Octane No:-Octane number is defined as the percentage, by volume, of iso octane in the mixture of iso octane and h-heptane. It is the measure of rating of SI engine.
Cetane No:- Cetane number is defined as the percentage, by volume, of n-cetane in the mixture of n-cetane and alpha methyl naphthalene. It is the measure of rating of CI engine.   _{Your Comment}