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Thanks Phil; Here in California..."Premium" is 91 Octane...price hovering around $4.20 a gallon....Mark
Research Octane Number (RON) The most common type of octane rating worldwide is the Research Octane Number (RON). RON is determined by running the fuel in a test engine with a variable compression ratio under controlled conditions, and comparing the results with those for mixtures of iso-octane and n-heptane. Motor Octane Number (MON) There is another type of octane rating, called Motor Octane Number (MON), or the aviation lean octane rating, which is a better measure of how the fuel behaves when under load, as it is determined at 900 rpm engine speed, instead of the 600 rpm for RON.[1] MON testing uses a similar test engine to that used in RON testing, but with a preheated fuel mixture, higher engine speed, and variable ignition timing to further stress the fuel's knock resistance. Depending on the composition of the fuel, the MON of a modern gasoline will be about 8 to 10 points lower than the RON, however there is no direct link between RON and MON. Normally, fuel specifications require both a minimum RON and a minimum MON. In most countries, including Australia and all of those in Europe, the "headline" octane rating shown on the pump is the RON, but in Canada, the United States and some other countries, like Brazil, the headline number is the average of the RON and the MON, called the Anti-Knock Index (AKI, and often written on pumps as (R+M)/2). It may also sometimes be called the Pump Octane Number (PON). Difference between RON and AKI Because of the 8 to 10 point difference noted above, the octane rating shown in Canada and the United States is 4 to 5 points lower than the rating shown elsewhere in the world for the same fuel.
Hello James;....WOW & THANKS for the information in your post. I wonder how the high compression motors of today (10-1/2 to 1 compression ratio) handle the lower (91) Octane ratings of today....in the late 60's & 70's, I can remember Octane ratings of 105+++ ...would be interesting to dyno a motor using 91 Octane, record the results & then dyno that same motor using 105 Octane gas....I wonder how much horsepower would be gained from the higher Octane gas?......Mark
Octane rating or octane number is a standard measure of the performance of a motor or aviation fuel. The higher the octane number, the more compression the fuel can withstand before detonating. In broad terms, fuels with a higher octane rating are used in high-compression engines that generally have higher performance. In contrast, fuels with low octane numbers (but high cetane numbers) are ideal for diesel engines. Use of gasolines with low octane numbers may lead to the problem of engine knocking.
Sorry Mark .... please ... On Topic again ? TR SEA VIEW Any more sea view pics of Testarossa's ? (from Portugal ..)
