[RubyTues]

For my '13, The owners manual recommends a minimum of 87 Octane. But it also says, "Premium fuel will provide improved performance and is recommended for severe duty...." In CA, we have 87, 89 and 91. Price difference is about $.10 / grade. Sometimes, I see notices about 10% ethanol. So far, 800 miles, my motor is stock. mods will likely come later but in the meantime, has anyone really studied any difference using different grades of fuels? If so, what are your thoughts? Is it worth the price difference for the claimed additional performance? Is there really any additional performance?
Thanks in advance for your comments.

 

[superdutylee]

I run 87 most of the time except when I pull my toy hauler then I use 91. I have read where some say they get better mpg with 91 but I didn't see any increase using 91.

 

[joemac]

If there any an difference in performance it will be extremely marginal. I had seen an article claimed a 10HP increase from a Ford representative, but I've never seen this documented anywhere. It's not in the manual after extensively looking for it. There may be some extremely marginal gains with 87 possibly substantiating more knock or detonation versus 89. Nothing to scientifically substantiate this, purely subjective.

The manual does have a recommendation for premium fuel while performing sever duty tasks like towing a trailer.

Here it is straight from the manual:

“Regular” unleaded gasoline with a pump (R+M)/2 octane rating of 87 is recommended. Some stations offer fuels posted as “Regular” with an octane rating below 87, particularly in high altitude areas. Fuels with octane levels below 87 are not recommended. Premium fuel will provide improved performance and is recommended for severe duty usage such as trailer tow.

Improved performance. How much? Anyone's guess, unless Ford has officially published it somewhere that most of us are unaware.

 

[Raiderfan1890]

I only run 91 in my truck. Peace of mind.

 

[Grim Reaper]

Already had this discussion. Nearly as many differing opinioins as whether to use regular oil or synthetic.

It is my OPINION, that excluding some extraoridnary driving condition (high air temperature, lots of hills, heavy loads, wallet too thick, etc); the true benefit from using a higher octane fuel is only realized if you have your truck tuned to take advantage of the higher grade.

But, if you do have your truck tuned to run 91 or 93 octane, the dyno results show a much greater HP increase due to the turbos than a "naturally aspirated" vehicle. I plan to make this one of my first mods (re-tune my PCM) next spring (and if I plan to keep the truck.)

 

[Tax Man]

Concerning octane, I was thinking about running 91 octane pure gas as there are a number of stations selling it here. The problem is it is .50 cents more per gallon than 10% ethanol 87 octane. Even the stations selling 10% 91 octane are getting .30 per gallon more. I'd have to see a lot of improvement to justify that. Wonder if there are any real world numbers available? I might try it this summer-one month on 87 then one month on 91. Both 10% ethanol.

 

[Grim Reaper]

Concerning octane, I was thinking about running 91 octane pure gas as there are a number of stations selling it here. The problem is it is .50 cents more per gallon than 10% ethanol 87 octane. Even the stations selling 10% 91 octane are getting .30 per gallon more. I'd have to see a lot of improvement to justify that. Wonder if there are any real world numbers available? I might try it this summer-one month on 87 then one month on 91. Both 10% ethanol.

Hmmm, runs some actual dyno runs and post the results. You should also be able to deduct it from your taxes as both a "Business deduction" and "Repair & Maintenance". Or, is this truck strictly for "Personal Use Only"?

 

[Nasty Wendy]

You actually lose hp and tq when you use higher than needed octane fuel. It is the equivalent of retarding your timing and if done when not needed you leave hp/tq on the table. The higher the octane number - the slower the fuel burns, this is why diesel can run such high compression/boost, it burns really slowly making it ultra hard to auto-ignite aka knock or ping. Your computer has a target for ignition timing. That target does not change based on the fuel you use. You must use the fuel that allows the cpu to run the truck at that target. So if 87 will get the job done but you put 93 in then you lose power because the cpu will not advance the timing beyond its target to take advantage of the extra octane you have.....you just retarded your timing by the difference of the fuel burn between 87 and 93 octane....however much you thought that it would help it actually hurt. Now when your use of the truck puts it in situations that the engine load is higher than 87 can support at the target timing then you need to up the fuel octane so that the computer doesn't have to pull timing to run without 'knocking/pinging'. When tuners increase timing and or boost they dictate the need for higher octane fuel and you should use it. On a stock truck run 87 whenever possible and save the money on the premium fuel until you need it for towing ... heavier loads ... uphill ... into the wind ... in stop and go traffic ...

