Quote:
Originally Posted by M5Rick
We have just two petrols here 95 and 99 RON. I've seen gas pumps in North America with sometimes four or more selections of petrol (gas) even more with the RON going to just 93 maximum? seems a bit low, is that b/c of the bigger cats you use in some states.
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Oh it's not because of the CATS, its because we use AKI here in North America. AKI - stands for anti knock index and it is calculated by (RON: research octane number + MON: Motor octane number) / 2. So that's why it is a lower number than in Europe but likely the same in terms of "octane" when comparing top tier gas, but European gas is far superior than North American gas overall in terms of quality.
So AKI is the average of the 2 octane measurements. We generally have: 87, 89, 91, 93, and 94. Although 93 and 94 are only found in select areas.