Will supercars ever see 300 MPH ?

[Demon-Xanth]

Originally posted by: Skoorb

Originally posted by: Demon-Xanth
There IS a track that is a large 10 mile around donut with variable banking where cars have done sustained, long term top speed testing at. 300MPH can work on that tracks. For top speed, "light" isn't really the key. It's all about aerodynamics. You're not worried about acceleration, just trying to cram a shape through the air. Drag is not a linear function. Assuming wind resistance alone, lets assume a theoretical car takes 1HP to push it 10MPH. At 20MPH it will take 4HP, at 40MPH it will take 16HP, at 80MPH it will take 64HP, at 160MPH it will take 256HP, at 320MPH, it will take 1024HP. This is why 100MPH is easy, and 150MPH is not, and 200MPH is an accomplishment.

I've thought about this before. Let's say you take two vehicles of the exact same shape (same wind resistance). One weighs 3000 lbs and has 300 horsepower. The other weighs 6000 lbs and has 350 horsepower. The first vehicle has better acceleration, but the second would in fact have a higher top speed wouldn't it?

Not counting rolling resistance, (which WOULD be signifigantly higher), yes.

 

[Don Vito Corleone]

Originally posted by: Skoorb

IMO this is why the Carrera GT, SLR and Enzo are slower than the McLaren F1

Plus Britain > *

Hee hee - in all fairness, the SLR was designed at the fancy-schmancy McLaren digs in GB, not in Germany. I can't say I love the car, nevertheless . . .

 

[StageLeft]

Originally posted by: Demon-Xanth

Originally posted by: Skoorb

Originally posted by: Demon-Xanth
There IS a track that is a large 10 mile around donut with variable banking where cars have done sustained, long term top speed testing at. 300MPH can work on that tracks. For top speed, "light" isn't really the key. It's all about aerodynamics. You're not worried about acceleration, just trying to cram a shape through the air. Drag is not a linear function. Assuming wind resistance alone, lets assume a theoretical car takes 1HP to push it 10MPH. At 20MPH it will take 4HP, at 40MPH it will take 16HP, at 80MPH it will take 64HP, at 160MPH it will take 256HP, at 320MPH, it will take 1024HP. This is why 100MPH is easy, and 150MPH is not, and 200MPH is an accomplishment.

I've thought about this before. Let's say you take two vehicles of the exact same shape (same wind resistance). One weighs 3000 lbs and has 300 horsepower. The other weighs 6000 lbs and has 350 horsepower. The first vehicle has better acceleration, but the second would in fact have a higher top speed wouldn't it?

Not counting rolling resistance, (which WOULD be signifigantly higher), yes.

That explains why my maxima is such a bad mother @*$( on the highway!

 

[Hayabusa Rider]

Originally posted by: Skoorb

Originally posted by: Hayabusa Rider
The problem is not reaching that speed. It could be done in 6 months. What the real issue here is having a car that mom can drive to the store for a gallon of milk, and dad can go nuts in, AND have it work reliably for tens of thousands of miles at least. Having an engine rebuild every thousand of miles or less isn't something anyone is willing to pay.

Wtf? None of these supercars are anything close to capable of what you say. Nobody buys an enzo to go to the store for milk or have it work for thousands of miles without needing tons of work. All of these cars are like high maintenance women.

Being high maintenance does not mean non functional. There are people who drive these kinds of vehicles around town, and they do not expect a piston to fly through the hood of their car. Is that a "feature" I know nothing about?

There ARE vehicles which pass 300 mph every time in a quarter mile. They have brutal power not so much to reach that speed but to get to it in several seconds. They also routinely blow up.

At more "normal" accelerations, much less power, and therefore much less stress would be placed on an engine. If you are telling me that the leaders in auto building cannot beef up an existing engine and add nitrous etc, I think you sell them short. Likewise, the rest of the vehicle could be modified.

Result? Something no longer production, since it's wayyyyyyy expensive even by today's standards, and of lower reliability.

That is the challenge in building an auto. It must be "streetable", it must be at least as reliable as other cars in it's class, and it must be built using techniques that qualify as a "production" vehicle, however marginally that term is used.

 

[Hayabusa Rider]

Originally posted by: Demon-Xanth

Originally posted by: Skoorb

Originally posted by: Demon-Xanth
There IS a track that is a large 10 mile around donut with variable banking where cars have done sustained, long term top speed testing at. 300MPH can work on that tracks. For top speed, "light" isn't really the key. It's all about aerodynamics. You're not worried about acceleration, just trying to cram a shape through the air. Drag is not a linear function. Assuming wind resistance alone, lets assume a theoretical car takes 1HP to push it 10MPH. At 20MPH it will take 4HP, at 40MPH it will take 16HP, at 80MPH it will take 64HP, at 160MPH it will take 256HP, at 320MPH, it will take 1024HP. This is why 100MPH is easy, and 150MPH is not, and 200MPH is an accomplishment.

I've thought about this before. Let's say you take two vehicles of the exact same shape (same wind resistance). One weighs 3000 lbs and has 300 horsepower. The other weighs 6000 lbs and has 350 horsepower. The first vehicle has better acceleration, but the second would in fact have a higher top speed wouldn't it?

