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Old 12-02-2019, 04:15 PM   #1
3eyesraver
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Default Cobb Stage 2 with 10% Ethanol

I used to put 1-3 Gallon of Ethanol when I still had stock tune. I wonder if I can still do that with Cobb Stage 2 OTS map.

Cobb Intake, Cobb Downpipe, some catback, AP with Cobb St2 ots tune.
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Last edited by 3eyesraver; 12-02-2019 at 05:45 PM.
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Old 12-02-2019, 06:02 PM   #2
noobultimatum
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So a little bit of corn wont do damage even when not tuned for it. A LITTLE BIT being the important part.

The only time I used a gallon or 2 of corn in the tank was when my DAM dropped due to some bad gas. It helps pick up the octane.

If you have no issues, I would not do it. If you want the most out of the E content, get a tune for it --- pro-tune flex fuel or a canned e30 tune.
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Old 12-02-2019, 07:10 PM   #3
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I'm on an OTS tune and occasionally throw 2gal of e85 in my tank when i'm near a station that offers it. Seems to help combat knock, but if you're doing it in hopes of gaining noticeable hp on your butt dyno, then you'll probably be disappointed - I can't really tell the difference between pure 91 and the 91/e85 mix.

Phatbotti says:
"The simple answer is to just try it. If you put the ethanol in and the car knocks worse...stop doing it. If the knock decreases and the car feels better, then you're likely fine."

So to answer your question, yes, you can, but to actually reap any power benefits, you should get tuned for it like noobultimatum stated.
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Old 12-03-2019, 08:27 AM   #4
Norskie
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Ask Cobb and get a definitive answer.

I'll venture to guess that they've built the tune to handle common fuel blends, which in many places includes a mandatory 10% ethanol.

In my experience, with two exceptions, I've never found any performance differences with running 0-10% ethanol blends in any of my vehicles. Exception #1 is running on MAP's E30 OTS which is just fantastic, and Exception #2 is in carbuerated motors and leaving it for a month (untreated) is likely going to result in difficulties starting and sometimes require a carb cleaning.
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Old 12-03-2019, 11:43 AM   #5
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One to two gallons of E85 is not going to kill you on an OTS map, should get you around E15-E20 ish at most when combined with pump gas.

If you want performance for E85 get a flex fuel tune, or you can try an E30 map from various tuners, but then you have to guess on your blend which is not ideal.
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Old 12-03-2019, 12:17 PM   #6
scoobydooluth
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Pretty sure the map notes explicitly state they're designed for 10% ethanol content...with the implication that they need at least 10% to properly protect from knock/detonation.

Do you live somewhere with E0 as the standard fuel, or why did you previously add corn on the stock tune? Any issues when you datalog without it?
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Old 12-03-2019, 01:00 PM   #7
rtv900
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any OTS tune is for UP TO 10% ethanol

reason is because pretty much every pump in the US has UP TO 10%, not 10%.
So nobody knows

any small amount of ethanol is fine because you can't even tell what you are getting from 0 to 10
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Old 12-03-2019, 01:53 PM   #8
3eyesraver
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Default

Thanks guys for all the replies
Quote:
Originally Posted by noobultimatum View Post
So a little bit of corn wont do damage even when not tuned for it. A LITTLE BIT being the important part.

The only time I used a gallon or 2 of corn in the tank was when my DAM dropped due to some bad gas. It helps pick up the octane.

If you have no issues, I would not do it. If you want the most out of the E content, get a tune for it --- pro-tune flex fuel or a canned e30 tune.
I had issue before with Stock tune and 2 gallon of E85 helped. I haven't had any issue now but still carry the mentality of having some corn in my tank for assurance. I do want to go Cobb Flex Fuel in near future when this gift-getting season is over

Quote:
Originally Posted by WRBloo View Post
I'm on an OTS tune and occasionally throw 2gal of e85 in my tank when i'm near a station that offers it. Seems to help combat knock, but if you're doing it in hopes of gaining noticeable hp on your butt dyno, then you'll probably be disappointed - I can't really tell the difference between pure 91 and the 91/e85 mix.

Phatbotti says:
"The simple answer is to just try it. If you put the ethanol in and the car knocks worse...stop doing it. If the knock decreases and the car feels better, then you're likely fine."

So to answer your question, yes, you can, but to actually reap any power benefits, you should get tuned for it like noobultimatum stated.
Just start monitoring knock for the past week and notice -1, -2, -3 and one time -7 knock (scared the **** out of me - might hit a rock under or something). Running 1.6 Gallon E85 this tank and only twice the -1.41s shows up. I never used AC.

Quote:
Originally Posted by Norskie View Post
Ask Cobb and get a definitive answer.

I'll venture to guess that they've built the tune to handle common fuel blends, which in many places includes a mandatory 10% ethanol.

In my experience, with two exceptions, I've never found any performance differences with running 0-10% ethanol blends in any of my vehicles. Exception #1 is running on MAP's E30 OTS which is just fantastic, and Exception #2 is in carbuerated motors and leaving it for a month (untreated) is likely going to result in difficulties starting and sometimes require a carb cleaning.
Quote:
Originally Posted by gn4rwhals View Post
One to two gallons of E85 is not going to kill you on an OTS map, should get you around E15-E20 ish at most when combined with pump gas.

