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Re: Emissions Question

To: mgbob@juno.com
Subject: Re: Emissions Question
From: "Scott Gardner" <gardner@lwcomm.com>
Date: Sun, 7 Sep 1997 03:26:21 +0000
>    Well let's see about that---- the twin carb Bs consistently deliver
> 3-4 mpg better than the single Stromberg cars. How can a car burn that
> much more fuel and still deliver "cleaner air?"   To imply (or believe)
> that it does confounds reason.  
>   The air pump simply dilutes the exhaust.  It is axiomatic in many
> circles that "the solution to pollution is dilution."  I don't believe in
> that argument.
>   If you have received Moss Motoring within the last few days, you will
> find a fascinating article about fuels, tailpipe emissions, and the
> "adjustments" to the observed CO and HC levels.  
>   As the Bs that have air-injected heads suffer far more cracked heads
> than the standard ones, how can we work in an adjustment for the
> coke,coal,limestone,FE and all the other stuff that gets mined, burned
> and cooked to make the iron for replacement heads? 
>   Air pumps that are sensibly engineered to integrate with an engine
> designed with clean burning in mind, equipped with electronic controls,
> and sparkplugs that can fire lean mix at .040 gaps make sense.  In the
> case of the MGBs, they simply don't.
> Bob Howard
> Former Selectman, Assessor, Overseer of the Poor and Inspector of Fences
> Chairman, Conservation Commission
> Chairman, Town Planning Commission
> Member Maine Organic Farmer
> etc. (Who doesn't think he's insensitive to the environment)

I really don't think it's fair to say that an airpump simply "dilutes 
the exhaust".  As I understand it, the air pumped into the exhaust 
helps complete combustion of some of the hydrocarbons that would 
otherwise blow out the tailpipe unburned.  In that sense, an air pump 
reduces both the percentage of unburned hydrocarbons in the exhaust, 
as well as the total WEIGHT of hydrocarbons in the exhaust.
        This is not to say that I'm fond of the current testing methods.  
I've always thought a more fair benchmark would be something on the 
order of "micrograms of hydrocarbons emitted per mile traveled", or 
similar units, as determined by a run on a rolling road dyno.  A car 
could put out only half the %CO and ppm HC as my car, but if I'm 
getting three times the mileage he is, his is still the more 
pollutive of the two.
Scott

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