STC for Rotax Engine to use Mix fuel to meet AKI 91

Any number of octane mix calculators on the internet. Here's one:

http://www.bazellracefuels.com/Calcs/OC1.htm

Mike

As I understand per the attached Rotax document, Rotax allows mixing 100LL with automotive unleaded fuel to get the required 91 AKI.  

The challenge seems to be what is the AKI of 100LL?  I have used 100.

Brett

I read once that the AKI of 100LL is approximately 104.

Ed

No less than 50% 100LL to the lower 87 octane. A little more won't hurt.

Better safe than sorry.

In hindsight, I am confused / troubled by this attached Rotax document about adding 100LL to auto fuel to increase its octane to the required level.  

SI-912-016R13 states that the octane of the fuel for the 912ULS must be a minimum of 95 RON or a minimum of 91 AKI.  But, the example is given in terms of MON.  Odd to use units different than used in their specification.  AKI is the average of MON and RON. So, a minimum of 87 MON is required. 

It also states that the minimum MON of 100LL is 104. But, the ASTM specification for 100LL states that the minimum MON is only 99.6.  So, this appears to be wrong and that 104 is actually the minimum AKI. 

Am I misunderstanding something?  If so, please point out my error. 

Thanks.  

Brett