If you want performance for E85 get a flex fuel tune, or you can try an E30 map from various tuners, but then you have to guess on your blend which is not ideal.
I do want to go full Flex down the road. With Flex Fuel kit and protune, does it mean I can do a full tank of E85 or still have to mix with just higher E85 portion?

Quote:
Originally Posted by scoobydooluth View Post
Pretty sure the map notes explicitly state they're designed for 10% ethanol content...with the implication that they need at least 10% to properly protect from knock/detonation.

Do you live somewhere with E0 as the standard fuel, or why did you previously add corn on the stock tune? Any issues when you datalog without it?
I live in SoCal where E85 is rare but accessible. Lucky enough I live 4 miles from a gas station that offers E. I added corn to my stock tune before to improve drivability. I don't have any data just butt dyno. But seriously, car drove like **** before sometimes until I discovered this holy fuel.

Quote:
Originally Posted by rtv900 View Post
any OTS tune is for UP TO 10% ethanol

reason is because pretty much every pump in the US has UP TO 10%, not 10%.
So nobody knows

any small amount of ethanol is fine because you can't even tell what you are getting from 0 to 10
I definitely will ask Cobb and get to you guys with their answer as I always want to hear what they say.

I had the AP for awhile since I was still on Stock tune but my chicken self didn't want to plug it in so I couldn't monitor knocks. I noticed car drive like **** sometimes especially 3 of this elements change: temperature, elevation, and load. I started to ask around - a friend with a heavily modified fa20dit suggest me to run 3 gallon of E. The most I put in is 2.5 gallon, never 3. I "felt" a significantly improvement where the issue doesn't come back that often. Did that for every 2-3 empty tank for 8k miles. Again, no data log, no number to back it up just the "feel". So I would say I did this not because of +HP but for reliability.

Thank you guys. I will keep put corn in my mix once in a while to combat with knocks until going full Flex mode!
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Old 12-03-2019, 05:26 PM   #9
noobultimatum
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Quote:
Originally Posted by 3eyesraver View Post
Thanks guys for all the replies



I do want to go full Flex down the road. With Flex Fuel kit and protune, does it mean I can do a full tank of E85 or still have to mix with just higher E85 portion?
Flex fuel is a mix/blend of E85 and gasoline (whatever highest available -- 93 or 91)

You would still have to mix BUT the flex fuel sensor would adjust the tune accordingly based on registered E-content.

As far as I know, tuners have found that anything above a max E-content of E-55 or 60 has no additional benefits for the fa20dit motor. Plus, more E means less lubrication for the HPFP. So, you want to find a happy compromise between E and gas... even then, you want to run straight gas occasionally in order to avoid any issues with our HPFP.

My local flex fuel buddies pretty much daily on 93 and then run their desired E-mix for max power potential when they take it to the track or "mexico".
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Old 12-03-2019, 09:58 PM   #10
3eyesraver
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Quote:
Originally Posted by noobultimatum View Post
"mexico".
wH4t M3xIco?

I see. I thought I can get away with swiping my card twice at the gas station for each fuel when I go full Flex
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Old 12-04-2019, 11:58 AM   #11
gn4rwhals
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Just tell them you are filling up with gap sauce, stare right at them to assert dominance.
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Old 12-05-2019, 12:51 PM   #12
3eyesraver
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lmfao. Will do chief
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Old 12-05-2019, 03:37 PM   #13
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FWIW the pump probably already has E10 as the fuel, so putting 3 gal of E85 is putting you closer to E25 than E10. Watch your 1) fuel trims, though those will probably decrease, and 2) watch your AFR, make sure it doesnt get too lean. Ethanol takes more fuel to reach the same stoich, so your AFR will lean out the more ethanol you use because you are scaled for a different fuel. Stick with 1.5 gal, if that doesnt work consider getting a custom E Tune.
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Old 12-05-2019, 03:50 PM   #14
3eyesraver
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Quote:
Originally Posted by GlarryHoodDIT View Post
FWIW the pump probably already has E10 as the fuel, so putting 3 gal of E85 is putting you closer to E25 than E10. Watch your 1) fuel trims, though those will probably decrease, and 2) watch your AFR, make sure it doesnt get too lean. Ethanol takes more fuel to reach the same stoich, so your AFR will lean out the more ethanol you use because you are scaled for a different fuel. Stick with 1.5 gal, if that doesnt work consider getting a custom E Tune.
Appreciated your feedback. I will stick to 1.5 gal.

I was told keeping 14 while driving is good and it is 14.xx most of the time. My max is varies sometimes hit 25 depends on the acel.
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Old 12-05-2019, 05:44 PM   #15
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I assume you're talking about your AFR?

14.7 is what you should be seeing at cruise, that's what your car is targeting at least. Your car operates in Closed Loop Fueling when cruising around and not at WOT, you should always be targeting 14.7 at low load and cruise. That's not what you need to worry about, your car will correct fueling at low load. When you're at WOT is when you need to watch AFRs because you are no longer relying on your O2 sensor because you're operating in Open Loop Fueling. Make sure you aren't running too lean (high 11s to 12s) at WOT with only 1.5-3 gal of E85 or you're winding up getting detonation. Look up open vs closed loop fueling if this sounds too foreign.

You see 22.8 or whatever when you're injectors "turn off" on deceleration. 22.8 is just the highest voltage your O2 sensor reads. In reality it's leaner, but it's not under load so it doesn't matter.
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