How I Discovered My E50 Mix Was Actually E35, and the Risk I Didn’t Know I Was Taking

[mike@x-ph.com]

I’ve always believed that a flex fuel kit isn’t necessary when running OTS maps if you’re not concerned about the additional features. OTS maps are conservative enough that even if your ethanol mix isn’t perfectly accurate, you’ll still be fine since they’re designed to safely handle slightly lower octane levels.

While data logging on OTS maps isn’t mandatory because of their safety margins, it’s always recommended to do it at least once. The challenge with data logging is that it only captures how the car performs at that moment. If your ethanol mix changes down the line (the gas station’s mix varies), you won’t know unless you keep data logging regularly.

For example, I was running the Bootmod3 E50 map, and based on calculations, I filled my empty tank with 7 gallons of E85 and 6 gallons of 91, expecting the mix to be E50. Here’s the math:
(0.85 × 7) + (0.1 × 6) = 6.55 / 13 = ~E50

Yesterday, I installed the PTF flex fuel kit on my car and was surprised that the ethanol mix wasn’t even close to E50, but around E35. The “E85” from my gas station was closer to E50 than E85.

This means I had been running a more aggressive map than my fuel could support. As a result, I was likely losing power due to timing drops and, more importantly, risking serious engine damage.

Fortunately, nothing catastrophic happened, but this experience has made me a firm believer that anyone running E85 with any map should install a flex fuel kit, even when running OTS maps. It’s the best way to ensure your ethanol mix is correct, make max power and avoid damages.

Side Note: i also flashed my car with Bend Calibration flex fuel map, and its very impressive. i will have seperate threads in the future discussing Bend and the PTF flex fuel kit, but wanted to give you guys heads up on this experience.

[b_w.]

Have been pushing for an ethanol pump at one of my local tracks and the fuel supplier is reluctant for this very reason. An e sensor kit takes a lot of the risk out.

[Jaizero]

Originally Posted by mike@x-ph.com

I’ve always believed that a flex fuel kit isn’t necessary when running OTS maps if you’re not concerned about the additional features. OTS maps are conservative enough that even if your ethanol mix isn’t perfectly accurate, you’ll still be fine since they’re designed to safely handle slightly lower octane levels.

While data logging on OTS maps isn’t mandatory because of their safety margins, it’s always recommended to do it at least once. The challenge with data logging is that it only captures how the car performs at that moment. If your ethanol mix changes down the line (the gas station’s mix varies), you won’t know unless you keep data logging regularly.

For example, I was running the Bootmod3 E50 map, and based on calculations, I filled my empty tank with 7 gallons of E85 and 6 gallons of 91, expecting the mix to be E50. Here’s the math:
(0.85 × 7) + (0.1 × 6) = 6.55 / 13 = ~E50

Yesterday, I installed the PTF flex fuel kit on my car and was surprised that the ethanol mix wasn’t even close to E50, but around E35. The “E85” from my gas station was closer to E50 than E85.

This means I had been running a more aggressive map than my fuel could support. As a result, I was likely losing power due to timing drops and, more importantly, risking serious engine damage.

Fortunately, nothing catastrophic happened, but this experience has made me a firm believer that anyone running E85 with any map should install a flex fuel kit, even when running OTS maps. It’s the best way to ensure your ethanol mix is correct, make max power and avoid damages.

Side Note: i also flashed my car with Bend Calibration flex fuel map, and its very impressive. i will have seperate threads in the future discussing Bend and the PTF flex fuel kit, but wanted to give you guys heads up on this experience.

Yup lol

The E85 at my local station is E65 tested with one of those test tube things from Amazon.

Check out the app "Ethanol Mix Calculator" on the Google Play store. you can input the ethanol content of your mixes, along with remaining fuel in the tank, to calculate how much 91/E you need to keep running the same blend.

[rudebwoi]

Originally Posted by Jaizero

Yup lol

The E85 at my local station is E65 tested with one of those test tube things from Amazon.

Check out the app "Ethanol Mix Calculator" on the Google Play store. you can input the ethanol content of your mixes, along with remaining fuel in the tank, to calculate how much 91/E you need to keep running the same blend.

