Any advantage to 94 octane?

[Splinter]

I cant say I can REALLY notice a difference between 91 and 94. 94 is only about 2 bucks a fillup more than so I've been doing it.

[dzx]

Only if your knock sensor was going off using 91, which i kinda doubt.

[wiscon_mark]

if it was built for 91, then 94 really won't help unless you're pushing it to its absolute limits (bouncing redline) constantly, and then you'll reduce pinging by a hair.

Not worth it, really...

[Splinter]

Back to 91 I go

[EJ22_SLO]

Here in Slovenia (and rest of Europe) we use 94, 98 and 100 octane; my Subi runs on 94. I tried 100 oct. few times - only difference i noticed was smoother idling (no hesitations); in performance there wasn't noticable difference.
Prices (liter): 94 oct - 1,21 USD/L; 98 and 100 oct. - 1,24 USD/L

[Subtle]

Hi Slovenia
The highest octane available in BC is 94, so at whatever price you have an
advantage.

If the engine is tuned for 88, for example, there will be no gain in power
from using a higher octane. My twgn has a stand alone ECU and at 12#
boost the advance curve is tuned for 94--if 100 was available the tune
could be more aggressive.

In regions where only the lower octane is available I run at 7.5 boost, with
a noticable drop in performance. Even on a hot summer's day there was
no detonation. The boost wont go any lower.

[vrg3]

I think in Europe they're talking about RON, whereas in North America they're talking about AKI.

[All_talk]

My two cents...

When I had that car Splinter I noticed a bit of detonation on a hard launch when running 87 octane. The detonation tapered off very quickly which I believe was due to the knock sensor/ECU pulling back the timing. With 92 not only was the detonation gone, but I feel the performance was better.

In my ’91 SS 5MT I noticed the same issue on launch and also some detonation on quick throttle jabs in the lower gears, and again running 92 fixed these problems and seem to add some performance and smoothness. The 92 has also increased my gas mileage by enough to pay for the price difference, so same money, better performance and no engine damage.

BTW, Subaru does recommend “Premium Fuel Only” for the EJ22T.

Gary

[Splinter]

Oh the 91 is most definitely better than the 87, I can feel that

I just tried the 94 for a bit tho, but I couldnt feel an improvement

[Busdriver]

I usually always ran 87 in my NA, but the last two tanks were 94, and I must say it feels a little smoother at idle, pulling wise I can't tell I just RPM up to at the most 4000...
I'm trying to figure out gas mileage right now, first tank it didn't look better at all, maybe this one... either way I will stop using 87...

[Subtle]

Running on the knock sensor retards the ignition which changes the tune
to meet the characteristics of lower octane fuel. In this example, using
lower octane lessens the tune and the performance.

In so many words, the performance relates to the tune primarily and
only secondarily to the octane rating.

With tank of aviation gas with very high octane and at 12 boost I would
have the same performance as 12 and 94 octane, for which rhe ECU is
tuned. However, with the very high octane I could I could set the
mixture and the advance for performance.

next year.

[Tleg93]

They don't sell 91 here where I live but I usually fill up 1/2 with 93 and the rest with 89. It saves a couple bucks here and there.