Not counting rolling resistance, (which WOULD be signifigantly higher), yes.

I have a question about rolling resistance. Maybe it a semantic thing, but in today's run of the mill cars, the rolling resistance as I understand it to be defined decreases with speed, and the drag does the opposite. This is in part responsible for an optimal velocity for gas mileage. Even with good gearing, fuel consumption does not decrease in proportion with the reduction in drag. In other words, as some point going too slow hurts mileage.

What am I missing?

 

[Demon-Xanth]

The IMPACT of rolling resistance decreases. The resistance is still very much there. The reason why there is an optimal speed is that engines at idle use gas without making power. Engines usually have a sweet spot that they work most efficiently in, and the optimal speed is often in that sweet spot.

 

[Goosemaster]

Basically, you would need an extremely efficient power source and a vehicle designed solely for this purpose...ie rocket car.

In this case the factor that affect reaching the top speed are forces that oppose the vehicles movement and forces that aid its movement.

Of course I am reering to friction of all types, and the force which the engine delivers to the ground.

There is a problem however.

To say that you simply need a more powerful egine or better areodynamics is not enough. Seeing as how the vehicle will become airbone if not properly held in place by downforce-producing fins, the faster it goes, the greater the amount of downforce, and respectively, the greater the weight of the vehicle.

Think of it as you would tryign to reach the speed of light. Resistance increases, perhaps exponentially, as you increase speed and attempt to maintain an acceleration. The faster you go, the more power you need.


I suspect that this is whyjet cars have no problem with this. They are basically a lawn chair bolted on a somthign that would eat a Merlin engine for lunch.

You need to absolutely positively overdue it for those speeds.


Some of you may scoff at the Buggatti and comment that the extra 298kW that it puts out only results in an extra 10mph, but with such massive amounts of airresistance at that speed, and with such a large vehicle, those 10mph are fvking awesome.


In summary:

Jet cars > *.*

AND

Bruce Wayne was a smart little bitch but still a crzy mytherfker

 

[edmundoab]

hope they stay on the ground, soon to fly with those kinda speeds

 

[StageLeft]

Originally posted by: Hayabusa Rider

Originally posted by: Demon-Xanth

Originally posted by: Skoorb

Originally posted by: Demon-Xanth
There IS a track that is a large 10 mile around donut with variable banking where cars have done sustained, long term top speed testing at. 300MPH can work on that tracks. For top speed, "light" isn't really the key. It's all about aerodynamics. You're not worried about acceleration, just trying to cram a shape through the air. Drag is not a linear function. Assuming wind resistance alone, lets assume a theoretical car takes 1HP to push it 10MPH. At 20MPH it will take 4HP, at 40MPH it will take 16HP, at 80MPH it will take 64HP, at 160MPH it will take 256HP, at 320MPH, it will take 1024HP. This is why 100MPH is easy, and 150MPH is not, and 200MPH is an accomplishment.

I've thought about this before. Let's say you take two vehicles of the exact same shape (same wind resistance). One weighs 3000 lbs and has 300 horsepower. The other weighs 6000 lbs and has 350 horsepower. The first vehicle has better acceleration, but the second would in fact have a higher top speed wouldn't it?

Not counting rolling resistance, (which WOULD be signifigantly higher), yes.

I have a question about rolling resistance. Maybe it a semantic thing, but in today's run of the mill cars, the rolling resistance as I understand it to be defined decreases with speed, and the drag does the opposite. This is in part responsible for an optimal velocity for gas mileage. Even with good gearing, fuel consumption does not decrease in proportion with the reduction in drag. In other words, as some point going too slow hurts mileage.

What am I missing?

I think you've also got to consider the amount of fuel wasted by an engine simply being turned on, so if you're at 2 mph--even on a layer of air--you have no real air resistance or rolling resistance but you're burning a good bit of gas just keeping the engine on. AFAIK 50 mph is the optimal speed for gas for most people.

Anywy I agree with the above about reliablity. The more they tweak these cars the less likely the thing is going to get you from home to work without blowing up, so they can't just throw gobs of power into an engine bay and expect people to buy it.

 

[Hayabusa Rider]

Originally posted by: Demon-Xanth
The IMPACT of rolling resistance decreases. The resistance is still very much there. The reason why there is an optimal speed is that engines at idle use gas without making power. Engines usually have a sweet spot that they work most efficiently in, and the optimal speed is often in that sweet spot.

Makes sense. Thanks!

 

[ravana]

Originally posted by: Skoorb

Originally posted by: Hayabusa Rider
The problem is not reaching that speed. It could be done in 6 months. What the real issue here is having a car that mom can drive to the store for a gallon of milk, and dad can go nuts in, AND have it work reliably for tens of thousands of miles at least. Having an engine rebuild every thousand of miles or less isn't something anyone is willing to pay.

Wtf? None of these supercars are anything close to capable of what you say. Nobody buys an enzo to go to the store for milk or have it work for thousands of miles without needing tons of work. All of these cars are like high maintenance women.

You mean like hookers, one ride, very much dolla $$$$