10 Best Diesel Engines (In the Past 20 Years)

For more than 100 years, the diesel engine has lent its power to everything from locomotives, marine vessels, and construction equipment of every perceivable type. However, the diesel engine now plays a substantial role in the passenger truck market.

Most modern diesel engines provide good performance, fuel economy, and reliability. But, a handful of  engines stand out above the rest. Here are 10 of the best diesel engines to have entered production in the past 20 years.

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Best Diesel Engines

#1 – 6.7L Cummins – (Best for Towing)

In 2007, Cummins unveiled the latest B-Series engine, intended for use underneath the hood of the Dodge Ram. The 6.7L Cummins turbo-diesel was designed to replace the aging 24-valve 5.9L Cummins, which proved unable to keep up with increasingly stringent emissions standards.

The new 6.7L Cummins utilized the same cast-iron block and heads as the 5.9L before it, yet featured a wealth of new fuel/air delivery technology.

Additional updates to the 6.7L Cummins came in 2013, when the engine was ultimately equipped with SCR (Selective Catalyst Reduction). This technology netted the 6.7L a 10% increase in torque, while also slashing the engine’s overall emissions output.

In 2021, the 6.7L Cummins produces a staggering peak torque output in excess of 1,075 lb./ft.

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6.7L Cummins Specs

• Years: 2007-current
• Displacement: 6.7L
• Configuration: Inline-6
• Max. Horsepower: 420 hp @ 2,800 rpm
• Max. Torque: 1,075 lb-ft @ 1,800 rpm
• Bore x Stroke: 4.21 x 4.88 inches
• Valvetrain: OHV with 2 valves per cylinder
• Engine Weight: 1,060 lbs (dry)
• Aspiration: Turbocharged and Charge Air Cooled

#2 – 6.7L Power Stroke – (Best Ford Diesel Engine)

Ford’s 6.7L diesel served as the first engine of Power Stroke lineage not to be produced by International Navistar. Instead, the 6.7L Power Stroke was built completely in-house by Ford, in an attempt to stay relevant within the diesel market.

The 6.7L Power Stroke also served as a breath of fresh air to Ford enthusiasts, who had been left to contend with the abnormally problematic 6.0L and 6.4L liter Power Strokes of the decade prior.

Though the 6.7L Power Stroke initially boasted an output of 390 HP and 735 lb./ft. of torque, these figures have since been revised. Almost immediately after its unveiling, the 6.7L Power Stroke received a software update that boosted its rated output to 400 HP and 800 lb./ft. of torque.

In its most recent form, Ford’s 6.7L diesel is capable of churning out 475 HP, and 1,050 lb./ft. of torque.

6.7L Power Stroke Specs

• Years: 2011-current
• Displacement: 6.7L
• Configuration: V-8
• Max. Horsepower: 475 hp @ 2,800 rpm
• Max. Torque: 1,050 lb-ft @ 1,800 rpm
• Bore x Stroke: 3.89 x 4.25 inches
• Valvetrain: Conventional pushrod OHV with 4 valves per cylinder
• Engine Weight: 990 lbs (dry)
• Aspiration: Single sequential turbocharger (SST)

Related: What is Engine Derate?

#3 – 6.6L Duramax L5P – (Best Duramax Engine)

Chevrolet introduced the 6.6L Duramax L5P in 2017, as a replacement to the earlier LML Duramax of the same displacement. This engine would serve as the heavy-duty powerplant of choice for HD-series Chevrolet and GMC pickups.

The L5P was notable in comparison to earlier Duramax offerings, due to its use of revised cylinder heads, an updated camshaft, and a new variable-vane turbocharger.

The 6.6L Duramax L5P produces a total of 445 horsepower and 910 lb./ft. of torque. True to the past Duramax production, the L5P produces the vast majority of its torque at lower RPM ranges (90% @ 1,550 RPM). This proves highly beneficial in severe service towing applications.

Related: Duramax Diesel Fuel Economy Numbers

Duramax L5P Specs

• Years: 2017-current
• Displacement: 6.6L
• Configuration: V-8
• Max. Horsepower: 445 hp @ 2,800 rpm
• Max. Torque: 910 lb-ft @ 1,600 rpm
• Bore x Stroke: 4.05 x 3.89 inches
• Valvetrain: OHV with 4 valves per cylinder
• Engine Weight: 835 lbs (dry)
• Aspiration: Electronically controlled and actuated variable geometry turbocharger

#4 – 7.3L Power Stroke – (Most Reliable)

Even today, nearly three decades after its initial release (1994), the 7.3-liter Power Stroke is still highly regarded for its unparalleled degree of reliability. The 7.3-liter Power Stroke was designed through a joint venture between Ford and International Navistar, for use within Ford’s Heavy-Duty series trucks.

