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2012 MP4-12C
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Discussion Starter · #1 ·
To run purely E85 in our cars you must upgrade injectors to 1050's and tune for it. This is a costly venture that is also time consuming (not saying it's not worth it, but a consideration). I have a tune for 100 octane and I have E85 pumps readily available. This got me thinking about mixing at the pump.

Using this calculator Octane Calculator - www.bazellracefuels.com it suggests 11 gallons of E85 and 8 gallons of 93 octane will give a 100 octane formula. Using another calculator somewhere I found it specifically took into account E85 and 93 octane, not just octane ratings. That resulted in a 50/50 mix, which is essentially E50.

So my question for you, or discussion, is have you ever mixed fuels to get a boost? Did you monitor the octane rating? Have you tried doing exactly what I'm thinking on stock injectors? I've seen posts of people doing it in other cars, and some even claiming full E85 in non-flex fuel cars (which I wouldn't do), but I'm also pretty sure none of those people were tuned for higher octanes so it kind of negated the whole experiment.
 

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You mentioned mixing to target the octane you want, however e85 makes less power at an equal volume as gasoline, so with a 50/50 mix without increasing the volume of fuel I don't think that much would work. My tuner told me 2 gallons max.
 
2012 MP4-12C
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Discussion Starter · #3 ·
I understand the volume must be increased, hence the fuel injector need at full E85. As long as the pump and injectors can supply the appropriate volume, that shouldn't be an issue. Agreed?
 

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I understand the volume must be increased, hence the fuel injector need at full E85. As long as the pump and injectors can supply the appropriate volume, that shouldn't be an issue. Agreed?
A tuner would no better than me but I don't think so, our ecu is programmed to detect octane, when you switch to e85 it has to be "told" to push more volume with each injector pulse. If you run 50% e85 yes the car will detect the octane and therefore run more aggressive timing, however I don't think the car will know to pump more volume of fuel. A car that's fexfuel from the factory can do that.
 
2012 MP4-12C
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Discussion Starter · #5 ·
A tuner would no better than me but I don't think so, our ecu is programmed to detect octane, when you switch to e85 it has to be "told" to push more volume with each injector pulse. If you run 50% e85 yes the car will detect the octane and therefore run more aggressive timing, however I don't think the car will know to pump more volume of fuel. A car that's fexfuel from the factory can do that.
I suppose I could ask M-Engineering as they tuned it for 100 octane. I think our ECU's don't detect octane but detect knock and adjust accordingly. Volume can be controlled by the on/off frequency of injectors as they have full pressure behind them all the time. I believe it's simply not an issue till it's demanding more fuel "on" than it can provide.
 
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I suppose I could ask M-Engineering as they tuned it for 100 octane. I think our ECU's don't detect octane but detect knock and adjust accordingly. Volume can be controlled by the on/off frequency of injectors as they have full pressure behind them all the time. I believe it's simply not an issue till it's demanding more fuel "on" than it can provide.
Well yes it detects octane by listening for knock, but would an ecu tuned for 93octane or 100 know how to handle 50% E85?
 
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Discussion Starter · #7 ·
Well yes it detects octane by listening for knock, but would an ecu tuned for 93octane or 100 know how to handle 50% E85?
That's the question at hand. What matters more, the octane or the ethanol content? E85 could be as low as 70% ethanol also.
 

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I wonder too EMF…if you were to run the m-engineering 100 octane map on 50/50 e85/93 blend, would it work safely?
 

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Why would u even want to mix and experiment in a car like this ? Just have map switching and run the proper fuel for the map .

The 2 fuels also have different weights and burn rates and just mixing them and trying to max out that map slot is not advised . If anything it would be something I would do if I was running say a 93 octane map and wanted it to be extra safe so u add a few gallons max of e85 or race gas to keep octane up and knock down.

But to try and mix the right amount of e85 with pump 93 to equal 100 I don't think is a good idea.

I'm sure Jon or someone from Mengineering will chime in soon tho .
 

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That is 100% correct, you can't just mix for octane like you would with race fuel. E85 is a completely different ball game, without a flex fuel map with the appropriate sensors added to your car this would not be optimal. I would bet the car would be down on power significantly.
 
