Discussion
jjr1 said:
[quote=Top Trump][quote=jjr1]Two cars both have a 0-60 time of 5 seconds.
For Car A:
0-80kmh in 4 secs(0-50mph):
distance = 0.5 * (0+80) * 4 = 160m
80-100kmh in 1 sec (50-62mph):
distance = 0.5 (80+100) * 1 = 90m
Total distance covered = 250m
For Car B:
0-80kmh in 1 secs(0-50mph):
distance = 0.5 * (0+80) * 1 = 40m
80-100kmh in 4 secs (50-62mph):
distance = 0.5 (80+100) * 4 = 90m
Total distance covered = 360m
>> Edited by silver993tt on Monday 8th May 13:49
>> Edited by silver993tt on Monday 8th May 14:34
Crikey, I thought this thread started off discussing the new 911 Turbo,, get back to the car.. All this bulls..t pub talk 0-60, faster than a, x slower than z etc.. is academic and gets away from the fact that this is a very serious and capable motor. I'm just annoyed that I can't afford one..
Well done Porsche - keep raising the bar!
We were just saying that all this talk about 0-60 is irrelevant as it is not a good indicator of a cars performance. Are you a bit stupid and can not follow two lines of thought in one thread?
Oh yes, I must be stupid, unlike Porsche drivers, great cars - drivers, well...
rumplestiltskin said:
0-60 is a good indicator. Its not the best indicator (a little like top speed) but its a good indicator of a cars overall performance.
With very few exceptions, if say a car does 0-60 in under 4 secs its seriously fast in all other areas (in gear acceleration for example)
Show me a car that does 0-60 in less than 4 secs but is slower from 60-120 than a car that does 0-60 in 6 secs. Don't think there is one.
R.
Hear, hear.
To statistically get a true view of a car's performance we would need 100s of different metrics per car - which would be impossible to mentally interpret and compare for a mere mortal such as myself. Hence, we have settled on a single metric - and 0-60 is that metric. It's not perfect, but it's not bad.
Will
silver993tt said:
Two cars both have a 0-60 time of 5 seconds.
Car A accelerates to 50 in 4 secs and then takes a further 1 sec to get to 60
Car B takes 1 sec to get to 50 and then a further 4 secs to get to 60
Are you guys telling me that the above two cars have travelled the same distance?
A bit of an extreme example
On second thoughts...
I see what you mean now. Car B reaches 50mph in next to no time. In the 4 seconds from 50mph to 60mph it is going at a higher speed for longer than Car A, therefore it covers more ground.
In other words, Car A is spending more time at lower speeds than Car B reducing the distance travelled.
Using the formula: distance = 0.5 (Start Velocity + End Velocity) * time taken (seconds)
(MPH converted to Kmh for easier calculation):
For Car A:
0-80kmh in 4 secs(0-50mph):
distance = 0.5 * (0+80) * 4 = 160m
80-100kmh in 1 sec (50-62mph):
distance = 0.5 (80+100) * 1 = 90m
Total distance covered = 250m
For Car B:
0-80kmh in 1 secs(0-50mph):
distance = 0.5 * (0+80) * 1 = 40m
80-100kmh in 4 secs (50-62mph):
distance = 0.5 (80+100) * 4 = 90m
Total distance covered = 360m
>> Edited by silver993tt on Monday 8th May 13:49
>> Edited by silver993tt on Monday 8th May 14:34
You appear to be confusing kilometres per hour with meters per second:
Car A travels 69.4m
Car B travels 111.1m
The whole thing is flawed mathematics. I expect everyone is bored with the exercise anyway but here's my bit.
To get one thing straight, the assumption that the speed involved is the average of the start speed (always zero) and the terminal velocity added together and halved is incorrect. As everyone knows acceleration is not linear.
The correct formula for distance travelled is simply:
Distance covered = Avergage speed X time. Note: average speed is unlikely to be in any car the: start speed + final speed / 2
As acceleration is far faster in the lower gears you spend much less time doing the lower speeds, the average speed will be biased far closer to the terminal velocity than zero. So it can never be the two added together divide 2
taken to the extreme to illustrate:
A. - If I had one real special space age drag car that gets to 59mph in 0,1 sec flat then spends 3,9 secs finding the next 1 mile and hour to get to sixty. Its average speed will tend towards being very close to 59 mph and it will have covered a lot of ground in 4 sec. (actual ground covered if ave taken as 59 mph is = 59 miles X 4/3600 = 0.06555 miles or 105 metres (at roughly 1600 metres a mile).
