Diesel engines are the true workhorses of the automotive industry. Though they don’t quite produce the raw horsepower and torque of their gasoline-fueled counterparts, diesel engines are more fuel efficient, durable, and reliable overall.
Figure 1: The Cummins 6.7L is on our list as one of the best modern diesel engines. Source: TFLTruck.
If you’re looking to put a diesel engine in your truck, you already know what a big and complicated decision this can be. Diesel engines are very complex devices, and there is an enormous spectrum of good and bad ones to choose from. When built right, diesel engines are tough and dependable. But when built wrong, they quickly develop serious mechanical problems that will burn a hole in your wallet in order to fix.
Sources: TruckTrend Network.
The 4 Best Diesel Engines
We’ve picked out 5 of the best diesel engines on the market, based on a consideration of power, reliability, ease of use, and price. We’ve selected one each from 4 major makers. First, we’ll look at two engines for the Dodge Ram: the Chrysler 3.0L EcoDiesel and the Cummins 6.7L. Then we’ll consider the best Power Stroke engine and Duramax engine for all your Ford and Chevy trucks.
Chrysler 3.0L EcoDiesel Engine (AKA RAM 1500 EcoDiesel)
Figure 2: The 3.0L EcoDiesel’s small size belies its big power. Source: Diesel Army.
The 3.0L EcoDiesel was first available in 2014 for 1500 series Rams and Jeep Grand Cherokees.
As its name suggests, is exceptional in its fuel efficiency and emission standards. Its emission controls include a cooled diesel exhaust catalyst exhaust gas recirculation, as well as a pretty click diesel particulate filter. This engine is, in fact, one of the few light-duty diesel engines every produced, and quite possibly the only one readily available today.
We spoke to sales representatives from Three Rivers Chrysler Jeep Dodge in Pittsburgh, PA. They told us that, “generally speaking, [the 3.0L EcoBoost] is highly sought after and designed to get great gas mileage while still having a decent amount of pulling power.”
They added that, “when you get them, which is rare, they’re super popular. Boom gone! Just like that.” The moral of this story is clear: if you see a Ram with a 3.0L EcoDiesel, grab it while you have the chance.
Figure 3: A Ram 1500 with an EcoDiesel engine. You’ve seen these emblems before, right?
This engine is a V-6 with 240 HP at 3,600 RPM and 420 lb-ft of torque at 2,000 RPM, all with a bore and stroke value of 3.27×3.6. Special features include a DOHC valvetrain with 4 valves per cylinder and high-pressure common rail fuel injection. With all that, this engine can carry up to 1,620 lbs. of payload, and tow a maximum of 9,200 lbs.
Like a couple other engines on this list, it comes with a water-cooled variable geometry turbocharger. It all sits comfortably on a tough, aluminum alloy head and compacted graphite iron block. The block is further strengthened with a nice, tough bedplate. The engine itself is somewhat narrow compared to other diesel engines (at 60 degrees for the V-shaped block). This tight angle keeps block mass low and boosts fuel efficiency while also saving space in the engine bay.
Cummins 6.7L Diesel Engine
With a power rating of up to 385 HP at 2,800 RPM alongside an impressive torque rating of 865 lb-ft at 1,700 RPM, this engine is for serious diesel truck drivers. In fact, some of these engines have been known to put out 400 HP and hit the eye-popping value of 1,000 lb-ft of torque!
This engine features an OHV valvetrain with 4 valves per cylinder and a high-pressure common rail fuel injection system with Bosch CP3 injection pump induction. The higher capability pressure pump is a particularly notable feature. The compacted graphite iron block (CGI) block, along with thick flex plates, affords greater overall strength and enables the exceptional power and torque ratings. Finally, the variable-geometry Holset turbocharger afford this engine excellent, modern induction.
Currently, the Cummins 6.7L engine is powering 2019 Ram heavy-duty pickup trucks. These vehicles can make full use of the engine’s exceptional power and torque ratings. For either 2500 or 3500 Rams, the power and torque are typically around 370 HP and 850 lb-ft, respectively.
“The Cummins engine was around for a long time, but it was so good that Dodge used the Cummins model rather than designing their own,” our friends at Three Rivers Chrysler Jeep Dodge told us. “Essentially, “Cummins has been around for years just known for being great diesel engines. Ram decided to use them.” In fact, Cummins has recently celebrated their 30-year partnership with Dodge Ram.
Ford Power Stroke 6.7L Diesel Engine
Figure 6: The Power Stroke 6.7L is miles ahead of its predecessor Power Stroke engines. Simply put, the 6.7L is everything that the older 6.4L engine should have been. Source: Ford Authority.
Power Stroke engines go way back. The brand began as a collaboration between Ford and Navistar, then going under the name of International Truck and Engine Corporation (ITEC). It turned out to be quite a rocky relationship, with constantly shifting emissions standards forcing the pair to redesign the Power Stroke several times.
After the commercial disappointment of the 6.4L Power Stroke engine—which suffered from numerous mechanical and performance problems—the 6.7L was hailed as something of a comeback for the brand. Introduced in 2011 and built in-house by Ford (having ditched Navistar after the failure of the 6.4L), the Power Stroke 6.7L did not disappoint. It is a sleek, compact, and powerful engine that uses compacted graphite iron to allow for superb weight savings. It features a Bosch common-rail injection system and has 4 pushrods per cylinder.
The 6.7L clocks in at 450 HP at 2,800 RPM with a torque of 925 lb-ft at 1,600 RPM. Its bore is 3.9”, stroke is 4.25”, and has a quite unique 16.2:1 compression ratio.
In sum, the 6.7L is an upgrade over every other Power Stroke engine. Our advice is simple: get the 6.7L, don’t even think about getting an older Power Stroke model. It’s lighter, stronger, miles more dependable, and more efficient. For more details, see our article on the best Ford diesel engines.
The Power Stroke is also available as a 3.0L version for the Ford F-150. This version is turbocharged and offers a very nice power and torque ratings at 250 HP and 440 lb-ft of torque. With it, the F-150 can tow up to 11,400 lbs. and handle a payload of up to 1,940 lbs.
The 3.0L Power Stroke was first made available for the Ford F-150 in 2018. Though it had been available in the Land Rover Discovery and Land Rover Range Rover for a while, this was the first time the F-150 was outfitted with a diesel engine.
Duramax L5P 6.6L Diesel Engine
The Duramax L5P, first released in 2017, is substantially more durable than previous Duramax models and features 445 HP along with a staggering 910 lb-ft of peak torque and a 16.0:1 compression ratio. With its cast-iron block and induction-hardened cylinder walls, the LP5 can take quite a beating, and was first used in the Chevy Silverado in 2017.
Figure 8: A Chevy with a Duramax L5P installed. Source: GMC.
Key features of the LP5 include advanced electronic and structural redesigns over previous Duramax engines; strengthened cylinder and engine blocks; electrically controlled variable geometry turbochargers with enhanced max boost pressure; and a new air intake system complete with hood scoop.
Additionally, the new L5P version of the Duramax includes a new patented design in which air comes in through the top of the engine. This produces a significant boost in torque and power compared to previous versions. This engine can handle cold weather no problem. A Chevy equipped with this engine comes with a winter front that can clip in and keep the engine compartment warm and prevent air freezing up.