87 to 93 octane

[Snakebitten]

I don't understand how advancing spark increases compression.

Where's the tutorial?
?
Sorry, couldn't resist.

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[powerboatr]

i can say this about 92 non ethanol fuel
on my 2013 eco boost i used it almost 80% of the time and purchased said fuel at a station that catered to marine engines so they had 92 non ethanol, up until 2018.
if ran 87 for a few tanks, the seat of pants and mpg changed
when i went back to 92 the get up and go and mpg changed for the positive. not enough imo to warrant the extra cost....but engine felt smoother and had pwr imo at a smoother more responsive manner, this was 1st gen eco and no sport mode and had 6 spd with 3.55 gears 4x4
my 2016 exp was 4x4 6 spd and 3.73 gears, i could run 87 and it ran very well, if i ran a few tanks of 92 non ethanol it smoothed out and managed a few degrees better of mpg as in maybe 1 mpg,
pulling a heavy trailer it seemed to like the 92 over 87 . it had more ommph and downshifted less on highway at 65 mph pulling 8k lbs flat bed trailer.

the 2013 never liked pulling anything over 3500 lbs, not sure why, it would always seem like it was being held back, even with the flat bed. it also had a new intercooler from ford and 6 new coil packs early in its life because it would kick and buck at 65 pulling a trailer.

the 2022 with 10 spds and 3.31gear and 4x4, imo is so different from the other two. locking out 9 and 10 when towing heavy , it responds with great mpg vs load. it does seem to notice 92 within 2 tanks full, but not nearly as much as the other two vehicles did
for me now, in my area 92 non ethanol is a ghost. no body has it so i run 89 in the edge and the 2022 and they both seem to like it.

if i was going on a long heavy pull trip, i would opt for 92 just as a precaution to help engine under the intense heat and load .

my boat loved 92 and avgas...it was a total new animal with 110 low lead

 

[diambo4life]

I don't understand how advancing spark increases compression.

Where's the tutorial?
?
Sorry, couldn't resist.

It's people who don't know wtf they are talking about.

 

[Snakebitten]

If you monitor the fuel related Pids, it's really really easy to see how the engine management on the 3.5 Ecoboost responds to octane.

Watch KR (knock sensor data)
Watch Spark Advance
Watch OAR (octane adjust ratio)

While it's true that the co$t of 93 might not be worth it if you are viewing it solely as economics.
But I just enjoy the warm and fuzzy of knowing that the combustion chamber is enjoying the meal.

 

[Calson]

My Mercedes CLK had a high compression engine and I got the best fuel economy with 93 octane gas. Going to 87 or 89 octane gas saved me 10-20 cents per gallon at the pumps but the engine would have the spark retarded to prevent knock and so my fuel economy fell by 10%.

With my vehicles with engines with lower compression ratios there is no gain with higher octane gas. Octane only refers to pre-ignition resistance and not to the btu value of the fuel.

High compression engines or engines that have a lot of carbon buildup in the head and valves may benefit from high octane gas that is less prone to pre-ignition than regular gas. Some engines are much more prone to carbon buildup around the valves and this is a known issue with certain older engine designs.

I can increase the fuel economy of any car or truck by driving more prudently and avoiding fast acceleration and driving at the speed limit as much as possible. I may need to leave the house 5-10 minutes sooner but that is a minor adjustment to make.

 

[Tmaffetone50]

exactly like said above. The 93 octane makes more power per stroke due to how Ford set these trucks up. More power means that for a lot of your time driving you may use less throttle than with 87, which in the end uses less fuel and gives you higher range. Is it worth the extra cost? That’s up to you. I only run 93 octane and couldn’t care less about the extra few dollars per tank!

Do you have a 5.0?

 

[Calson]

The engine computer does detect pre-ignition and alters the timing as a result. With my coupe that had a higher compression engine if i used 89 instead of 93 octane gas the spark was retarded and my fuel economy would decrease.

The computer "knew" that the 89 octane fuel was being burned. No reason not to expect the computer to sense that a higher octane fuel as being burned and to adjust the projected mpg and the distance until empty.

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