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Discussion Starter · #1 ·
Hey All,

Just wondering for the individuals that already have their 2022 BRZ, have you run both 91 and 93 in your car and what type of performance differences have you noticed. The city I'm in only has 91 with the exception of one gas station that carries 93. I'm looking more for the performance differences on the 6MT BRZ as that's what I have ordered but curious of how the Automatic does in comparison as well.
 

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I can’t give you a comparison but I asked my dealer what I should put in my car when I picked it up. 91 is available everywhere and at one chain of gas stations I can get 94. The dealer said 91 octane is good in the car, several of the guys at the dealership have or did have the 1st gen BRZ and only used 91 octane. I recently heard from a friend who bought that crazy 702hp Dodge Ram TRX that his dealer told him not to use the Petro Canada Ultra 94 Octane because they have had problems with the injectors which they blame on that particular fuel.
 

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Discussion Starter · #3 ·
I can’t give you a comparison but I asked my dealer what I should put in my car when I picked it up. 91 is available everywhere and at one chain of gas stations I can get 94. The dealer said 91 octane is good in the car, several of the guys at the dealership have or did have the 1st gen BRZ and only used 91 octane. I recently heard from a friend who bought that crazy 702hp Dodge Ram TRX that his dealer told him not to use the Petro Canada Ultra 94 Octane because they have had problems with the injectors which they blame on that particular fuel.
I don't think i have ever seen 94 octane in the U.S. after 93 I only ever see 100+ octane racing fuel. I was told 91 would work but not perform as well. Even reading the Owner's Manual it says 91 can cause engine knock.

From the Owners Manual:

Fuel Requirements
The engine is designed to operate using
unleaded gasoline with an octane rating
of 93 AKI (98 RON) or higher.
If unleaded gasoline with an octane
rating of 93 AKI (98 RON) is not available,
unleaded gasoline with an octane rating of
91 AKI (95 RON) may be used with no
detriment to engine durability or
driveability.
However, you may notice a slight
decrease in maximum engine performance
and you may hear some knocking
(pinging) from the engine while using 91
AKI (95 RON) fuel. Use of 91 AKI (95
RON) fuel will not affect your warranty
coverage.
▼ Fuel octane rating
Using a gasoline with a lower octane
rating can cause persistent and heavy
knocking, which can damage the engine.
Do not be concerned if your vehicle sometimes
knocks lightly when you drive up a
hill or when you accelerate. See your
dealer or a qualified service technician if
you use a fuel with the specified octane
rating and your vehicle knocks heavily or
persistently.
 

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Very high compression needs more octane. My sate has 93 all over the place so thats what it will get at 1st. As soon as an E85 tune is out there, I will be making that switch. I have never heard of 94 octane, but if it was available, I would not hesitate to run it. I would not take 1 guys word on anything. Especially when the vehicle in question is a dodge. They fail under the most perfect conditions.
 

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Discussion Starter · #5 ·
Very high compression needs more octane. My sate has 93 all over the place so thats what it will get at 1st. As soon as an E85 tune is out there, I will be making that switch. I have never heard of 94 octane, but if it was available, I would not hesitate to run it. I would not take 1 guys word on anything. Especially when the vehicle in question is a dodge. They fail under the most perfect conditions.
I've always wondered how E85 handles. My Tundra says it can run on E85 but never tried it.
 

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I don't think i have ever seen 94 octane in the U.S. after 93 I only ever see 100+ octane racing fuel. I was told 91 would work but not perform as well. Even reading the Owner's Manual it says 91 can cause engine knock.

From the Owners Manual:

Fuel Requirements
The engine is designed to operate using
unleaded gasoline with an octane rating
of 93 AKI (98 RON) or higher.
If unleaded gasoline with an octane
rating of 93 AKI (98 RON) is not available,
unleaded gasoline with an octane rating of
91 AKI (95 RON) may be used with no
detriment to engine durability or
driveability.
However, you may notice a slight
decrease in maximum engine performance
and you may hear some knocking
(pinging) from the engine while using 91
AKI (95 RON) fuel. Use of 91 AKI (95
RON) fuel will not affect your warranty
coverage.
▼ Fuel octane rating
Using a gasoline with a lower octane
rating can cause persistent and heavy
knocking, which can damage the engine.
Do not be concerned if your vehicle sometimes
knocks lightly when you drive up a
hill or when you accelerate. See your
dealer or a qualified service technician if
you use a fuel with the specified octane
rating and your vehicle knocks heavily or
persistently.
I read that as well in the manual which prompted my question to the dealer. I will very happily put the best fuel in my car I can get. I will do some more research on the ultra 94 available in Canada and hopefully my friend with the ram was misinformed. I don’t think I have ever seen 93 at a pump in Canada before.
 

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Discussion Starter · #7 ·
I read that as well in the manual which prompted my question to the dealer. I will very happily put the best fuel in my car I can get. I will do some more research on the ultra 94 available in Canada and hopefully my friend with the ram was misinformed. I don’t think I have ever seen 93 at a pump in Canada before.
That's interesting wonder if 94 there is same as 93 here. My dealer was like yeah 91 will be find and they will provide a full take of gas of 91 when I pick it up. I was like can't you just give me a gas card so I can go get the higher octane lol.
 

