93 octane in California (?)

[Gotch]

Adding 10% ethanol will make 85 octane go to 87, but adding 10% ethanol won't raise 91 E0 to 93.

And no, the 110 or 113 would be the "effective octane rating" of ethanol already taking into account all the evaporation cooling etc. The actual standard rating for ethanol is about 100 AKI, and gas stations use the standard.

....not in Canada, sorry for my northern confusion. Our rating is Ron+Mon/2 or some crap like that.... regardless, 100% ethanol in the Great White North is 113ish

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[Gruber]

Mon of ethanol is 105-110 and ron is 125-130 so not sure what youre going about.

And what is the source of these numbers? The Corn Growers Association?

There is no range here. RON and MON are determined on standard engines in stricly standard condintions. And ethanol is ethanol. There are no different kinds of ethanol. So it's not from this to that, but a lot more precise number. The average AKI of pure ethanol (as given on US fuel pumps) is less than 100:

 

[Gotch]

Not Corn Growers association...lol but here’s some information.
https://mnbiofuels.org/media-mba/blog/item/1511-octane-and-ethanol-for-beginners

 

[FlexRex]

And what is the source of these numbers? The Corn Growers Association?

There is no range here. RON and MON are determined on standard engines in stricly standard condintions. And ethanol is ethanol. There are no different kinds of ethanol. So it's not from this to that, but a lot more precise number. The average AKI of pure ethanol (as given on US fuel pumps) is less than 100:

Whats the source of that table? The interweb? If so not better than any of my source hypocrite.

source: interweb

https://www.unitedpetroleum.com.au/fuel/e85/

Says e85 is 105oct, so does next source.

https://iowarfa.org/ethanol-center/e85/e85-facts/

 

[Gruber]

Please recognize that science trumps the Corn Growers Association. These people who give fake numbers for RON, MON, don't even know how RON, MON are defined.

The data in the table I copied above come from a paper in the Fuel scientific journal:

[49] Yates A, Bell A and Swarts A. Insights relating to the
autoignition characteristics of alcohol fuels. Fuel 2009;
89(1): 83–93.

The table itself was Table 4 in another paper quoting the paper above:
"The most reliable values for true octane numbers for
ethanol and methanol are considered to be those pre-
sented in Table 4 [49] and it is clear that the two alcohols
have very similar octane number ratings."

This is:
Pearson, R.J. & Turner, James & Bell, Arthur & de Goede, Stefan & Woolard, Chris & Davy, Martin. (2015). Iso-stoichiometric fuel blends: Characterisation of physicochemical properties for mixtures of gasoline, ethanol, methanol and water. Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. 229. 111-139. 10.1177/0954407014529424.

https://www.researchgate.net/public...xtures_of_gasoline_ethanol_methanol_and_water

 

[Gruber]

Not Corn Growers association...lol but here’s some information.
https://mnbiofuels.org/media-mba/blog/item/1511-octane-and-ethanol-for-beginners

Yep, Minnesota Biofuel Association.....
Btw. now that I started warming up to ethanol, the really bleeding edge environmentalists took positions strongly against biofuels, as even worse for environment than petroleum.... I guess they noticed that someone is actually making money on ethanol, and that hurts them....

 

[FlexRex]

I see

https://energy.mit.edu/wp-content/uploads/2008/01/MIT-LFEE-08-001-RP.pdf

Thats MIT saying 102 and 129. So i dunno man.

Also, explicitly notes how higher then ron octane rating is achieved thru cooling effects (in dit engines) of ethanol only vs a calculated value rating. Main point really.

screen from another science source saying same thing.

source: https://www.sciencedirect.com/science/article/pii/S1110062119300613

So it isnt just 105oct at 100%. Thats calculated garbage not real life. Its what started my post/rant about this.

 

[FlexRex]

Let me finish w this

My wrx went from 225whp to 350whp on e50 mix. More precisely it went from 260 to 350 between fbo stg2 91oct and fbo stg2 e50 tunes. Thats 35% gain only limited by tune, car is capable of maxing out at 380-400whp but mine is a daily conservative tune, so saying e50 knock resistance wasnt the limit but rather the tune was. So that 35%+ increase is how id look at how much better knock resistance ethanol gives over gasoline.. thats real life measured data. MIT paper concludes up to 40-45% efficiency increase in real life engine performance.

 

[Gruber]

As I said, these people don't understand, or neglect what RON and MON are. The engine used for definition of these numbers is carbureted. Yes, not DI, not even port injection, it has a carburator. RON and MON are defined by runing the fuel is this specific standard engine, not any other. This standard RON/MON engine is not greatly affected by the alcohol cooling effect.

Alcohol evaporation will cool the mixture and increase effective knock resistance. They can calculate the effect of alcohol cooling and give some effective octane ratings for any specific engine in existence. For example, they can say that their calculated or even measured in some other engine octane rating of some specific fuel blend is 105 for this BMW engine, 108 for that Ford engine and 102 for the other Honda engine. But they can't say it's RON or MON, because these were already properly measured, they are what I quoted above, and they won't change.
Gas station pump labels are based or the real standard RON/MON, because not all car engines are the same, and not all are DI.

 

[Civii]

I’m in SoCal and add about a gallon or slightly more of E85 to my tank of 91. It was recommended by DRob & Corey to help get closer to 93 for their TSP Tune. I can say it definitely helps with knock & Knock Control.

 

[FlexRex]

Hey man still MIT says one is 129 and other 102 far from 105 and 90 you claimed from some non MIT source. Carburator is a herring, drop it, irrelevant. We are discussing DIT engines and ethanol use.

Bottom line is effective knock resistance not theoretical one. Effectively it increases 40-45% efficiency as that is defined by knock threshold. Whats 40-45% of 93oct? Exactly..

So adding e85 1gal to 91oct will DEFINITELY increase both theoretical octane to 93 and effective to 95-6 or so.

All in DIT engines of course..

 

[FlexRex]

@Civii a practical problem w mixing ethanol blends and gasoline is that additives in one may not mix well w other, and viceversa. I could be wrong though, never confirmed it myself.

Do they dispense e30 straight from the pump in california? If so, why not consider an e30 tune or e25 tune and run e30 anyway. Otherwise I would at least make sure that mixing e85 and unleaded is 100% fine. I run straight e85 which in az is 51% really so no mixing involved otherwise i would have a definite answer on this already.

 

[JT Si]

@Civii a practical problem w mixing ethanol blends and gasoline is that additives in one may not mix well w other, and viceversa. I could be wrong though, never confirmed it myself.

Do they dispense e30 straight from the pump in california? If so, why not consider an e30 tune or e25 tune and run e30 anyway. Otherwise I would at least make sure that mixing e85 and unleaded is 100% fine. I run straight e85 which in az is 51% really so no mixing involved otherwise i would have a definite answer on this already.

I, too, read about this problem. If the gas you're already getting is E10, wouldn't that have to mean the additives are ethanol safe?

Or are we talking the additives in the E85 vs. the additives in the other pump gas?

 

[FlexRex]

Good logic. Assuming that true then mixing with E0 fuels would be THE no-no we must have read about. Assuming being the operative word.

Yes e85 additives vs additives in non e85 gas.

 

[JT Si]

Good logic. Assuming that true then mixing with E0 fuels would be THE no-no we must have read about. Assuming being the operative word.

Yes e85 additives vs additives in non e85 gas.

I'm having a hard time finding media regarding the additives in E85 being potentially incompatible with the additives in pump gas.

I am, however, finding media regarding additives in pump gas being incompatible with high ethanol fuels with regards to precipitating. This does not apply to low % ethanol blends like E10 or E15.

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