aerodynamic drag and body style

[Stan Weiss]

Originally Posted by Dragsinger

Specifficly 3rd gen Camaro [which is what I am building] especially the drag cause by rear of body shape. What shape or spoiler can help?

Or, since it is 1/8 mile bracket racing, is it a non-issue?

To me, it seems it is important because the last 1/2 of track is over 80 MPH. Also, it you are racing into a head wind the drag will be increased.

Any feedback?

Hi Larry,
Aerodynamic drag is a function of both Coefficient of Drag and Frontal Area. Many times shown as CDA. If we keep the Frontal Area constant at 20 sq ft and the speed constant @ 100 MPH. A CD of 0.34 will produce an Aerodynamic drag of 51 HP while a CD of 0.38 will produce an Aerodynamic drag of 57 HP. The amount of Aerodynamic drag HP will increase with MPH and the HP difference between 0.34 and 0.38 will increase with increased MPH.

Stan


PS Maybe a graph which also includes 0.42 CD will show this better.

[Dragsinger]

Stan,

somewhere I saw a chart about body styles and aero drag. [may have been your chart]
that chart showed the 3rd gen Camaro with a relatively low COD and the 3rd gen Firebird among the lowest.

I have even considered installing a 3rd gen Firebird ft fenders and facia on my Camaro. Would doing that be worth the effort plus finding a Firebird ft and painting it?

Is the frontal drag the most critical? With rear drag less of an issue?

[Stan Weiss]

Larry,
Frontal Area is the area that the car has when looked at from the front. You should be able to measure width and height and calculate your frontal area. Google calculate frontal area of a car What year is your car?


Stan

[ss3011]

The aero package on the 91-92 Pontiac Firebird was reportedly the lowest CD of any GM car . Pontiac was very proud of that fact , and that was in many magazine articles . The frontal area was similar to the Camaro , but the front shape was way different . Rear shape was similar to Camaro , but air was able to flow under the spoiler.

[gsa612]

I remember reading an article by Lingenfelter back in the early 70's.On his S/S 69 Camaro rag the car picked up a bit of MPH using only the front spoiler,and lost using the rear.The car would MPH around 115.In those days you would have to run both (as part of the SS package) or none at all.On my '71 it picks up about a 1/2 a MPH (more in a strong headwind) with the front spoiler...gsa612

[nickh]

Larry I ran a 82 z28 with the ground effects and I had a large rear deck wing, car was very stable at 185 mph in 1/4 mile..LOL

[Jackie McCracken]

On a 79 Malibu wagon the factory rear spoiler is worth almost 3mph on car that runs just at 100 without it in the quarter.. and the reason for it is that it pulls air from the roof and routes it down the back window (to keep it clean in civilian life) which fills in the vacuum hole behind the car. and if you're wondering how big and powerful that "vacuum hole" is, it is what the cars that make turns use to create their ground effects downforce in sufficient quantities to be able to drive one across the ceiling upside down. The "vacuum hole" is also the reason behind drafting in nascar, if you can get in close enough it will damn near pull you along... need proof of what good aero can do? How about 174 on a bicycle...peddling.


what you really want to do with the front of the car is to smooth the air and keep it out from under the car, along the sides and roof you need to keep it flowing smoothly, and a the back you need to eliminate the "vacuum hole"...


Jackie

[Steve Polhill]

Originally Posted by Dragsinger

Stan,

somewhere I saw a chart about body styles and aero drag. [may have been your chart]
that chart showed the 3rd gen Camaro with a relatively low COD and the 3rd gen Firebird among the lowest.

I have even considered installing a 3rd gen Firebird ft fenders and facia on my Camaro. Would doing that be worth the effort plus finding a Firebird ft and painting it?

Is the frontal drag the most critical? With rear drag less of an issue?

Hey Larry watch this video. in this case the front end was a disaster for drag but the most gains were picked up with work done on the rear of the car.

[Stan Weiss]

Some numbers I have.

'84 Firebird Trans Am W62 Aero 0.30
No numbers for a '84 Camaro

'88 Firebird Trans Am GTA 0.31
'88 Camaro IROC 0.34

'91 Firebird Trans Am GTA 0.31
No numbers for a '91 Camaro

Stan

[junior barns]

non-issue! unless you are running 130 mph in my opinion