The 7.3L Power Stroke utilized a new technology, known as Hydraulic Electric Unit Injection (HEUI), which eliminated the need for a dedicated injection pump. Instead, low pressure fuel was injected under substantial force, by using high pressure engine oil to create hydraulic pressure within each injector.

7.3L Power Stroke Specs

• Years: 1994-2003
• Displacement: 7.3L
• Configuration: V-8
• Max. Horsepower: 275 hp @ 2,800 rpm
• Max. Torque: 525 lb-ft @ 1,600 rpm
• Bore x Stroke: 4.11×4.18 inches
• Valvetrain: OHV (overhead valve) with 2 valves per cylinder
• Engine dry weight: 920 lbs (dry)
• Aspiration: Single turbocharger, Garrett GTP38 (wastegated)

#5 – 6.6L Duramax LBZ

Though short-lived, the 6.6L Duramax LBZ still remains prized among consumers, thanks in large part to its simple, yet highly efficient design. The LBZ Duramax was first introduced during mid-2006 production, as a replacement for the prior LLY Duramax.

However, this engine was ultimately retired from service following the 2007 model year, following the introduction of the LMM Duramax. 

Although the Duramax LBZ was generally well received, it was not without several substantial faults. The most notable of the LBZ’s weak points came in the form of premature piston failure. This problem tended to be especially prominent in modified engines, which produced power in excess of stock values.

Duramax LBZ Specs

• Years: 2006-2007
• Displacement: 6.6L
• Configuration: V-8
• Max. Horsepower: 360 hp @ 3,200 rpm
• Max. Torque: 650 lb-ft @ 1,600
• Bore x Stroke: 4.06×3.90 inches
• Valvetrain: OHV (overhead valve) with 4 valves per cylinder
• Engine Weight: 835 lbs (dry)
• Aspiration: Single turbocharger, Garrett GTP38 (wastegated)

#6 – 3.0L EcoDiesel

FCA, Chrysler’s parent company, jumped headlong into the idea of furnishing a diesel engine for both the RAM 1500 and Jeep Grand Cherokee in 2014. The company would ultimately settle upon the 3.0L EcoDiesel as its engine of choice.

This engine was manufactured by VM Motori, another subsidiary of FCA, based in Cento, Italy. 

Following the 2019 model year, the 3.0L EcoDiesel was pulled from the Grand Cherokee’s options list. However, the engine continued to serve the RAM 1500, even undergoing a substantial update in 2020, which increased the EcoDiesel’s total output to 260 horsepower and 480 lb./ft. of torque.

See Also: V-6 vs V-8 Engine Comparison

3.0L EcoDiesel Specs

• Years: 2014-current
• Displacement: 3.0L
• Configuration: V-6
• Max. Horsepower: 260 hp @ 3,600 rpm
• Max. Torque: 480 lb-ft @ 1,600 rpm
• Bore x Stroke: 3.27 x 6.30 inches
• Valvetrain: DOHC with 4 valves per cylinder
• Engine Weight: 505 lbs (dry)
• Aspiration: Turbocharged and intercooled

#7 – 5.9L Cummins (24V ISB)

In its earliest form (6BT), the 5.9L Cummins served as the diesel powerplant of choice for the Dodge Ram, dating back to 1989. These earlier 5.9L engines were known simply by most as the “12-valve Cummins”, due to their 2-valve per-cylinder head configuration.

Then in 1998, the 12-valve 5.9L was replaced by the newer 24-valve ISB-series 5.9L engine. Both variants of the 5.9L were known for their innate reliability, and are still highly prized today.

Unfortunately, the 5.9L Cummins met the same unceremonious fate as many other earlier diesels. Increasingly stringent emissions standards relegated the 5.9L into non-compliance, rendering it unfit for continued uses as a production engine. The 6.7L Cummins would ultimately replace the aging 5.9L in 2007.

5.9L Cummins ISB Specs

• Years: 1998-2007
• Displacement: 5.9L
• Configuration: Inline-6
• Max. Horsepower: 325 hp @ 2,900 rpm
• Max. Torque: 610 lb-ft @ 1,600 rpm
• Bore x Stroke: 4.02 x 4.72 inches
• Valvetrain: OHV, 4 valves per cylinder, solid lifter camshaft
• Engine Weight: 1,150 lbs (dry)
• Aspiration: Single turbocharger, air-to-air intercooler

#8 – 6.6L Duramax LB7

General Motors first introduced the 6.6L LB7 Duramax in 2001, as a much anticipated replacement for the company’s aging 6.5 Detroit diesel. The LB7 gained a loyal following among consumers, who appreciated the engine’s increased performance, over the somewhat anemic 6.5L Detroit to come before it.

