Originally Posted by Chris L.
Apleschu.....thanks, I was hoping someone with a better understanding would clear it up a bit. So if you were to guess about something like an octane rating for diesel....what would it be?
There is no octane rating for diesel. Just does not work. (you can't measure distance in gallons either LOL)
For diesel the rating is called cetane, and if there is any comparison, at all then you can roughly say cetane is the exact opposite of octane, but then again, even that is a VERY weak and wrong comparison. The cetane number of diesel fuel goes up the easier the fuel is ignited AND the more energy content the fuel has. In gas(petrol) there is no reference to energy content, in cetane/diesel there is. In essence a cetane of 50 is very good fuel, has good flammability and high energy content, 40 and below is getting iffy, but modern diesel engine will use that as well, (just use a bit more of it because the energy content goes down) Kind of like the gas/alcohol mixture. But since diesel is an oil to begin with the engines are much more relaxed in terms of which fuel they want.
But bottom line: You CANNOT compare octane to cetane they are two different measuring schemas.