Calculation won't matter if the station isn't giving full e85. Sensor is the way to go.

[mike@x-ph.com]

Originally Posted by rudebwoi

Calculation won't matter if the station isn't giving full e85. Sensor is the way to go.

+1

but instead of sensor, i recommend the flex fuel kit so it does not only tell you the mix but also adjust your map automatically

[Jaizero]

Originally Posted by rudebwoi

Calculation won't matter if the station isn't giving full e85. Sensor is the way to go.

No shit.

The calculation helps you put the same mix in every time, regardless of fuel quantity left at fillup, without having to guess.

[Jaizero]

Originally Posted by mike@x-ph.com

+1

but instead of sensor, i recommend the flex fuel kit so it does not only tell you the mix but also adjust your map automatically

I like to make sure I have the same mix in every single time regardless of fuel quantity left in the tank, that's what the app does.

Not sure why people are thinking I'm saying don't go with the flex fuel kit, I have one myself lol.

[kamilbaran]

it’s surprising to me that some people still think pump e85 is 100% e85 especially in the winter months. Most of the pumps usually are e50-85 and during the cold months they will be around e55-65. Even during the summer months most of these pumps never reach e85 but usually e75-80. personally i use X85 from vp racing and i know im putting the best quality ethanol I can. No more trying to see what % the pump has or risking it for some possibly bad gas. To each their own but most of these pumps rarely are a set e85

[Jaizero]

Originally Posted by kamilbaran

it’s surprising to me that some people still think pump e85 is 100% e85 especially in the winter months. Most of the pumps usually are e50-85 and during the cold months they will be around e55-65. Even during the summer months most of these pumps never reach e85 but usually e75-80. personally i use X85 from vp racing and i know im putting the best quality ethanol I can. No more trying to see what % the pump has or risking it for some possibly bad gas. To each their own but most of these pumps rarely are a set e85

X85 is $11.00 a gallon lol.

Absurd.

[kamilbaran]

Originally Posted by Jaizero

X85 is $11.00 a gallon lol.

Absurd.

Not wrong, bulk it’s slightly cheaper but regardless i don’t drive my f80 enough miles to really feel the dent in my pocket even with it burning a fair bit during pulls. In my area in general we struggle with anything better than e70 in the pumps and i’m set up for straight e 85

[mike@x-ph.com]

Originally Posted by kamilbaran

it’s surprising to me that some people still think pump e85 is 100% e85 especially in the winter months. Most of the pumps usually are e50-85 and during the cold months they will be around e55-65. Even during the summer months most of these pumps never reach e85 but usually e75-80. personally i use X85 from vp racing and i know im putting the best quality ethanol I can. No more trying to see what % the pump has or risking it for some possibly bad gas. To each their own but most of these pumps rarely are a set e85

I would not have been surprised if it was E75, or even E70 but I'm surprised its this low and still being advertised as E85

to get my E55 mix, I'm filling up with 100% E85 without any mixing, that's just ridiculous LOL

[kamilbaran]

Originally Posted by mike@x-ph.com

I would not have been surprised if it was E75, or even E70 but I'm surprised its this low and still being advertised as E85

to get my E55 mix, I'm filling up with 100% E85 without any mixing, that's just ridiculous LOL

Yeah i know your struggle. I don’t even wanna put the effort in testing all the pumps locally to me because i know it will never be what I want. I don’t get it either it’s truly annoying to find a straight e85 pump in some areas, even though it is technically a better alternative to regular gas.

[mike@x-ph.com]

Originally Posted by kamilbaran

Yeah i know your struggle. I don’t even wanna put the effort in testing all the pumps locally to me because i know it will never be what I want. I don’t get it either it’s truly annoying to find a straight e85 pump in some areas, even though it is technically a better alternative to regular gas.

i wonder why they dont keep the same mix all year long.

they sell 87,89 and 91 octane here and they charge you more money for 2 more octane, but somehow E55 and E85 is the same cost and you dont even know what you are getting