B. - Is a rocket it hardly moves for the first 3,9 secs while the fuse burns and it inches forward at barely 1 mile an hour, but in the last tenth of a second it ignites hurtling the rocket car to 60mph in 0.1 secs getting it also to 60 mph at the tick of the 4th second whereafter a parachute opens and it is restrained at 60mph. for 39/40th's of the time this car did vertually no distance at all before shooting to 60mph and no further just in a tenth of a second time for the 4 second to apply. Distance covered equals ave speed times time. the average speed over the 4 sec's would be about 1.5 MPH if the rest of the time it was virtually still apart from the final tenth of a seconds squirt to 60 this would give a distance covered of 0.01666 or 2.6 metres, pretty impressive lurch to its terminal velocity! i can feel a nose bleed coming on.
Clearly A had convex aceleration and the rocket was concave (flat before becoming exponetial). One spent a lot of time at a good speed therefore covering a lot of distance the other fizzed then popped for a mere moment. To calculate distance you need to understand the rate of change of velocity, commonly known as acceleration (acceleration is the first derivetive of velocity for calculus buffs).
For distance covered immediate acceleration good, late acceleration bad. As the one will produce a higher average speed over the same time frame even though the terminal velocities may end up the same.
I am aware that 993TT (great car by the way) did a similar type scenario with a speed break at 80km/h which illustrates the difference in distance covered above but he still took the average of two numbers one of which always has to be zero and the interim speed of 80km/h if you add the two numbers and divide by two that still assumes linear acceleration between the two points, instead of aknowledging the acceleration is higher lower down with most typical cars (apart from my rather cranky rocket in scenario B).
Right now I am sure everyones got a headache, and no I won't be running the numbers over the 1/4 mile to see who wins, (I capped the rocket with a parachute, weren't you paying any attention at the back of the class. You yesss you, if you don't eat your meat, you can't have any puddin')
To get one thing straight, the assumption that the speed involved is the average of the start speed (always zero) and the terminal velocity added together and halved is incorrect. As everyone knows acceleration is not linear.
The correct formula for distance travelled is simply:
Distance covered = Avergage speed X time. Note: average speed is unlikely to be in any car the: start speed + final speed / 2
As acceleration is far faster in the lower gears you spend much less time doing the lower speeds, the average speed will be biased far closer to the terminal velocity than zero. So it can never be the two added together divide 2
taken to the extreme to illustrate:
A. - If I had one real special space age drag car that gets to 59mph in 0,1 sec flat then spends 3,9 secs finding the next 1 mile and hour to get to sixty. Its average speed will tend towards being very close to 59 mph and it will have covered a lot of ground in 4 sec. (actual ground covered if ave taken as 59 mph is = 59 miles X 4/3600 = 0.06555 miles or 105 metres (at roughly 1600 metres a mile).
B. - Is a rocket it hardly moves for the first 3,9 secs while the fuse burns and it inches forward at barely 1 mile an hour, but in the last tenth of a second it ignites hurtling the rocket car to 60mph in 0.1 secs getting it also to 60 mph at the tick of the 4th second whereafter a parachute opens and it is restrained at 60mph. for 39/40th's of the time this car did vertually no distance at all before shooting to 60mph and no further just in a tenth of a second time for the 4 second to apply. Distance covered equals ave speed times time. the average speed over the 4 sec's would be about 1.5 MPH if the rest of the time it was virtually still apart from the final tenth of a seconds squirt to 60 this would give a distance covered of 0.01666 or 2.6 metres, pretty impressive lurch to its terminal velocity! i can feel a nose bleed coming on.
Clearly A had convex aceleration and the rocket was concave (flat before becoming exponetial). One spent a lot of time at a good speed therefore covering a lot of distance the other fizzed then popped for a mere moment. To calculate distance you need to understand the rate of change of velocity, commonly known as acceleration (acceleration is the first derivetive of velocity for calculus buffs).
For distance covered immediate acceleration good, late acceleration bad. As the one will produce a higher average speed over the same time frame even though the terminal velocities may end up the same.
I am aware that 993TT (great car by the way) did a similar type scenario with a speed break at 80km/h which illustrates the difference in distance covered above but he still took the average of two numbers one of which always has to be zero and the interim speed of 80km/h if you add the two numbers and divide by two that still assumes linear acceleration between the two points, instead of aknowledging the acceleration is higher lower down with most typical cars (apart from my rather cranky rocket in scenario B).
