RPM at top speed
Discussion
Having just come back from a glorious blast in the french region of Alsace, I found an empty piece of german autobahn on the way back and decided to give it a go with the hood down. I managed to get my Griff 500 up to 150 mph when my guts left me...I've heard to many stories of bonnets coming loose at high speeds 
. The car felt very stable though apart from the almost deafening noise from engine and wind. What surprised me was that the tach showed 5800 rpm at 150. The car reached that speed surprisingly quickly and makes me think there was quite a bit left, especially with the hood up. Does anybody know what rpm you would reach at true top speed?
P.S. Don't you just love it when people are already staring at you when you drive around a corner because they heard you coming a long time before
Cheers Andy
. The car felt very stable though apart from the almost deafening noise from engine and wind. What surprised me was that the tach showed 5800 rpm at 150. The car reached that speed surprisingly quickly and makes me think there was quite a bit left, especially with the hood up. Does anybody know what rpm you would reach at true top speed? P.S. Don't you just love it when people are already staring at you when you drive around a corner because they heard you coming a long time before
Cheers Andy
Probably the easiest way to tell is to put the car in 5th and then record the Revs at 75mph, then double it and you have the revs at 150
For instance, my shed does 50 at 3000rpm in 4th IIRC, so that means that I could do 100 at 6000rpm in 4th, and I'm just over 65 at 3000 in 5th which means that if I could ever get there, I would do 130 at 6000rpm, but I have yet to find a piece of road long enough
For instance, my shed does 50 at 3000rpm in 4th IIRC, so that means that I could do 100 at 6000rpm in 4th, and I'm just over 65 at 3000 in 5th which means that if I could ever get there, I would do 130 at 6000rpm, but I have yet to find a piece of road long enough
You can also multiply it up from the 5th gear ratio, although air resistance will doubtless stop the car ever getting to the theoetical maximum, you know, inverse square law etc. The same reason (theoretically) that you can't go faster than the speed of light, as it takes infinite energy to do so. Haven't tried that out yet though...
quote:
except your tyres will have grown a bit more at 150. OK, not much maybe, but they will!
Kmmm and you think that the speedo and rev counter are that accurate to detect it
Don't forget to add the effect of tyre pressure increasing as well.
There is a tyre/speed/rpm calculator/spread sheet on my web site if you want to play what if games...
Steve
www.tvrbooks.co.uk
'Interesting theory! any chance you could expand on that Rich...'
Yep - but I warn you, I've just consumed a fair aount of red wine.... To accelerate an object requires energy. The closer it gets to the speed of light (c) the more energy is needed for any given increase in velocity. As I recall, if you extrapolate the speed/energy graph, when it gets to 'c', energy reaches infinty.
'c' is 186,000 miles per second, which is 669,600,000 mph. If you get your Griff up to 150mph and crush the accelerator into the Wilton, you'll see what I mean. You're only doing 0.000000022 of 'c' and you're stuffed already. Nevertheless, dspite this hopeless and puny speed, Mr Einstein's Law of Relativity is already applying (it takes over where Mr Plod's raygun stops) and your car is starting to get shorter to outside obervers. Plus, if you keep going like that for long enough and far enough, when you get back to your mates you'll be slightly younger - compared to them - than when you left.
More wine anybody?
Yep - but I warn you, I've just consumed a fair aount of red wine.... To accelerate an object requires energy. The closer it gets to the speed of light (c) the more energy is needed for any given increase in velocity. As I recall, if you extrapolate the speed/energy graph, when it gets to 'c', energy reaches infinty.
'c' is 186,000 miles per second, which is 669,600,000 mph. If you get your Griff up to 150mph and crush the accelerator into the Wilton, you'll see what I mean. You're only doing 0.000000022 of 'c' and you're stuffed already. Nevertheless, dspite this hopeless and puny speed, Mr Einstein's Law of Relativity is already applying (it takes over where Mr Plod's raygun stops) and your car is starting to get shorter to outside obervers. Plus, if you keep going like that for long enough and far enough, when you get back to your mates you'll be slightly younger - compared to them - than when you left.
More wine anybody?
John,
Allow me to recommend a book you may enjoy... "A Brief History of Time" by Stephen Hawking. I read it whilst away on business last summer, didn't understand a word of it - but it looked good sitting reading it in the hotel restaurant!
p.s. Ted, when you gonna put a spell checker on the post facitity?
>> Edited by richb on Tuesday 25th June 10:37
Allow me to recommend a book you may enjoy... "A Brief History of Time" by Stephen Hawking. I read it whilst away on business last summer, didn't understand a word of it - but it looked good sitting reading it in the hotel restaurant!
p.s. Ted, when you gonna put a spell checker on the post facitity?
>> Edited by richb on Tuesday 25th June 10:37
'Don't forget about the effect of increasing mass as velocity increases. Travelling at 'c' the mass of an object will reach infinity, and no amount of diet coke and salad is going to affect that.'
Thanks! That's the bit I forgot, and it explains why infinite energy is needed, since you're trying to accelerate infinite mass.
Thanks! That's the bit I forgot, and it explains why infinite energy is needed, since you're trying to accelerate infinite mass.
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