Atkinson motor and fuel octane

[huunvubu]

Because my original question explained that a higher octane gas could possibly create a better gas mileage and power due to the combustion cycle

Could, would, maybe, hopefully, possibly: seems like a bunch of wild speculation and guessing without any actual hard facts.

As others here have also stated even if you get this supposed "extra gas mileage and power" you end up losing overall because of the increased price of "higher octane gas".

I will only put in 87 octane gas in my Hybrid Maverick as stated in the owner's manual.

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[Vewdu]

It's a 20K truck. Put regular in it and drive it. You wont see a noticeable difference between regular and premium.

 

[mamboman777]

Because my original question explained that a higher octane gas could possibly create a better gas mileage and power due to the combustion cycle

The best gas for higher mileage is ethanol free gas. Ethanol has lower energy density than gasoline mixed with ethanol. Octane does not play a part.

That being said, in Texas, where I live, ethanol free gas so much more money that it's not worth it.

 

[oldfatguy]

May I add a question to this thread? Does octane go down with aging, stored/unused fuel?

yes octane goes down , at 30 day it is can be lower and the fuel you get at the pump is 21 day old on average, so if something is going to sit for a longer time there is good reason to put the best fuel you can get in it

 

[dvibs07]

It's a 20K truck. Put regular in it and drive it. You wont see a noticeable difference between regular and premium.

The point of this thread was to figure out if it would be best to put a lower or higher octane in, so you can do whatever you like, but the information in this thread has been amazing.

 

[dvibs07]

Could, would, maybe, hopefully, possibly: seems like a bunch of wild speculation and guessing without any actual hard facts.

As others here have also stated even if you get this supposed "extra gas mileage and power" you end up losing overall because of the increased price of "higher octane gas".

I will only put in 87 octane gas in my Hybrid Maverick as stated in the owner's manual.

Look back at the older posts, you might learn something

 

[Bootstrap6]

. But since 20 January 2021 it's getting tougher to afford.

Thats unfortunate but at least your gas didnt start going up until after jan 20th. My gas was going up quick and high months before that. Kind of around the time my state started opening back up from the pandemic and more people began driving again. The prices plateaued for me around summer and have since begun to come down thankfully. Main reason I ordered the hybrid to hopefully alleviate the gas "free market" greed somewhat lol

 

[huunvubu]

Look back at the older posts, you might learn something

Yes I learned that there is a religion here with the "use higher octane posts" crowd that you could, maybe, hopefully, possibly get higher MPG and/or power posts. Facts are not required for a religion. Notice the complete lack of defense to the fact that using the higher grade(s) of gas will negate any perceived gain in said MPG/Power.

 

[Vewdu]

Look back at the older posts, you might learn something

As someone with an Atkinson that is the basis for the maverick platform, you will not see any difference. I've put premium a handful of times into my 2.5 and each time my mileage didn't change enough to warrant the price. Not to mention there was no difference in power, engine noise, etc. I believe the manual for the Mazda even says to just put regular in it, don't bother with premium.

Yes I learned that there is a religion here with the "use higher octane posts" crowd that you could, maybe, hopefully, possibly get higher MPG and/or power posts. Facts are not required for a religion. Notice the complete lack of defense to the fact that using the higher grade(s) of gas will negate any perceived gain in said MPG/Power.

Forums are a hive mind of people that have next to zero clue about what they're talking about, mostly because their own "research" begins shortly before a thread is made... Let them be blissfully ignorant and leave it to their dealer/mechanic to deal with.

 

[fbov]

higher octane gas could possibly create a better gas mileage

As someone with an Atkinson that is the basis for the maverick platform, you will not see any difference.

Octane has no effect on mileage. My lowest tank mileage was 93 octane, but 15% ethanol.

Ethanol-free fuel has a clear mileage benefit, but it doesn't make up for the added cost.

 

[Bmr4mav]

87 regular. Everything else is a waste of money. The Prius community has already done all the research you could ever think of.

 

[nikorasu]

yes octane goes down , at 30 day it is can be lower and the fuel you get at the pump is 21 day old on average, so if something is going to sit for a longer time there is good reason to put the best fuel you can get in it

Please cite your sources on this.


Fuel at the gas station is not 21 days old on average. You know how I know? I deliver fuel.

The age of fuel in the bulk tank changes yes, but it is always being refreshed. Now maybe some back ass in the woods station with a single pump has older fuel, but most stations no.

 

[oldfatguy]

Please cite your sources on this.


Fuel at the gas station is not 21 days old on average. You know how I know? I deliver fuel.

The age of fuel in the bulk tank changes yes, but it is always being refreshed. Now maybe some back ass in the woods station with a single pump has older fuel, but most stations no.

 

[oldfatguy]

Please cite your sources on this.


Fuel at the gas station is not 21 days old on average. You know how I know? I deliver fuel.

The age of fuel in the bulk tank changes yes, but it is always being refreshed. Now maybe some back ass in the woods station with a single pump has older fuel, but most stations no.

some of use live in the back woods , thats what my locale fuel suppler claims the age of our fuel is in rural mn

 

[Aherpa]

With an Atkinson engine the 13:1 compression is mostly theoretical. The intake valve is kept partially open at the beginning of compression so some of the A/F mix is pushed back out of the cylinder. Therefore the total compressed volume (and effective compression ratio) is lower allowing operation on regular octane. The advantage is this allows the post-combustion expansion to utilize the full stroke for maximum efficiency.

Octane rating, on its own, does not produce more power. It simply allows higher compression. So an engine that does not take advantage of this through high compression ratio or forced induction (turbo/supercharger) won't make more power. Ethanol, however, has less power density than gasoline. So regular octane fuel without ethanol will produce the highest efficiency. Availability of that will depend on where you are. Often only Premium fuel is available ethanol-free and if the cost difference is greater than the increase in efficiency it's not worth spending more.

Thanks for the great explanation about the role of octane in a internal combustion engine.
I live in Iowa and buy ethanol, partly to support my neighbor farmers, but mostly because I've already paid for some of it in the form of subsidies. It gets less mileage but the price difference makes that up in my vehicles. It is also good at absorbing moisture and in Iowa winters, that's important and it's built into the fuel. I don't have to buy a can of something else to dry the fuel.

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