87 vs 91 Octane and 2.5T Torque/RPM specs

[MichalP]

Wishful thinking:

Well, I could only hope for this kind of fuel consumption. Current trip using 91 Octane but 34 km downhill + another 15km highway. Average still around 12 L/100km because later I need to drive up the hill

On a more serious note. I couldn't find a similar topic anywhere. For models 2022 and 2023 Mazda specifies that with Premium gas - 93 Octane, max torque is reached actually at 2500rpm instead the typicall 2000rpm. Not a huge difference but I could feel the difference. Granted maybe it was gas quality possibly but I am so used to feel the kick with acceleration around 1500-2000rpm. Now I need to wait way passed 2000 until really I am reaching 2500rpm to have the same experience. It could be all very subjective but in city driving there is a slight delay now.

I am not talking even about extra horsepower with higher Octane because I rarely can reach 3500-4000 rpm range.

I only decided to use higher Octane because where I am right know (Okanagan Lake in BC, Canada) gas prices are significantly lower than in coastal area and knowing we will be staying in mountain area, I wanted to see if even higher torque (320) might make a difference when driving up the mountain and twisted roads around the lake.

Well conclusion is that at least for me it feels like waste of money. No advantage so far from extra HP (too low rpm obviously), also higher torque at low rpm also is not there anymore since looks like I need to reach at least 2500rpm to feel it.

I am going to update this thread once I get back to regular gas.

Any opinions?

 

[leeharvey418]

Do you have a calibration certificate for your butt dyno?

 

[MichalP]

Do you have a calibration certificate for your butt dyno?

Well no, but I did drive almost 400km from the west coast of BC to Okanagan, using regular gas, passing two mountain ranges on the way with total driving distance of almost 700km total from the last fill and everything felt as usual. After arriving I put 68L of premium gas into the tank and the car just feels slightly different in terms of power delivery. I drove this car from new with total of 42K now so my butt dyno is sort of used to the feeling.

I am not saying it's not subjective but even in Mazda CX-9 specs for 2022 there is a clear indication of max torgue with higher rpm when using premium gas. This change only occurs with upgraded engine for 2022 and 2023.

 

[leeharvey418]

Had you been using regular gas all along? I know that the system is supposed to get real-time feedback from its various sensors, but I also know that I’ve seen evidence that it takes a while to adjust to things like changes in fuel.

 

[Boland01]

My wife drives our 2023 turbo. I switched from 93 to 87 octane over a year ago. No difference in feel or mileage for her. I guess if you were in the upper rpm range you might feel a difference but for everyday driving I can't. Same with our 2025 CX70 Premium Plus S.

 

[sm1ke]

Any opinions?

Regarding the 2000 vs 2500 RPM change in torque feel, you're saying that with 87 octane, it feels like the turbo kicks in at 2000 RPM, but when you use 91+, the turbo kicks in at 2500 RPM instead? That, to me, makes a lot of sense. If you're a city driver, it makes sense to run 87 and keep the power lower in the RPM range. You wouldn't have enough time or road to accelerate past 4000 RPM most of the time. If you're on the highway, it makes sense to run 91+ so you'd get the power in the upper RPM range for passing, and you wouldn't need turbo engagement while cruising along at lower RPMs.

 

[jadmt]

living in Montana we can drive fast...I just returned from a 3000 mile road trip...I mainly used 91 octane as never saw anything higher at the pump in Montana, North Dakota or Minnesota...all but two tankfuls were non ethanol. in order to feel a difference you really have to be up higher in the rpms which is not normal driving for most situations..I use the sport mode all the time. I did notice on this trip which I have taken many times, including this past December, I got the worst mpg ever. I usually get around 28-30+ and this trip was 24mpg most tank fulls and highest on one tank was 27mpg. lots of wind and rain tho...

 

[leeharvey418]

You wouldn't have enough time or road to accelerate past 4000 RPM most of the time.

You and I drive differently.

 

[MichalP]

I use the sport mode all the time. I did notice on this trip which I have taken many times, including this past December, I got the worst mpg ever. I usually get around 28-30+ and this trip was 24mpg most tank fulls and highest on one tank was 27mpg.

One thing I noticed also. Even with sort of regular driving as long as I keep rpms below 3K I can expect decent fuel economy. So that means no more than 100-110km/h. The moment I let myself loose If I can, mpg goes down like crazy. It's fun to drive this car but realistically so far I have never seen myself going above 5K rpm. No need in this part of Canada where I live.

 

[N7turbo]

Regarding the 2000 vs 2500 RPM change in torque feel, you're saying that with 87 octane, it feels like the turbo kicks in at 2000 RPM, but when you use 91+, the turbo kicks in at 2500 RPM instead?

Probably not the terminology I would use but I know what you're referring to: a difference in the powerband. The way this would be explained is a change in spark timing by the computer, basically timing would be advanced more when noticing no knock coming from the knock sensors due to the fuel.

I would like to see someone just put one of these cars on a dyno. Otherwise all the butt dynos and synthetic charts produced by Mazda don't mean much as they are not empirical (no offense to anyone).

 

[sm1ke]

You and I drive differently.

Everyone drives differently, but I wasn't explaining how I drive. I was explaining the general driving behaviour of a city driver. I suppose I could be more specific there - what I meant was that in densely packed urban settings, traffic lights and speed limits make it more difficult to reach high RPMs, unless you're flooring it from light to light.

I fill with 93 because my daily commute is a mix of city and highway, and I have a JB4 installed to get a little more out of 93. I get over 4k RPM on a daily basis thanks to onramps and merge lanes.

 

[leeharvey418]

I get over 4k RPM on a daily basis thanks to oblivious drivers who merge without the slightest concern over whether the space they're trying to occupy is already taken.