fesycresy
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| posted on 9/12/08 at 02:04 PM |
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Top speed / final ratio / drag coeff question
Thought this was simple, but now I'm confusing myself.
Take a Busa @ 180bhp with a 3.38 diff, 205-60-13's and using Chris Gamlins calculator, the top speed shows a theoretical 127.30mph.
Now if the same engine gave out 250bhp, would this increase the top speed ?
Or, is the final ratios the limiting factor when these top speeds are calculated, bearing in mind the box ratios for the Busa.
And how about the drag coeff ?
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The sooner you fall behind, the more time you'll have to catch up.
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jacko
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| posted on 9/12/08 at 02:21 PM |
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Put it in the Gamlins calculator and see what comes up
Sorry i have no idea
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aka Keith
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| posted on 9/12/08 at 02:24 PM |
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fesycresy
I had always assumed that the calculator did not take into account drag, such that the max spead was a function of max revs, final drive and tyre
size.
To answer you question therefore, I had thought the answer would be:
assuming that the max revs does not changes, then the theoretical max speed would not change, but the time taken to get to the top speed would be
reduced.
If however at 180bhp the car was in reality hitting a a drag factor that stopped it hitting a real 127, then a 205 bhp engine may well get it to the
thoeritical max.
make sense?
[Edited on 9/12/08 by aka Keith]
[Edited on 9/12/08 by aka Keith]
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Mr Whippy
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| posted on 9/12/08 at 02:37 PM |
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Generally a larger engine allows you to increase the cars maximum speed through changing the final drive ratio, while maintaining the engine rpm that
produces the most power, which is not usually the maximum possible rpm as it tends to fall off near the engines limits. Its also to do with the torque
generated as it’s a constant push against the car rather like climbing a steep hill.
However trying to get a shed to go fast is a good way to waste lots of money in the wrong place, cure the cause not the symptom.
[Edited on 9/12/08 by Mr Whippy]
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afj
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| posted on 9/12/08 at 03:07 PM |
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so how fast would said car go if it had 25bhp
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Mr Whippy
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| posted on 9/12/08 at 03:12 PM |
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quote:
Originally posted by afj
so how fast would said car go if it had 25bhp
my Beetle has that much power and will do a terrifying 60mph.........if given long enough.......and a tail wind 
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