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I've always wondered how E85 handles. My Tundra says it can run on E85 but never tried it.
E85 is over 100 octane. Its burns clean and engines that can accept it, love it..!! The only issue is that it cuts your fuel economy by about 20-25%. In most places its still a fair trade. Here in IL E85 sells for about a dollar less per gallon than premium. In the end you consume more E85 but the cost remains basically the same. These engines will make AT LEAST 25 wheel horsepower more with no changes other than a tune and tank full of E85.
 

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Discussion Starter · #9 ·
E85 is over 100 octane. Its burns clean and engines that can accept it, love it..!! The only issue is that it cuts your fuel economy by about 20-25%. In most places its still a fair trade. Here in IL E85 sells for about a dollar less per gallon than premium. In the end you consume more E85 but the cost remains basically the same. These engines will make AT LEAST 25 wheel horsepower more with no changes other than a tune and tank full of E85.
Nice. My Tundra will automatically calculate for E85 or a mix of E85 and another octane level. Or at least that's what the manual says. I've never tried it. But like you said for the BRZ I would have to have a tune for it. I might try it once I get my car and have had it for a Lil while.
 

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Hey guys,
I onced asked my self the same question as well as a youtuber did.

Please consider that we use a different method of calculating our octane numbers.
It's usually like this:
90 AKI octane = 95 RON octane
93 AKI octane = 98 RON octane
95 AKI octane = 100 RON octane
Numbers are just estimated.

This is what he found out for a Mercedes AMG C63s:
Handwriting Font Line Display device Electronic device


Basically what the picture is saying:

- Change from 90 AKI to 93 AKI = 3,78% more power
- Change from 90 AKI to 95 AKI = 5,6% more power


P-Norm = hp at crank
P-Rad = hp at wheel
P-Schlepp = drive train loss in hp
M-Norm = torque in Newtonmeter

They also explained that the difference get's really interesting in the high rev ranges. The numbers shown are peak hp numbers. But as the engine climbs the rev range the ECU has to cut back fuel with low octane fuel to protect the engine. So at the end of the rev range the difference in power climbs to nearly 10%.

Font Line Parallel Rectangle Electronic device


575,73hp against 561,63hp against 522,11hp.
I would take the expensive fuel for this reason alone. To protect my engine at high revs.
The 5-10% more power are a welcomed plus.
 

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Discussion Starter · #11 ·
Hey guys,
I onced asked my self the same question as well as a youtuber did.

Please consider that we use a different method of calculating our octane numbers.
It's usually like this:
90 AKI octane = 95 RON octane
93 AKI octane = 98 RON octane
95 AKI octane = 100 RON octane
Numbers are just estimated.

This is what he found out for a Mercedes AMG C63s:
View attachment 3226

Basically what the picture is saying:

- Change from 90 AKI to 93 AKI = 3,78% more power
- Change from 90 AKI to 95 AKI = 5,6% more power


P-Norm = hp at crank
P-Rad = hp at wheel
P-Schlepp = drive train loss in hp
M-Norm = torque in Newtonmeter

They also explained that the difference get's really interesting in the high rev ranges. The numbers shown are peak hp numbers. But as the engine climbs the rev range the ECU has to cut back fuel with low octane fuel to protect the engine. So at the end of the rev range the difference in power climbs to nearly 10%.

View attachment 3227

575,73hp against 561,63hp against 522,11hp.
I would take the expensive fuel for this reason alone. To protect my engine at high revs.
The 5-10% more power are a welcomed plus.
Thanks for this post. A lot of good info. Gives me more reason to drove a little further to get to the one gas station that carried 93 AKI
 

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I see a lot of people mentioning e85 tunes on the 86/BRZ. Are people tuning on straight e85 without the need for upgrading the fuel pump and/or injectors OR are they tuning on e85 mixtures (ie; e30, etc.)? What kind of increases are people seeing or have seen on e85 tuning over 93 oct...especially on a naturally aspirated motor?
 

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E85 is over 100 octane. Its burns clean and engines that can accept it, love it..!! The only issue is that it cuts your fuel economy by about 20-25%. In most places its still a fair trade. Here in IL E85 sells for about a dollar less per gallon than premium. In the end you consume more E85 but the cost remains basically the same. These engines will make AT LEAST 25 wheel horsepower more with no changes other than a tune and tank full of E85.
At least 25 horsepower sounds right from what I've read and I was thinking maybe 30 with the bigger motor. ~255 hp and 215 ft/lbs torque in a 2800 pound car is just perfect for a street car. Very close to stock 996 power to weight ratio. The great part about a tune like (without header or exhaust) is dealer will probably never know you did it unless they go to trouble to check reflashes. I have a Stage 2 tune on my diesel Touareg without any pipes (trying to make it through my Dieselgate warranty period) and my dealer fixes codes/sensors for free and never says anything.

