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Re: driving questions

Subject: Re: driving questions
From: Chris Delling <>
Date: Thu, 27 Nov 1997 23:23:33 -0500
At 10:21 AM 11/29/97 -0500, wrote:
>In a message dated 97-11-28 , 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?


What I think you are assuming is that your 15-20 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.

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