best diesel engine

Best Diesel Engine  – 10 Most Reliable Units on the Market

Before diesel engines became must-have in heavy-duty trucks, they could be found in ships, submarines, and trains. Primarily used in the shipping industry, this engine was invented in the late 19th century by a Rudolf Diesel. In the ‘70s, diesels became even more in-demand when gas prices escalated. In an attempt to combat rising fuel prices, vehicle makers started offering diesel engines as they claimed better fuel efficiency and higher miles per gallon.



Still, if a diesel motor isn’t adequately maintained or serviced, it can cause several problems, either internal or external issues. A poorly serviced diesel engine can potentially cause issues with the internal combustion system and can easily damage the entire system. Here is the list of the 10 best diesel engines from top manufacturers.


1. 6.6L Duramax LB7 – Overall Best Diesel Engine

The LB7 Duramax was originally introduced in 2001 as GM retired its 6.5L Detroit diesel. The Duramax was superior to the outdated Detroit and marked a revolutionary turning point for Chevrolet and GMC pickups in the diesel marketplace. The engine is unique to other Duramax units as it predates emissions regulations. As such, it’s praised for reliability and has been regarded as a particularly economical variation of the engine.

The LB7’s applications are in the GMC Sierra HD, GMC TopKick (medium duty), Chevrolet Silverado HD, and Chevrolet Kodiak (medium duty). As impressive as General Motor’s new engine platform appeared, the LB7 had issues with fuel injectors failing. Injector failures were so often that GM was forced to recall these units and replace them with an updated design. In addition, to give loyal customers with a sense of reassurance, the warranty was extended to cover the new injectors for up to 200k miles.

Specs

  • Displacement: 6.6L;
  • Layout: V-8;
  • Power: 300 hp;
  • Torque: 520 lb-ft;
  • Bore x Stroke: 3.87 x 4.13 inches;
  • Valvetrain: OHV with 4 valves per cylinder;
  • Engine weight: 835 lbs;
  • Aspiration: Turbocharged and intercooled.
6.6L Duramax LB7 – Overall Best Diesel Engine

2. 6.7L Power Stroke – Best Ford Diesel Engine

The 6.7L Power Stroke is an in-house built engine for the Ford Super Duty – most reliable diesel truck engine. Ford designed, engineered, and produced its own diesel engine to maintain profitability and a competitive edge in the growing diesel segment. This’s the first Power Stroke not manufactured by longtime partner, International Navistar.

For 2020 Ford presented the 3rd Generation 6.7L Power Stroke diesel, rated at a high peak 1,050 lb-ft of torque and 475 hp. While the revised engine includes several significant changes, the most notable is its new piston design. The engine uses a steel piston with a relatively short overall height. Reducing the height of the piston recompenses for the increased weight of steel, much heavier material than the previous aluminum design. The result is a piston that’s in weight to the pre-2020 piston. Still, it has improved strength/resilience and lower friction thanks to its smaller profile.



Specs

  • Displacement: 6.7L;
  • Layout: V-8;
  • Power: 475 hp;
  • Torque: 1,050 lb-ft;
  • Bore x Stroke: 3.89 x 4.25 inches;
  • Valvetrain: Conventional pushrod OHV with 4 valves per cylinder;
  • Engine weight: 1,100 lbs;
  • Aspiration: Single VGT turbocharger.
6.7L Power Stroke – Best Ford Diesel Engine

3. 7.3L Power Stroke – Best Powerstroke Engine

The 7.3L Power Stroke diesel is engineered as the replacement for the aging 7.3L IDI. Even though the engines share the same displacements, the designs are entirely different. It’s a turbocharged, direct injection diesel engine manufactured by International Navistar. The “Power Stroke” trademark belongs to Ford, so you’ll only find the 7.3 “Power Stroke” in Ford applications.

The 7.3L Power Stroke turbodiesel is famous for its HEUI (hydraulic electric unit injector) injection system, which utilizes highly pressurized engine oil as a medium for making fuel pressure directly in the injector body, as opposed to a system needing a typical injector pump. Instead of an injection pump, the 7.3L Power Stroke uses a high-pressure oil pump (HPOP) and a low-pressure lift pump to produce fuel pressures up to 21,000 psi.

