What octane do you put in your 3rd gen? POLL

I'm going to go into some very high level detail for how this works on a Subaru, since that's what I've tuned. Being as Subaru and Toyota are partners, I can only assume the approach is similar.

There are 5 tables/values that come into play in your timing. Base Timing, Dynamic Advance, Dynamic Advance Multiplier, Knock Learning and Knock Detection Correction.

Total Timing = (Base Timing + ((Dynamic Advance * Dynamic Advance Multiplier) - Knock Learning) - Knock Detection Correction)

At any given RPM/Load value your ECU is going to try and give you the most timing advance possible for the tune. Being tuned on 87 octane does not mean there shouldn't be any detonation. There can and will be detonation based on a variety of factors including fuel trims, atmospheric condition, driver input, and inconsistencies/imperfections in parts and operating conditions, ethanol levels, fuel impurities, etc.

The ECU is constantly having to adjust, every single tank.

Providing a higher octane than the "minimum recommended octane" that you'll find in your owners manual most certainly, absolutely, 100% does not mean you will LOSE power, nor will timing ever under any circumstance, REDUCE as a result of octane increase alone.

Increased octane, providing more pre-detonation resistance with no other factors coming into play, will allow you to run higher total timing and provide better drivability and potentially increase mileage.

Having spent hours on a Dyno tuning for varying octane levels including maps for methanol injection, I will tell you that adjustments were always being made based on the brand of fuel, different stations, different times of the year, and different amounts of ethanol in the fuel.



After running 91 without ethanol since purchase, I ran 87 w/ ethanol for two tanks and felt several noticeable dips in the powerband resulting in some surges as transitions in load/rpm occurred. I switched back to 91 and the surging is gone.

Run what you want, but please don't mislead people with bad information.

 

Oh you ride a billy goat...

 

Doesnt it say researched 91 octane in the manual?

 

Just some droppings for exploring about ethanol

https://www.fuelfreedom.org/wp-content/uploads/Ethanol-Facts.pdf

I particularly want to hilite the part that says ethanol has a higher octane rating.

 

And from our ever trusted government

https://www.consumer.ftc.gov/articles/0210-paying-premium-high-octane-gasoline

Don't waste your money on higher octane

 

I run Shell 91 when I happen to be next to one when I fill up; otherwise, I run 87.

 

i get 2mpg better with super. however the $ difference does not pay off with the 2mpg increase, my math has it at 4mpg improvement to be worth the upgrade if the super is .40 more.