How will octane effect O2 mV?

[Snorman]

At WOT in 1st, 2nd and 3rd I'm seeing ~820mV on the SM. KR is 0.0.
Since I drive the car only for fun, I have run good gas in it. I usually mix Sunoco 94 and Sunoco GT100 about 3:1. This gives me about 95.5 octane (RON). There is a point on a stock (boost level, timing, etc.) car that too much octane will actually kill power. I know this is true on most late model EFI cars.
Will lower octane lower my O2's and actually make the car run better if I can get it into the 750-770 range?
S.

 

[blackbuick87]

You want to run the least amount of octane that will allow 0.0 KR. So go to Sunoco and fill up with 94 and see if it knocks

 

[bruce]

Boy, have you guys fallen for the new car hype.

There ain't no such thing as too high of octane available at the pumps now a days.

And there is a difference in gas blends from regular to premium, and it's in the additive package. The premium stuff will burn with less ash, and the side benifit is less carbon in the chamber, and longer lasting exhuast valves.

It always pays to run the best fuel you can.

While the new cars have two or more timing tables, and select them on the response of the knock sensor, the car will have better WOT with premium.

Just cause it don't audibly knock, doesn't mean it's all well and good inside the engine.

 

[blackbuick87]

Not talking about additives, just octane. There is absolutely no added benefit to running more octane than you need. You will just lower your combustion chamber temps. If you want to get into additives that is a different discussion

 

[Snorman]

In most late model cars, higher octane will not increase performance past a certain level.
I've seen dyno tests of stock 5.0's running 100 octane and they lost 10-12rwhp.
The combustion is slowed past the point of efficiency, and performance will suffer.
So are O2 mV and octane rating unrelated?
S.

 

[ijames]

So far as I know there is no change in O2 volts with octane. I've talked to lots of people and tuned on a few cars with unleaded pump and race and leaded race gas and never seen a change. As for the 5.0 that lost power with the 100 octane unleaded, did they use a wideband O2 sensor to verify that the air/fuel ratio was the same? The 100 and 104 stuff has lots of MTBE in it which will lean out the motor some unless compensated for.