Specs

  • Displacement: 7.3L;
  • Layout: V-8;
  • Power: 275 hp;
  • Torque: 525 lb-ft;
  • Bore x Stroke: 4.11×4.18 inches;
  • Valvetrain: OHV (overhead valve) with 2 valves per cylinder;
  • Engine dry weight: 920 lbs;
  • Aspiration: Single turbocharger, Garrett GTP38 (wastegated).
7.3L Power Stroke – Best Powerstroke Engine

4. 6.6L Duramax LP5 – Best Year Duramax Diesel Engine

GM highly anticipated reveal of the next generation Duramax diesel was momentarily interrupted by inadvertently publishing details of the engine’s torque and horsepower figures through General Motor’s website. The Duramax L5P features many improvements and upgrades that produce 445 horsepower and 910 lb-ft of torque in addition to managing the rigorous conditions experienced under such loads.

Although the engine measures in at 6.6L of displacement (using the identical cylinder bore and stroke-like previous generations), it’s not far from being characteristically classified as a new design. The Duramax L5P replaced the outgoing LML for the 2017 model year GMC Sierra HD pickups and Chevrolet Silverado.

Specs

  • Displacement: 6.6L;
  • Layout: V-8;
  • Power: 445 hp;
  • Torque: 910 lb-ft;
  • Bore x Stroke: 4.05 x 3.89 inches;
  • Valvetrain: OHV with 4 valves per cylinder;
  • Engine weight: 1,100 lbs;
  • Aspiration: Electronically controlled and actuated variable geometry turbocharger.
6.6L Duramax LP5 – Best Year Duramax Diesel Engine

5. Chrysler 3.0L EcoDiesel – Best Small Diesel Engine

The 3.0L EcoDiesel entranced in the 2014 Ram 1500 and Jeep Grand Cherokee, where it became the first factory-direct diesel engine solution in a 1/2 ton pickup in more than a decade. The 3.0L EcoDiesel is produced by VM Motori, an Italian manufacturer and current subsidiary of FCA, in Cento, Italy. Though the EcoDiesel remains available in the Ram 1500, it was retired in Jeep Grand Cherokee applications following the 2019 model.

From 2014 through 2019, this 4 cylinder diesel engine was rated at the peak of 240 horsepower and 420 lb-ft of torque. The EcoDiesel was revised for 2020, likely thanks to competition from General Motors and Ford Motor Company, which increased power by 20 horsepower and torque by 60 lb-ft in addition to enhancing the fuel economy ratings for both two- and four-wheel drive models.

Specs

  • Displacement: 3.0L;
  • Layout: V-6;
  • Power: 240 hp;
  • Torque: 420 lb-ft;
  • Bore x Stroke: 3.27 x 6.30 inches;
  • Valvetrain: DOHC with 4 valves per cylinder;
  • Engine weight: 505 lbs;
  • Aspiration: Turbocharged and intercooled.
Chrysler 3.0L EcoDiesel – Best Small Diesel Engine

6. 6.6l Duramax LBZ

The LBZ boats more aggressive engine tuning, yielding a substantial increase in horsepower and torque over its predecessor (LLY). This four-cylinder diesel engine produces 360 horsepower and 650 lb-ft of torque to the LLY’s 310 horsepower and 605 lb-ft. By mid-model year for ’07, the LBZ was efficiently replaced by the emissions compliant, diesel particulate filter equipped LMM.

The 6.6L Duramax LBZ’s applications included the GMC Sierra HD, GMC TopKick, Chevrolet Silverado HD, and Chevrolet Kodiak. In the aftermarket, the LBZ is extremely popular for its excellent performance potential, an abundance of support, and the fact that it’s the last model manufactured without a diesel particulate filter. Information released by GM at the introduction of the LBZ state that the engine has an increased piston pin diameter and thicker connecting rod section over previous generations in addition to an enhanced block casting.

Specs

  • Displacement: 6.6L;
  • Layout: V-8;
  • Power: 397 hp;
  • Torque: 910 lb-ft;
  • Bore x Stroke: 4.06×3.90 inches;
  • Valvetrain: OHV (overhead valve) with 4 valves per cylinder;
  • Engine weight: 835 lbs;
  • Aspiration: Single turbocharger, Garrett GTP38 (wastegated).
6.6l Duramax LBZ



7. Cummins 6.7L Engine for RAM

The 6.7L Cummins is the newest of the B-series engine lineup, introduced mid-model year in 2007. Replacement of the former 5.9L ISB was required as the result of stricter Federal emission standards and the need for a more competitive platform to permit future growth under growing industry constraints.

