I picked up my repaired F150 and returned the rented F250 today. Anticipating this I have been trying to figure out how to quantify the perceived power of the two engines. More specifically, the feeling that when you are pulling onto a highway from a stop with traffic approaching at 100ft/sec and stomp the go pedal the diesel has to think about it for a second or two while the EcoBoost seems to have a much shorter delay. I had been noticing that when pressed the diesel seemed to pull harder in 2nd gear than it did in first. One interesting bit of information was that I could not get the diesel to spin its tires on asphalt while I have to really work at not spinning tires with the EcoBoost. The diesel does pull very strongly from 2nd gear on but by then the anxiety of getting hit by oncoming traffic has diminished quite a bit. Passing power felt very impressive but that is not something that I do a lot on the roads around here. The data in the charts may shed some light on that when I get the tests completed.
The first element in analyzing this was to choose a suitable place to run acceleration tests without being dangerous or grossly breaking the law. I found one near my house in the form of a low traffic highway with straight section about 1/2 a mile long and a steady 3.5% grade to keep top speeds within reason. My GPS showed about an 80ft elevation increase from the starting point to where I reached 70mph. Plus, it features a 65mph speed limit and no place to hide a speed trap.
The sign in the foreground seems to make a good starting point. It is just before the climb starts and that could help get engine rpm and therefore the turbo to speed up quickly.
The second element was data collection that was both cheap and easy to use. I found an app called Drag Racer that seems to fit the bill. You just turn it on, stop, wait for the app to say that it is ready, then stomp the go pedal and the app does the rest.
Here is the data from 3 runs with the diesel. I will try to get some runs with the EcoBoost in the next few days. The speed indicated in at the top was just my speed at the instant that I took the screen shot. The data in the chart below it is what is important.
I got cut off on the second run and could not reach 70mph but kept it because it helps confirm the repeatability of the other two runs. I was amazed at how repeatable the data is. While it may or may not be accurate it should be good for comparing the two engines.
On the original subject of fuel mileage I ended up with 568 miles of pulling the trailer at 11.0mpg before starting the acceleration tests. I wound up the tests making a 35 run to pick up a boat. The road was 2 lane highway with some moderate hills and a maximum speed limit of 55mph. I held it to 57mph. The trip up was empty and the return trip with the boat in tow. I was very pleasantly surprised with the showing of 23.4mpg on empty run and 14.8mpg with the boat. Both readings are a little higher than I would expect from my 3.5 EcoBoost. My brother had borrowed the boat and reported about the same mileage as the diesel when towing with his 2.7 EcoBoost but quite a bit better empty. His truck is 2wd which gives it a small advantage.
My final observations are that the F150 still has a noticeable edge on ride quality. On sharp bumps and potholes the 250 felt like the tires were bouncing all over the place though they did quickly settle. The 250 was a little more in control of the trailer but not that dramatic, perhaps because I have LT tires and supplemental air bags on my 150. The 250 seemed to be about 3" higher and was a lot more challenging for me to get into. The 250 struggled for traction trying to get up a gravel section of my driveway, much more than any other vehicle that I have owned. I guess that is due to the weight of the diesel engine up front. I could have engaged 4wd but with manual hubs that would have been really annoying.
