Anyone running higher than 87?
- Thread starter Monterra
- Start date
Yes they did not, Mazda did specify higher octane in Europe for the Skyactiv gasoline engines with 14:1 compression ratios, tuned for higher octane fuel.
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costermonger
Member
- :
- CX-5
You're not wrong - you can waste money on higher octane fuel and it won't damage the car. Still don't know why anybody would elect to feed an engine an octane rating other than what it was designed for - which is always the minimum listed by the manufacturer.
Interesting article in R&T, below is an excerpt I found relevant:
"If the engine is tuned for regular but fueled with something of higher octane, things are a tad more complex. Most modern knock-sensed ignitions seek MBT timing and thus, at least in theory, profit from the added octane. Some, though, have preset ceilings beyond which they won't advance.
And, in all cases, the differences depend on engine families, their octane sensitivities and intended performance levels. Without a stopwatch or dyno—and apart from your pocketbook—you may not even notice any detriment or benefit. By the way, in R&T performance testing at the track, we arrange matters to use Shell's locally available premium of 91 pump octane.
What of midgrade? There's logic involving "legacy vehicles," older high-mileage machinery designed for regular. Even in these days of unleaded fuel, other combustion byproducts can cause deposits in the chamber that may increase octane appetite just a bit. The added octane of midgrade (blended at the pump from the station's premium and regular) might be just enough to counter this.
Ethanol, used as an extender in much of our gasoline, is also an octane enhancer. Blended at a minimum of around 6 percent, its pump stickers state "up to 10 percent ethanol" to account for refinery optimizations of catalytic cracking, isomerizing, alcohol enhancement and other techniques.
Additive packages enhance the properties of gasolines. Detergents reduce carbon buildup, all the more important these days with high-pressure direct-injection hardware. Antioxidants improve the storage and tank life. Corrosion inhibitors and dyes are also added. It's generally suggested—and no suppliers deny—that premium fuels have more extensive (spelled $$$) additive packages."
http://www.roadandtrack.com/go/news/new-technology/premium-fuel-futures
So maybe it is waste, maybe it isn't, maybe its cheap piece of mind (2.5%) with hopeful expectation of power/econ gain even if <2.5%. I've never put 89 in anything other than my Stihl equipment that now specs it but for some reason it just feels like the right move for this motor and we're talking $50/year 15000/30= 500*.1- or roughly one wild night at the sizzler
"If the engine is tuned for regular but fueled with something of higher octane, things are a tad more complex. Most modern knock-sensed ignitions seek MBT timing and thus, at least in theory, profit from the added octane. Some, though, have preset ceilings beyond which they won't advance.
And, in all cases, the differences depend on engine families, their octane sensitivities and intended performance levels. Without a stopwatch or dyno—and apart from your pocketbook—you may not even notice any detriment or benefit. By the way, in R&T performance testing at the track, we arrange matters to use Shell's locally available premium of 91 pump octane.
What of midgrade? There's logic involving "legacy vehicles," older high-mileage machinery designed for regular. Even in these days of unleaded fuel, other combustion byproducts can cause deposits in the chamber that may increase octane appetite just a bit. The added octane of midgrade (blended at the pump from the station's premium and regular) might be just enough to counter this.
Ethanol, used as an extender in much of our gasoline, is also an octane enhancer. Blended at a minimum of around 6 percent, its pump stickers state "up to 10 percent ethanol" to account for refinery optimizations of catalytic cracking, isomerizing, alcohol enhancement and other techniques.
Additive packages enhance the properties of gasolines. Detergents reduce carbon buildup, all the more important these days with high-pressure direct-injection hardware. Antioxidants improve the storage and tank life. Corrosion inhibitors and dyes are also added. It's generally suggested—and no suppliers deny—that premium fuels have more extensive (spelled $$$) additive packages."
http://www.roadandtrack.com/go/news/new-technology/premium-fuel-futures
So maybe it is waste, maybe it isn't, maybe its cheap piece of mind (2.5%) with hopeful expectation of power/econ gain even if <2.5%. I've never put 89 in anything other than my Stihl equipment that now specs it but for some reason it just feels like the right move for this motor and we're talking $50/year 15000/30= 500*.1- or roughly one wild night at the sizzler
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Yes-That's the same here in Australia.