Right now I am sure everyones got a headache, and no I won't be running the numbers over the 1/4 mile to see who wins, (I capped the rocket with a parachute, weren't you paying any attention at the back of the class. You yesss you, if you don't eat your meat, you can't have any puddin')
Doing 0 to 60 times has so much to do with traction and reaction it is basically useless, the best way to gauge your car for power, torque etc and keep it in one piece is the 60 to 130 time, here are some examples
1. Enzo: 7.0 seconds (magazine test)
2. CGT: 7.3 seconds (magazine test)
3. Ruf Turbo R 7.4 seconds (3-4 shift), 8.7 seconds (2-3, 3-4 and 4-5 shift)
4. RS Tuning 993 TT 7.7 seconds (3-4 and 4-5 shift), 8.6 seconds (2-3, 3-4 and 4-5 shift)
5. F430: 9.5 seconds (magazine test, Euro version)
6. F50: 9.6 seconds (magazine test)
and so on.............
1. Enzo: 7.0 seconds (magazine test)
2. CGT: 7.3 seconds (magazine test)
3. Ruf Turbo R 7.4 seconds (3-4 shift), 8.7 seconds (2-3, 3-4 and 4-5 shift)
4. RS Tuning 993 TT 7.7 seconds (3-4 and 4-5 shift), 8.6 seconds (2-3, 3-4 and 4-5 shift)
5. F430: 9.5 seconds (magazine test, Euro version)
6. F50: 9.6 seconds (magazine test)
and so on.............
O.K. guys, here goes...
I will (hopefully) help answer the Vette Z06 /vs. 997 Turbo Question.
I own a 2007 Porsche 997 turbo with ALL the bells and wistles. (triptronic, sport crono, ceramic brakes, etc...) and my best friend has a 2006 - Z06.
My car is about 1 sec. faster from 0-60 than his.
The Porsche is also about 1 sec. faster in the qtr. mile and will walk away from the Z06 on any back road. And no, It isn't becouse I'm a better driver. The all wheel drive has a lot to do with all of the above.
When we run them from a stop light, his car has trouble hooking up (loads of wheel spin).
I love the sound of the Z06 as compaired to my turbo. The Z06 is very much "in your face" if you like that kind of stuff. Also, He (Randy) paid 1/2 what I did. I could have pursched two Vette's for what I paid for the Turbo.
Both cars are a blast to drive. Randy has had his car for a year and when I steped up to the plate, I bought the Porsche at twice the money and I am still happy I did, and would do so again. I would have to say, when it comes to the overall driving experience he and I both agree, if you have the cash buy the Porsche. This car does it all and does it very well. The 997 may not be twice to car for twice the money, but there is a very noticable difference in the two cars. To be fair, you really can't compair the two in the same way.
I will (hopefully) help answer the Vette Z06 /vs. 997 Turbo Question.
I own a 2007 Porsche 997 turbo with ALL the bells and wistles. (triptronic, sport crono, ceramic brakes, etc...) and my best friend has a 2006 - Z06.
My car is about 1 sec. faster from 0-60 than his.
The Porsche is also about 1 sec. faster in the qtr. mile and will walk away from the Z06 on any back road. And no, It isn't becouse I'm a better driver. The all wheel drive has a lot to do with all of the above.
When we run them from a stop light, his car has trouble hooking up (loads of wheel spin).
I love the sound of the Z06 as compaired to my turbo. The Z06 is very much "in your face" if you like that kind of stuff. Also, He (Randy) paid 1/2 what I did. I could have pursched two Vette's for what I paid for the Turbo.
Both cars are a blast to drive. Randy has had his car for a year and when I steped up to the plate, I bought the Porsche at twice the money and I am still happy I did, and would do so again. I would have to say, when it comes to the overall driving experience he and I both agree, if you have the cash buy the Porsche. This car does it all and does it very well. The 997 may not be twice to car for twice the money, but there is a very noticable difference in the two cars. To be fair, you really can't compair the two in the same way.
ponkyporky said:
The whole thing is flawed mathematics. I expect everyone is bored with the exercise anyway but here's my bit.
To get one thing straight, the assumption that the speed involved is the average of the start speed (always zero) and the terminal velocity added together and halved is incorrect. As everyone knows acceleration is not linear.
The correct formula for distance travelled is simply:
Distance covered = Avergage speed X time. Note: average speed is unlikely to be in any car the: start speed + final speed / 2
As acceleration is far faster in the lower gears you spend much less time doing the lower speeds, the average speed will be biased far closer to the terminal velocity than zero. So it can never be the two added together divide 2
taken to the extreme to illustrate:
A. - If I had one real special space age drag car that gets to 59mph in 0,1 sec flat then spends 3,9 secs finding the next 1 mile and hour to get to sixty. Its average speed will tend towards being very close to 59 mph and it will have covered a lot of ground in 4 sec. (actual ground covered if ave taken as 59 mph is = 59 miles X 4/3600 = 0.06555 miles or 105 metres (at roughly 1600 metres a mile).
