Originally Posted by erick212
Yes but, I believe there are two ways to rate(calculate) the octane... Do you know what way they rate it?
Yes but, I believe there are two ways to rate(calculate) the octane... Do you know what way they rate it?
3, actually. RON, MON, and AKI. US/Canada use AKI (anti-knock index) also known as (R+M)/2 method. Otherwise, RON (research octane number) is commonly used worldwide, and MON (motor octane rating) also known as aviation lean octane rating.
Because of these differences, and how they are calculated via RPM, ignition timing, preheating, and such, the same numbers can mean very different things. A basic rule, though, when comparing numbers worldwide (America's AKI versus RON worldwide), is the America's octane rating number is shown 4 or 5 points lower than similar gas used worldwide. So for the exact same gas, the RON (worldwide) could be 95, but the AKI (US/CAN) will be 90.
MON I've never really looked into, so as for the differences between the posted octane ratings versus MON I don't know. From what I remember it's similar to RON but results in a lower numbered rating. If the RON is 95, the MON will be significantly lower, somewhere in the 85 range.
Here's a quick conversion for common US to Worldwide octane ratings:
US........Worldwide
87..........91/92
90..........95
93..........97/98
97/98.....102