What’s the Best Diesel Truck Engine on the market?

What’s the Best Diesel Truck Engine on the market?


So you want to drive a diesel truck? Nice choice. The diesel sensation, a trend now spreading from Europe to the U.S., is an innovative way to conserve fuel and decrease strains on the environment we live in. But since diesel engine technology still requires a fair amount of maintenance and expense compared to gas engines, you’ll want to look for the most reliable and cost effective diesel engine there is. So here’s a comparison of the Best Diesel Engines currently on the market, accounting for reliability, power, and fuel economy.

Power is always an attractive feature in trucks. As a side note, if you’d like to see the most powerful diesel—as in, the engine of engines, the most powerful diesel engine in the world—go here. But for the purpose of this article, we’re talking about diesel engines you’d be able to fit in your car.


A word on fuel economy

One of the major strengths of diesel is fuel economy, and if you’ve bought or are looking at buying a diesel car/truck, this is no doubt an important point to you. Like any truck driver, you’re looking for an engine that will guzzle as little fuel as possible while still providing all the brawn you need. Since a wide range of factors beyond the engine itself contribute to fuel economy, it’s difficult to pin down exactly how efficiently an engine uses fuel. Engine manufacturers recognize that fuel economy is important to buyers, and many of them construct innovative designs to improve this. We will make a point to specify where such innovations have been made.


Horsepower, Torque, and RPM

A few variables will come up here that you should at least have a rudimentary understanding of (of course, if you already understand these technicalities, just skip on ahead to the engines!). These are some of the specs you’ll see listed for any given engine, and they should be taken into consideration. They’re the main ones you want to look out for. In case you aren’t familiar with horsepower, torque, and RPM, we’ll give you a simple overview.

Horsepower is a unit of measurement. We won’t throw mathematics at you. Horsepower relates to how much energy an engine produces and is one of the several factors that determine how fast a car will go.

Torque relates to how much an engine can carry. If you’re not specifically looking for an engine that can hall heavy loads, this should be less of a deciding factor for you than horsepower. To understand a little more of the technicalities of torque, go here.

RPM (revolutions per minute) is the number of rotations the engine’s axis makes in a minute. Do I want a high RPM or a low RPM? Some engines are made to run with a high RPM and some aren’t. There’s one thing to keep in mind, though. The higher the RPM, the more work the engine is doing, the more strain is being put on it. This may affect both the lifespan and the fuel economy of the engine. The tradeoff is that a higher RPM usually generates more horsepower/torque.

When viewing engine specs, you’ll see both the horsepower and the torque listed with an RPM number beside them. For instance, one engine might have 350 horsepower at 2,000 RPM and another engine might have 350 horsepower at 1,000 RPM. This does not mean that additional calculation needs to be done to understand the horsepower. Both engines have 350 horsepower. The only difference is that one of them is rotating at twice the rate of the other. In a situation such as this, we’d recommend you go for the lower RPM engine.


Now that we’ve taken horsepower, torque, and RPM into consideration, here are some our picks for the most hardy and powerful engines on the market…


Pickup Truck Engines

In this article we’ll focus on both pickup truck engines and the larger commercial truck engines. Of course, commercial truck engines will have significantly more power than pickup truck engines. So in deciding what “the best” diesel engine is, there has to be a dichotomy made between regular truck engines and large/commercial truck engines, because in all likelihood you’re only looking for one or the other. We’ll start with regular pickup truck engines.


6.7L Cummins Turbo Diesel (Aisin AS69RC trans.)

Cummins manufactures a number of engines, from pickup truck to largest of industrial engines. The 6.7L Cummins Turbo Diesel is the latest and most power installation of Cummins’ B-series engines. can be found in some of the Ram 2500 and 3500 series variations. The Cummins 6.7L is a very popular engine, and according to CumminsEngines.com, 80% of Ram pickup owner make the optional choice to get it. The engine was first introduced in 2007 and since then has had several improvements. The 2011 version of the 6.7L Turbo Diesel, according to CumminsDieselSpecs.com, produced a 10% increase in fuel economy, as reported by Ram Trucks (so go for a post-2011 version of this engine!!).

Cummins goes to lengths to boast of their engine’s durability, even creating an online “Cummins Turbo Diesel High Mileage Club” for those who’ve driven over 100,000 miles with their Turbo engine.


6.7L Cummins Turbo


385 at 2,800 RPM

Torque (lb.-ft.)

865 at 1,700 RPM


Inline 6-cylinder


The Cummins Turbo has a relatively hardy torque, although other engines may rise above it in terms of horsepower. See more of the 6.7L’s specs here.


The Duramax® 6.6L Turbo-Diesel LML (aka Duramax 6600)

According to DuramaxDieselSpecs.com, the 6.6L Turbo-Diesel LML was GM’s response to Ford’s Power Stroke engine (see next engine). This is the engine you’ll find in the 2015 Chevy Silverado 3500 HD as well as the GMC Sierra 3500 HD. It includes a diesel exhaust break, which helps with maintaining a desired speed on steep slopes. The 6.6L Turbo-Diesel uses diesel exhaust fuel injection to reduce emission levels significantly. Developed to be used vigorously and to last at least 200,000 miles, it’s considered the cleanliest and most powerful Duramax engine.


Duramax Turbo-Diesel[1]


397 at 3,000 RPM

Torque (lb.-ft.)

