He was discussing his 2.7 F150
which only comes in an Ecoboost.

 

The 'ideal' fuel is that which provides you with the performance you need at any given time. When I'm towing, I need 93 because it lets me extract 100% of the engine's available power, and it runs cooler than when I run lower octane fuel. When I'm not towing, I'm not calling on the engine to produce more than 50% of it's power, so it's not generating a lot of heat via boost. Under those conditions, I need the 3¢ per mile I save with 87.

'Ideal' isn't just an indicator of horsepower, it's an indicator of most favorable conditions. If the engines suffered major mileage loss, delivered power poorly, or developed NVH issues, using 87 wouldn't be ideal, but... they purr along just fine on 87 if you treat them like they are 3.5l engines designed to run on 87 (which can't generate 420 or 480lb-ft). They do it well, and only lose a bit of mileage to the Ti-VCT's because they are always spinning the turbo. 87 is the ideal fuel for some driving conditions, 93 is the ideal fuel some other driving conditions.

 

93 gas definitely impacts the characteristics of my engine and gearing compared to 87/88 gas on my 2.7L ecoboost.

My observation is I ran roughly ~0.75 - 1 gear lower on my 10r80 transmission on the highway towing my ~6500 lbs tt using 88 octane gas compared to 93. I say 88 because my tank still had some 93 in it and then I filled it up with 87. To elaborate on what I did, I often drive at 65 mph on interstate 75 in TN between Chattanooga and Knoxville using 93. In this config tow/haul mode typically selects 9th gear for all driving conditions up to light inclines and 7th/8th gear for the more significant rolling hill climbs. My one trial with 88 octane caused tow/haul mode to stick me in 8th gear most of the time with more frequent use of 6th gear to maintain speed on some hill climbs. What was interesting to me is when exiting a hill climb and driving level or downhill the computer still selected 8th unless I accelerated to 67-68 mph temporarily where it would enter 9th, then I could back off to 65 where it stayed in 9th.

One more anecdote. Another time I did this route towing with 93 and forgot to enable tow/haul mode for a good 20 minutes after a rest stop and I didn't notice it. When I finally did I saw I was in 10th gear going 65 mph which is around 1800 rpms. All this with a 24 foot travel trailer being pulled behind me. I am quite impressed with what the 2.7 can do.

 

Currently on the road now pulling 6500lb trailer and running 87 octane. Don't need the added expense of 93 to gain ONLY 50 HP. Never floor it so the engine has ample power with 87.

 

You have that option.

 

Good to know, but since it wasn't mentioned, I wasn't aware of it. Either way: what I posted is still correct, whether it applies to his truck or not. Yes, high-compression engines are usually built for & benefit from high-octane fuel.

 

So the information you posted is still correct if it’s an engine that can’t take advantage.

Appreciate the posted information.