Mazda recommends 91 octane for the 2.5,so it must be the difference in the ECU.
costermonger
Member
- :
- CX-5
Interesting article in R&T, below is an excerpt I found relevant:
"If the engine is tuned for regular but fueled with something of higher octane, things are a tad more complex. Most modern knock-sensed ignitions seek MBT timing and thus, at least in theory, profit from the added octane. Some, though, have preset ceilings beyond which they won't advance.
And, in all cases, the differences depend on engine families, their octane sensitivities and intended performance levels. Without a stopwatch or dyno—and apart from your pocketbook—you may not even notice any detriment or benefit. By the way, in R&T performance testing at the track, we arrange matters to use Shell's locally available premium of 91 pump octane.
What of midgrade? There's logic involving "legacy vehicles," older high-mileage machinery designed for regular. Even in these days of unleaded fuel, other combustion byproducts can cause deposits in the chamber that may increase octane appetite just a bit. The added octane of midgrade (blended at the pump from the station's premium and regular) might be just enough to counter this.
Ethanol, used as an extender in much of our gasoline, is also an octane enhancer. Blended at a minimum of around 6 percent, its pump stickers state "up to 10 percent ethanol" to account for refinery optimizations of catalytic cracking, isomerizing, alcohol enhancement and other techniques.
Additive packages enhance the properties of gasolines. Detergents reduce carbon buildup, all the more important these days with high-pressure direct-injection hardware. Antioxidants improve the storage and tank life. Corrosion inhibitors and dyes are also added. It's generally suggested—and no suppliers deny—that premium fuels have more extensive (spelled $$$) additive packages."
http://www.roadandtrack.com/go/news/new-technology/premium-fuel-futures
So maybe it is waste, maybe it isn't, maybe its cheap piece of mind (2.5%) with hopeful expectation of power/econ gain even if <2.5%. I've never put 89 in anything other than my Stihl equipment that now specs it but for some reason it just feels like the right move for this motor and we're talking $50/year 15000/30= 500*.1- or roughly one wild night at the sizzler
That's a good article. As I said, going up a grade isn't hurting anything - just costs more (and if it's only 10 cents a gallon extra, 89 is a lot cheaper where you are than here - where it's at least 10 cents a litre extra). The only thing I'd add is that while it is certainly true that premium contains more detergent than regular, the extra detergent content compared to a decent quality regular fuel isn't conclusively beneficial. Rather than buying premium to ensure you're combatting deposits (and you should be conscious of the need to do this with a direct injection system like ours), just make sure you buy "Top Tier Detergent" gasoline fairly regularly. Basically every name brand is meeting this specification now, so you should be more than safe as long as you don't run your car on no-name fuel exclusively.
If you want to spend a few pennies extra per gallon (in the US), you'd get more benefit from ethanol free gas than you will from a higher octane. Actual real-person tests with a 2013 Ford Focus (which is also a high compression DI engine) showed about a 5% increase in mileage going from 87octane to 93octane - with a price increase of $0.30/gallon.
However, switching from 87 octane E10 to 87 octain E0 (ethanol free) gave an increase of about 8% with a cost increase of only $0.10/gallon.
Of course, you might encounter some difficulties actually finding E0 gas. In my own case, I have to drive about 15 miles out of the way to find it - which completely negates any savings from better economy.
However, switching from 87 octane E10 to 87 octain E0 (ethanol free) gave an increase of about 8% with a cost increase of only $0.10/gallon.
Of course, you might encounter some difficulties actually finding E0 gas. In my own case, I have to drive about 15 miles out of the way to find it - which completely negates any savings from better economy.
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Not to make a big deal about this but I just checked the US version on Fords website under specifications and it states the Focus has 12-1 compression?
Ooops -- you are correct. I'll edit my post (to say "high compression" instead of 13:1.) The point is still valid, though...
Thanks for the correction.
costermonger
Member
- :
- CX-5
I would love to see what kind of mileage my CX-5 would get if I could find E0 fuel, but in Canada the minimum is 5% (and the average seems to be slightly over 6%). We haven't got anything as bad as E10 yet, but give it time - ethanol is cheaper than gasoline, so the oil companies can make more money per unit of fuel, while simultaneously hurting our mileage.. It's an excellent deal for them!
I'll have to look for E0 when I'm in the US next.
I'll have to look for E0 when I'm in the US next.
