Re: High RPMs at highway speed?

[Philip Rose <pjrose@servtech.com>]

Scott,
You've done it again! A superb answer to a good question!!

P.R.


>Date: Mon, 07 Jun 1999 15:50:22 -0700
>From: Scott Fisher <sefisher@cisco.com>
>Subject: Re: High RPMs at highway speed?
>
>Sam Clough asks his original question again, after we went off on an
>interesting digression:
>
>> Why do our cars run such high RPMs on the Interstate?
>
>The main reason is so that the engines are in the strongest part of the
>powerband at cruising speeds, to make passing safe and easy.  This is a
>factor of the cam timing, port velocity, and other design parameters,
>which in turn are all conscious decisions on the part of the engineers.
>
>You might gain an appreciation of the cars' design by asking the same
>question from Ingolstadt's point of view -- why do U.S. and Japanese
>cars run such low RPM on the Interstate?  There's no real "right"
>answer; it's more a case that each band of engineers is working from a
>different perspective.  And examining that perspective is something I've
>had a lot of fun doing for many years; I hope I can convey a sense of
>that fun ain this posting.
>
>> In the A6 at 80mph it's turning 3,600.

[snipped, reluctantly]

>In short: you're probably okay driving 3600 RPM on the freeway, but
>change your oil and timing belt when you're supposed to. :-)
>
>- --Scott Fisher

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