765 at 1,600 RPM




Go for a post-2010 model of this engine, as the 2011 model produced an 11% increase in fuel mileage. This and specs on other 2011 design/operation improvements found here.


The 6.7L Power Stroke™ V8 Turbo Diesel

Built with a lightweight compacted graphite iron engine block and aluminum cylinder heads to reduce weight, the 6.7L Power Stroke is powerful and fuel efficient engine. Piston-cooling jets improve engine longevity and it has “instant start” glow plugs for cold weather ignition starts. It has up to five injection events per cylinder per cycle in order to reduce noise and emissions. It also has integrated exhaust gas recirculation, “Selective Catalytic Reduction,” and a “Diesel Particulate Filter” which serve to control and reduce emissions. This and other specs here.

1The Power Stroke is primarily used in Ford’s line of SUPER DUTY trucks. The SUPER DUTY line has provided a number of reliable heavy duty trucks over the years, including the F-450 and F-550, which are two of SWEngine’s more popular truck engines. The 2015 SUPER DUTY is availed with either a gas engine or a 6.7L Power Stroke™ Turbo Diesel engine. Here’s the specifications:


Power Stroke™


440 at 2,800 RPM

Torque (lb.-ft.)

860 at 1,600 RPM




This according to Ford.com. Check out the full specs page here.


Commercial Engines

If you’re looking for the right diesel engine to put into a commercial vehicle, consider some of the engines listed below. These engines are used in some of largest industrial trucking vehicles.


The Paccar MX13

The first engine to use compacted graphite iron in both the cylinder block and head, the Paccar MX13 designed for a becoming mixture of smoothness and durability. It has filters, a thermostat, and an oil cooler attached directly to the engine and dependable electrical system with fully encapsulated wires. This engine can be found in some Peterbilt trucks. According to Peterbilt.com, the MX13 has a B10 design life of one million miles. Its built in PACCAR Electronic Control Module precisely manages the engine’s fuel consumption for optimum fuel economy. The engine’s common rail system maintains injection pressures of 2,500 bar, helping to minimize fuel consumption, emission, and noise levels. A rear-mounted gear train and a floating oil pan also make the engine run quieter. The MX13 also boasts a construction of light-weight parts for a better weight-to-brawn ratio.


Paccar MX13[2]


380-500 at ~1,500 RPM

Torque (lb.-ft.)

1,450-1,850 at 1,000 RPM


Inline 6-cylinder



The Cummins ISX15

Talk about an engine! With an advertised horsepower of between 400 and 600, the Cummins ISX15 truly is a powerful and beautiful machine. It can boast this substantial horsepower without sacrificing fuel economy. It’s great for large/commercial trucks and is found in a lot of International Trucks and Freightliners. The ISX15 has a variable geometry turbocharger, which “enhances response and control with electric actuation for infinite adjustment, providing exact boost at any rpm” (this and more specs here).

It has a B50 life of over one million miles. Its “XPI Fuel System” precisely controls fuel consumption at high pressures which, along with its electronic engine controls, enables multiple injection events per cycle. Cummins strove to construct simple, smooth, and effective operation into this engine.

Cummins ISX15


400-600 at 1800 RPM

Torque (lb.-ft.)

1450-1850 at 1,100-1,200 RPM


Inline 6-cylinder


The Detroit DD16®

Designed with a sharp eye for engine performance, the Detroit DD16 is used for large/commercial trucks like those made by Freightliner, and it aptly fits the description “heavy duty.” Detroit advertises it as their largest and toughest engine. It employs BlueTec® SCR emissions technology and the Amplified Common Rail System (ACRS™) to monitor and help lower emissions, noise, vibrations and fuel consumption. The integrated three-level Jacobs® brake adds braking versatility (for quieter braking, shorter stops, and downhill control) and minimal engine wear.

The DD16 really shines through with its torque. If you want an engine that can pull monumental loads, this may be the one for you. It has plenty of pulling power and can work smoothly and efficiently instead of grunting and coughing under a heavy load like lower-torque engines. The DD16 is more than a workhorse; it’s a behemoth!


Detroit DD16[3]


475-600 at 1,800 RPM

Torque (lb.-ft.)

1,850-2050 at 1,100 RPM


Inline 6-cylinder


As you can see, this beast has a significant amount of both horsepower and torque. Detroit also manufactures a few lower-caliber engines such as the DD15 and the DD13. To compare the differences between these various Detroit engines, and to see more specs on the DD16, go here.


Picking the best diesel engine for your truck

diesel-mdThese have been some of the key players in pickup truck and commercial truck engines. The engines listed have been tested and improved over time and define the upper field in industry standards. Choosing a particular diesel engine, like any car buying decision, should be done with specific consideration of your needs. If you need more grit and hauling power, look for something with more torque. If you want speed and engine power, look search for the best horsepower. If fuel-to-mileage is a big thing for you, look for reputable engines that promise great fuel economy through design/constructions. Naturally, some balance of all of the above is to be desired.


Making the purchase

Picking an engine is a hassle in of itself, but finding a good place to buy it is an entirely new challenge. Look around both locally and online, and as usual, we highly recommend you buy used. If you have an idea of what engine you want, hop over to www.swengines.com/heavy-duty-trucks.php and fill out a super-fast, easy quote. We have a truly vast inventory, so it’s likely that the engine’s in stock at a great price. 🙂


/ Diesel engine / Tags: ,

Share the Post

About the Author


Comments are closed.