However, the LB7 remains popular today for its lack of emissions control equipment, which had not yet been mandated upon its release.

GM’s 6.6L LB7 did, however, experience considerable issues with premature fuel injector failure. Luckily, the manufacturer remedied such shortfalls with the release of an updated injector in the years that followed.

Subsequently, GM also extended warranty coverage of these updated injectors to appease consumers.

Duramax LB7 Specs

• Years: 2001-2004
• Displacement: 6.6L
• Configuration: V-8
• Max. Horsepower: 300 hp @ 3,100 rpm
• Max. Torque: 520 lb-ft @ 1,800 rpm
• Bore x Stroke: 3.87 x 4.13 inches
• Valvetrain: OHV with 4 valves per cylinder
• Engine Weight: 835 lbs (dry)
• Aspiration: Turbocharged and intercooled

#9 – 5.0L Cummins

Many know the 5.0L Cummins as the motivating factor behind all diesel-powered Nissan Titan pickups. However, this engine was originally offered to Dodge, for use in the RAM 1500, though Dodge ultimately settled on the 3.0L EcoDiesel as its engine of choice instead.

This, of course, was a decision that proved beneficial for Nissan fans who desired something special beneath the hood.

While the 5.0L Cummins is less fuel efficient than the 3.0L EcoDiesel, it does carry a significantly higher output. The 5.0L Cummins produces 310 horsepower and 555 lb./ft. of torque, which nicely backs the Titan’s 12,000-pound towing capacity.

5.0L Cummins Specs

• Years: 2016-2019
• Displacement: 5.0L
• Configuration: V-8
• Max. Horsepower: 310 hp @ 3,200 rpm
• Max. Torque: 555 lb-ft @ 1,600 rpm
• Bore x Stroke: 3.70 x 3.54 inches
• Valvetrain: DOHC with 4 valves per cylinder
• Engine Weight: 899 lbs (dry)
• Aspiration: Turbocharged and intercooled

#10 – 3.0L Duramax LM2

In 2020, General Motors staked a claim in the growing ½ ton diesel market, by introducing the 3.0L LM2 Duramax for use in their Silverado and Sierra 1500 pickups.

This engine would then become available for the Chevy Tahoe/Suburban, GMC Yukon/Yukon XL, and Cadillac Escalade. The 3.0L Duramax LM2 is of an inline-six design, much like Cummins’ 5.9L and 6.7L powerplants.

The Duramax LM2 is also a noteworthy performer, producing 277 horsepower, as well as 460 lb./ft. of torque. This proves sufficient enough to provide towing capacities in excess of 9,500-pounds in GM pickups or 8,500-pounds in various GM SUVs.

Duramax LM2 Specs

• Years: 2020-current
• Displacement: 3.0L
• Configuration: Inline-6 
• Max. Horsepower: 277 hp @ 3,750 rpm
• Max. Torque: 460 lb-ft @ 1,500 rpm
• Bore x Stroke: 3.30 x 3.50 inches
• Valvetrain: DOHC Design 4 valves per cylinder
• Engine Weight: 467 lbs (dry)
• Aspiration: Single ball bearing, liquid cooled variable geometry turbocharger (VGT)

Duramax vs Cummins vs Power Stroke Reliability

Few can argue against the fact that each of the diesel industry’s top-three manufacturers (Duramax, Cummins, and Power Stroke) have produced their share of fine engines. However, not all such offerings are created equally.

In terms of reliability, it is difficult to find any better value than those engines produced by Cummins. From the earliest 6BT 12-valve to today’s 6.7L inline-six, reliability has always been a strong suit of Cummins production.

However, one would be misguided to overlook the merits of numerous offerings from Duramax and Power Stroke. Both manufacturers produce stellar engines, as long as a consumer comes to the table well-informed.

While the 7.3L and 6.7L Power Stroke V8 both receive high praise from the bulk of consumers, opinions of the 6.0L and 6.4L Power Stroke tend to be far more negative.

Likewise, earlier Duramax engines experience a wealth of costly fuel injector failures, though such issues are now long since a thing of the past. 

Regardless, it is safe to say that the bulk of consumers will find significant favor in any of the ten diesel engines we have covered. Each has proven itself outwardly reliable, and more than capable of handling the bulk of tasks that can be asked of it.

If you, yourself, are considering the purchase of a diesel-powered pickup, look no further than any model featuring one of the engines above.

Best Diesel Engine Comparison Chart

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Josh Boyd

Josh has worked as a full-time mechanic for over 12 years, with 6 ASE (Automotive Service Excellence) certifications under his belt. He began his career as an automotive technician at local Toyota dealership and has since transitioned to specializing in diesel trucks and equipment.

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