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From: throopw@dg_rtp.UUCP
Newsgroups: net.auto.tech
Subject: Re: Gas Mileage
Message-ID: <103@dg_rtp.UUCP>
Date: Tue, 21-Jan-86 18:14:57 EST
Article-I.D.: dg_rtp.103
Posted: Tue Jan 21 18:14:57 1986
Date-Received: Thu, 23-Jan-86 21:15:19 EST
References: <576@adelie.UUCP>
Lines: 27

> I have noticed that my gas mileage drops by 15-20% every winter

I think the effect has two major components, and I'm not sure which is
greater.  First, the thermal component.  The car is breathing colder air
in the winter, and this heat must come from somewhere.  In this case, in
order to get cold air to expand the "same ammount" as hot air (and hence
provide the same amount of power) more gas must be burned.

Second, the humidity component.  Winter air is *much* less humid than
summer air.  A little water in the air works wonders for power output.
In fact, some aircraft engines used to be water injected, and there are
(mostly useless, but not totally bogus) gadgets that humidify intake air
on a standard carburated engine.

As to what you can do about it, you can make sure that your input air is
preheated as far as is possible (most cars nowadays route the intake
past heated engine surfaces).  You might want to look into
humidification gadgets, but this is *far* *far* more likely to be a
rip-off in one form or another.

And oh, yes, if you have snow and ice sitting on your car, the wind
resistance goes way way up, so scrape it every morning.

> Jeff Moskow  {harvard | decvax!cca!emacs}!adelie!jeff
-- 
Wayne Throop at Data General, RTP, NC
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