Here are the results of my experimentation with 87+ octane gas. I hope they prove useful to you in making your own decision based on your environment and needs.
Basically, I had read many of the same articles that provide some insight but no definitive answers (no improvement with higher octane if your manufacturer recommends lower, may see improvement in high compression engines, will only spend more money, etc) and found that they all pretty much come to the same conclusion: YMMV.
So I decided to try it out and see how my "mileage" varies
First, I set out to determine what my objective should be. Because I am not equipped to measure power and responsiveness in an objective manner, I decided this would be nice to have but not my primary objective. Next, using readily available tools, it is fairly easy to accurately measure MPG (or km/l) and determine if there is any improvement. Although I would like to get better mileage for each tank, I would ultimately prefer to save money. Using known gas prices at any time, I can calculate my $/mile and determine which option offers better savings. In the end, i decided my objectives would be:
Primary: Save $
Secondary: Increase MPG
Nice to have: perceived performance improvement
Next, I set out to minimize any factors external to octane that may affect MPG. After much reading I came up with the following list:
- Brands/Locations
- "Topping it off"
- Environmental conditions
- Modifications to the vehicle
- Variations in driving conditions i.e. highway/city/traffic
- Driving style (I recognize that the biggest contributor to variance in MPG is between the drivers brain and the gas pedal)
To mitigate the risk of any of these affecting the outcome significantly, I:
- Purchased gas from the same station each time and excluded results that differed to greatly when I could not. I think it is important to note that all gas in my area - regardless of octane level - is ethanol-blended up to 10%.
- Filled my tank in the same way every time: fill->click->wait 5 seconds->fill->click->end. (I did the second fill/click because I am used to diesel in my other car which foams and was not sure if it was the case with gas and wanted to minimize variances due to foaming)
- Spread my experiment as much as possible across "snowless seasons"
- Did not make any surprise trips to the mountains
- Did not haul any special loads of bricks in the trunk; although I could not tell my kids to walk to the shopping mall (hey kids...Daddy is running an experiment!)
- Delayed purchasing of lighter OZ Racing Alleggerita HLT wheels
- Tried to keep my routine the same and noted results that differed to greatly when I could not.
- Spent at least a month "stabilizing" my driving style to get consistent results with my starting octane level in order to do the same with the new level.
The results are as follows:
Octane 87: Average 9.34 l/100km (High of 9.629 l/100km with traffic, low of 8.8 l/100km all highway with the wind at my back)
Basically, in optimal conditions, the best I could do was 8.8 l/100km.
Octane 91: Average 8.14 l/100km (High of 8.592 l/100km, low of 7.432 l/100km)
Basically, my worst result was better than anything I could acheive using 87 octane.
As far as cost goes, @ current gas prices of 1.419$/l for 87 octane and 1.524$/l for 91 octane I pay 13.25$/100km (87 octane) and 12.40$/100km (91 octane) respectively.
But...did I meet my objective?
Primary: Save $ -> Not much. Since I do 15000km in a year, I will have saved about 127$... not significant enough to warrant a change.
Secondary: Increase MPG -> Yes. For my area, conditions, driving style and car I get more mileage with higher octane fuel.
Nice to have: perceived performance improvement -> None. Any change is to minor for me to be able to tell.
Will I stay on the 91? Sure. I might not save big but I certainly don't pay more plus I go to the pump less often. Why not?
With this data I will try different pumps in my area and see if I notice significant changes in quality of fuel.
As with any results, your vehicle, driving style and environment is different so YMMV Just don't listen to the anecdotal stuff, I encourage you to try it yourself. Who knows what you will discover.
I hope this helps.
Basically, I had read many of the same articles that provide some insight but no definitive answers (no improvement with higher octane if your manufacturer recommends lower, may see improvement in high compression engines, will only spend more money, etc) and found that they all pretty much come to the same conclusion: YMMV.
