[sustran] low compression vs high compression

[Roberto Verzola]

 >The old reasons against high compression are not necessarily
 >true any longer, as the combustion can now be regulated to 
 >vary in temperature and to have more idealized "swirl".  

Barry Commoner was quite definite that high-compression engines
produced worse pollution than low-compression ones. Can you please
substantiate your statement, which seems to contradict Commoner's
conclusions? (Not that I am looking for a debate; I was simply
convinced by Commoner's very strong arguments, and I haven't seen
convincing counter-arguments or substantiation yet from postings
here.)

 >Most two stroke motorcycles have relatively low compression
 >ratios.  They can be boosted, but at great expense in reliability,

This confirms what I suspected: that motorcycles in general are
low-compression engines. According to Commoner again, the main
products of combustion in a low-compression engine are water, carbon
dioxide and unburnt fuel. In high-compression (and therefore
high-temperature too) engines, chemistry kicks in and produces a
different set of combustion by-products, which are worse pollutants.

 >are polluters more because of their primitive design of 
 >carburetion and lack of valves as much as anything else. 

This seems to imply that a more primitive design means more pollution,
which is not necessarily so. In fact, Commoner's message, in his
chapter "The Technological Flaw" was that often more modern designs
are more counter-ecological (and he cited quite a number of examples,
not only automobiles), because design is guided less by ecological
than by profit considerations.

Obet Verzola