Question about stock ECU/Octane parameters.

[Hy Octane]

Hi gang..
My 6 lives in SoCal and is forced to use the 91 reformulated fuel we have here. Since 91 is the minimum octane allowed in these cars, I regularly will stop and add 5-6 gallons of 100 octane racing fuel at my local 76 station to bring it up to 93+.. The difference in the smoothness and power is really noticeable ( you lucky dogs who live in cities where 93-94 is available).. This got me to thinking.. What is the stock USA ECU able to handle as far as Octane? We hear tuners saying that "they have 100 oct fuel maps and so on, but if you use straight 100 fuel, the ECU isnt programmed for it and its a waste". So, does anyone know what octane range these stock ECU's are programmed to handle?
:confused:

[SoCal]

I have read somewhere (maybe in this forum, though a quick search came up dry) that because of engine characteristics and the way the stock ECU is programmed, there is no benefit to running the RS6 with gasoline above 96 octane. I've done that a few times myself, blending 91 or 93 with 100 at the pump to end up at 96, and the performance increase is noticeable.

Where do you get 100 in LA? There used to be a 76 Station that carried it in Brentwood and the old station in Santa Monica Canyon also had it (at an insane price). I had thought that all of the 76 stations stopped carrying it and am glad to hear I am mistaken.

[Skaala]

damn.......

in Norway you only get 95,98, and 99V-power at our gas stations. :revs:
A very very few, only a couple in the whole country offer 92
Is is worth to be said that one litre of fuel costs $1.80 + - 0.20 depending on the oil price.

[Hy Octane]

Hey SoCal. There is a 76 station at bundy and San Vincente that sells 100. Its really expensive now due to the recent oil debacle, was $5 a gallon .. now its almost $8!!

[SoCal]

Paul, Thanks for the Brentwood station tip.

Skaala, octane measurements are different. In the USA and Canada, we use the average of the Research Octane Test (RON) and the Motor Octane Test (MON), which is R+M/2. In Europe, you use just the RON, which is higher.

So, what is called 91 octane in Europe is equivalent to our 87. What would be called 95 octane in Europe is equivalent to our 91. And your 98 is our 94.

According to Wikipedia: "The most common type of octane rating worldwide is the Research Octane Number (RON). RON is determined by running the fuel through a specific test engine with a variable compression ratio under controlled conditions, and comparing these results with those for mixtures of isooctane and n-heptane.

"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. MON testing uses a similar test engine to that used in RON testing, but with a preheated fuel mixture, a 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. Normally fuel specifications require both a minimum RON and a minimum MON.

"In most countries (including all of Europe and Australia) the "headline" octane that would be shown on the pump is the RON, but in the United States and some other countries the headline number is the average of the RON and the MON, sometimes called the Anti-Knock Index (AKI), Road Octane Number (RdON), Pump Octane Number (PON), or (R+M)/2. Because of the 8 to 10 point difference noted above, this means that the octane in the United States will be about 4 to 5 points lower than the same fuel elsewhere: 87 octane fuel, the "regular" gasoline in the US and Canada, would be 91-95 (regular) in Europe."

Hope this helps.