Is flex fuel also E85?

[Brent Davis]

51% to 83% Ethanol. Its flex fuel because it could be anywhere in between this range. Pumps labeled E85 vary as well. Best to have a flex fuel tune or you need to test and modify the tune for the correct %.

So smokin, do you think it is safe to say that it is E85? I say this because even the Sheetz store manager keeps telling me that it is E85 even though there's no markings saying that it is E85.

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[wireeater]

Yes it's Flexfuel. If you look at the actual picture above the price, it will say E85 on it. All I run in mine is Sheetz E85 (N/A). That sticker is more of a disclaimer so they are not busted for false advertisement but it shouldn't matter if you are running a flex tune. Anything in the 50+ range is fine. Even some turners say the benefits are negligible after E50. The only time you would want to worry about that E85 is if you are running a strict E85 only tune. You would want to test it on fill ups to determine how much ethanol content is has. Winter time is typically when you will get the least amount of ethanol content because they make winter blends.

 

[smokinzx14r]

So smokin, do you think it is safe to say that it is E85? I say this because even the Sheetz store manager keeps telling me that it is E85 even though there's no markings saying that it is E85.

Never heard of Sheetz before so I looked up the website , they do say it is E85 .. We use Thornton's E85 down here and it does test at E84 to E85 .. So I think you will be just fine but if you have any worries get a tester from Quick Fuel , summit sells them as well as Jegs .. Here is one on Ebay > http://www.ebay.com/itm/QUICK-FUEL-...m2ea6a91f51:m:mjZFyrSpn8woTI6LpN_0eGw&vxp=mtr

 

[phunk]

Flex Fuel is the term used to describe a vehicle equipped with an Ethanol content sensor and a Flex Fuel specific "tune" that allows it to automatically, and immediately, adjust for any blend ratio of gasoline and ethanol.

E85 is a blend of fuel intended for Flex Fuel vehicles. If its true E85, it will contain 85% Ethanol and 15% gasoline.

Most gasoline has at least some Ethanol in it, up to 10% or so. Modern vehicles fuel systems are constructed from materials that are Ethanol compatible due to this, and they equipped with a "tune" that will run as you expect with blends of 0-10% or so Ethanol, and probably even quite a bit of headroom in newer cars with factory wideband O2 sensors.

You can run E85 in a non Flex Fuel vehicle, but this means you must make the appropriate changes to the fuel system to handle the extra volume of fuel required to run E85, and you must inform your tuner so that they properly calibrate your ECU. This will work perfectly and your car will be considered as converted to run E85 while on this tune, but since it is not Flex Fuel, you should ONLY run E85 for as long as this tune is installed to your computer.

Many people will build-up their fuel system for E85, and ask their tuner to send them both an E85 tune and a 93 octane (or 91) tune and then they can just manually switch between the tunes rather than adding Flex Fuel capabilities to the car. Adding Flex Fuel means adding a sensor to the fuel stream, and the ECU running the engine must support Flex Fuel and be calibrated for it.

What is most usually marketed as E85 fuel, is in fact not true E85. This, I suspect, is why your local gas station is advertising it as "Flex Fuel" rather than E85. Because 90% of stations selling E85 are not being accurate by calling it E85 unless it is truly and precisely 85% Ethanol. Most stations are selling blends anywhere between 55-90% Ethanol, and it can vary often even at the same pump. They can do this because this fuel is *intended* for Flex Fuel vehicles that can adapt to any blend.

The precise mixture of Ethanol rarely matters to their customers, because their cars will run on any blend of it anyway as they are Flex Fuel equipped. But for those of us who convert our cars to run high percentages of Ethanol, we usually dont add Flex Fuel capabilities, so we prefer the fuel we pump into our tank to be very closely matched in Ethanol content to the blend that we used when tuning the car.

Some people will add a content sensor or get the testing kits so that they can make sure the blend is close enough to whatever blend they tuned for.

Now what I will say here, many will disagree with. But I have owned high compression boosted engines on "E85" for the last 6 years straight and my opinion is based on my own experience and that only. And here it comes, take this part with a grain of salt cause your tuner will say im an idiot (listen to him, not me. i tune one of my cars myself, but not my mustang)..... Its just not that sensitive of a matter. Around here, E85 pumps are usually dispensing about E75 or so. Tuning with this, I am then happy to get within 10% of that when I fill up, so E65-E85 whatever, ive never seen it measurably effect my car. I watch my knock, timing, and A/F in my cars and never seen it act up after a refill. By not tuning the engine to the brink of knock, it will have some tolerance. Not to mention, both my cars (Mustang and Z) have advanced knock feedback and wideband O2 feedback.. they will be OK if the percentage fluctuates a little.

This might be a geographical thing, but here in Chicago area, true E85 is not very common at the pumps. I recommend people here to tune at E75 or E80 tops, to give them margin in both directions for what they will find at the pump. After all, if you want to get an exact percent in your tank, its very easy to just top off a little gasoline and bring the blend DOWN to what you are tuned for. But if you need to raise the E content, well, thats a bitch.

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