That's a load of rubbish higher octane fuels don't have lower energy than lower octane fuels.
Next thing you will be telling us higher octane fuels burn slower
Running low octane or high octane in stock chainsaws the operator wouldn’t even notice a difference between the two that's the reality. That is providing the low octane fuel isn't contaminated with ethanol if that's the case about any e-free high octane fuel will out perform it.
All depends on what they use to change the octane rating. Vp Fuels has some articles on this matter. It's not that the fuel contains less BTU's just less of the BTU's are actually used.
Quotes from VP fuels website:
Realize first that octane is a measurement of a fuel’s ability to resist detonation—nothing more. The two types of machines used for testing octane—a Motor Octane machine and a Research Octane machine—were designed in the 1930s. They were designed to test for octane numbers from the 0-100 range, therefore, any number above 100 is an extrapolation.
But bear in mind, a fuel’s ability to prevent detonation is a function of more than just octane
. For example, VP’s fuels—oxygenated or nonoxygenated—vaporize much better than competitive fuels with comparable octane ratings. This means VP fuels cool the intake charge, burn faster and yield more efficient combustion. As a result, the “effective” octane rating of VP’s fuels is even higher than the rating generated by the octane test. As a result, VP fuels will prevent detonation more effectively than competitive fuels with comparable MONs.
Can you over octane an engine?
Yes you can over octane an engine. Generally you will get sluggish throttle response. Also you may get fouled plugs and deposits in the exhaust ports and headers. When an engine is trying to burn a fuel that has too much octane, the burn rate is incorrect and all of the fuel won’t be used up. This excess usually gets left as a deposit or gets pushed out the exhaust. It is important to match your engine’s needs with the correct fuel.