kehyler

I’m not sure I understand Ford’s ratings for 4x4 supercrews with the short wheelbase. For 2018, the 3.5 ecoboost (2x4) with 3.15 gears and the 2.7 ecoboost with 3.73 gears (4x4) should both put roughly the same torque/hp to the rear wheels. The 3.5 ecoboost with 3.15 gears is rated to tow 10.7k lbs, yet the 2.7 ecoboost with 3.73 gears is rated to tow 9k lbs. Can someone help me understand the disparity between the ratings?

Meathead

iTrader: (2)

The 2.7 is a smaller and less powerful motor. It can't handle the strain of pulling more. It is simple math.

kehyler

I choose different gear ratios to neutralize that point. (The 2.7 has roughly 17% less power, so I gave it 17% more gear ratio advantage.)

Jeff1024

There are other differences between the 3.5 and 2.7L trucks. The GVWR on the 2.7 is lower for one. Also may have something to do with how hard the 2.7 has to work to produce the power as compared to the 3.5. Tow ratings are established as a max you can pull without overheating the drivetrain or engine, 3.5 is running a lot less boost to make power as compared to the 2.7.

But I am no engineer, so I honestly dont know.

kehyler

Yeah, I'm wondering what specific difference it is.

Flamingtaco

This is not apples to apples. The 2.7 is a smaller block with less surface area to transfer heat from the pistons to the coolant. The ability of the coolant to absorb heat at the block and dump it at the radiator has an impact in determining tow rating.

If no one cared if the 2.7TT cost as much as the 3.5TT, it could have been designed to have similar heat transfer capabilities as the 3.5. However, that would defeat the point of having different engines, which serves to provide options to meet the demands of customers with different needs.... super mpg friendly and cheapest option (3.5), mpg friendly but capable (2.7TT), old-timey-wimey Tim Allen [j/k, powerful, cheaper to maintain (5.0)], and max power with potential for efficiency (3.5TT).

berniedes

I suspect if anything, Ford is advertising the towing capacity of the 2.7 with 3.73 below 10,000 lbs as to not compete against the 5.0 engine.

kehyler

I'm not sure I feel compelled by that reason. If block size was a significant reason, I am confused as to why the 5.0 L has an indistinguishable tow rating at a comparable gear ratio as the 2.7 L.

kehyler

I am hoping (but to be honest, open to) that Ford didn't derate the 2.7 for marketing purposes to push what are likely higher profit engines. Unfortunately, this is the only self-consistent reason that I can come up with at the moment.

marshallr

It is an old saying, but even with high tech engines "there is no replacement for displacement". Smaller engines can do a lot, but gearing only goes so far. The smaller engine will always have to work harder. For occasional use I'd bet the 2.7 with the right gearing will move a pretty heavy load, far more than it is rated for. Almost all engines will for limited use. But doing so long term will wear out components a lot sooner.

If this 45 year old truck can move this load so can a new truck with the 2.7, but I don't recommend it.