Hennessey Cadillac Tuned Hits 220 mph on Texas Highway

[Juiced1]

Pretty wicked V

[rez333]

Beautiful car!!

But I think this car should be AWD. GM needs a GTR killer, and it makes sense that the CTS-V would be that car.

[CamaroDreams07]

Originally Posted by Captain Awesome

Drag is proportional to the square of the speed of the moving object.

FD=1/2ρv*2CDA

FD is the force of drag, which is by definition the force component in the direction of the flow velocity

ρ is the mass density of the fluid

v is the velocity of the object relative to the fluid

A is the reference area

CD is the drag coefficient

Since everything else is the same except for velocity, the drag is directly proportional to the square of the speed.

So the drag on a car going 203MPH versus 220MPH could be expressed as

41209/48400 = 85.1%

In theory, it should take just under 15% less horsepower to get the identical car moving 203MPH instead of 220MPH.



So, there must be other losses at work here...

You lost me on all of that. I'm just relaying what I saw on Top Gear UK when they reviewed the Veyron.

*We have armadillos in our trousers. It's really quite frightening*

[Scrappy Doo]

That's moving.

[camaro-dreamer]

Originally Posted by Captain Awesome

Drag is proportional to the square of the speed of the moving object.

FD=1/2ρv*2CDA

FD is the force of drag, which is by definition the force component in the direction of the flow velocity

ρ is the mass density of the fluid

v is the velocity of the object relative to the fluid

A is the reference area

CD is the drag coefficient

Since everything else is the same except for velocity, the drag is directly proportional to the square of the speed.

So the drag on a car going 203MPH versus 220MPH could be expressed as

41209/48400 = 85.1%

In theory, it should take just under 15% less horsepower to get the identical car moving 203MPH instead of 220MPH.



So, there must be other losses at work here...

Nah, you just forgot that power equals the force vector dotted with the velocity vector. Neglecting the other forces such as friction (actually quite small in this instance) losses through the drive train, etc., it takes around 27% more horsepower to go from 203 to 220mph. Since the average car loses around 20% through the drive train, you should need around 34% more horsepower.

[Captain Awesome]

Originally Posted by knowitman

If you watch the video, the CTS-V was still accelerating when he backed off at 220.5 mph. He just had to back off since they were only given so much distance to actually do the test.

Ok. so the ZL1 apparently had the same length and may have been able to go faster as well.

I would guess that the gearing was different and that may have also been a contributing factor.

[Captain Awesome]

Originally Posted by camaro-dreamer

Nah, you just forgot that power equals the force vector dotted with the velocity vector. Neglecting the other forces such as friction (actually quite small in this instance) losses through the drive train, etc., it takes around 27% more horsepower to go from 203 to 220mph. Since the average car loses around 20% through the drive train, you should need around 34% more horsepower.

That makes sense. Thanks.
Given the variables in these test, we can't show empirical proof this is accurate. We'd need the same car using a track with no length restriction.

We should get the Mythbusters involved.