A few questions for the tuners here. There appears to be a few performance benefits running E85 in an FFV Truck without having special E85 tuning. The FFV F150 with the 5.0 supposedly picked up 15HP and 10TQ just from switching fuels.

If you are running a handheld tuner or Uprev tuning, can you use E85 and get some gains even though the tunes are for gasoline? The handheld tuners and Uprev tuning have never said you can run E85 in an FFV on their tunes. Is this a problem or will the ECU automatically compensate for the E85 even though you are tuned for gasoline? Thanks in advance. Here's a couple of online article notations running E85 in your FFV:


The 5.0 is rated at 360 horsepower (at 5,500 rpm) and 380 pounds-feet of torque (at 4,250 rpm) running on regular unleaded gasoline. It's positioned as the midrange, high-volume engine choice for the F-150, below the more powerful 3.5-liter EcoBoost V-6 (365 hp and 420 pounds-feet of torque) and conventional large-displacement 6.2-liter V-8 (411 hp and 434 pounds-feet of torque).

But the 5.0 is also flex-fuel capable. Flexible-fuel vehicles are designed to run on gasoline or a blend of up to 85 percent ethanol (E85).

Burning E85 fuel boosts 5.0 engine power to 375 hp and 390 pounds-feet of torque, said Mike Harrison, Ford's program manager for V-8 engines.

Ethanol has a higher octane and heat-of-vaporization point than gasoline, meaning it combusts at a higher temperature and with greater force (higher compression) than gasoline, while also having a greater capacity to cool the fuel/air mix in the cylinder before combustion. This inherent efficiency is what enables the 5.0 to produce more power while burning E85 instead of regular unleaded fuel.

There's a trade-off, though. Even though E85 combusts with greater force, it has less energy per gallon than regular unleaded gasoline, so fuel economy is worse when burning E85.


Why is Ethanol a better fuel ?
1. It has a much higher evaporative cooling power than gasoline so the intake air charge in the cylinder is significantly cooler that it is with a comparable mixture of gasoline --- that means higher VE.

2. Its octane as blended in E85 is about 100, its blending octane when added to gasoline is rated at 118, so it is a very cost effective octane booster.

3. Ethanol burns faster than gasoline but has a slightly longer ignition delay during the slow burn phase of combustion so the engine does not do as much negative work fighting rising cylinder pressures due to large ignition advances. The total ignition advance for E85 is almost identical to the ideal advance for gasoline so it does not cause the PCM problems when you mix them.

4. At proper mixture you actually are releasing more energy in the cylinder due to the higher quantity of fuel you can burn. ( Ethanol can burn effeciently at much richer mixtures than gasoline can) That means about a 5% increase in energy release all by itself.

5. Peak combustion pressures are actually lower for ethanol than for gasoline but the cylinder pressures stay higher longer, so you have more (longer) crank angle that is usable by the engine. This lower peak cylinder pressure also helps with detonaton control.

6. Theorethically, the gain is 5% just by switching fuel. 350 hp X 5% = 15 hp,

 

Since it produces less energy the only way it could yield more HP is if the fuel tables sense / adjust to advance ignition timing.

Octane doesn't produce HP either.

 

Flex fuel vehicles have sensors in the fuel tank to detect how much alcohol is in the fuel. In the pcm there is a table for alcohol composition and spark adder. Basically, the more alcohol it sees, the more ignition timing is added leading to higher torque.