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2021 Crosstrek Limited
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Discussion Starter · #1 · (Edited)
Like some of us already knew.

1. Does an engine designed to operate on Regular gasoline produce more horsepower when operated on Premium?
- No consistent differences in maximum horsepower were recorded.

2. Does an engine designed to operate on Regular gasoline get better fuel economy when operated on Premium?
- No significant differences in fuel economy were recorded.

3. Does an engine designed to operate on Regular gasoline produce fewer tailpipe emissions when operated on Premium?
- No consistent differences were recorded.


Source:
 

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2021 Crosstrek Outdoor - "Trekov"
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Three of the things that factored into my decision to get a Crosstrek:

1. Engine burns regular-grade gasoline.
2. One of the few available GDI engines that does NOT have a hair dryer (turbo).:whistle:
3. Engine burns regular-grade gasoline.
 

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Three of the things that factored into my decision to get a Crosstrek:

1. Engine burns regular-grade gasoline.
2. One of the few available GDI engines that does NOT have a hair dryer (turbo).:whistle:
3. Engine burns regular-grade gasoline.
1=3 :unsure:
 

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2021 Crosstrek Outdoor - "Trekov"
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Well, personally when people called engine does not create more power with premium gas, I find it is very misleading. Engine almost always can create better power with higher octane, it is just the Engine Control Module(ECM) that comes with the car will dictate whether the engine will make more power or not. For Crosstrek, somehow the ECM can not utilize higher octane gas because it will not aggressively optimize like the typical Japanese brand such as Honda, Mazda. However, the latest Crosstrek ECM update seems giving better torque and response, but I have not got chance to dyno it, but the fuel economy seems slightly worse.
 

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Well, personally when people called engine does not create more power with premium gas, I find it is very misleading. Engine almost always can create better power with higher octane, it is just the Engine Control Module(ECM) that comes with the car will dictate whether the engine will make more power or not. For Crosstrek, somehow the ECM can not utilize higher octane gas because it will not aggressively optimize like the typical Japanese brand such as Honda, Mazda. However, the latest Crosstrek ECM update seems giving better torque and response, but I have not got chance to dyno it, but the fuel economy seems slightly worse.
The ECM control in this case has all to do with engine timing and what the engine is designed for. That is, some engines are designed to use premium fuel and if regular is used the engine timing is retarted to prevent knocking. For example Mazda spec's their 2.5l turbo with premium and regular. Audi recommends premium on their 2.0l turbo, but only says that performance will degrade if regular is used. In the case of the Crosstrek, IMHO the ECM doesn't advance the timing if premium is used for Crosstrek's engines and regular is recommended.
 

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2018 Orange Subaru Crosstrek Limited
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Well, personally when people called engine does not create more power with premium gas, I find it is very misleading. Engine almost always can create better power with higher octane, it is just the Engine Control Module(ECM) that comes with the car will dictate whether the engine will make more power or not. For Crosstrek, somehow the ECM can not utilize higher octane gas because it will not aggressively optimize like the typical Japanese brand such as Honda, Mazda. However, the latest Crosstrek ECM update seems giving better torque and response, but I have not got chance to dyno it, but the fuel economy seems slightly worse.
Don't doubt that there is truth in what you say. It appears that manufacturers are working a balance of costs, efficiency, waste, durability and power. It probably boils down to what some suit says is the correct balance. Maybe could have a little more power on the Subaru with changes but there will be a cost(s) for the allowance. Personally I'm ok with it. Never bought the car thinking it would run as well as it does as I was previously wedded to Toyotas.

Somewhere back in the murky depths of time there is my tag for running the quarter mile at Seattle International Raceway in my '68 Ford Pickup, 6clyd, three on the tree, loaded with fire extinguishers (we were grudge race firefolks) and drunken friends (I did not drink,) at all out speed I turned a mid 20 second quarter mile...I doubt those in the stands thought I was actually trying. Pretty sure the Crosstrek could dust that pickup off no problem even with its little four cylinder chugging away on regular. Ok with me until a Rolls Royce Merlin engine is gifted to me from a P-51 Mustang and then I'll reconsider an engine swap and maybe go to mid range gas. Vrooom vrooom, I wonder how far the CVT would launch if using that engine?
 

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2022 Subaru Crosstrek Sport
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Three of the things that factored into my decision to get a Crosstrek:

1. Engine burns regular-grade gasoline.
2. One of the few available GDI engines that does NOT have a hair dryer (turbo).:whistle:
3. Engine burns regular-grade gasoline.
Isn't the Outdoor the Canadian equivalent of the American Sport version? Mine has a turbo lol
 

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I started using 93 in my pickup when towing, my theory is, I am not expecting more HP or torque with 93, but not to lose any compared to 87..let me explain...since there are knock sensors, then there is a possibility that the ECM will retard the timing thus causing some loss of power...if running 93, less chance of a situation where the timing would be retarded.

-thoughts?
 

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I started using 93 in my pickup when towing, my theory is, I am not expecting more HP or torque with 93, but not to lose any compared to 87..let me explain...since there are knock sensors, then there is a possibility that the ECM will retard the timing thus causing some loss of power...if running 93, less chance of a situation where the timing would be retarded.

-thoughts?
the crosstrek ecm use very conservative timing, so even you put load, the existing timing is almost never causing knocking.
 

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2015 XV Crosstrek Premium CVT, 2019 Impreza Sport MT, 2001 Forester S 4EAT, 2013 Outback Premium CVT
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Looks like it has more impact (in either direction based on the car) than removing the charcoal filter lol!
With only two runs each, the numbers seem to be within the standard error for dyno runs.

I was working on my kids WRX yesterday that he just got (2019) wanted to remove the Charcoal Filter for the heck of it. It never had one apparently, maybe turbo cars don't get them ?
 

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2021 Crosstrek Limited, Pure Red
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With only two runs each, the numbers seem to be within the standard error for dyno runs.
Yep, using higher-octane fuel and removing the charcoal filter are both on the list of "completely pointless things to do to your Crosstrek, that people do anyway just because they want to do something." Whatever makes you happy, though.

Peaty, is that a different kid, or did the Crosstrek get traded for a WRX? No idea about the charcoal filters on those ... maybe the turbos don't get them?
 

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2015 XV Crosstrek Premium CVT, 2019 Impreza Sport MT, 2001 Forester S 4EAT, 2013 Outback Premium CVT
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Yep, using higher-octane fuel and removing the charcoal filter are both on the list of "completely pointless things to do to your Crosstrek, that people do anyway just because they want to do something." Whatever makes you happy, though.

Peaty, is that a different kid, or did the Crosstrek get traded for a WRX? No idea about the charcoal filters on those ... maybe the turbos don't get them?
I was surprised it didn't' have one too. But you'd be able to tell if it was there and removed. I'm going to say it's a turbo thing until I can check more of them.

Different kid :) My oldest got married last Friday. So my youngest came home for the wedding. My oldest just traded his Lexus RC-F for the WRX a week or so ago. I was driving Liam's old Forester which is still chugging along at 222K miles.

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