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hi all. i'm running the burger tuning jb4 (which is fantastic) and i'm wondering how many gallons of e85 i should put in on a full-tank (minus the room for the e85, obviously). i put 3 gallons in last night, but i'm wondering if 2 would have been sufficient. the goal with the e85 is to be able to run the next level of map setting. thanks for any input as i wait for the email response from burger tuning. the car is stock other than the tune, just fyi.
hi all. i'm running the burger tuning jb4 (which is fantastic) and i'm wondering how many gallons of e85 i should put in on a full-tank (minus the room for the e85, obviously). i put 3 gallons in last night, but i'm wondering if 2 would have been sufficient. the goal with the e85 is to be able to run the next level of map setting. thanks for any input as i wait for the email response from burger tuning. the car is stock other than the tune, just fyi.
Hi Enjracing,
So assuming you're using 91 octane (BC I know where you live).
E85 (if it is actually 85, most of the time it is something less, could be as low as 55) is about 106 octane. So, depends on what your target octane rating is.
Think of this easy math approach using an even 10 gallons of fuel:
9 gallons of 91 octane - 91 x 9 = 819
1 gallon of 106 octane -106 x 1 = 106
So assuming you're using 91 octane (BC I know where you live).
E85 (if it is actually 85, most of the time it is something less, could be as low as 55) is about 106 octane. So, depends on what your target octane rating is.
Think of this easy math approach using an even 10 gallons of fuel:
9 gallons of 91 octane - 91 x 9 = 819
1 gallon of 106 octane -106 x 1 = 106
If I made that blend a little differently:
8 gallons of 91 octane - 91 x 8 = 728
2 gallons of 106 octane - 106 x 2 = 212
212 + 728 = 940 / 10 gallons = 94 Octane.
Hope this is what you're looking for
Best,
Acta
thanks very much for that! to run map 2, i am looking to have at least 93 octane. knowing that, unfortunatelt, i was just told that the e85 at the station that i got it from, only tests at around 54. uuuuggggg,
thanks very much for that! to run map 2, i am looking to have at least 93 octane. knowing that, unfortunatelt, i was just told that the e85 at the station that i got it from, only tests at around 54. uuuuggggg,
Yep, and that's the problem.
E50 is about 102 octane, so if you are sure you're putting in E50ish
Then with 91 octane pump gas You can blend in 93 octane for 10 gallons something like this
Here is a chart that might help you going forward. It is showing some higher numbers than I have used in the past. I always calculated E85 at 106, this chart is putting it at 109. I have no way of validating the chart.
It's giving some "mixing formulas" in the right hand column. I've always found working an even 10 gallon blend was the easiest and it can be calculated and blended right at the pump using your iphone calculator.
Notice on the E85 line, far right it says straight VERIFIED E85 from the pump, verified being the operative word there.
Here is a chart that might help you going forward. It is showing some higher numbers than I have used in the past. I always calculated E85 at 106, this chart is putting it at 109. I have no way of validating the chart.
It's giving some "mixing formulas" in the right hand column. I've always found working an even 10 gallon blend was the easiest and it can be calculated and blended right at the pump using your iphone calculator.
Notice on the E85 line, far right it says straight VERIFIED E85 from the pump, verified being the operative word there.
EXACTLY. so, for a 17 gallon tank with 91 octane, i would need about 5 gallons to get to 93 octane? excuse my tragic math.
So far we've exchanged 5 or 6 posts about a single question regarding "proportions". Mixing different fuels to obtain a desired octane output.
That is one side of a two sided coin. There is another completely different challenge mixing different fuels. I haven't even asked about it BC in your first post you mentioned a tune and said you're posing a question to the tuner about mixing ethanol with gasoline. I don't know anything about this tune or how it is set up, so I haven't touched this side of the coin, but now will just caution you until you clear it with your tuner.
The other side of the coin that deals with disparate fuels is Stoichiometry. Gasoline and ethanol have very different stoichiometric coefficients.
Gasoline's stoic is 14.7:1
Ethanol's stoic is 9:1
When blending these two fuels of differing stoichiometrics, they too will result in a new stoic proportional to the ratios of the fuels in the mixture. With ethanol's stoic of 9.1, it requires much more fuel in proportion to parts of air than gasoline does at 14.7:1. That means when you blend fuels, you also change the volume of fuel needed to complete combustions, but that's not possible without some tune modifications.
