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e85 questions xenocron tap in

Old 01-26-2008, 06:14 PM
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Default e85 questions xenocron tap in

i want to run this fuel since its plentiful around here and at 2.40 a gallon is pretty awesome i know that its not as powerful/efficient as a petroleum fuel but its 105-107 octane fuel i was just wondering who has tried it.

what should the afrs be on thie fuel? i have tried searching around i have found a few sites but im not finding it.
and xenocron have you ever played with it as im looking for you to make up a basemap for it
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Old 01-26-2008, 07:31 PM
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Default Re: e85 questions xenocron tap in

E85 requires roughly 1.3-1.5 more fuel than regular old gasoline. Most people run a standard gasoline calibrated wideband oxygen sensor and shoot for the exact same fuel ratios as they would on gasoline. So around 11-12:1 in boost, ect ect ect.

http://en.wikipedia.org/wiki/E85_in_standard_engines

One thing people ignore is that on a standard gasoline engine, "max rich" is 0.8503 which is pretty close to the "max lean" of E85. This means to be on the safe side of E85, you should tune richer than you would typically. This is kind of not true at the same time because E85 has some better burn qualities and cools intake charges so really most of the time we run richer to get slightly cooler combustion temps when this isn't necessary with E85 as it comes naturally. Most people have success tuning at around 11.5:1 in boost. I'd stick around that number.

The last big thing to remember about E85 is it's not always 85% ethanol and 15% gasoline. During the winter it changes to about 70/30 which changes everything dramatically. It will require a full retune so you should make sure when you fill up how much ethanol to gasoline you are getting. There are some ethanol meters on the market. They aren't cheap though. The more gasoline in the mix, the lower the octane mixture but theoretically you should get significantly better fuel economy. But at the same time, air density increases during the colder months so you need more fuel. I doubt the differences offset each other though.
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Old 01-27-2008, 10:59 AM
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Default Re: e85 questions xenocron tap in

cool cool well it wont be driven in the winter time. im just hoping xeno can hook me up with a base map.
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Old 01-27-2008, 04:05 PM
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Default Re: e85 questions xenocron tap in

Take a good running basemap. Select all of the fuel. Multiply by 1.35. Done.
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Old 01-27-2008, 04:23 PM
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Default Re: e85 questions xenocron tap in

But can't you also argue that since ethanol cools as it evaporates and lowers the engine temps greatly and since it has such a high resistance to detonation you could lean it out to a smaller multiplier than 1.35?
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Old 01-27-2008, 04:29 PM
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Default Re: e85 questions xenocron tap in

it takes more e85 becuz its not as efficient as petrol fuels..
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Old 01-27-2008, 04:32 PM
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Default Re: e85 questions xenocron tap in

Originally Posted by TorganFM
But can't you also argue that since ethanol cools as it evaporates and lowers the engine temps greatly and since it has such a high resistance to detonation you could lean it out to a smaller multiplier than 1.35?
On a basemap, I wouldn't make that argument at all. Injectors can act funny and take to changes differently. Lower density air charge means more fuel to stay at the same AFR. There are a whole bunch of variables. Just comparing stoich vs stoich, you are talking about about a 1.3x difference. On a basemap, I'd stick to that.

As for once you are tuning what fuel ratios you should shoot for, well the best way to find out is experiment. Use the information found on wikipedia as your baseline and work with it. Theoretically when people are tuning gasoline engines, we should shoot for around 12.5:1 and then tune timing to get more or less power/safety. In actuality, it doesn't work that well. A combination of tweaking ignition timing and running richer is what seems to work best. It is up to the tuner to find where theory and reality meet.
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Old 01-27-2008, 05:13 PM
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Default Re: e85 questions xenocron tap in

i got a lot of info from that there, does the tuner need to know about how to tune this fuel? or is it pretty basic to regular gas.. i want e85 but if its goin to be a hassle i will just run two maps and get pump and a race fuel.
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Old 01-27-2008, 06:10 PM
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Default Re: e85 questions xenocron tap in

It's just like tuning any other fuel ever made/used. You look at what the scientists have tested and tune for that air fuel ratio and apply any safety margin you think you may need to apply. Then you advance timing until you don't make any more power or detonation occurs. Tuning isn't black magic. It's just applying known data and theory to real life situations. If you just want a decent tune out of E85, just tune for similar AFRs as you would with gasoline and tune timing as normal. It can be that simple.
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Old 01-27-2008, 06:29 PM
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Default Re: e85 questions xenocron tap in

right on thanks a lot
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