BS - Point me to the part number for the sensor that checks octane levels.

The ECU does a knock check. If there is no detonation it's not going to pull timing. It's called a knock sensor.

Higher octane = no gain.

The only thing that will provide more power would be to add boost.

 

Right around 600 miles on the truck currently...from what I have read, it will improve over time, but I'm not holding my breath. I didn't buy this truck for mileage, it was a big improvement over my '10 Lariat with the 5.4 as far as power and towing capability goes, so I am happy.


I need to get the computer reflashed for larger tires so I don't have to constantly do the math in my head for speed and MPG, but it isn't that big of a deal. As for the mileage vs the 6.2, they are similar...but the 6.2 doesn't pull near as hard, so I'm very happy with the ecoboost in that department. My brother has an '11 Limited with the 6.2, and he is getting 12-13 mpg...and when we race, I can pull 2-3 lengths on him from a stop and hold it until the speed limiter kills it.

 

You're right, there isnt a sensor that specifically checks the octane rating of the fuel, but rather a detonation sensor. The F150 EcoBoost has twin independently variable camshaft timing and direct injection, which allows for very precise adjustments to optimize combustion. As you said, higher octane means slower burn time. Slower burn time means more controlled detonation, and that is the point, really. When the air intake, fuel delivery, detonation, and exhaust are all optimized and timed right, you get the highest power, thus, the highest efficiency. A lower octane fuel, such as 85 or below, may detonate before the intake valves are completely closed or before the piston has reached the top, resulting in less efficient combustion, which would yield less power.


If that didn't convince you, then maybe Ford engineers will. Here is a statement right out of the manual:

3.5L V6 EcoBoost™ engine
Your vehicle is designed to run on regular fuel with an octane rating of
87 or higher. For best overall performance, premium fuel with an octane rating of 91 or higher is recommended. The performance gained by using premium fuel will be most noticeable in hot weather or in severe duty applications such as towing a trailer.

 

I didn't say there was a sensor to check for octane levels, I said it is tuned to check for octane levels. Yes, it is most likely done with a knock sensor. My guess is that the PCM can determine the octane rating pretty closely based on the knock sensor(s), but for all I know, there may be a way to measure octane dynamically.

The same concept allowed the '09-'10 models to get an extra 10HP and 25 lb-ft of torque on E85.

Now, if you would kindly remove your foot from your mouth so that you can eat your crow, it would be greatly appreciated. Thank you!

 

As I said in my first post.

IF THERE IS NO DETONATION WITH 87 THERE WILL BE NO GAIN FROM ANY HIGHER OCTANE.

Meaning if the engine is running with full timing and not pulling any.... NO GAINS.

And to the manual comments...

"The performance gained by using premium fuel will be most noticeable in hot weather or in severe duty applications such as towing a trailer."

Meaning that it might pull timing while HOT or Towing running 87 octane. Key word being MIGHT. Not normal every day driving.

You guys are kidding yourself if you think you're going to gain anything from higher than 87 octane.

 

Hence the experiment...if there is no difference in fuel economy, i'm out 7-8 bucks, if there is, cool. I suspect some gains since it is already hitting 100 degrees here in south texas.

The manual says most noticeable in hot weather and towing...that doesnt mean that in normal driving conditions there wont be any performance increase, it means that they will simply be less noticeable. Your arguement is fallacious by denying the antecedent.

 

Believe what you want. I've tuned plenty of cars/trucks/bikes with turbos and superchargers and know all about how to make HP. I can tell you without a doubt adding higher octane to a factory stock tune isn't going to do anything but burn a hole in your pocket.

If you want to prove me wrong take it to the dyno and show me the difference.

 

Could it be possible that the ecoboost is tuned for 91 octane, and the PCM is "pulling timing" to allow the 87 octane?

 

8 bucks a tank aint going to burn a hole in my pocket

And, Expy03 makes a good point, it is possible that the the engine is tuned for 91 octane and is being timed back.

 

Took me a bit, but I found the link. The Ford Engineer stated that the new 6.2 will see a power improvement with the use of higher octane. So if the 6.2 has the ability, then it makes since why the ecoboost would also.

http://www.ford-trucks.com/forums/92...ml#post8833938

 

@ 460 ft lbs/TQ on premium, or so the story goes from a Ford source...

 

For what it's worth, the 2011 Mustang sales pamphlet mentions that fuel mileage ratings were calculated using 91 octane fuel. My son is running 87 octane Conoco in his '11 3.7L V6 and has a best of 35 mpg highway with cruise set at 70 mph. That's above the 31 mpg it's rated at.

I run 93 octane Shell in the summer month's in my '94 Gen. 1 Lightning and 89 octane in the winter month's. It will pre detonate if I run 87 octane. It is mostly stock with timing set at factory spec's.

 

Have you written software for a 32-bit processor that calculates optimal spark timing every 5 milliseconds? Every engine today uses the knock sensor to determine under the current conditions (temp, humidity, altitude).

Fact: Higher octane means the park can be advanced more which provides more power.

If you don't need the power, then you gain efficiency by using a lower percentage of available power.

That said, 500 or 1000 miles is too low to learn much as the this engine processor (and trans too) are fine tuning the fuel and spark maps as the engine mechanical parts break in. It seems to take about 5k miles for today's engines to get to optimal power and fuel economy.

 

I will believe Ford over you, as I would guess they know their engines better than a shadetree tuner. How many '11 F150's have you tuned to know all of this about them again?

The point is, the new factory tunes from Ford are optimized to take advantage of higher octane fuel if it is present. If it is not present, it will run fine on '87, just with less power, and potentially less fuel economy.

 

YA