 

[RubyTues]

Agree and disagree. Generally, I do not think you will get much more performance, other factors being equal. It is not, however, that one fuel burns faster or slower than another. The octane rating has to do with how fast the fuel ignites after the spark. (Higher octane allows more spark advance). I don't know but think the ecm should be able to adjust the timing for the higher octane. That's what it's for, after all.

So, has anyone run a couple of tanks with 87 octane and then a couple of tanks with 91 octane? If so, did you feel any difference? Did you measure the fuel economy?

 

[joemac]

While higher octane fuel does burn slower than a comparative lower octane fuel. As a driver, it would be extremely difficult to note any difference between the two. Even in a perfectly configured scientific evaluation the difference in HP and TQ by the burn speed of the fuel alone would be hard to even assess. I've yet to come across any reference material that performs this test. Doesn't mean it doesn't exist, or doesn't have warrant, just not something most of us have ever come across and produced as factual reference. Reference might be a PCM log of a run 35% throttle from a stop through 5th gear. One with 87 octane, one with 93 octane, capture timing metrics, knock counts, and measure torque, and calculate HP.

There's a significant trade off if the octane requirement of the engine is demanded and not available versus running higher than needed octane without the engine demanding that level of octane at that period of time.

The difference being the first scenario is possible to produce detonation with potential catastrophic effect to the engine, the other scenario with more octane than demanded, the engine just runs without any concerns of detonation catastrophe.

Ford has some reason for recommending premium in sever duty situations, but offers no guidance for using premium fuel when not demanded by the engine. The safe play seems to be sufficient octane for the job and conditions.

 

[joemac]

So, has anyone run a couple of tanks with 87 octane and then a couple of tanks with 91 octane? If so, did you feel any difference? Did you measure the fuel economy?

Doing it this way, there's simply not a reasonable way to eliminate all the other variables that are in play to corroborate something scientifically about higher octane being a measurable and quantifiable detriment to performance.

In general one wants sufficient octane for the scenario and situation that will be demanded from the engine. Running more octane than demanded, the only thing is certain is one wallet will be lighter.

This is why race gas is offered in multiple octane levels. Running methanol has an octane and cooler combustion benefit. It all has to work in concert with the intended application.

 

[Nasty Wendy]

Without getting into the technicalities you can think of your choice of octane as you would think of focusing a camera lens. Perfect focus makes for the nice picture, that's your target octane. If you run higher or lower octane then your picture will be out of focus. You don't continue turning the focus ring on the lens after you've achieved focus because then you are back out of focus and running more octane than needed ruins your 'focus'. Is that enough focus for you? It works on F150s too. Some cameras have auto focus where the camera's cpu makes the necessary adjustments to maintain focus. This is what the vehicle's ecm is doing when it pulls timing from its target value. It focusing the picture for you. What it cannot do though is back the camera away from a subject that is to close to focus on, the photographer has to do that. That is the same as not using TO MUCH octane. The vehicle's cpu cannot adjust for more than needed octane, you have to that with your choice of fuels whether its your Focus, Ferrari, or F150.

Actually I'm not familiar with Ferrari's cpu it maybe more advanced.

 

[NewEcoBeast]

There seems to be a wealth of misinformation here. Octane does not equate to a faster burning fuel. Octane rating is a fuels ability to resist detonation. Detonation, paraphrased, is when your fuel goes BOOM by itself before it should. It may do this because as you compress the fuel/air mix the temp goes up dramatically. Think of the crank spinning and your rod coming around to it's apex where instead of being pushed by the crank the rod is now pushing back on crank. If the fuel goes boom before you reach this apex then you have a shock wave pushing down while the piston is still coming up. There is a magic point in the cycle where you want the fuel to combust(20 degrees ATDC) and this is what your timing controls. I don't know much about the PCM in the F150, but I suspect that it constantly adjusts timing to find the "optimal" timing by utilizing knock sensors for efficiency reasons. This means that if, because of severe duty(high heat, heavy load, ect), your engine could use the extra octane rating to get to that magic point then the engine would perform better on the higher octane; however, during normal applications 87 and 91 octane will perform the same because both fuels contain the same amount of energy and both fuels reach that efficient point in your engines cycle.

Here are some articles to back up my statements:
RK Tek 2-Stroke Heads: Exposing the Myths of High Octane
Sunoco Race Fuels | Beyond Octane
Whitfield Oil Company Flame Speed, Octane Number & Horsepower
What If Dyno.com - Combustion Dynamics for Poor Man's Dyno Low Budget Engine Test Stand for testing of HHO, ION, Water Vapor
Racing Gasoline Comparisons

Google has many more hits.