This is the part we've not discussed (and I cannot unless I did the tune). The more ethanol you proportion to gasoline, you'll reach a threshold when the system in is incapable of physically fueling the AFR of the ethanol side of the mix. Tuners go past stock setups using flex fuel setups, but based on other mods, might include larger injectors, bigger fuel pumps, and possible two VVEs (Virtual Volumetric Efficiency). VVEs BC the AMG GT platform uses a "speed density" form for fueling and no MAF.
With the much higher stoic of ethanol, once you reach a threshold of "blend" with gasoline, a new VVE is going to be needed (possibly along with the other physical components mentioned earlier), otherwise you'll run lean to dangerously lean following the factory VVE. VVEs are not that easy to setup and not that many tuners know how to get that done. But, your tuner could have modified the factory VVE already and might be able to handle a little more ethanol, but be careful just mixing huge proportions on your own.
So, again, not really touching this topic, but you need to validate the ethanol mix with your tuner to be sure.
In this thread, I'm just playing around with the easy math to get you to the octane you requested, nothing else.
So far we've exchanged 5 or 6 posts about a single question regarding "proportions". Mixing different fuels to obtain a desired octane output.
That is one side of a two sided coin. There is another completely different challenge mixing different fuels. I haven't even asked about it BC in your first post you mentioned a tune and said you're posing a question to the tuner about mixing ethanol with gasoline. I don't know anything about this tune or how it is set up, so I haven't touched this side of the coin, but now will just caution you until you clear it with your tuner.
The other side of the coin that deals with disparate fuels is Stoichiometry. Gasoline and ethanol have very different stoichiometric coefficients.
Gasoline's stoic is 14.7:1
Ethanol's stoic is 9:1
When blending these two fuels of differing stoichiometrics, they too will result in a new stoic proportional to the ratios of the fuels in the mixture. With ethanol's stoic of 9.1, it requires much more fuel in proportion to parts of air than gasoline does at 14.7:1. That means when you blend fuels, you also change the volume of fuel needed to complete combustions, but that's not possible without some tune modifications.
This is the part we've not discussed (and I cannot unless I did the tune). The more ethanol you proportion to gasoline, you'll reach a threshold when the system in is incapable of physically fueling the AFR of the ethanol side of the mix. Tuners go past stock setups using flex fuel setups, but based on other mods, might include larger injectors, bigger fuel pumps, and possible two VVEs (Virtual Volumetric Efficiency). VVEs BC the AMG GT platform uses a "speed density" form for fueling and no MAF.
With the much higher stoic of ethanol, once you reach a threshold of "blend" with gasoline, a new VVE is going to be needed (possibly along with the other physical components mentioned earlier), otherwise you'll run lean to dangerously lean following the factory VVE. VVEs are not that easy to setup and not that many tuners know how to get that done. But, your tuner could have modified the factory VVE already and might be able to handle a little more ethanol, but be careful just mixing huge proportions on your own.
So, again, not really touching this topic, but you need to validate the ethanol mix with your tuner to be sure.
In this thread, I'm just playing around with the easy math to get you to the octane you requested, nothing else.
All the Best,
Acta
wow, tnx again for such fantastic and detailed info. burger tuning told me to run 5 gallons on a full tank if using verified 85-plus. thoughts?
Acta,
Geez, you're the 'Man'! I didn't realize reading the conversation between you both how scientific a 'tune' should be. It's making me second guess if a tune is worth it for me personally.
1) finding a trustworthy tuner & 2) more importantly, knowing what kind of gas/ethanol I am putting into my GT from the pump.
For anyone interested in running high percentages of E85 or even full E85. We offer upgraded high and low pressure fuel pumps for the majority of AMG Vehicles.
BTW, did you find someone to do the installs you wanted?
If not, I might have someone else. I had my car wrapped by a company close to Scottsdale Quarter and I am sure they would be able to help if you're still looking. They do a bunch of high end stuff. Let me know.
07-18-2022, 02:44 PM
