Highest Octane For Stock ECU??

ZzzZz

What's the highest Octane our stock ECU can effectively utilize? 91? 92? 93? 94?

Here in California, the highest is 91 but I've been able to try 93 and 94 as well.

I know there will be doubters but the 93 definitely had an impact on performance. The engine ran smoother, with that harse noise near redline every magazine describes becoming less clattery and more throaty. Throttle response was improved and so was MPG. Response going part-throttle was greatly improved.

The 94 made the engine seem lazy and out of breath. The engine is quieter going through the RPMs than the 91 but throttle response was bad and it seem to rev up slower.

Just yesterday I was low on gas and decided to finish off my 93. I drove spiritedly and made note of overall sound and feel. Once it was on empty, I filled up a tank of 91. Immediately I noticed a difference in engine sound in the mid to upper RPMs and throttle response.

Since this was just my perception I was looking to try and get others' experiences and try and align my butt-dyno with a real dyno (concrete #'s).

kdo2milger

i only put 93 in here...i would stay away from 91, its not much different than 89 honestly...

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ZzzZz

People here in Cali would shoot you over here if you dare compare 91 to 89!

Unfortunately, you can't get higher than 91 at gas stations here.

khtso

We can only buy 91 here in California, unfortunately.

ZzzZz

Race Gas Stations in SoCAl

Octane Blending Chart

ishthemienguy

yea..California suks! off topic a little bit but, have anyone tried to add the octane boost into any of your vehicle? not just the 370z but any car was just curious if the stuff works.

ZzzZz

I've tried it on others cars but didn't notice much. I heard that you have to put a lot of bottles in just to boost octane by a couple points and not what is directed on the label. I guess I just don't trust that it works.

the_student

Yeah, most of us Californians usually have 91 around. In San Jose, there is actually one station with 100 octane that you can mix with 91 and get around 95/96 octane.

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.

JoeD

Yes, my friend's 76 station in Redwood City offers 100-octane unleaded at the pump, too. However, on practically any stock car, it will hurt performance rather than help.

It's only in the case where a car is dyno-tuned to run on a specific grade where there will be an improvement. Only then in the hands of a competent tuner will you reap the benefits of "more octane."

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.

the_student

I assume that US versions of the 370Z were optimized for 93-octane. And since here in Cali we usually have 91, would you say if we are able to mix 100 and 91 octane to achieve a 93 octane level, that the cars will perform more to their peak performance? It would be a relative increase in performance from filling the tanks with 91...in theory.

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

Doubtful.

The only production-car I can think of which was optimized for anything but 91 is the Veyron. Everything else is made to run on 91-octane, as California is the biggest car-market in the country.

Mix any octane of fuel you want in a 370Z...there will be no varience on a dyno greater than what there would have been even if you didn't change the gas from pull-to-pull.