Comparing 87 to 91 octane for the 2.5L non-turbo engine

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'16.5 CX-5 AWD
This is true but...

Unless you drive like a grandma , soft on pedal, flat roads, and all highway miles, and you actually track you mileage and calculate your mpg than most people will not notice the difference.

How you drive, f.i. stomping on the gas pedal will affect your mpg far more so than e85 versus the real stuff.

Also some top gasoline e85 performs better and may only be a slight decrease in mpg when using certain brands.

So e85 will always get less fuel efficiency but overall, you may not notice much depending on your driving habits. The OP probably hasn't noticed much difference because other factors affect mpg as well.

And at the end of the day, the e85 should be cheaper so $$ wise, it all balances out.

It soon won't matter as real gasoline is quickly becoming the elusive purple unicorn.

There is no real gas on my commute to work and to get pure gas for my lawnmower requires traveling 30 minutes (out of my way) in opposite direction from my house. If this station stops selling pure, will be hard pressed to find another location.


NONE of this is true. Gasoline has 19948 BTU/lb HHV. Ethanol has 12769 BTU/lb. Instead ot a stoichiometric ratio of 14.7:1, ethanol is 9:1. So, ethanol has 64% as much energy so you have to burn 1.5+ times as much to get the same horsepower and at 1.63 times as much to reach stoichiometry to control emissions, It DOES have a higher Octane rating, but to take advantage, the engine needs a higher compression ratio. That's nearly impossible to change on the fly to optimize a different fuel.

E85 is an abject failure. It uses a precious food crop to produce an inefficient fuel. Once ethanol is produced, it is better stored in charred oak barrels for future consumption. E10 is nearly as bad with the same loss of food supply. The 10% contamination alone requires the engine to burn 4.5% more fuel to reach stoichiometry, then add the BTU reduction of ethanol and the engine must about 7% more fuel to accomplish any task. Most of my cars have burned about 10% more fuel on E10.

I avoid it.
 

ZoomZoomCX3

Member
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Mazda, CX-3 GX AWD
I never liked the idea of food stocks being used for machine fuel. I use Chevon non-Ethanol 94 in my CX3 and my wife's CRV. When I'm filling my CX3 or My wife CRV with non-Ethanol 94 and I see people with high end cars using the cheapest fuel with Ethanol while the world has a food shortage, very sad to say the least.
 
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2016.5 CX-5 GT AWD titanium/black 2016 Miata Club ST MT white
I never liked the idea of food stocks being used for machine fuel. I use Chevon non-Ethanol 94 in my CX3 and my wife's CRV. When I'm filling my CX3 or My wife CRV with non-Ethanol 94 and I see people with high end cars using the cheapest fuel with Ethanol while the world has a food shortage, very sad to say the least.

While I personally don't like ethanol mixed with my fuel, I doubt VERY seriously that the use of ethanol in our fuel supply is taking the corn out of anyone's mouth.
 
Personally as the thread seems to be shifting to lightly political, if you're worried about fuels then buy a Tesla..... ;)
As for the octane I find it hard to debate with people that don't data log an event from their driving and see that under load conditions the engine power drops mainly from the Mazda ECU compensating for not using higher octane fuel to support those loads.



Odrapnew: the more you post about your Mustang the more it makes less sense. Your ECU VE tables must be radical? ;)
 
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2014 Ford Explorer Sport, 2009 CX9(Wife's)
Personally as the thread seems to be shifting to lightly political, if you're worried about fuels then buy a Tesla..... ;)
As for the octane I find it hard to debate with people that don't data log an event from their driving and see that under load conditions the engine power drops mainly from the Mazda ECU compensating for not using higher octane fuel to support those loads.



Odrapnew: the more you post about your Mustang the more it makes less sense. Your ECU VE tables must be radical? ;)

LOL, obviously I'm not the bestest (yeah, you read that right) at explaining.
It makes sense in my head because I've been playing around with the tune lately.

In short, the ECU in my stang doesn't optimize for different octane fuel. Has to be done manually via tuning software.
 
LOL, obviously I'm not the bestest (yeah, you read that right) at explaining.
It makes sense in my head because I've been playing around with the tune lately.

In short, the ECU in my stang doesn't optimize for different octane fuel. Has to be done manually via tuning software.
I think we are waaaay off topic. Maybe start a thread about this?
Yes I can understand having a file created for different fuel types and octane used to upload or if you have a access with stored files to "on the Fly upload.

Stand alone ECUs are a beeeeeecth to get them to run correctly without lots of reading and understanding every aspect of how an engines runs. Normally this takes a couple of classes in ECU Calibrating or having a really good friend that is experienced helping you.
I am also confused by your statement that your ECU cannot be optimized for octane values. The whole point of a standalone as with many ECU access programs is to do among others things exactly that?

I read data logs a couple times a week and if I feel inspirational to make adjustments in small RPM area's at a time as needed. The adjustments are small and still take over an hour or more to do all of them correct but more safely for the engine.
 
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2014 Ford Explorer Sport, 2009 CX9(Wife's)
I think we are waaaay off topic. Maybe start a thread about this?
Yes I can understand having a file created for different fuel types and octane used to upload or if you have a access with stored files to "on the Fly upload.

Stand alone ECUs are a beeeeeecth to get them to run correctly without lots of reading and understanding every aspect of how an engines runs. Normally this takes a couple of classes in ECU Calibrating or having a really good friend that is experienced helping you.
I am also confused by your statement that your ECU cannot be optimized for octane values. The whole point of a standalone as with many ECU access programs is to do among others things exactly that?

I read data logs a couple times a week and if I feel inspirational to make adjustments in small RPM area's at a time as needed. The adjustments are small and still take over an hour or more to do all of them correct but more safely for the engine.

To be clear, I didn't say cannot, I said doesn't.

What I mean is that the ECU (again, in my Mustang) doesn't learn/adjust anything by itself due to octane changes.

I can make changes in the tune to optimize it for a specific octane, but then it won't be optimized for a different one. If I optimize it for 93 octane and then fill up with 87 (no other changes), engine could go boom.