Premium vs regular fuels

[Packofcrows]

93 you'll notice bit more response and better mpg. Thats it. 91 it feels the same as 93 but with about 3-5mpg less. IMO

I only use Shell 91 or Chevron 91. No 93 in central CA

[itsAlex]

I also use Shell 91, there's Esso 94 around here but as the manual says, 91 is minimum. It's not recommended, but it gets the job done safely. Besides, I rarely ever go above 3500 rpm, if it matters.

[FR-Sky]

Originally Posted by Tcoat

Manual says: Recommended 93 Required minimum 91. All is good in the world.

Well,,they do have 100 near my area,,but its 10$ a gallon lol

[softgrip]

I'm all about BP Ultimate. Every fillup for my WRX, and now the BRZ is getting the same loving.

[PureShield]

Originally Posted by itsAlex

I also use Shell 91, there's Esso 94 around here but as the manual says, 91 is minimum. It's not recommended, but it gets the job done safely. Besides, I rarely ever go above 3500 rpm, if it matters.

Except that's based off of American 91 octane not Canadian 91. Canadian 91 is more like 87-89 American.

[retoocs]

Originally Posted by mdm

And cleaners/detergents are a separate issue, they are about preventing/removing carbon buildup in the intake system, especially on intake valves (unless the engine uses direct injection, then of course fuel detergents can't clean the intake valves because the valves do not come into contact with fuel).

Cleaning capability is per se indepent of octane rating, though some brands put more cleaners in their premium (high octane) fuels.

Cleaners/detergents also have no effect on HP, at least not directly. I mean, if there were no or insufficient cleaners, gradually carbon buildup would interfere with engine operation and reduce HP, but that's not the effect the OP has in mind, I suppose.

All gasoline is supposed to contain cleaners, there are standards for that. But - at least in the US - some gas brands set their own higher standards: "Top Tier" gas.

Not all direct injection have the injectors only in the combustion chamber. The D-4S system in the 86's have a port injector too. [ame="https://www.youtube.com/watch?v=zc8aUxBZlsU"]2013 Scion FR-S | D-4S Technology Explained - YouTube[/ame]

Cleaners/detergents and other additives do affect hp. The additives doesn't contribute to producing power. Most gasoline around the country is about 97% so you are losing about 6 hp over getting 100% gasoline.

[mdm]

Originally Posted by retoocs

Not all direct injection have the injectors only in the combustion chamber. The D-4S system in the 86's have a port injector too.

Sure, I should have said "unless the engine uses only direct injection"

[Tcoat]

Originally Posted by PureShield

Except that's based off of American 91 octane not Canadian 91. Canadian 91 is more like 87-89 American.

No. Canadian octane is measured in AKI exactly the same as the US. So 91 here is exactly the same as 91 there. Don't know where you heard different.

[VTEC]

Originally Posted by FR-Sky

Well,,they do have 100 near my area,,but its 10$ a gallon lol

Well you don't have to fill the whole tank with 100, that would expensive and overkill. But you can mix 100 with 91 to get 93 octane. There's a chart posted somewhere on here by one of the California members that shows you how many gallons of each to mix in order to get whatever octane you are looking for.

But an easier way might be just to order a case of octane booster and add some to each fill up

[PureShield]

Originally Posted by Tcoat

No. Canadian octane is measured in AKI exactly the same as the US. So 91 here is exactly the same as 91 there. Don't know where you heard different.

My local clubs tuner at Drift Office has tuned and modified over 180 FR-S/BRZ's and has done extensive testing using Canadian 91/94 vs American 92 vs E85 and has shown that are gas is far inferior especially when dealing with a force-fed motor.

[Tcoat]

Originally Posted by PureShield

My local clubs tuner at Drift Office has tuned and modified over 180 FR-S/BRZ's and has done extensive testing using Canadian 91/94 vs American 92 vs E85 and has shown that are gas is far inferior especially when dealing with a force-fed motor.

Then they better get that info to the government. They can blow the whole highly regulated and monitored fuel industry away.

[Tcoat]

Originally Posted by VTEC

Well you don't have to fill the whole tank with 100, that would expensive and overkill. But you can mix 100 with 91 to get 93 octane. There's a chart posted somewhere on here by one of the California members that shows you how many gallons of each to mix in order to get whatever octane you are looking for.

But an easier way might be just to order a case of octane booster and add some to each fill up

Why? Unless you are going to tune for it higher octane than 93 does nothing at all for you.

[PureShield]

Originally Posted by Tcoat

Then they better get that info to the government. They can blow the whole highly regulated and monitored fuel industry away.

Haha I don't personally know @Tcoat I'm just relaying the info. I've read different things all over the internet and heard different things in person. I've also read that American gas stations can put lower rated numbers on the pump than what the fuel may actually be and that the sign on the pump is just the lowest of what you may get???? Who knows.

[Hotrodheart]

Originally Posted by Tcoat

How is this even a question? read the manual. It will tell you what you should and must use.
The octane levels are for reducing knock ONLY! Higher octane fuel does not give you more power really. What it does is allows the engines with learning ECUs to adjust the timing higher. This is where the "more power" is created.
As a society that identifies higher numbers as being stronger or better I think many people totally misunderstand octane rating. High octane fuel is intended to reduce preignition in high compression engines it is not stronger or better than low octane fuel in any other way. To grossly over simplify what is happening the higher the octane fuel the harder it is to ignite not the other way around. Sure you can run high octane in a regular engine but it is not doing a single thing for you. You should not run lower octane in a high compression engine though since you run the risk of damage. New engines with self adjusting timing this risk is not huge but run too low in an older engine and you better be good at fixing it.

@tcoat how does it run on maple syrup?