Running Full E85 on a E30 BM3 Tune

CenTexMKV

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Hey guys,

Probably a stupid question. I have E85 available locally? Is there any danger running full E85 on a bootmod3 E30 tune?




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satindragon

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Couple of reasons.

For starters, without a tune designed to take advantage of it, you won’t see much of a performance gain. More importantly, I’d be highly surprised if the stock high pressure fuel pump and injectors have the headroom to satisfy the volume requirements of running full E85 under high load.

You’ll likely end up tripping a protection because the engine will run lean under load. From a performance and practicality perspective, you get your biggest bang for the buck around E50.

Volume requirements increase fairly substantially past E50 without a ton of benefit as far as knock resistance. Assuming the in-tank pump is up to the task, the route most people will likely take for running E85 is to add port injectors controlled by some kind of piggy back like a split second or megasquirt. In a max-effort or full time race car, sure but for a car you’re going to primarily street drive, it’s really not worth it.

Not to mention that your fuel economy is also going to get far worse as you increase the ethanol percentage.

Hope this helps.
 
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65sohc

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I just (today) traded my 2016 GT350 in on a Supra. The Shelby had a Lund flex fuel tune so I could run whatever ethanol% I wanted without worrying about the exact percentage. You guys are talking about running e30. How critical is that 30% and how are you determining it?
 

Ozzy8690

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I just (today) traded my 2016 GT350 in on a Supra. The Shelby had a Lund flex fuel tune so I could run whatever ethanol% I wanted without worrying about the exact percentage. You guys are talking about running e30. How critical is that 30% and how are you determining it?
First off, welcome and congratulations! I had a flex fuel tune on my turbo FRS as well. Just fill up whatever amount and the ECU adjusted for it. My Supra is still stock, but from what I’ve gathered here and through talking with some shops, getting as close as you can to 30% is highly critical if you’re running an E30 tune. Most people I’ve seen are either googling the mixture by gallons for a final e30 mix or are using those ethanol content test tubes. I know Twisted Tuning offers a flex fuel kit so I’m hoping they chime in.
 

satindragon

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Ideally you'd want to have a sensor and guage to measure the ethanol content. When I had my Focus RS, I ran the setup from Zeitronix. Worked flawlessly. The reason why measuring is so important is because unless you've verified the ethanol content from the E85 pump, you really don't know what you're getting.

Most pumps will designate "at least XX percentage". I've personally seen E85 pumps have ethanol content ranging from E50 to E85. Reason why this is important is because any calculator you use assumes that you know the percentage of ethanol that's coming out of the pump.

As far as criticality, that comes down to how aggressive your tuner is being. I imagine that most are going to leave some margin in case their customer doesn't get the mixture exactly right.
 

madweazl

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Thought I read the manufacturer recommended no higher than e25?
 

65sohc

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First off, welcome and congratulations! I had a flex fuel tune on my turbo FRS as well. Just fill up whatever amount and the ECU adjusted for it. My Supra is still stock, but from what I’ve gathered here and through talking with some shops, getting as close as you can to 30% is highly critical if you’re running an E30 tune. Most people I’ve seen are either googling the mixture by gallons for a final e30 mix or are using those ethanol content test tubes. I know Twisted Tuning offers a flex fuel kit so I’m hoping they chime in.
Thanks. I spent many years on MKIV.com before switching to a series of Mustangs in 2005. Fortunately where I live in central CA they don't seem to change the ethanol %. I bought e85 at the same station for three years and it was always 79-82%. I'm going to check out Twisted Tuning right now.
 

65sohc

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I just looked around Twisted Tuning and am sort of confused. I couldn't find a discrete tuning package for the Supra. They show custom tunes for $450 but there is no mention of how the tunes are uploaded to the ecu. They also show an ethanol content sensor but I don't see how that integrates into the tuning.
 

kissmyrs

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I would not do it, the amount of timing commanded in an e85 tune vs e30 is drastic, along with the other adjustments. I seen motors blow from this
 

satindragon

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Not to mention that the sweet spot for running ethanol is between E50 - E60. You get most of the knock resistance benefit at that level.

On my 550 whp Focus RS build from a few years ago, I didn't make a ton more power running full E85 vs. E60. I had more than enough fuel due to supplemental port injection but there was just no reason to do it. There was a big hit to fuel economy without much power gain.

As Justin said, E30 - 40 is where most people need to be. If you're building a maximum effort car then by all means knock yourself out. For a street car, E30 - E40 is all you need.
 

65sohc

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I was thinking of the convenience factor in a daily driver of just filling the tank with e85 without having to worry about ratios of e85 to normal e10 to achieve the desired ethanol percentage. I ran flex fuel in a GT350 for four years. e50 seemed to be the sweet spot as far as driveability. The etoh content at the station I used was very consistent so I could probably nail the proper percentage within 10% in the Supra but I don't know if that is good enough.
 

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Running full E85 is not advisable on the E30 map as your fuel system may have a difficulty keeping up given the fuel volume demands on this high output tune.

There are a number of sensors that have mobile apps connecting over bluetooth that give you the current ethanol % which are convenient.

Generally speaking in terms of bootmod3 E30 OTS maps, they're built and tested all around the World in all sorts of climates/ambients/driving conditions and you don't have to worry about having the exact 30% blend as there's always some wiggle room left in them and its easy to fill up at pumps as the map will be just fine anywhere from E25-E45. E50 and up you may have some issues with fuel trims getting too high but that's starting to push it anyways for an just an off the shelf map.
 

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