 

[NewEcoBeast]

Forgive the crude explanation. It's 345 in the morning over here in Europe and I just got done passing out guns for the oncoming watches. Time for me to go back to bed.

 

[scap99]

Forgive the crude explanation. It's 345 in the morning over here in Europe and I just got done passing out guns for the oncoming watches. Time for me to go back to bed.

Hope it's a quiet evening...

 

[Tax Man]

I do take a deduction for business use of my vehicle, and I'm sure I could find a category for this expense.

 

[MajorPain]

Ethanol is the biggest enemy in today's gas that goes into our trucks.

I have read so many discussions on this topic across multiple web sites that I think I have now become an internet expert too....lol. It's my understanding that the ecoboost is unlike any engine setup that most of us are used to. It has more than one map programed within and with it's multiple sensors, etc. it will advance timing to the octane level. From the guys who have already beat this to death, the biggest change is in using 91 octane pure gas. Do a Google search and you'll see this talked heavily across a few F150 sites.

 

[Nasty Wendy]

The octane rating of gasoline is a gauge of how easily the fuel will auto ignite (auto ignite = detonate = ping = knock). The lower the number the more easily the fuel auto ignites. As the octane goes up it raises the fuel's resistance to auto ignition but it also increases the time it takes it to reach combustion from intentional ignition. This is what I mean by 'slower burning'. The higher octane gasoline will take more time to ignite than lower octane gasoline. You won't be able to time how much longer an ounce of 93 octane burns vs an ounce of 87 octane. That is not the 'slower burn' I mean. It simply is slower to ignite under the same conditions. Slower in this context means fractionally slower. If you look at the application of higher octane to eliminate detonation you need to see the big picture of whats happening and how small/fast it is. At 2400 rpm each piston is making 20 power strokes per second. That means the spark plug is firing every 5 hundreths (.05) of a second. At 4800 rpm each plug is firing twice as fast (.025). The difference in the time it takes regular vs premium to ignite is micro seconds. There is no time for anything that will take any longer. This difference is enough to keep combustion at the proper event timing. This difference is enough that the fuel can withstand more volatile conditions such as higher compression/higher heat without auto igniting.

I worked as a lab technician at a refinery for 13 years until health issues forced me out. I have experience and knowledge from the battlefield of the refinery laboratory. Strangely enough however I think I may have learned more about the practical application of over doing octane while racing my Grand National. I would go to the track and put C116 race fuel in the car and run it. I always wondered why my car wouldn't run as fast as other folks who had nearly the same combo as I did. In a conversation with an 'Old Pro' I mentioned that I thought some guys weren't being honest with either what their cars ran or what their combos were. He confirmed that their combos could produce the timeslips they were claiming. I asked him why in the hell is my car not doing it. We went over everything and when I told him I run C116 he said 'THATS YOUR PROBLEM'. According to him I didn't need anything more than 104 octane and possibly only 100 octane to make my runs at my boost/timing levels. Next time I went to the track I put in 104 instead of 116 and the car freakin' flew!!! I got brave and used 100 octane on a following trip and the car loved it. As I lowered my octane towards what the car NEEDED it ran faster and stronger. This is first hand experience.

Take what you want from this. Do what you want with it. I'm only telling you what I know to be true from my job, training, and real world application.

'Premium' = micro seconds between ignition and combusiton

 

[joemac]

And this can go and go on to the depths of the internet and way off the intended subject matter of the OP. Lots of reference to race gas and details by those in and around the racing or performance oriented applications. This is certainly context, but falls short of scientific evaluation of the pump gas formulation that's the focal point.

Detonation is the precognition of fuel before the spark event in the cylinder. It doesn't boom by itself. The heat in the cylinder is the source of pre-ignition event of the fuel by either not enough fuel causing a lean condition and driving up cylinder temperature or insufficient fuel octane. I digress.

If someone can scientifically substantiate higher octane can be scientifically proven to decrease the performance of the EB post the reference material here.

I like others here have experience with race fuels from performance vehicles I've owned. This doesn't make me an expert.

The OP inquired if anyone had studied the differences using different grades of fuels? The answer at this point is no.

The OP inquired about thoughts and opinions. Lots of that here to read there.

The OP also inquired about evaluation of the price difference relative to the claimed additional performance and if there was really any additional performance. Ford has specific addressed or not addressed this in the manual.

 

[Nasty Wendy]

And this can go and go on to the depths of the internet

I agree.