>An air cooled engine must have sloppy tolerances because of the tremendous expansion/contraction as a result of the great temp range in which it must
   operate.<

>>So how do you explain the "sloppy tolerances" of a jet engine?-- It too is air cooled.<<

>>>Jeez, wasn't "cylinders" enough of a hint?  Just add piston in front of engine.<<<

Wouldn´t a piston added to the front end of a jet engine disturb the airflow and make the cooling worse, thus requiring even bigger tolerances???

Tim