2012 MP4-12C
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Discussion Starter · #11 ·
Why would u even want to mix and experiment in a car like this ? Just have map switching and run the proper fuel for the map .

The 2 fuels also have different weights and burn rates and just mixing them and trying to max out that map slot is not advised . If anything it would be something I would do if I was running say a 93 octane map and wanted it to be extra safe so u add a few gallons max of e85 or race gas to keep octane up and knock down.

But to try and mix the right amount of e85 with pump 93 to equal 100 I don't think is a good idea.

I'm sure Jon or someone from Mengineering will chime in soon tho .
I have map switching, just not for E85, because I haven't done injectors. For what I'm doing I'm not sure I can justify doing all the E85 stuff to run full E85. I've also planned on doing a video with the 93 tune and extra octane vs straight 93 and I was going to wrap that into the 100 octane testing also.

I've contacted Jerry already, no response yet, but it is still lunch time on a Monday for them.
 
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Discussion Starter · #12 ·
The official response from M-Engineering regarding the thoughts is "We don't recommend mixing E85 with 93 octane to get 100 octane. For the 100 octane map, only use fuel with the octane rating of 100 or higher."
 

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The official response from M-Engineering regarding the thoughts is "We don't recommend mixing E85 with 93 octane to get 100 octane. For the 100 octane map, only use fuel with the octane rating of 100 or higher."
Pretty muxh exactly what my post said and what I figured they would say .

Just to many possibilities and variables and it's kind a cheating way to get 100 octane cheaper than just buying race gas .
 
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Discussion Starter · #14 ·
Pretty muxh exactly what my post said and what I figured they would say .

Just to many possibilities and variables and it's kind a cheating way to get 100 octane cheaper than just buying race gas .
It's less about the cheap and more about the available. I'm not the casual driver, and I can mix E85 at the pump so that's easiest to attain. Buying, storing, and pouring 18 gallons at a time really sucks.
 
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Why not go with meth injection and have a tune made for that. Rather than deal with e85, race gas, mixing and availability wouldn’t that make more sense? Also meth with 93 is supposed to yield 104 to115 octAne mix.
 
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Discussion Starter · #16 ·
Why not go with meth injection and have a tune made for that. Rather than deal with e85, race gas, mixing and availability wouldn’t that make more sense? Also meth with 93 is supposed to yield 104 to115 octAne mix.
I don't want to deal with checking another tank manually, forgetting to add some, not having enough, etc.
 
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My 2 cents here is that flex fuel "mixing pump E85 with pump 93" is the most difficult tuning to dial in and very unlikely you would reach the 100 octane consistent goal. The major variable being the exact octane rating of the pump E85. You could test it one week and it may actually be E55 or lower and the next week it could test as E85. Most E85 pumps I have seen will have a range on them. The tuners I have worked with state if you can and want to go E85 do the required fuel system upgrades and run the best/highest octane E85 you can get and test it every time you fill up. I personally run 93 octane with a 93 tune and an octane booster to get closer to 100 octane. (No E85 readily available where I live) This will keep the knock sensors happy but will require more frequent spark plug changes.
 
2012 MP4-12C
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Discussion Starter · #18 ·
My 2 cents here is that flex fuel "mixing pump E85 with pump 93" is the most difficult tuning to dial in and very unlikely you would reach the 100 octane consistent goal. The major variable being the exact octane rating of the pump E85. You could test it one week and it may actually be E55 or lower and the next week it could test as E85. Most E85 pumps I have seen will have a range on them. The tuners I have worked with state if you can and want to go E85 do the required fuel system upgrades and run the best/highest octane E85 you can get and test it every time you fill up. I personally run 93 octane with a 93 tune and an octane booster to get closer to 100 octane. (No E85 readily available where I live) This will keep the knock sensors happy but will require more frequent spark plug changes.
What octane booster are you using?
 
2012 MP4-12C
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Discussion Starter · #20 ·
VP Racing Fuels Madditive Octanium
I've used it in my E55, I was going to try Boostane since it's O2 sensor friendly but someone crashed and shut the track down. Torco I think is the on that fouls plugs.
 
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