Bob Palmer wrote:
> Steve,
>
> I think somehow you got the first formula mixed up a little;
>
> >Some handy formulae:
> >
> >rpm@60mph=
> >(mph)*(revmotor/revaxle)/((60min/hr)*(revmotor/revaxle)*(miles/tirerev))
> >
>
> The differential ratio, which you indicate here by "(revmotor/revaxle)"
> should only be in the denominator. You don't make this same mistake when
> you re-arrange the equation in terms of speed. Also, the first equation,
> when corrected, is good for all speeds, not just @ 60 mph.
>
> Bob
Bob is correct. That's what happens when you 'cut and past' wrong. Thanks
Bob.
On the rear axle ratio question, though, you are assuming a non overdrive
transmission and in top gear (1:1) This formula is applicable for all
gears, if you plug in the right numbers. That way you can find the rpm at
any speed in any gear. Doesn't mean the car will do it. You can get 8,000
rpm, however, if you accidentally shifted from third, wound out, to second
instead of fourth. Don't laugh, happened to many a Porsche owner with a
dog-leg fifth. Wanted to downshift to 4th and got second. The electronic
rev limiter didn't help. The engines can come apart.
Steve Laifman < One first kiss, >
B9472289 < one first love, and >
< one first win, is all >
< you get in this life. >
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