The yo-yo for me seems to come and go. Sometimes worse than others. What I was hoping the hi octane gas might do is end the weak start/stumble. Our Cooper fires right up and sounds strong. The S sometimes sounds like it's barely able to start, then you get the stumble after about 5-10 seconds, then it's gone.

 

hey Tuls,

I have a MTH tuner file, tuned for 98 RON (australian octane rating is different to the US's i think). Do you think if i ran 100 Octane fuel it would make a big difference? Like the difference between running normal unleaded and premium?

 

It's all about timing retard. If you car currently pings to the point where the ECU pulls timing, then running higher octane fuel will help cure some pinging, which in turn the ECU doesn't retard as much. Which means more advanced timing and in turn means more hp potential.

Will 2 octane points help? Depends upon how much timing retard you car is running? Will an average joe feel the difference? Probably not. Will the engine thank you? Yep!

Will running higher octane on an unboosted (read: normally aspirated) Cooper help? Again, depends if you're running into timing retard due to pinging. More than likely (this is my guess) a n/a cooper, modded or not, will not be seeing timing retard (again my best guess)

 

not very nice to call people names

 

If your name is "timing", you've got more things to worry about

 

where in miami are you looking? all i see at the pumps is 87, 89, 93

 

When I lived in Miami there was 93 all over the place.

 

As Dominicminicoopers stated higher octane will only prevent pinging, detonation, or knocking. it won't make any power difference thats noticeable, unless you switch to 110 octane leaded fuel also known as C16 or Turbo Blue. In order for you to run Leaded fuels, you would need a wideband O2 sensor and no catalytic converter. Very much illegal (the removal of catalytic converter) unless you happen to happen to use it as a race car.

 

I did find 93 in Miami (Kendall) at Mobil. Otherwise, it's still 91.

Think maybe we should shoot some diesel in with the 91? (kidding!)

Edit: Sorry for turning this regional. I found 100+ octane gas is supposedly being sold at the gas station on the corner of Krome and 8th Street, and also inside the Tamiami Airport. They're calling it "AV" gas at both places. What is that???