Highest Octane For Stock ECU??

ZzzZz

That's the question though, where is the sweet spot between 91-94? Why pump 94 when you can save money with 91 right?

Was never suggesting 100octane+ is beneficial for a stock 370z.

Driftomodachi

From what I have heard, 100 octane in Japan is like the 91 octane here and 91 octane there is like the 87 octane here. And since the z is a "world car" the ecu should compensate and performance should improve with the highest octane the car was designed to run on which is 100 octane.

Not sure how true that is

DEpointfive0

The US doesn't use Octane, we use AKI, average knock index. You cannot compare it to the rest of the world

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molamann

No wonder I couldn't find anything above 91 here in Los Angeles.

JoeD

Highest performance will be achieved on the lowest octane fuel possible without knock. If you run 87-octane and the engine does not knock/ping, then it will run better than if you had filled 91+.

Yes, there is such a thing as too much octane, and no..."octane-boosters" you buy in a bottle from Auto Zone do absolutely nothing.

That said, I have a hard time believing one can feel a difference with 91 vs. 92/93/94-octane on a stock car.

ZzzZz

True.

You have to remember that, with modern cars, the ECU will dial back timing to prevent knock/ping. If you put 87, it will dial timing back and reduce performance but it will be fine. On the flip side, if you put 91, it will advance timing to give greater performance.

Now the unknown is: what octane is necessary for the ECU to advance timing to the MAX? Timing from manufactures might be designed around 91-gas as a requirement but is it really "optimized"? Is their untapped potential?

Silly analogy but it's kind of like how you can overclock CPUs to realize performance gains over stock by simply advancing the timing. The CPU is marketed and rated at 3.0GHz but it can go higher.

JoeD

Given proper conditions absent the externalities that would otherwise cause the ECU to pull timing (excessive heat and/or very high load), that figure can even be lower than 91-octane. However, in real-world conditions, my guess is that it's right around there where timing will not be advanced further.

Snakes709

iiunno what the dealership put in the car but for my first fill up i put 94 in...there are only a few gas stations here in edmonton that sells 94. I didnt notice any difference.

kannibul

Seems a lot of people believe high octane = higher power.

It's been covered here and NUMEROUS places on the web that this is not the case, yet the myth still prevails.

Hmm...I should email mythbusters.

ZzzZz

I don't think members on this site believe on an absolute level that high octane always equals higher power. It's not always the case.

But when your talking in terms of going from 87 to 93 for your 370z, your "equation" actually does apply.

kannibul

Going from 87 to 91, sure with OUR cars and others that recommend 91 octane per manual...

Going from 91 to anything above it, snake oil.

Shunya

I've never ran anything under 94 octane in my life...
I love my cars so I'm gunna feed it with real food

kannibul

That's the whole problem right there.

Higher octane gas isn't better for your car...

Shunya

well is it a bad thing using 94 octane? why should fuel lower than 94?

my mechanic told me that my engine requires me to use 94octane.
after internal work had been done.

kannibul

What internal work did you have done?