Higher octane rated fuel burns more slowly than lower octane rated fuel, which is how it helps prevent detonation or pre-ignition. It can also be considered more ignition resistant too. <span style="color: rgb(255, 0, 0);">This was true in the 1970's when fuel was blended with tetra ethyl lead and high aromatics compounds (large ring structures). TEL is a flame retardant and aromatics being double bonded ring structures disassociate slowly hence slower burning. Its no longer true with unleaded fuels since the octane is recovered with highly branched paraffins</span>.With our small gas engines, they do not need the high octance fuels and if anything it reduces performance as it doesn't burn as well inside the small engines.<span style="color: rgb(255, 0, 0);"> Complete non sense. Octane requirement is not governed by cubic capacity but by compression ratio. Our 2 strokes don't need high octane because they are relatively low compression. My kart engines, also 2 stroke 100cc engine where higher compression and required higher octane.</span>
In the past in Europe car engines tended to be smaller and the high performance engines had a large number of cylinders in order to keep the pistons smaller, thus they developed 10, 12, and 16 cylinder engines for their sports cars. This was done because a smaller cylinder and piston didn't have detonation or pre-ignition problems like a larger cylinder and piston would have. Also in Europe at the time high grade high octance gasoline was harder to obtain too. Buit here in the USA the big muscle car engines developed having large cylinder and pistons and they had to have higher octane fuels to prevent detonation and preignition. A similar effect is with airplane engines, especially the huge large displacement engines. <span style="color: rgb(255, 0, 0);">More complete and utter nonsense. European car designers designed smaller cars because of shorter distances between towns, and the overall desire to have good handling cars that could be enjoyed on narrow country lanes. Smaller engines were a result of a desire for light weight.</span>
Now thenfor our small RC gasoline engines, they do not have enough displacement to take advantage of high octane fuels. We need lower octane fuels in order to get more of the fuel to burn inside the engine properly. Thus with our little gas engines you would likely have more of a loss of performance using high octane fuel. <span style="color: rgb(255, 0, 0);">More rubbish. Once the spark provides the activation energy to get the mix going it burns due to temperature, pressure and mixture ratio. Higher octane provides a safety against detonation or uncontrolled ignition, nothing more. Compression ratio is the governing factor, it has nothing to do with displacement.</span>
But some fuels like, aviation high octane fuel, does not have ethanol in it, and some people prefer that fuel as it may mean less problems with the carburetor rubber parts degrading over time. Our USA pump gasolines tend to contain ethanol and other substances that can cause the rubber parts to deteriorate faster. A similar reason is there for using the more expensive pre-mix gasolines sold at many stores here too as it doesn't contain ethanol either and also has a more simple mix of chemicals in it too. <span style="color: rgb(255, 0, 0);">Will it stop....Gasoline with ethanol is actually a simpler mix of chemicals. Ethanol free gasoline requires a more complex mix of hydrocarbon to get the octane back. Any engine sold in a ethanol market has compatible seals. The Ethanol is a non issue from a seal compatibility perspective. Fuel storage is a factor if you live in a humid environment. AVGAS is about 90% Alkylate which is a highly branched hydrocarbon that provides excellent octane, very fast flame speed and because its a much simpler mix of hydrocarbons, excellent storage stability. The TEL is added to raise the octane further but mostly to protect older avgas burning engines. Ethanol can be used as a aviation fuel as Brasil has been proving for the past 25years. Issues with your fuel stability at home is largely your fault. Store it the way your fuel marketer suggests, not according ot the principals of internet experts....</span>
Now in some cases advancing the ignition timing on a small RC engine may help with buring the high octane fuel. But this has to be pretty much, determined on a case by case trial. It may not work with the small engines all that much.Then there is the compression ratio for the engine too, a high compression engine may need the higher octane fuel to prevent detonation or preignition. <span style="color: rgb(255, 0, 0);">Advancing the timing won't influence the octane requirement on a low compression ratio 2 stroke...</span>
But I expect that our small RC engines would either have a small performance loss, or <span style="color: rgb(255, 0, 0);">no performance improvement (most likely)</span>and maybe a slight increase in fuel consumption burning high octane fuel. <span style="color: rgb(255, 0, 0);">Absolute drivel</span>
Some facts and myths about high octane fuel from a car website:
• Knock occurs when cylinder pressures are high. It is normal for an engine to ping a little at full throttle
because cylinder pressures are very high at full throttle. Engine knock, however, should not be ignored
since it can result in serious damage to the engine.</p>
• High octane gasoline burns slower than low octane gasoline. The slow burn prevents engine knock when
cylinder pressures are high. <span style="color: rgb(255, 0, 0);">Only true if it is blended with a metallic octane booster</span></p>
• If your engine runs well and does not knock or ping on low octane gasoline, there is no advantage in
switching to higher octane gasoline.</p>
• If your engine knocks or pings, it does not necessarily mean something is wrong with the gasoline. It could
be a problem with the engine’s electronic control systems, ignition timing or exhaust gas recirculation. On a
high mileage engine, a carbon build-up in the cylinders can increase cylinder pressures and cause knock.</p>
• Almost all of today’s new cars have fuel-injected engines that need to use gasoline with a detergent additive.
They do not necessarily need high octane gasoline with a detergent additive. Generally, new automobiles
need high octane gasoline only if the manufacturer recommends it.</p>
• Always follow the auto manufacturer’s octane recommendations in your owner’s manual.</p>
• High octane gasoline improves mileage.
In general, if your car is designed to run on 87 octane gasoline, high octane gasoline will not improve
mileage. If switching to high octane gasoline does improve mileage, you might find that your engine, or its
control systems, need repair.</p>
• High octane gasoline gives quicker starting.
No, it doesn’t. <span style="color: rgb(255, 0, 0);">Not necessarily true, it depends on the season. In winter the volatility requirement of the fuel is higher so more butane goes into the fuel. Butane vapourises quicker and that results in quicker start. Generally higher octane fuels will have a percent more butane than a lower octane fuel but still remain within the volatility range.</span></p>
• High octane gasoline increases power.
If your car is designed to run on 87 octane gasoline, you shouldn’t notice any more power on high octane
gasoline. Again, if it does make a noticeable difference, your engine, or the engine’s electronic control
systems, may need repair. <span style="color: rgb(255, 0, 0);">Not necessarily true. If the engine is designed to run on higher octane, a lower octane fuel will result in the ECU changing the engine settings to a more conservative map meaning the engine runs in a lower power mode.</span></p>
• High octane gasoline has been refined more – it is just a better product.
Additional refining steps are used to increase the octane; however, these additional steps do not necessarily
make the gasoline a “better” product for all engines. They just yield a different blend of hydrocarbons that
burn more slowly. The additional steps also increase the price.
<span style="color: rgb(255, 0, 0);">Again, not necessarily true. Its only true if more benzine structures are present to recover the octane lost due to removing TEL. If Alkylate is used then the fuel actually burns faster. This stuff is 20 years out of date!</span>