What do "Motor or Research" octane#s mean?

[GSX-PKV]

Just wondering... The street gas I use is Rockett 100 octane unleaded. The motor octane is #96 and the research #106. What do those #'s mean. The 100 rating seems to be an average of the 2 ratings but I don't get why there are multiple ratings. Paul

 

[RUQWKNF]

Here ya go.
VP Racing Fuels

At the top of the screen, click where it says, "Octane Numbers: What They Mean."

HTH
Patrick

 

[Turbo6Smackdown]

theres 3 octane ratings. research, motor, and pump. pump (which is what you should go by) is research, plus motor, divided in 2. to give an average.

theyre just different tests they put the gas thru, to get those numbers.

go here, and read ALL of it. youll come out sounding like a rocket scientist.
Fuel System

 

[VadersV6]

When you go to the gas station, under the octane sticker, you'll see a formula, something like R+M/2 or something like that. Basically, its just getting an average between research octane and motor octane, which gives you the pump octane. Say alcohol is 110 and pump is 91. Say you're pumping equal amounts of alky and 91 pump gas...or actually a stoichiometric ratio of alky, and the same for 91 pump gas...they have different stoich ratios because they have different energy content. 110 + 91 / 2= 100.5 octane. People who say spraying alky has no octane raising effect...I dont know why they're saying this. Not only does the evaporative effect rapidly cool the incoming air charge to extremes, no matter how you slice it, alcohol is a fuel, which has its own energy content and its own octane. You would have to know the exact amount of alky you're spraying so you could do calculations, but odds are unless you're really fast, you're not running a stoich or even greater than stoich ratio of alky. So the end average octane may end up being something like 96-98.

 

[Fuelie600]

The only number you should be concerned with is "motor" octane. Some companies market their products numerically high by having higher "research" octane numbers which will raise the R+M/2 average. Remember it is the "Motor" octane that counts. If you look at certain race fuels ( like VP ), the fuel is rated at "Motor" octane only, eg. VP 116= 117 Motor. Reseach octain is just a numbers game. Brian

 

[GSX-PKV]

Thanks for the info! Paul