Elvis Hargrove wrote in a message to John Demott:
-> But would you do that now with a restored auto?
 EH> Lord yes!  It didn't hurt them then and it won't now.  After
 EH> all, John, and explosion is an explosion!  Low compression,
 EH> low octane explosions are just less violent; the fuel burns
 EH> slower.
   I think you got it backwards.  Low octane gasoline is more volatile than 
high octane gas.  The knock and ping you hear from low octane gas is the 
result of preigition of the cheap gas (poping off before the sparkplug 
sparks).  The higher the compression of an engine, the more likely 
preignition will occur, so the less volatile higher octane gasoline (which 
used to refer to the amount of "octane" in the fuel, as opposed to the more 
volatilte heptanes and hexanes.  Since then other compounds that burn more 
slowly  have been added to raise the "octane" rating of fuel).
   You might say "But Ken, if the higher octane fuel burns slower, how come 
it's used in hi performance engines?"  The answer is, that with higher octane 
fuel, you can control the combustion process with spark, rather than the fuel 
mixture just going off at random (knock and ping).  With hi octane gas you 
can dial the distributor in to the most power with high compression!
 
Ken T. 
--- timEd-B11
---------------