How fast will a Z4 actually go?
- Thread starter DaveZ4C
- Start date
Actually, 120'ish is easy in this area. Just have to find a time, and place, a little more open for 150+. I know of a few areas, but the traffic during my awake and driving times, leave no wiggle room for idiots. You know the kind that want to shoot all the way across to the left lane upon merging, without looking :x
DaveZ4C said:
I don't know the robin, but even some Ferraris aren't slippery enough. I've been doing some comparos to the 360 and its performance specs are very similar to my M Coupe with 3.91 gears. The 360 is drag limited to 184mph, I've read (in the Evo/Octane Ferrari anniversary article compilation).
This thread is pretty funny. I like the VSG talk :lol:
Some notes.
Pressure drag increases with the square of the velocity (assuming all other things are constant). Viscous drag is more difficult to predict and at low mach numbers viscous drag is on the same order of magnitude as pressure drag, so you can't ignore it. Most people use the coefficient of drag as a way of characterizing the shape of the car and the viscous drag at a certain Reynold's number. But the coefficient of drag the automobile industry gives is completely useless for any sort of drag prediction calculations.
The one thing you can count on is that at a given engine RPM and gear ratio, you'll be doing a specific velocity in the car.
Expansion of the tires isn't really worth determining since it'll be very small compared to the actual tire radius.
Of course RPM limiters also get in the way, along with speed limits and police. Then you also have to worry about speedo error which in BMWs always indicates higher than actual speed.
So, what does this all mean? In a vacuum you can easily calculate the maximum theoretical speed of a car. In reality, it's much harder to predict, depending on weather conditions and wind directions and whether you're going up/down hill or on flat ground, are all going to affect the maximum speed you can achieve in the car.
So the best way to figure out how fast your car will go is take it some place without speed limits and find out for yourself and take your GPS to measure it
Some notes.
Pressure drag increases with the square of the velocity (assuming all other things are constant). Viscous drag is more difficult to predict and at low mach numbers viscous drag is on the same order of magnitude as pressure drag, so you can't ignore it. Most people use the coefficient of drag as a way of characterizing the shape of the car and the viscous drag at a certain Reynold's number. But the coefficient of drag the automobile industry gives is completely useless for any sort of drag prediction calculations.
The one thing you can count on is that at a given engine RPM and gear ratio, you'll be doing a specific velocity in the car.
Expansion of the tires isn't really worth determining since it'll be very small compared to the actual tire radius.
Of course RPM limiters also get in the way, along with speed limits and police. Then you also have to worry about speedo error which in BMWs always indicates higher than actual speed.
So, what does this all mean? In a vacuum you can easily calculate the maximum theoretical speed of a car. In reality, it's much harder to predict, depending on weather conditions and wind directions and whether you're going up/down hill or on flat ground, are all going to affect the maximum speed you can achieve in the car.
So the best way to figure out how fast your car will go is take it some place without speed limits and find out for yourself and take your GPS to measure it
Dammmittt said:This thread is pretty funny. I like the VSG talk :lol:
Some notes.
Pressure drag increases with the square of the velocity (assuming all other things are constant). Viscous drag is more difficult to predict and at low mach numbers viscous drag is on the same order of magnitude as pressure drag, so you can't ignore it. Most people use the coefficient of drag as a way of characterizing the shape of the car and the viscous drag at a certain Reynold's number. But the coefficient of drag the automobile industry gives is completely useless for any sort of drag prediction calculations.
The one thing you can count on is that at a given engine RPM and gear ratio, you'll be doing a specific velocity in the car.
Expansion of the tires isn't really worth determining since it'll be very small compared to the actual tire radius.
Of course RPM limiters also get in the way, along with speed limits and police. Then you also have to worry about speedo error which in BMWs always indicates higher than actual speed.
So, what does this all mean? In a vacuum you can easily calculate the maximum theoretical speed of a car. In reality, it's much harder to predict, depending on weather conditions and wind directions and whether you're going up/down hill or on flat ground, are all going to affect the maximum speed you can achieve in the car.
So the best way to figure out how fast your car will go is take it some place without speed limits and find out for yourself and take your GPS to measure it
I'm betting 1 beer and one beer only, he google'd that or got it off some site concerning calcaluting max speed.
Medium Dave
Member
I don't know about cars (I guess they're the same) but in helicopters the power required increases as the cube of the speed. That would mean that as well as being harder to get the increases in speed at the top end, all those horsepowers get used up quicker......... or something like that.
or too lazy to learn, either way, i'm not one.
2dogs said:SO....How fast will the bugger go.............................some one tell me.
It's already been stated.
Multiply your wheel circumference by the number of revolutions per minute, divide that number by the square root of your weight in kilos, add 4 and multiply by pi.