So I decided to try it out and see how my "mileage" varies
First, I set out to determine what my objective should be. Because I am not equipped to measure power and responsiveness in an objective manner, I decided this would be nice to have but not my primary objective. Next, using readily available tools, it is fairly easy to accurately measure MPG (or km/l) and determine if there is any improvement. Although I would like to get better mileage for each tank, I would ultimately prefer to save money. Using known gas prices at any time, I can calculate my $/mile and determine which option offers better savings. In the end, i decided my objectives would be:
Primary: Save $
Secondary: Increase MPG
Nice to have: perceived performance improvement
Next, I set out to minimize any factors external to octane that may affect MPG. After much reading I came up with the following list:
- Brands/Locations
- "Topping it off"
- Environmental conditions
- Modifications to the vehicle
- Variations in driving conditions i.e. highway/city/traffic
- Driving style (I recognize that the biggest contributor to variance in MPG is between the drivers brain and the gas pedal)
To mitigate the risk of any of these affecting the outcome significantly, I:
- Purchased gas from the same station each time and excluded results that differed to greatly when I could not. I think it is important to note that all gas in my area - regardless of octane level - is ethanol-blended up to 10%.
- Filled my tank in the same way every time: fill->click->wait 5 seconds->fill->click->end. (I did the second fill/click because I am used to diesel in my other car which foams and was not sure if it was the case with gas and wanted to minimize variances due to foaming)
- Spread my experiment as much as possible across "snowless seasons"
- Did not make any surprise trips to the mountains
- Did not haul any special loads of bricks in the trunk; although I could not tell my kids to walk to the shopping mall (hey kids...Daddy is running an experiment!)
- Delayed purchasing of lighter OZ Racing Alleggerita HLT wheels
- Tried to keep my routine the same and noted results that differed to greatly when I could not.
- Spent at least a month "stabilizing" my driving style to get consistent results with my starting octane level in order to do the same with the new level.
The results are as follows:
Octane 87: Average 9.34 l/100km (High of 9.629 l/100km with traffic, low of 8.8 l/100km all highway with the wind at my back)
Basically, in optimal conditions, the best I could do was 8.8 l/100km.
Octane 91: Average 8.14 l/100km (High of 8.592 l/100km, low of 7.432 l/100km)
Basically, my worst result was better than anything I could acheive using 87 octane.
As far as cost goes, @ current gas prices of 1.419$/l for 87 octane and 1.524$/l for 91 octane I pay 13.25$/100km (87 octane) and 12.40$/100km (91 octane) respectively.
But...did I meet my objective?
Primary: Save $ -> Not much. Since I do 15000km in a year, I will have saved about 127$... not significant enough to warrant a change.
Secondary: Increase MPG -> Yes. For my area, conditions, driving style and car I get more mileage with higher octane fuel.
Nice to have: perceived performance improvement -> None. Any change is to minor for me to be able to tell.
Will I stay on the 91? Sure. I might not save big but I certainly don't pay more plus I go to the pump less often. Why not?
With this data I will try different pumps in my area and see if I notice significant changes in quality of fuel.
As with any results, your vehicle, driving style and environment is different so YMMV
Just don't listen to the anecdotal stuff, I encourage you to try it yourself. Who knows what you will discover. I hope this helps.
Thanks for the well done experiment and the results H1C23!
It sounds like you took care of most of the common sources of error.
The one area of concern that I see is that you:
'Spent at least a month "stabilizing" my driving style to get consistent results with my starting octane level in order to do the same with the new level. '
Does this mean that you measured your 87 octane consumption for over 1 month, and than switched to 91 octane for one month?
I really hope not, because if so, the car breaking in (more broken in car = better MPG according to a number of threads on here), tire wear (more worn tires = marginally less miles reported by odo) may have given the 91 octane a slight advantage.
Switching every tank would have also not been a 'perfect' way to do this experiment because the ECU would not immediately respond to the changed octane and it's possible that the pump for 87 had a slightly different pump shut-off compared to the 91.
Overall, this by far looks like the best experiment of 87 vs 91 that I have read about.
For me personally, the MPG I see with 91 is usually lower than 87. I do however notice a slight improvement in the sound of the engine at low RPM and heavy throttle. The higher octane gets rid of a slight tapping sound that I can hear at over ~50% throttle at under 3000RPM.
This slight improvement that I have observed in refinement, and possibly power causes me to drive a little bit more quickly with the 91 octane, making the tanks where I try to use 91 return the highest fuel consumption.
It sounds like you took care of most of the common sources of error.
The one area of concern that I see is that you:
'Spent at least a month "stabilizing" my driving style to get consistent results with my starting octane level in order to do the same with the new level. '
Does this mean that you measured your 87 octane consumption for over 1 month, and than switched to 91 octane for one month?
