Swapping in 3.55 or 3.31 Gears into a 4WD

[nitrobass24]

To be fair I wasn’t complaining but rather trying to explore options to further increase the MPGs.

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[dafish]

I would not change the gearing. For some of use that would hurt MPG, not help. Why?

As has been mentioned, efficiency goes to hell when these things go into boost. I downshift on some hills (ok, I lock out a few gears), and when towing I stone lock out 2 or three gears. I do this on both an Eco 3.5 and a PB. Both deliver better mpg when off boost. Both are max tows with 3.73's. If I had lower (numeric) gearing the gear jump between gears gets bigger (not helpful), I'd need to drop more gears and more often (also not helping). Added up I believe my MPG would be worse, with an Ecoboost, with lower (numeric) gearing. With an NA vehicle this would likely help. Here not so much. And of course the 10spd already has a ton over overdrive gears.

My bet is MPG improvements are best chased by:

1) Aero improvements
2) Water injection
3) A better shift strategy (I wonder if any tuners are looking at, can, force a downshift instead of pulling timing?)

BTW, chasing MPG with higher tire pressure does a wonderful job of killing ride quality. AP over ~35 PSI has a tiny improvement in efficiency.

 

[nitrobass24]

Thanks I did see improvement moving from 35 to 42 PSI but the ride quality certainly took a hit.

 

[Suns_PSD]

I had noted before that I saw a DROP in mpg going to the Livernois tune, contrary to other's opinions. My truck was pretty new at that point, and I was still learning the thing, but I had suggested a solid 1 mpg drop, although I felt it was really a bit more than that at around 1.5 mpg loss.

Anyways, I pulled my tune a few days back to get some warranty work done, and the truck definitely has been getting notably better mpg with the stock programming.

It's too soon to state anything conclusively as I'd need a full tank to know, but what I can say is that my morning commute has never averaged more than 22mpg (usually about 21 mpg) and I averaged over 24 mpg this morning in pretty ideal conditions. This in spite of the fact that my truck has never before had so many aero-reducing mods as it does right now.

 

[amschind]

I don't think that a diff swap helps the PB. The PB needs WIDER gears, which can only come from the transmission. Nobody but Ford can change the gears in the 10R80.

A 4.6:1 to 0.5:1 transmission would benefit the PB as would a bigger electric motor and a smaller ICE. This is because short gears on the bottom help it stay in electric mode. On the top end, taller gears would allow for the fuel economy seen in the OP example.

With current Ford parts, a 2.3l I4 plus the (RIP) Aviator hybrid 100 HP motor plus a wider ratio 10R80 would've maxed towing and mileage for the PB. Ford went for power, so we got a truck that is more powerful than a Raptor and which can beat a Raptor R with bolt on mods and get good to okay mileage (obviously not all at once, but I can do really powerful and good mileage at the same time).

The PB powertrain belongs in the Ford GT.

 

[TheGoatman]

I had noted before that I saw a DROP in mpg going to the Livernois tune, contrary to other's opinions. My truck was pretty new at that point, and I was still learning the thing, but I had suggested a solid 1 mpg drop, although I felt it was really a bit more than that at around 1.5 mpg loss.

Anyways, I pulled my tune a few days back to get some warranty work done, and the truck definitely has been getting notably better mpg with the stock programming.

It's too soon to state anything conclusively as I'd need a full tank to know, but what I can say is that my morning commute has never averaged more than 22mpg (usually about 21 mpg) and I averaged over 24 mpg this morning in pretty ideal conditions. This in spite of the fact that my truck has never before had so many aero-reducing mods as it does right now.

Hate to say to just throw more money at it. And some will argue against it here. I strongly recommend an intercooler with the tune.

I put it off for almost two years and I regret waiting.

 

[Calson]

If you check the EPA figures for the same engine in a 2WD and a 4WD truck the difference in mpg is about 2 more miles with 2WD. For the 2023 3.5L trucks the combined is shown at 21 mpg with 2WD and 19 mpg with the heavier 4WD truck.

Calculate how much of a difference in a year it would make if you drove your normal annual miles and got 21 mpg instead of 19 mpg and compare that to the $1000 or more it will cost to swap out the gears. One can increase their miles per gallon dramatically by driving smarter so as to maximize economy.

