Ethanol mix for beginners

Nocturnal LE

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Just learning about tuning and ethanol mixes and had a few questions that I'm having trouble finding the answers to.. Lets say you are at the pump and you're trying to get an e30 or e40 or whatever mix...

Do you always first test the E85 with a test kit to determine ethanol content? Or if you have a Fuel-it sensor do you guestimate, run the car for a few minutes, and re-assess ethanol content with the software? I understand there is no flex fuel available for the Supra yet, so I'm assuming you need to be very precise.

How accurate is the Supra in determining how many gallons of gas are left in the tank? Ie. you have about 1/4 tank of 93 octane and now you are going to an ethanol blend. if I remember correctly Supra Connect just tells you how many miles to empty.

When driving the car, what are some indicators that the ethanol content is off if you don't have a sensor?

Thanks!
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65sohc

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Here is an excellent tool for blending normal gas with e85 to arrive at the desired percentage of ethanol. I used e85 in my GT350 for almost four years. It had a gauge that read out the ethanol content so I didn't need to test it. I used four different stations and the ethanol percentage was always 78-82%. It would be advisable to check it the first time so you know what you're starting with and occasionally thereafter but I certainly don't think it's necessary to check it every time.

https://www.tuneplusinc.com/pages/tuning-tools
 

65sohc

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Also the Supra Connect Phone app tell you how many gallons left, not just range.
 

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There is a flex fuel kit that Twisted Tuning sells and Burger Motorsports has one as well for the MKV. The ethanol gauge would be on an app on your phone.

From what I've gathered for Ethanol blends, it is best to run the car til you hit Reserve on the tank. Next you fill up a certain amount of E85 (use the pump meter to see how much you put in), then fill the rest with pump gas. Here is a chart that I see pop up on forums for various cars for E30 blends. This would obviously need to be adjusted for other blends.

Stratified E30 mixing guide.png
 

65sohc

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The calculator I linked has a number of advantages. You can set it for any ethanol percentage. It also takes into account the concentration of the residual fuel still in your tank. You can ignore the "Select car" option.
 

RichSC

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I'm on an E50 blend with mine currently. Ethanol locally has been kinda shit lately, with most E85 pumps coming in low. I test mine each time I fill up to make sure I get the mixture mostly correct and then just check it on my Fuel It sensor after. Just because the pump says E85 does not necessarily mean that's what it's actually at for ethanol content.

I'll use the tank function under the secret menu to give me an estimate of how much is left in the tank, test the E85 pump and then fill it with 91/E85 accordingly to get my mix.
 

65sohc

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I'm on an E50 blend with mine currently. Ethanol locally has been kinda shit lately, with most E85 pumps coming in low. I test mine each time I fill up to make sure I get the mixture mostly correct and then just check it on my Fuel It sensor after. Just because the pump says E85 does not necessarily mean that's what it's actually at for ethanol content.

I'll use the tank function under the secret menu to give me an estimate of how much is left in the tank, test the E85 pump and then fill it with 91/E85 accordingly to get my mix.
Living in CO it's not surprising they change the blend according to season. Here in central CA it doesn't change. I monitored every tank I got for four years in my flex fuel Shelby with the onboard electronics and it was always 80%.I bought a vial tester last week and confirmed.
 

RichSC

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Living in CO it's not surprising they change the blend according to season. Here in central CA it doesn't change. I monitored every tank I got for four years in my flex fuel Shelby with the onboard electronics and it was always 80%.I bought a vial tester last week and confirmed.
Not so much season dependent, just depends on what they produced and filled the tank with. March when I was still on E30, it was at about 78-80%, then has been around 60% the past month and a half (for the station I normally use). Went to fill up today and tested again, 80%.

We are lucky though in that we have a local facility that blends their own and it’s always right at 85, just a bit of a drive from where I live.
 

65sohc

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I just read something interesting. In California e85 is exempt from the Motor Fuel Tax because it burns cleaner. However it must contain the full 85%. Otherwise it loses its exemption.
 

65sohc

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E50 is easy to calculate. It is pretty much a 51% e85:49% e10 ratio. That's what we have in Calif. So with a typical fillup 5.5 gal. e85 and 5 gal e10 and you're good.
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