I really hope not, because if so, the car breaking in (more broken in car = better MPG according to a number of threads on here), tire wear (more worn tires = marginally less miles reported by odo) may have given the 91 octane a slight advantage.
Switching every tank would have also not been a 'perfect' way to do this experiment because the ECU would not immediately respond to the changed octane and it's possible that the pump for 87 had a slightly different pump shut-off compared to the 91.
Overall, this by far looks like the best experiment of 87 vs 91 that I have read about.
For me personally, the MPG I see with 91 is usually lower than 87. I do however notice a slight improvement in the sound of the engine at low RPM and heavy throttle. The higher octane gets rid of a slight tapping sound that I can hear at over ~50% throttle at under 3000RPM.
This slight improvement that I have observed in refinement, and possibly power causes me to drive a little bit more quickly with the 91 octane, making the tanks where I try to use 91 return the highest fuel consumption.
phunky.buddha
Booga Booga?
- :
- DFW TX
- :
- No mo MZ5 want MX5
Good data! Some suggestions:
Use the exact same pump every time. That's what I do when I fill up at home so I can maximize consistency.
Get an MPGuino so you can measure instantaneous economy using injector duty cycle x rpm, plus measure through a bunch of other different methods.
Measure with identical conditions at cruise over a specific stretch of road- like exactly 60mph with the same tire pressure, outside temperature, car setup, direction, lane of highway, wind speed (if possible, or pick a windless day), time of day, cargo weight, tank fill, etc.
I say all this but haven't done a similar test myself- the best I can compare with is full-tank trips with the cruise control on, but those are pretty consistent. I'll pick up an MPGuino one day and measure how I've suggested, but I'm more likely to measure octane benefits on the stock tune on the dyno via power gain rather than check for gas mileage.
Use the exact same pump every time. That's what I do when I fill up at home so I can maximize consistency.
Get an MPGuino so you can measure instantaneous economy using injector duty cycle x rpm, plus measure through a bunch of other different methods.
Measure with identical conditions at cruise over a specific stretch of road- like exactly 60mph with the same tire pressure, outside temperature, car setup, direction, lane of highway, wind speed (if possible, or pick a windless day), time of day, cargo weight, tank fill, etc.
I say all this but haven't done a similar test myself- the best I can compare with is full-tank trips with the cruise control on, but those are pretty consistent. I'll pick up an MPGuino one day and measure how I've suggested, but I'm more likely to measure octane benefits on the stock tune on the dyno via power gain rather than check for gas mileage.
Hi piotrek. Regarding the "stablizing period", what I did was:
- run on 87 for 1 month to to try and get consistent results
- run on 87 for 2 months recording my results
- run on 91 for 2 months recording my results
I took posession of the vehicle @ 8000 km so the break-in may still have been a factor.
Thanks very much for your suggestions, I did not think of break-in or tire wear. I still have some time to go before winter so I will switch back to 87 for the next month an record the results.
Hi buddha. Thanks also for your suggestions. I was doing same station, but not same pump. Will definitely incorporate it into my routine. And the MPGuino is interesting. This is the first time I hear of this device and will certainly consider it.
Finally, both of you deserve 1000 internet points for actually taking the time to read through that lenghty post
- run on 87 for 1 month to to try and get consistent results
- run on 87 for 2 months recording my results
- run on 91 for 2 months recording my results
I took posession of the vehicle @ 8000 km so the break-in may still have been a factor.
Thanks very much for your suggestions, I did not think of break-in or tire wear. I still have some time to go before winter so I will switch back to 87 for the next month an record the results.
Hi buddha. Thanks also for your suggestions. I was doing same station, but not same pump. Will definitely incorporate it into my routine. And the MPGuino is interesting. This is the first time I hear of this device and will certainly consider it.
Finally, both of you deserve 1000 internet points for actually taking the time to read through that lenghty post
Thanks for the info H1- I'm pretty shocked/encouraged your results showed that much delta. I really don't expect similar but I'm going to run a few tanks of 89 after seeing 27ish mostly 70-75 hwy cruising on the first two of 87. My price delta would be roughly half what yours is (that's if I step up again to 91) so I see no good reason not to try this asap. Even if I spend 5% more on 91 to go 5% further per tank I'd consider that winning- added range=less frequent stops for fuel I'll record/report my results.
I'll record/report my results.
