoiler actually caused lift, very bad at those speeds. He set the new record at that time of 300.788 MPH
http://www.kugelkomponents.com/bonne...onneville.html

jollythought

I guess since it wont really affect mpg and I dont plan on going over 200 mph anytime soon, I will just pick a gfx style based on looks..Is that a modified 92 bumper on that 92 firebird that broke the record?

TTOP350

iTrader: (8)

Shall I try and find my old Pontiac brochures for the 82-84s and scan them for you?? Not that .05 makes a monster difference buuuut a lot of sources of information on this are incorrect.

BlackenedBird

iTrader: (5)

I know what the early ones cd is. .29 with those flat wheel "hubcaps". It doesn't address the 91/92 bodies AND TPI-Formula350-'s link shows that the 91/92 was what? 27mph faster in its run? At those speeds aerodynamics are WAY more valuable than horsepower.

88 GTA with 1600hp to do 283 vs 92 Firebird with 1200 hp to do 301.

EDIT: Found the Kugel Firebirds horsepower. And tell me guys....If a 1600hp 88 is SLOWER than a 1200hp 92? Which one has the better aerodynamics?
http://www.hotrod.com/featuredvehicl...tiac_trans_am/

TTOP350

iTrader: (8)

Did you look at the 91 front bumper on the 300mph car?
Its a fiberglass front bumper with the front park/fog light holes filled in and almost flat. Similar shape as factory buuut far from it.
That 300mph car spent some decent time in a wind tunnel. AND there is more to top speed than HP an front bumper. The bumper, lower air dams and spliters do a lot of work to direct air around the car and keep it from going under. Weight of a car has a lot to do with it also. I don't remember the weight of either car.
The other 88 cars bumper is a factory part.
Taken from Hot Rod
The rules are rigidly structured, and Banks’ car reflects them perfectly. This is no aerodynamic perfect bullet groomed in a wind tunnel; it’s an unmodified production body running at near-production ride height with the stock factory aero package. Banks horsepower boosts it into the stratosphere of speed and Pontiac’s incredibly aerodynamic production styling provides its astonishing high-speed stability. Of all the cars originally considered for the project, the Pontiac Trans Am GTA rated the highest chance of success based on its aerodynamics alone. The Trans Am is as stable at 280 mph as it is at 60 mph, and that represents a major miracle of modern automotive design – the near-perfect shape.

BlackenedBird

iTrader: (5)

The Banks 88 GTA was not 100% stock either. The nose was modified. Read about it & you will learn that.

Bottom line guys? I DON"T CARE! You all keep touting the early birds with the aero wheels but nothing more than that!

"than its 1981 predecessor. It also was the most aerodynamic production Firebird to date with a drag coefficient of 0.33. The new Trans Am took things a bit further, with a coefficient of .32. The Trans Am body would continue to improve aerodynamically over the years, and by 1985 would be the most aerodynamic vehicle to ever be released from General Motors with a 0.29 coefficient of drag.

1985----The Trans Am drag coefficient was measured at 0.32 but was as low as 0.29 with the standard Aero wheels instead of the High-Tech turbo aluminum wheels. At the time, it was the most aerodynamically efficient car GM ever produced."

Only the '85 had the .29 AND only if it had the Aero wheels.

This whole thing is starting to amuse me. Thanks for the laughs guys! I was ready to let a dead dog lie until you brought it back up.....

stealtht/a

iTrader: (1)

Where's that from blackened? That's what I was looking for to confirm my gfx combo is the best!

paul_huryk

Hot Rod had an article in 1989 where they featured a 1989 Trans Am that had been set up for top speed racing. With a modified (deeper) stock front spoiler and a 650hp NASCAR motor it went 238mph, as fast as a McLaren F1, which weighs over 1,000lbs less and has a smaller frontal area. That car would need about 1350 to 1,400 to touch 300mph and that car was running 0.25 CoD.

I'm not sure that 1,200hp will get you to 300mph in these cars, even in top speed trim, it is going to take more like 1,400 to 1,500 to get there, so I'm calling BS on their 1,200 hp. And the article says 1,266 anyway...

The 88 is probably geared somewhat off for the 300mph barrier - a few 100 rpm below your power peak and the car slows down a bit (compared to optimal) due to the aero loading and lower available power.

TPI-Formula350-

Wonder if the 1992 Firebirds world speed record of 300 mph has been broken since it was achieved in 1999.

BlackenedBird

iTrader: (5)

I Copy & Pasted got the info from the links the other guys provided.

Tell Kugel they are full of BS then. And both cars said "just over 1600" and "Just over 1200" 1266 seems to be "just over 1200" to me. Funny how you want to believe one article but not the other article.


Both cars were going for the Land Speed Record so I'm pretty certain Banks would not have Handicapped himself by gearing it wrong.

And quite frankly I'm tired of this. I tried to just let it die before but somebody felt the need to dig it up again & call me out. It is getting bad when people are trying to make their claims based on "I call bs" & "I don't believe" & "probably" & such. Have fun boys!

Jeffs82TA

iTrader: (1)

KITT was the most aerodynamic PERIOD it flew through the sky which NO other F-Body could ... Case closed!