B. - Is a rocket it hardly moves for the first 3,9 secs while the fuse burns and it inches forward at barely 1 mile an hour, but in the last tenth of a second it ignites hurtling the rocket car to 60mph in 0.1 secs getting it also to 60 mph at the tick of the 4th second whereafter a parachute opens and it is restrained at 60mph. for 39/40th's of the time this car did vertually no distance at all before shooting to 60mph and no further just in a tenth of a second time for the 4 second to apply. Distance covered equals ave speed times time. the average speed over the 4 sec's would be about 1.5 MPH if the rest of the time it was virtually still apart from the final tenth of a seconds squirt to 60 this would give a distance covered of 0.01666 or 2.6 metres, pretty impressive lurch to its terminal velocity! i can feel a nose bleed coming on.
Clearly A had convex aceleration and the rocket was concave (flat before becoming exponetial). One spent a lot of time at a good speed therefore covering a lot of distance the other fizzed then popped for a mere moment. To calculate distance you need to understand the rate of change of velocity, commonly known as acceleration (acceleration is the first derivetive of velocity for calculus buffs).
For distance covered immediate acceleration good, late acceleration bad. As the one will produce a higher average speed over the same time frame even though the terminal velocities may end up the same.
I am aware that 993TT (great car by the way) did a similar type scenario with a speed break at 80km/h which illustrates the difference in distance covered above but he still took the average of two numbers one of which always has to be zero and the interim speed of 80km/h if you add the two numbers and divide by two that still assumes linear acceleration between the two points, instead of aknowledging the acceleration is higher lower down with most typical cars (apart from my rather cranky rocket in scenario B).
Right now I am sure everyones got a headache, and no I won't be running the numbers over the 1/4 mile to see who wins, (I capped the rocket with a parachute, weren't you paying any attention at the back of the class. You yesss you, if you don't eat your meat, you can't have any puddin')
Unfortunately, the equation falls over if time is not constant, which it's not in certain parts of the universe. Too much to drink tonight. To get one thing straight, the assumption that the speed involved is the average of the start speed (always zero) and the terminal velocity added together and halved is incorrect. As everyone knows acceleration is not linear.
The correct formula for distance travelled is simply:
Distance covered = Avergage speed X time. Note: average speed is unlikely to be in any car the: start speed + final speed / 2
As acceleration is far faster in the lower gears you spend much less time doing the lower speeds, the average speed will be biased far closer to the terminal velocity than zero. So it can never be the two added together divide 2
taken to the extreme to illustrate:
A. - If I had one real special space age drag car that gets to 59mph in 0,1 sec flat then spends 3,9 secs finding the next 1 mile and hour to get to sixty. Its average speed will tend towards being very close to 59 mph and it will have covered a lot of ground in 4 sec. (actual ground covered if ave taken as 59 mph is = 59 miles X 4/3600 = 0.06555 miles or 105 metres (at roughly 1600 metres a mile).
B. - Is a rocket it hardly moves for the first 3,9 secs while the fuse burns and it inches forward at barely 1 mile an hour, but in the last tenth of a second it ignites hurtling the rocket car to 60mph in 0.1 secs getting it also to 60 mph at the tick of the 4th second whereafter a parachute opens and it is restrained at 60mph. for 39/40th's of the time this car did vertually no distance at all before shooting to 60mph and no further just in a tenth of a second time for the 4 second to apply. Distance covered equals ave speed times time. the average speed over the 4 sec's would be about 1.5 MPH if the rest of the time it was virtually still apart from the final tenth of a seconds squirt to 60 this would give a distance covered of 0.01666 or 2.6 metres, pretty impressive lurch to its terminal velocity! i can feel a nose bleed coming on.
Clearly A had convex aceleration and the rocket was concave (flat before becoming exponetial). One spent a lot of time at a good speed therefore covering a lot of distance the other fizzed then popped for a mere moment. To calculate distance you need to understand the rate of change of velocity, commonly known as acceleration (acceleration is the first derivetive of velocity for calculus buffs).
For distance covered immediate acceleration good, late acceleration bad. As the one will produce a higher average speed over the same time frame even though the terminal velocities may end up the same.
I am aware that 993TT (great car by the way) did a similar type scenario with a speed break at 80km/h which illustrates the difference in distance covered above but he still took the average of two numbers one of which always has to be zero and the interim speed of 80km/h if you add the two numbers and divide by two that still assumes linear acceleration between the two points, instead of aknowledging the acceleration is higher lower down with most typical cars (apart from my rather cranky rocket in scenario B).
Right now I am sure everyones got a headache, and no I won't be running the numbers over the 1/4 mile to see who wins, (I capped the rocket with a parachute, weren't you paying any attention at the back of the class. You yesss you, if you don't eat your meat, you can't have any puddin')
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