My have things changed

ShinerBock wrote:

Yes. Compare a 2015-2016 F150 3.5L N/A(that is the only years Ford put an N/A 3.5L in an F150) fuel mileage to a 3.5L Ecoboost engine and you will notice that the Ecoboost uses more fuel. The concept around the Ecoboost is that it uses less fuel than larger displacement engines while delivering better fuel economy and more or the same power than that larger engine.

A diesel is not like a gaser and is not regulated by air. Diesel is regulated by fuel and uses whatever air that it has available to burn said fuel. The more air you add to same amount of fuel will increase its horsepower and its efficiency. Add a turbo to a diesel and inject the same amount of fuel, and you have more horsepower without using more fuel. Add an intercooler and the same amount of fuel and again, you will have more horsepower with the same amount of fuel.

This is a major reason why small 3.0L diesels have the same amount of horsepower and torque of the larger displacement diesel engines of 20 or 30 years ago while using less fuel. Things like turbos, intercooler, higher injection pressures, and so on allowed a 3.0L diesel today have the same(if not more) amount of power than a 7.3L or 8.9L diesel of yesterday. However, as with anything, there only so much power that can be had on the same amount of fuel and in order to make more power you will need more fuel.

What people also tend to forget about all of this is that you need to compare power ratings and capabilities of these engines from those decades ago(not halt ton to half ton or HD to HD), and in this regard they have increased efficiency significantly. A half ton diesel has the same if not more power than big HD diesels of years ago while having the same capabilities. So if you needed to tow 8k back then, then you would have needed an HD truck, but today it can be done with a half ton with a smaller displacement engine that makes the same if not more power while achieving much better fuel economy.

Today's HD trucks with 6.X liter engines also grew in power and capability and can be compared to medium duty to light heavy duty trucks with 12.X liter and up engines from decades ago in terms of what they can haul and in that regard they are way more efficient. People tend to wrongfully compare HD trucks of today to HD trucks of yesterday even though the capabilities of the two are no where near each other. Largely because what we tow nowadays is much heavier than we towed back then. You would need a class 4, 5, 6, or 7 truck back then to tow what class 2b and 3 trucks can tow today.

In regards to your old N/A diesel to your buddies 2008. I am willing to bed that his truck is a lot larger and heavier, you are comparing old highway speeds that used to be 55 mph or 60 mph to today's speed limits of 70 and 75 mph, different driving styles, and a way more powerful engine that adds more fuel for more power, but if it it added the same amount of fuel then it would make more power than the N/A diesel while achieving the same if not better fuel economy.

You are confusing the ability to generate more HP with fuel efficiency.

Sure a modern 3.0l turbo diesel can produce the power of a bigger NA diesel...but it uses pretty much the same fuel when both engines are producing identical power. As long as the engines are within normal operating ranges, power is largely a function of HP output.

As far as comparing to my brother-in-law, that was based on following him, so similar speeds and driving pattern. The trucks are within a couple hundred pounds. So no, being turbo doesn't automatically result in better efficiency.