In a message dated 96-06-23 03:00:02 EDT, cmoran@cswnet.com (Colin A Moran)
writes:

<< 
 Why then do so many aircraft engines have horizontaly opposed engines? They
 run at that rpm for long periods.  Also why has porsche used horizontaly
 opposed engines for so long if there was an rpm limit so low?  I read in
 Marks Engineering Hand Book that horizontaly opposed engines have the same
 benifits as a v type engine.  A horizontaly opposed engine is a V with
 180deg between banks.   
     My $0.02 worth :-)
 Colin A Moran
  >>
Space utilization is the main reason.  Also, it is probably much easier to
cool an engine with air in this configuration.  What about those Radial
piston engines?  Those things amaze me.
Dennis.