At 10:21 AM 11/29/97 0500, DANMAS@aol.com wrote:
>In a message dated 971128 , I wrote:
>Given that Jerry is correct, and assuming that Christopher is also correct
>(and I believe he is  thanks for the clarification, Chris), Just how much
>more efficient can an engine be just by dropping the rpm by 820? How much
>difference in throttle position is there? If it takes 15  20 hp to move the
>car at freeway speeds in fourth, it still takes 15 20 hp to move the same
>car at the same speed in OD. Is there enough difference in efficiency to make
>a real difference? How long will it take to pay for the cost of converting to
>an OD if you don't already have one, particularly since most of the driving
>we do in these cars is off the freeway?
>
Dan
What I think you are assuming is that your 1520 h.p. figure is a constant.
It's not. The higher gearing provides a mechanical advantage. The engine
does not have to put out as much power to move the car down the road. 820
R.P.M. is significant (about a 25% reduction from a 3500 R.P.M. cruise
speed). If you don't think so, check your R.P.M. at 40 in third, and again
in fourth.
