cmalk98

A little info to preface this story. 2013 5.0 crew cab with 3.73's Have never run the "flex fuel" aka E85 in my truck until just recently. It was $2.79 a gallon and regular unleaded 87 octane was $3.19 at the time. So, a .40 cent per gallon cheaper. My truck has the 36 gallon tank and I ran it damn near all the way dry. The low gas warning light was on befor I got to the station. I went ahead and filled up the truck all the way with the E85 just to try it out and see if there was any felt difference in power or how the fuel economy would be affected. I did not notice any increase in power with the truck as some other users have stated. Seemed exactly the same to me. Before using the E85 my overall average hovers around 14.5 to 15mpg. I'm almost done running this tank of E85 through the truck and my average is 11.8 mpg. Myself, I don't really see myself running this much unless the cost per gallon is higher that .40 cents due to the decrease in gas mileage. I live in southern Illinois and it has been unusually cold this winter. I just don't get all the hype about it. What are your thoughts on whether it "is worth it" to run E85? I also wanted to add I have a friend who works for IDOT Illinois dept. of transportation who uses almost all ford trucks exclusively and he told me there are multiple trucks in the fleet with engine problems / failures due to E85 as he stated the E85 is worse on engine wear / longevity. Thoughts???

ClaySlayer

I believe in the manual it states to try and never run only E85 BUT if you do to run a tank of E10 or less through it every ~3 tanks or something like that. With that said, ethanol is pretty corrosive so I'm sure high concentrations could jack up some things over the long haul. About every 6 months or so I let it get down to about 1/4 tank and fill up with E85 and beat on the truck for a few days to "clean out the pipes"...not sure if it really does anything or not but it's fun. As far as increased power goes I doubt you notice much in the winter with the already colder/denser air the motor is less likely to need the more knock resistant fuel (Premium Unleaded & E85). The higher the load on the engine (hills, towing, etc) and the hotter the temps the more it shines. I don't think it'll ever be cheap enough compared to regular to make it economical.

SultanGris

It gets about 20% less fuel economy therefor it has to be 20% cheaper to break even. Anything more than 20% produces savings.

camino70

Exactly the info I was looking for. Thanks!

mechanicboy

All true except it isn't the ethanol that's corrosive, it's the fact that it's hygroscopic, meaning it readily absorbs water from the air and that water causes the corrosion (at least this is what I'm told). As a rule of thumb you never let a vehicle with e85 in it sit for more than a week without being driven because of this.

I'm currently running a 50/50 mix in my volvo as a fuel system cleaner and because I was taking it out to race so I wanted some protection.

I'm surprised that the OP didn't notice a power increase even in the cold weather. Perhaps he doesn't have that sensitive of a butt dyno lol. I always found the best results on the second tank of e85 because the first was diluted because the leftover gas which the OP probably was using 87 based on his comparison statement.

This all being said, the fastest trucks currently on this forum run E85 in some fashion. It's really good for performance and safety while flogging the truck because it's resistance to detonation.

It does lower fuel economy overall but in some instances it is better than others. I found that when climbing altitude at high speeds, 75-80 from Houston TX to Midland TX, I would get the same fuel economy maybe even better than on 93. I have a Aeroforce gauge and could see the timing drop below 10 degrees sometimes with 93 but on e85 it never went below 28 except until WOT. Also, the hotter the day the more you will benefit from e85.

Edit: I remembered that you said it's been unusually cold where you are. In colder weather they often reduce the amount of ethanol in e85. E85 means a maximum of 85% ethanol but could legally be as little as 51%. You probably have E70 right now meaning mixing with the fuel you already have in the tank you have less than 70% ethanol in your tank. I use a ethanol tester when I fill up to verify I'm actually getting 85%.

king nothing

Why would you see a power increase from E85? It has less BTUs than gas. This is why you have to inject more of it into the engine (worse fuel mileage) to get the same power. The only advantage E85 has over gas is in boosted or high compression NA applications. Because of the increased octane an engine can run higher cylinder pressures (compression or boost) without fear of detonation. All things being equal, E85 will make less power/gallon

HCFX2013

I will never, ever, ever go near pure E85 with my truck.

SultanGris

That's why it burns more gallons!

king nothing

exactly. And its GREAT for high boost applications

mechanicboy

You answered your own question. Because it can run higher cylinder pressures without fear of detonation. You can run more timing(which creates more cylinder pressure) and when the temperature increase they don't have to pull timing like with gas.

Anyone who has has a carburetor vehicle and turned the distributor a few degrees knows what a few degrees in timing can do for power!

BTW, at 10.5:1 compression, our trucks are high compression.

But makes more power overall.