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Path: utzoo!watmath!clyde!burl!hou3c!rs
From: rs@hou3c.UUCP (rs)
Newsgroups: net.auto
Subject: Re: "The biggest farce ever" faster speed =? better mpg
Message-ID: <647@hou3c.UUCP>
Date: Thu, 21-Jun-84 14:32:00 EDT
Article-I.D.: hou3c.647
Posted: Thu Jun 21 14:32:00 1984
Date-Received: Fri, 22-Jun-84 07:47:16 EDT
References: <2104@ihnss.UUCP> <714@ut-ngp.UUCP> <141@godot.UUCP>
Organization: Bell Labs, Holmdel, NJ
Lines: 24


It is worthy to note that the transmission is also important in
determining what the optimum cruising speed is, for fuel ecomony
purposes, as well as the other factors.  In particular, manual transmission
cars are sometimes equiped stock with innappropriate transmissions
for highway cruising.  For example, my brothers 1973 Datsan Z would
get ~20 mpg at 70 mph and ~16 mpg at 60 mph primarily because of the
3rd and 4th gear ratios and the corresponding engine speed. (as well
as the mandatory downshifts to get passing power at 60 mph).
My 1968 Camaro had a 3 speed manual transmission that was geared such that
the engine was turning about 3500 rpm at 55 mph.  A lower ratio rear-end
would have brought the rpms down for highway cruising, as well as give
me more usable power in the lower gears (instead of just buring rubber when
a fast start was attempted).  A friend of mine did that with his 1978 Z-28
(350 ci. with a 4 barrel carb).  His engine used to turn ~3600 rpm at 60 mph
and now turns ~2400 rpm at 60 mph.  On a recent long distance trip (to Canada)
he got ~20-22 mpg on the highway.


Bob Switzer
AT&T Bell Labs
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