93 vs 91

[bpeckham]

And we have only 91 in California, so I'm missing two octane numbers. Gah!

As @MCN1SMO said, the car retards timing with lower octane fuel (since it can't be compressed as much without ignition before the spark), but how does it do this? Is there some sort of knock sensor that tries aggressive timing and then backs off if it detects knocking?

 

[raceheart]

The Sunoco 93 here in NJ is gold. Use it on all of my performance cars and notice the difference.
We have 94 replacing 93 at many stations for the same price... Anyone know if 94 will get more HP than the advertised 400 or it won't matter with the factory tune?

 

[D2M]

And we have only 91 in California, so I'm missing two octane numbers. Gah!

As @MCN1SMO said, the car retards timing with lower octane fuel (since it can't be compressed as much without ignition before the spark), but how does it do this? Is there some sort of knock sensor that tries aggressive timing and then backs off if it detects knocking?

Yes, exactly. On the newer cars like our Zs they will not only pull timing from sensing knock but may also lower the boost level by using the electronic waste gates if the octane gets too low or temperatures get too high.

 

[citrus]

While in CA I could only find 91 and I could feel the lack of punch.

Which brings up the topic of octane enhancers. In WA I can find 92.

D

We only have 92 octane here in Washington and I always wonder what I'm missing with that 1 octane difference.. Don't understand why 93 isn't standard everywhere for premium.

Also curious about the effects of 92 up here, Costco's specifically.

 

[raceheart]

Just FYI, Nissan doesn't recommend any aftermarket octane boosters as per the owners manual, but gives MotorTrend a case of it to test the car.

"Nissan delivered this preproduction 2023 Z with a case of octane booster and instructed us to add half a bottle to every tank of 91-octane gas, because 93-octane premium fuel isn't easily found in our home state of California. Curious to see what would happen, we added the octane booster, and it seemed to work: The knocking and power warning disappeared, acceleration became more consistent, and the times dropped by a couple tenths."

https://www.motortrend.com/reviews/2023-nissan-z-performance-first-test-review/

 

[METROdigital]

I've been a Chevron customer forever but will buy Shell.

I've never had the patience to sit in Shorelines gas line.

 

[Koryak]

Most octane boosters contain MMT (manganese) which auto makers frown on due to possible emission control damage at high doses. Low doses won't even discolor spark plugs let alone the reddish looking tailpipes I've seen at track events. I've used Boostane and Torco street formulas in supercharged and turbo engines to increase 91 to 93 in hot weather.

 

[MacCool]

I ran an AI search in the area for sources of 93 octane. ChatGTP was not helpful. Of the six stations that Google's AI identified, four of them were no-go and one station was closed. I did find it in a station right at the entrance to Brainerd International Raceway at $3.75/gallon. I didn't wring it out on the way home, but I do suspect that there is more there than on 91 octane. Time will tell....

Half a tank later...first time driving with 93 octane...noticeable improvement in performance. Not so noticeable in Standard drive mode, but really wakes up in Sport mode. I was on the highway, went to pass a couple of cars and was pretty impressed with the responsiveness to that tap on the accelerator.

 

[Zenogias]

Half a tank later...first time driving with 93 octane...noticeable improvement in performance. Not so noticeable in Standard drive mode, but really wakes up in Sport mode. I was on the highway, went to pass a couple of cars and was pretty impressed with the responsiveness to that tap on the accelerator.

Your post made me curious so I went to a distant race track gas station that had variable octane up to 108.. Filled it up with 94, and was pretty stunned how big of a difference it made. First thing I noticed, the idle smoothed out. Second thing, engine sounds better. Finally, as you said in your previous post, acceleration noticeably improved.

After seeing the difference, I am a little miffed that 93/94 isn't available at normal gas station in my state. It clearly makes a huge difference and I now have to live with that knowledge.

 

[MacCool]

Your post made me curious so I went to a distant race track gas station that had variable octane up to 108.. Filled it up with 94, and was pretty stunned how big of a difference it made. First thing I noticed, the idle smoothed out. Second thing, engine sounds better. Finally, as you said in your previous post, acceleration noticeably improved.

After seeing the difference, I am a little miffed that 93/94 isn't available at normal gas station in my state. It clearly makes a huge difference and I now have to live with that knowledge.

Yeah, around here, every gas station and convenience store has 91 octane and most have 91 octane/no ethanol (boats and snowmobiles). The only place I found 93 octane was at a gas station/convenience store right at the main entrance to Brainerd International Raceway. It was $3.75/gallon, which is even cheaper than most 91 octane around here.