View Single Post
  #18  
Old June 14th 08, 04:32 AM posted to rec.aviation.owning
Newps
external usenet poster
 
Posts: 1,886
Default Lycoming to approve 93 octane auto gas for O-360 & IO-360

JGalban via AviationKB.com wrote:
Newps wrote:
Temp has almost nothing practical to do with the octane required. What
matters is the internal cylinder pressure.


I agree that cylinder pressure is the primary factor, but intake
temperatures can push detonation margins lower. That's why intercoolers and
water injection systems were invented.


Yes, but raise the temperature of the air and you lower its density
altitude which reduces the octane requirement. So temp plays a factor
but it's a complex relationship.