Dad's RV-10
Well Known Member
The Aerosport data plate on my IO-375 indicates the minimum octane rating is 91/96. 91/96 is an aviation fuel produced by Hjelmco Oil.
This article about UL91 says in part, "As an aside, remember that aviation fuels are usually denoted by their lean MON octane rating (MON = Motor Octane Number). Thus, 100LL = 100 MON and UL91 = 91 MON. Hjelmco still uses the lean/rich MON numbers to denote their fuel, thus Helmco’s 91/96UL would be the same as a 91 MON aviation fuel. To add to the confusion, most countries denote octane ratings for highway vehicles according to their RON (RON = Research Octane Number), except the US, which uses the Anti-Knock Index, AKI (AKI = (RON+MON)/2 )..."
It seems that 91/96 is the same as 91 aviation fuel but not the same as 91 auto fuel.
So what should a fuel tank placard indicate for this engine? Simply "Min Octane 91/96"?
If it were to say "Min Octane 91," one might assume 91 auto fuel is acceptable.
This is likely minutia but I'm curious to hear some thoughts.
Thanks.
This article about UL91 says in part, "As an aside, remember that aviation fuels are usually denoted by their lean MON octane rating (MON = Motor Octane Number). Thus, 100LL = 100 MON and UL91 = 91 MON. Hjelmco still uses the lean/rich MON numbers to denote their fuel, thus Helmco’s 91/96UL would be the same as a 91 MON aviation fuel. To add to the confusion, most countries denote octane ratings for highway vehicles according to their RON (RON = Research Octane Number), except the US, which uses the Anti-Knock Index, AKI (AKI = (RON+MON)/2 )..."
It seems that 91/96 is the same as 91 aviation fuel but not the same as 91 auto fuel.
So what should a fuel tank placard indicate for this engine? Simply "Min Octane 91/96"?
If it were to say "Min Octane 91," one might assume 91 auto fuel is acceptable.
This is likely minutia but I'm curious to hear some thoughts.
Thanks.
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