The Toyota Prius has been a favorite of competitive high mpg drivers for years. Anyone can get 45 mpg with no change in driving behavior but the competitive drivers can get 60 mpg or more with the same cars and no modifications to the car, only the way they drive.

I average 19 mpg with my 2022 4WD with the 3.5L engine and I know from my own experience that I can get more than 24 mpg by driving at slower but still legal speeds. I also know how many minutes I am going to save by driving at 75 mph instead of 70 mph on any trip. Driving at 80 mph or 1.33 miles per minute as compared to 70 mph or 1.16 miles per minute, I save 0.17 minutes with each mile driven or with a trip of 10 miles I save 1.7 minutes. I cannot see the value of burning 15% more fuel to save less than 2 minutes of my time.

Air drag is the key factor in fuel economy and it increases with the square of the vehicles speed. Drive twice as fast and there is 4 times as much air drag to overcome.

 

[Suns_PSD]

If you check the EPA figures for the same engine in a 2WD and a 4WD truck the difference in mpg is about 2 more miles with 2WD. For the 2023 3.5L trucks the combined is shown at 21 mpg with 2WD and 19 mpg with the heavier 4WD truck.

Calculate how much of a difference in a year it would make if you drove your normal annual miles and got 21 mpg instead of 19 mpg and compare that to the $1000 or more it will cost to swap out the gears. One can increase their miles per gallon dramatically by driving smarter so as to maximize economy.

The Toyota Prius has been a favorite of competitive high mpg drivers for years. Anyone can get 45 mpg with no change in driving behavior but the competitive drivers can get 60 mpg or more with the same cars and no modifications to the car, only the way they drive.

I average 19 mpg with my 2022 4WD with the 3.5L engine and I know from my own experience that I can get more than 24 mpg by driving at slower but still legal speeds. I also know how many minutes I am going to save by driving at 75 mph instead of 70 mph on any trip. Driving at 80 mph or 1.33 miles per minute as compared to 70 mph or 1.16 miles per minute, I save 0.17 minutes with each mile driven or with a trip of 10 miles I save 1.7 minutes. I cannot see the value of burning 15% more fuel to save less than 2 minutes of my time.

Air drag is the key factor in fuel economy and it increases with the square of the vehicles speed. Drive twice as fast and their is 4 times as much air drag to overcome.

If you average 20mpg, you burned .5 gallon of fuel while driving those 10 miles. Depending on location that cost about $1.50. An increase of 15% means you spent .23 cents to save 2 minutes. If you drive long enough to save an hour, that hour cost you an extra $6.90 in fuel.

Not sure what your time is worth, but it's probably worth more than $6.90/ hour.

That said, I don't drive 80 mph because it uses a LOT more fuel and I have to worry about more things, but 65-70mph is a really good balance I think and although 55 mph does get great mpg, the cost savings isn't worth that much time sacrifice.

 

[Samson16]

but the competitive drivers can get 60 mpg or more with the same cars and no modifications to the car, only the way they drive.

They won’t live long enough driving around central Florida like that to spend their savings.

 

[Suns_PSD]

Hate to say to just throw more money at it. And some will argue against it here. I strongly recommend an intercooler with the tune.

I put it off for almost two years and I regret waiting.

Can you elaborate on this?

I hardly tow, and don't go to the dragstrip. Mostly just drive to where I need to go. What are the advantages in my circumstances?

But you have piqued my interest for sure.

What's involved for install? Do you need to pull the bumper?

Which brand of intercooler would you buy if doing it again?

Thanks.

 

[TheGoatman]

Can you elaborate on this?

I hardly tow, and don't go to the dragstrip. Mostly just drive to where I need to go. What are the advantages in my circumstances?

But you have piqued my interest for sure.

What's involved for install? Do you need to pull the bumper?

Which brand of intercooler would you buy if doing it again?

Thanks.

I don’t tow. It just have more pep and less wheezing driving around.

If you have a Powerboost, I would recommend the Livernois. Not a fan boi, but the only one I know of that’s a legit drop in. No cutting. No removing shields. No messing with the pedestrian speaker.

It installs from the bottom. Takes like 20 minutes. No removing anything to access.

 

[TheGoatman]

I saw you said you had knock on the summer as well. I would be shocked if it wouldn’t remove that.

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