dan coupe wrote: I filled up with it in France (by mistake - thinking it was normal unleaded). Car ran ok, but the fuel economy dropped by about 10% (from getting well over 330 miles out of a tank to just under 300 miles).
So the government and oil companies persuade us to use 10% more fuel to be green. Right... Of course the fuel will be 10% cheaper won't it? Won't it?
bryan young wrote: The advice is however, to use Super grade of fuels, much more expensive, but contains little ethanol :thumbsup:
The advice that super grades contain little ethanol should not necessarily be trusted because ethanol is a cheap octane booster.
As an example, here in Ontario there is an Ultra grade at Petro-Canada stations, which is 3-4 octane points higher than Super grade fuel. In most areas of the province, the additional octane is provided by...wait for it...you guessed it: ethanol. The following is directly from Petro-Canada's website:
"Why is ethanol an effective octane booster? The octane number written on the gas pump is Anti-Knock Index (AKI). It’s an average of two octane ratings using the same test equipment but using different operating conditions. The methods produce a Research Octane number (RON) and a Motor Octane Number (MON). Both were once considered important and that’s why AKI is an average of the two. With modern engines and fuels systems, recent studies have shown that RON is more important than MON. So in these cars, the higher the RON the better these cars perform. For an AKI rating of 91 the lower the MON the higher the RON. This difference is called sensitivity. All gasoline components have different sensitivity. Most hydrocarbon components have low sensitivity. Ethanol has high sensitivity and so, modern performance cars benefit from gasolines with ethanol. Why does ethanol have higher sensitivity? One reason is related to the cooler combustion that results from ethanol combustion. Higher knock tendency is directly related to higher combustion temperature.
Here is a comparison of two fuels with different octane with and without ethanol.
91 Grade - no ethanol
RON 97.2
MON 85.6
Ultra 94 - with ethanol
RON 101.5
MON 88
Notice the difference in RON number from 91 grade without ethanol (97.2) and the RON of Ultra 94 (101.5). The difference is 4.3 numbers. That is significantly more than the 3 numbers difference between 94 and 91 AKI labelled on the pump. That is why gasoline with ethanol can be the best performance fuel for today's cars."
Right... Of course the fuel will be 10% cheaper won't it? Won't it?
