[sustran] low compression vs high compression engines

[Eric Bruun]

I think that there is still some confusion of issues here.

High compresssion does not automatically mean over-powered. 
Being over powered is a different issue. Diesel engines have
higher compression than gasoline, but are substantially more
efficient in terms of work per unit of fuel. They are not
popular in small vehicles because they are heavier to resist
the higher pressures, and they cost a lot more.

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".  

Most two stroke motorcycles have relatively low compression
ratios.  They can be boosted, but at great expense in reliability,
which is the tradeoff made for racing engines.  But again, they
are polluters more because of their primitive design of 
carburetion and lack of valves as much as anything else. 
Companies are not selling more advanced engine designs in the
less developed world.

Eric