FUEL

[orlando_wrx]

edit- Just read the article and see that they do indeed list the testing methods of RON an MON, so I'm deleting my post to avoid repetition.

[Geo]

Actually MON was created to more closely rate the octane as vehicles consume it under load, seeing as how the controlled environment of the RON test didn't relate to average operating conditions. As the RON uses a CFR (combustion fuel research) engine, MON tests use basically the same setup with a few variables.
[/b]

Indeed.

However, a bit of history..... (from the Gasoline FAQ)

"During the late 1940s - mid 1960s, the Research method became the important
rating because it more closely represented the octane requirements of the
motorist using the fuels/vehicles/roads then available. In the late 1960s
German automakers discovered their engines were destroying themselves on
long Autobahn runs, even though the Research Octane was within specification.
They discovered that either the MON or the Sensitivity ( the numerical
difference between the RON and MON numbers ) also had to be specified. Today
it is accepted that no one octane rating covers all use. In fact, during
1994, there have been increasing concerns in Europe about the high
Sensitivity of some commercially-available unleaded fuels."

[Tak]

One of the strongest reasons to run proper race fuel (purchased in drums, not out of a pump) is simply for fuel consistency. What you buy at the pump has an uncertain storage condition, may be contaminated with water, and (in many parts of the country) is adjusted seasonally to reduce summer emissions. Any of these will undo all those hours spent on the dyno finding the last bit of HP.

That said, I race a rotary, and just can't bring myself to spend $6+ a gallon, so I tune with summer fuel, and consistently buy the same brand (Chevron for no particular reason)...

Cheers!

Tak
#29 ITA, SFR.