I would do an E85 tune in heartbeat and probably never do exhaust/header just to free up budget on things that matter like braking/handling improvements and not wanting car to be any louder. 25% mpg loss is nothing to me as there's an E85 station near my house and it wouldn't be my daily driver anyway.
 

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One of the issues with e85 (especially in the Midwest) is that e85 is only TRUE e85 from say May through October. Then gas stations start bringing in a winter blend that may only be as high as e60-e70 out of the pump. If you're driving your 86/BRZ throughout the year and you're tuned on e85, you'll need a method to calculate the ethanol content.
 

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Just note that "increases" dont happen just from octane. On cars that say "premium required" you really need to use at the very least 91 octane just for the safety of the engine. There are adjustments that the cars computer can and does make to adjust for differences in fuel, but its not infinite. Filling up on 87 octane and driving it hard will more than likely cause serious damage. As for the dyno numbers, its not that you really make more power on higher octane, its that you make LESS with octane lower than. required. In the case of most cars that only ask for regular 87 octane fuel for example it is a complete waste of money to put in anything higher. You will not unleash any secret power that the manufacturer was trying to hide from you and the old "its top tier" cleaner gas with better detergents and all that probably played a role back in 1975, but by modern standards it doesnt make a bit of difference.
 

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One of the issues with e85 (especially in the Midwest) is that e85 is only TRUE e85 from say May through October. Then gas stations start bringing in a winter blend that may only be as high as e60-e70 out of the pump. If you're driving your 86/BRZ throughout the year and you're tuned on e85, you'll need a method to calculate the ethanol content.
The options are to get a flex fuel sensor based tune that reads the actual ethanol content and adjust in real time to whatever blend is in the tank. This method allows you to switch between premium, E85 or any mix in between. It also costs around $1500 for the sensor, tuning device and email tune sessions.
The other option is using the open flash tablet. That method uses a simple flash tune and no ethanol sensor. The car does still adjust to the ethanol content in the tank but it is not instant and real time. The car monitors AFR, knock and fuel trims at all times. The OFT method uses these numbers to adjust to whatever ethanol content is in the tank. It may not be as precise or offer the flex fuel ability, but it also only costs $500 and gets the job done quite well. Many people fill up at the same gas stations like clockwork anyways. A single delivery of E85 at a station in IL may last an average gas station 3 months before they get another delivery. It just isnt popular. So the car wouldnt be making drastic changes all that often. The key is just dont beat the snot out if the car the instant you leave the gas station. People have been using both methods for years and years now with no issues. I can see the benefits to either way.
 

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I see a lot of people mentioning e85 tunes on the 86/BRZ. Are people tuning on straight e85 without the need for upgrading the fuel pump and/or injectors OR are they tuning on e85 mixtures (ie; e30, etc.)? What kind of increases are people seeing or have seen on e85 tuning over 93 oct...especially on a naturally aspirated motor?
You can run straight E85. You need either a flex fuel or dedicated E85 tune... Thats it. The D4S injection system is fully compatible with E85. No need to change pump or injectors. That changes once forced induction comes in. A car on premium fuel can typically keep a stock pump and injectors, but they are missing out on a lot of power. The switch to E85 makes much more on forced induction, but they flow requirements are much greater and stock injectors just cant flow enough. In this case people upgrade the in tank pump and the low pressure port injectors. I dont think I have ever seen anyone replace the high pressure injectors. Yes, this 4cyl has 8 fuel injectors.
 

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OP- my opinion it to run 93+ (AKI) and settle for 91 if you're in a bind.



I can’t give you a comparison but I asked my dealer what I should put in my car when I picked it up. 91 is available everywhere and at one chain of gas stations I can get 94. The dealer said 91 octane is good in the car, several of the guys at the dealership have or did have the 1st gen BRZ and only used 91 octane. I recently heard from a friend who bought that crazy 702hp Dodge Ram TRX that his dealer told him not to use the Petro Canada Ultra 94 Octane because they have had problems with the injectors which they blame on that particular fuel.
I was running a tuned MK6 GTI (Cobb), a tuned Focus RS (Livernois) and both tuners were very happy with my logs running Petro Canada Ultra94. Every engine is different of course, but I think the fuel is OK.

Esso also has 93 which we could run. Shell 91 (non-ethanol) would be my choice if I had to go 91, but I will be staying 93/94 as much as possible, with preference to Ultra94.
 

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I have to assume Subaru takes into consideration that many states are limited to 91 octane, California and many other states - I certainly hope it's at least safe to use 91 octane as I and potentially many others will be limited to 91.
 

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Discussion Starter · #20 ·
I see a lot of people mentioning e85 tunes on the 86/BRZ. Are people tuning on straight e85 without the need for upgrading the fuel pump and/or injectors OR are they tuning on e85 mixtures (ie; e30, etc.)? What kind of increases are people seeing or have seen on e85 tuning over 93 oct...especially on a naturally aspirated motor?
I'm not sure, most the videos i've seen has been just a flash of the ECM. I'm sure upgrading components would be better with a tune v/s not doing it.
 
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