Thor Forums

[JamieGeek]

Originally Posted by Chance

With due respect, you missed the meaning of the message on multiple levels.

Motorhomes burn most of their fuel while cruising at highway speeds, not stuck in traffic like many Ford F-150 pickups that are used as daily drivers. My reply was to contradict Bob’s comment about having a tiny engine powering a generator or alternator that would then power electric motors. For a motorhome driven mostly on highways, Bob’s idea would be VERY inefficient. That’s why it’s not done. If it saved fuel, we’d be doing it already. It’s technically possible, but makes no real sense.

Your comment about the 2.7L EcoBoost is misleading at a technical level in many ways when applied to a motorhome that requires 100 HP or more to maintain speed on highway.

A 2.7L EcoBoost does save a little fuel compared to a 5.0L V8 on the highway when compared on an empty F-150 pickup, but they require a fraction of the power that a 20,000-pound motorhome requires. Many motorhomes need roughly 3 times as much power as a pickup, which is why they only get 8 MPG versus 24 MPG for a pickup at same highway speed.

Engine size makes a difference, but it’s the motorhome size and weight that makes it necessary to have a much larger engine to optimize fuel economy. If you make engine too small, it will actually end up getting lower MPG. That’s why Ford determined that a 7.3L V8 was best for large trucks and motorhomes.

As I stated in other threads, a +/- 5L EcoBoost could have developed the same or more power and torque as a naturally aspirated 7.3L V8, but it would cost more and not get enough added fuel economy to justify the added costs.

It’s a complicated subject, and difficult to discuss in a meaningful way without hijacking this thread.

It is done every day across America: Diesel-electric locomotives are a Diesel engine connected to a generator which connects to electric motors at the drive wheels.