RE: Timing Belt

["PAT MARTIN" <MARDKINS@msn.com>]

2 problems with that.  One is the obvious $$$.  It must cost more to put those 
pretty little recesses in the piston.  
Second, I wonder if the efficiency would be effected by having crevices that 
might not let the gasses combust effectively.
Diesels do not use a spark to combust the gas they use compression hence the 
high compression.

Pat Martin
864000csq 2 1/2 cat back, H&R-Boge,advanced and loving it.  Drilled and 
stopping it.  Koenig Cobra 16x7 with AVS Intermediates, K&N.
95 subaru legacy 
Bothell, Wa.

So is the only conceptual difference between an interference and a 
non-interference design the fact that the latter is higher compression? (I'm 
speaking in practical terms here, I guess you could always create a high 
compression free running engine by using funky pistons with recesses in them 
where the valves would go should the cam belt break) or is there something
else I'm missing?
Second, how come diesel engines can run so much higher compression?  I imagine 
it has something to do with the qualities of the fuel compared to gasoline, 
but I can only guess to what they are (slower, more controlled explosion?).