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Thinking of switching over to E85, have a few questions -

My main concern down here is the lack of E85 stations. Is it easy and safe to switch back and forth between E85 and pump gas? Suppose I was out of E85 and only had conventional gas nearby. If I run the tank out of E85 (as close as I can get anyway) and fill up the rest with 91, that should dilute the E85 enough to switch to my 91 map, correct? The reverse should also be true? Run it out of 91 and fill up the rest with E85..?

Monitoring ethanol content is a must, what is required to install a zeitronix unit? Any other E85 GTR's down here? Please chime in.
 

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Discussion Starter · #4 ·
Was thinking about E85 as well but just seems too inconvenient with the lack of gas stations.


I don't feel like carrying gas cans...
I definitely wouldn't if I still lived in OC, up in LA I have a couple stations around me.
 

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Monitor E85 is not a must. If you run out your tank and fill up you should be fine. Either way, monitor your air/fuel mixture. Our computer can correct over 20% either direction (it is shown in your log). So as long as you are hitting your air/fuel mixture target you are fine. Typically you want within 95-105% on lt fuel correction. So during the switched tanks, it will be off more. I have never monitored my E85 content although supposedly we only have 2 grades. in my area.. I would make sure get bigger than 1000 cc injectors because it is not enough in under 40 deg weather for me.
 

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^Goonthree is correct. If your tuner does a good job with the tune and provides E85 + a backup 93 octane map, you can easily switch between the two. Because of the closed loop system, you just need to run the car low on one, fill up with the other, and switch to appropriate map.

(Same reason why with the closed loop system, the fluctuations in E85 alcohol content aren't that big of a deal.)

Hope this helps.
 

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Discussion Starter · #8 ·
Monitor E85 is not a must. If you run out your tank and fill up you should be fine. Either way, monitor your air/fuel mixture. Our computer can correct over 20% either direction (it is shown in your log). So as long as you are hitting your air/fuel mixture target you are fine. Typically you want within 95-105% on lt fuel correction. So during the switched tanks, it will be off more. I have never monitored my E85 content although supposedly we only have 2 grades. in my area.. I would make sure get bigger than 1000 cc injectors because it is not enough in under 40 deg weather for me.
At the pump E85 is more E65 to E80 and anything in between as ethanol content varies. I want my tune spot on so I will likely have 2 tunes for ethanol, one for E70 which is probably around 96 octane equivalent and one for E85 which I will mix myself from barrels of E98 with pump gas. Maybe that's overkill but I just want safety and the right tune for the situation.

I also just plain like the idea of knowing exactly what kind of octane I have in the tank
 

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Just did this in my head, E65 vs E80 is extra 7.5% in fuel. So if your tune is spot on e65 and you went from to E80, your fuel trim will be 107.5%. If you read your log regularly, you will get that variation in temperature change. I am guessing around 20-25 degrees in ambient temp.
What you do can't go wrong, I am happy with the safe guards in my tune.
 

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I've had E85 on mine for quite some time now. Originally I had 2 MAPs, one in slot 0 for E85, and one in slot 1 for 91 octane (highest we have here), I had no issues switching back and forth between the two. If I was switching from E85 to 91 for example I'd run it out of E85 as much as I reasonably could without being stranded, then fill up with 91 and switch to slot 1. If I felt extra cautious I'd fill it up again with 91 by the time I had 1/2 a tank. Most of the time though I just filled up with enough 91 to make it to the E85 station and did the same thing. On the HTA28 setup I had 3 MAP's, slot 0 was E85, slot 1 was E85/91 mix, and slot 3 was 91 only. No issues thus far.

One thing you want to keep in mind is that most stations have seasonal blends, here is a bit of info I dug up awhile ago:

Key (Ethanol/Hydrocarbons): Class 1 (85/15) is the summer blend; Class 2 (80/20) is the transition blend utilized in the spring and fall; and Class 3 (75/25) is the winter blend.

Chart from the National Ethanol Vehicle Coalition.



I'm not sure how drastically this would affect stoich and tuning because the fuel is so cool (temp) and such a high octane. Worth mentioning I think.

Some distributors use the following:

Season Minimum With Blend
Spring (March-May) 74% 76.6%
Summer (Jun-Aug) 79% 81.1%
Fall (Sept-Nov) 74% 76.6%
Winter (Dec-Feb) 70% 73%

So in the winter it can be as low as E70.

Luckily around where I am an enthusiast owns the E85 station I use and maintains the summer blend year round and constantly shows 85-190% ethanol. Hope that helps!
 

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You need the ethanol content sensor!

Then you need a tuner that's going to give you 3-4 maps for ethanol. Yes the car can compensate with fuel trims but that's NOT the correct way to do things.

When switching I tell all my customers to run their tanks low then fill then fill up. If you have a gallon or two of 91 octane and fill the car up with e85, it'll mix down to e60ish. Then on your next tank of e85 it'll mix to e70ish.. It'll tank a few tanks to get to e80-85. There isn't a huge difference in octane when going e60-e80, more of a fueling difference.
When my customers go the Cobb route I give them a e65, e70, e75, e80, e85

I personally have a sensor in my car and we're installing one in our shop GTR

John
 

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Fortunately we don't seem to have the low ethanol problem here in Colorado Springs, even in the winter. This was tested 2-18-12.

 

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The sensor is very cool for sure and good piece of mind. We installed one last week on a GTR and i'm sold on it. Will be keeping the kits in stock from here on out.
 

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Just got my analyzer installed, and it works great! Highly recommend to anyone using E85 or any ethanol based fuel.

This is where I located mine.
Looks good!

Zeitronix is def on my to do list, but realistically I'm not too worried until I turn up the boost. Soon...
 

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I would like to see some photos of the GM sensor installation. Thanks!
T1 Race did the install for my Zeitronix. Tony caught that the GM sensor only flows 200lph and if we put it directly in between the fuel return line that it would cause a disruption in the flow, so Tony and his crew tee'd in between the return line so that the sensor can still do its job without messing with the flow of the fuel system. I'll post picture of the install later tonight.
 

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The sensor is very cool for sure and good piece of mind. We installed one last week on a GTR and i'm sold on it. Will be keeping the kits in stock from here on out.
cost on the sensor?
 

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The kit is $587 and includes the flex fuel sensor, wire harness from the sensor to the display, and the display unit. I'll put some more pics up when they come in, probably tomorrow or Friday.

Installation isn't all that straight forward because the sensor is kind of big, but i'm going to try to come up with a 'PNP' kit for it. Will be after TX2K though, we're slammed getting ready for that at the moment.

Tuan said he'll put up some pics of the install we did on his tonight.
 

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Tony caught that the GM sensor only flows 200lph and if we put it directly in between the fuel return line that it would cause a disruption in the flow
That is critical info, thanks for mentioning this. I didn't even think about it, but I def didn't spend the time and money to make all -12/-10/-8 fuel lines only to have flow impeded by a little sensor.
 
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