I live in CA so only crap 91. After getting tuned and hearing that our cars were originally tuned for 93 by Infiniti, I started adding octane boosters semi regularly in the last few fill ups. Honestly, it was mostly because I just tuned my car and wanted to see if there was a performance difference.

My butt dyno thinks power gain is minimal. But power aside, the car simply runs noticeably smoother all around. Especially noticeable in low gear low RPM, the car feels a lot more sure of itself and does not stutter as much.

I think like my MPG went decreased again though lol.

Not sure if I'll keep boosting my octane but considering it because the car feels like it running better.

I'm curious how many people do it regularly.

 

91 is usually not too common around here ... its typically 87,89 and 93, so it always gets 93.

even when it is available, 91 is usually only a few cents cheaper, so i still get 93.

 

Found this info on line. "Together, the nine "ZEV states" and California represented 28 percent of new-car registrations in the U.S. in 2015, according to Automotive News (subscription required). But while the nine states are nominally included in the ZEV mandate, automakers do not generally treat them differently than ones that are not."

A "high-performance engine" has a higher compression ratio and requires higher-octane fuel to prevent it from prematurely igniting fuel before the spark plug does it.

So I'm thinking Nissan/Infiniti does not do a 91 octane tune and a 93 octane tune.

 

^ Sebastian from Specialty Z told me our cars were all tuned for 93 from Infiniti/Nissan.

 

This is pre-ignition. We don't suffer from that. Our high-compression engines experience detonation, or knock. This occurs after the spark plug fires. It's the "end gas" igniting at the rings and quench area before the spark plug induced flame front reaches it. Two high-pressure flame fronts dueling it out cause a sudden spike in cylinder pressure.

 

I've had the best performance using 93. Just seems to run better overall.

 

I have a hard time believing Infiniti would leave themselves open to that kind of liability, or that the stock tune is so aggressive that there is any significant performance difference between 91 and 93.

Perhaps you misinterpreted 93 for "Premium"

https://www.infinitiusa.com/content/...ner-manual.pdf

^^page 455 of the owners manual

Use unleaded premium gasoline with an octane rating of at least 91 AKI (Anti-Knock Index) number (Research octane number 96)

 

I may have gotten my words a little mixed up.

Sebastian said our engine was originally designed to run on 93.

 

Octane does not add power. Octane is simply a knock preventer.

Also Infiniti would not design it to run on 93 when it knows 91 is the most available in some areas.

 

The conversation about 91 and 93 octane actually came up while we were talking about knock. I don't want to say too much more because I'll probably get something mixed up, but I remember questioning it and chatting about it for a min or two. That's the only reason I remember so vividly about our engines being designed to run on 93.

That being said, do any of you guys have any proof one way or the other?

 

Besides the link to the owners manual where Infiniti recommends a minimum of 91 octane that I already posted???

 

Yeah, besides that. That doesn't really answer the question of whether the engine was originally designed with 93 as the optimal octane.

It can easily be tuned for 91. Just like how you can tune your car for 100 octane. And 2 octane is really not a drastic difference. People use less than the recommended octane all the time and their engines run fine for years.

Let's use a different car as an example too. What about an exotic car like Ferrari. Of how the car will run with less than optimal fuel. Their recommended is 91.

So obviously Ferrari has to list the car as requiring 91 because they want to sell to USA, especially states like California. And the car can pass emissions under that setting. But the car will perform best with better fuel.

I don't think anyone will argue that Ferraris are designed to run on 91.

 

Just because some guy from a shop told you that does not make it true. Why woukd you believe him over the Infiniti owners manual?

 

^ Because Sebastian is basically the most reputable VQ tuner in the USA right now. Whether it's here or the370z, everyone in recent years has been recommending Sebastian to do e tuning.

And didn't you read my post? Ferrari recommends 91 as well. Can you explain that one?

 

Because 91 is the lowest grade of "premium" fuel

California only has 91. No manufacturer is going to design an engine to run on a grade of gas unavailable in the most populous state in the US.

I don't understand the point you're trying to make.