Drag-Limited Top Speed?
07-16-2006, 01:42 PM
#1
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Join Date: Jul 2006
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Drag-Limited Top Speed?
Please note: These are theoretical questions. No one should be attempting top speed runs except under strictly controlled conditions and by professional drivers. I'm also completely ignoring the speed rating of the tires and the fact that you'd slide off the roads at these speeds...
Let's say you used a tune to remove the speed limiter. How fast will a Mustang GT go? By my calculations, running P235/50ZR18 tires on 18" wheels, top engine speed (6250 RPM) in top gear (0.68:1) gives a speed of 210 MPH. Clearly 300 flywheel HP is not enough to get anywhere near that, so how fast will it go before it runs out of steam? How much slower would the convertible be? How much slower with the top down?
Now let's say your mods brought the power up to 400 RWHP and raised the RPM limit to 6800. By this time you'd also have 4:10 gears so the theoretical max would be 199 MPH. How close to that could you actually get?
Let's say you used a tune to remove the speed limiter. How fast will a Mustang GT go? By my calculations, running P235/50ZR18 tires on 18" wheels, top engine speed (6250 RPM) in top gear (0.68:1) gives a speed of 210 MPH. Clearly 300 flywheel HP is not enough to get anywhere near that, so how fast will it go before it runs out of steam? How much slower would the convertible be? How much slower with the top down?
Now let's say your mods brought the power up to 400 RWHP and raised the RPM limit to 6800. By this time you'd also have 4:10 gears so the theoretical max would be 199 MPH. How close to that could you actually get?
07-16-2006, 05:04 PM
#2
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RE: Drag-Limited Top Speed?
You can probably find the drag coefficient somewhere and plug the basic equation. In reality you would need to add down force in the front and manage the air going under the car. So the "real" drag coefficient would be higher. The speed limiter on the car is probably set at a point where the computer model shows a certain amount of dangerous lift on the front. I imagine it's implemented to give Ford's lawyers' some defense material.
07-16-2006, 05:11 PM
#3
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Join Date: Jan 2006
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RE: Drag-Limited Top Speed?
Has anyone taken an S197 to Bonneville and ran it flat out? That IMHO would be the most practical test to do and compare it to the theory.
My guess is that the drag coefficient on this model of Mustangs is a lot higher than some of the previous more "aero" looking models. In addition, the drag coefficient is also probably a function of the speed itself.
Mike
My guess is that the drag coefficient on this model of Mustangs is a lot higher than some of the previous more "aero" looking models. In addition, the drag coefficient is also probably a function of the speed itself.
Mike
07-16-2006, 05:54 PM
#4
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Join Date: Apr 2006
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RE: Drag-Limited Top Speed?
add down force in the front and manage the air going under the car
One of the magazines had a highly modified car up close to 200. But they pulled the mirrors off it, big blower, etc, etc.
07-19-2006, 07:21 PM
#8
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Join Date: Apr 2006
Location: Dallas, TX
Posts: 245
RE: Drag-Limited Top Speed?
ORIGINAL: Scottbert
Please note: These are theoretical questions. No one should be attempting top speed runs except under strictly controlled conditions and by professional drivers. I'm also completely ignoring the speed rating of the tires and the fact that you'd slide off the roads at these speeds...
Let's say you used a tune to remove the speed limiter. How fast will a Mustang GT go? By my calculations, running P235/50ZR18 tires on 18" wheels, top engine speed (6250 RPM) in top gear (0.68:1) gives a speed of 210 MPH. Clearly 300 flywheel HP is not enough to get anywhere near that, so how fast will it go before it runs out of steam? How much slower would the convertible be? How much slower with the top down?
Now let's say your mods brought the power up to 400 RWHP and raised the RPM limit to 6800. By this time you'd also have 4:10 gears so the theoretical max would be 199 MPH. How close to that could you actually get?
Please note: These are theoretical questions. No one should be attempting top speed runs except under strictly controlled conditions and by professional drivers. I'm also completely ignoring the speed rating of the tires and the fact that you'd slide off the roads at these speeds...
Let's say you used a tune to remove the speed limiter. How fast will a Mustang GT go? By my calculations, running P235/50ZR18 tires on 18" wheels, top engine speed (6250 RPM) in top gear (0.68:1) gives a speed of 210 MPH. Clearly 300 flywheel HP is not enough to get anywhere near that, so how fast will it go before it runs out of steam? How much slower would the convertible be? How much slower with the top down?
Now let's say your mods brought the power up to 400 RWHP and raised the RPM limit to 6800. By this time you'd also have 4:10 gears so the theoretical max would be 199 MPH. How close to that could you actually get?
you'd need to explicitly model it to get an accurate answer without risking your life. basically it's force to wheels less rolling resistance less drag resistance.
I have the model that can estimate it for different horsepowers and gears etc.
using the stock GT, .35 Cd and an approximate formula for rolling resistance, I get a top speed of around 146 for the stock Gt.
If you are really interested, PM me and I'll put your parameters in my model and see what comes out
07-19-2006, 09:20 PM
#10
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Join Date: Apr 2006
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RE: Drag-Limited Top Speed?
I read somewhere that the top speed of a stock GT was around 137. At that point drag was a factor
Stupid as hell, sure, but just providing technical info here for those that need to know.