It’s the first Cummins to require a DPF (diesel particulate system), which captures more than 90% of soot from the exhaust stream and cleans itself via a process known industry-wide as “regeneration.” For the 2019 model, the revised 6.7L Cummins set an industry record by scoring the 1,000 lb-ft benchmark in torque output. Also, it’s the best diesel pickup engine for pulling or hauling heavy loads.

Specs

  • Displacement: 6.7L;
  • Layout: V-6;
  • Power: 275 hp;
  • Torque: 1000 lb-ft;
  • Bore x Stroke: 4.21 x 4.88 inches;
  • Valvetrain: OHV with 2 valves per cylinder;
  • Engine weight: 1,060 lbs;
  • Aspiration: Turbocharged and Charge Air Cooled.
2019 Ram Heavy Duty – 6.7-liter I-6 Cummins with 400 hp and 1000 lb.-ft of torque

8. Cummins 5.0L

Exhibited at the 2015 North American International Auto Show in Detroit, Michigan, the Nissan Titan XD’s development can be traced back to August 2013 when both engine manufacturer Cummins and automaker Nissan Motors confirmed they had partnered to install a 5.0L Cummins turbodiesel to the Titan pickup truck platform. The 4 cylinder Cummins diesel engine was previously offered to FCA’s Ram Truck division, who turned down the engine in favor of a smaller, more fuel effective engine from Italian manufacturer VM Motori.

A fully boxed “ladder” frame is used to deliver sufficient structural integrity for the Titan’s tow ratings, which surpasses 12,000 lbs on adequately equipped trucks. The core of the Nissan XD is Cummins’ 5.0L V-8, which generates a maximum of 310 horsepower and 555 lb-ft of torque.

Specs

  • Displacement: 5.0L;
  • Layout: V-8;
  • Power: 310 hp;
  • Torque: 555 lb-ft;
  • Bore x Stroke: 3.70 x 3.54 inches;
  • Valvetrain: DOHC with 4 valves per cylinder;
  • Engine weight: 889 lbs;
  • Aspiration: Turbocharged and intercooled.
Cummins 5.0L

9. 6.6L Duramax LML

The LML Duramax debuted in 2011 model Chevrolet HD and General Motors trucks. The latest variant of the 6.6L Duramax needs advanced emissions equipment, including the use of diesel exhaust fluid injection, to minimize nitrogen oxide emission levels by 63% over LMM powered trucks. It enables this 4 cylinder diesel to exceed currently mandated federal emissions requirements and potentially meet future requirements too.

Rated at 765 lb-ft of torque and 397 hp, the LML is significantly more potent than any prior Duramax. GM blindsided Ford with the release of these numbers, which were exposed shortly after Ford’s 6.7L Power Stroke became available.

Specs

  • Displacement: 6.6L;
  • Layout: V-8;
  • Power: 397 hp;
  • Torque: 765 lb-ft;
  • Bore x Stroke: 4.03 x 3.90 inches;
  • Valvetrain: OHV with 4 valves per cylinder;
  • Engine weight: 889 lbs;
  • Aspiration: Turbocharged and intercooled.
6.6L Duramax LML

10. 6.4L Power Stroke

The 6.4L Power Stroke was introduced for the 2008 model Ford Super Duty trucks . Strict emissions regulations and the overall questionable dependability of the 6.0L were x-factors that demonstrated a need for new, fresh engine design. Cleaner and quieter than its predecessors, the 6.4L Power Stroke was the first engine introduced to the market that used twin turbochargers from the factory and stayed the only engine to have such a turbocharger arrangement.

This’s also the first Power Stroke that utilizes a DPF to nearly eliminate particulate emissions. The new DPF and active regeneration system hugely hindered the engine’s fuel economy capability. However, the 6.4L Power Stroke has proved to be comparatively reliable and strong.

Specs

  • Displacement: 6.4L;
  • Layout: V-8;
  • Power: 350 hp;
  • Torque: 650 lb-ft;
  • Bore x Stroke: 3.87 x 4.13 inches;
  • Valvetrain: OHV with 4 valves per cylinder;
  • Engine weight: 1,130 lbs;
  • Aspiration: Turbocharged, twin sequential turbochargers, intercooled.
6.4L Power Stroke

Powerstroke vs Cummins vs Duramax Reliability

What sets the Powerstroke vs. Duramax vs. Cummins diesel engines apart from each other? How did these 3 most reliable diesel engines become some of the greatest components of machinery ever produced? Let’s take a look at the Cummins, Powerstroke, and Duramax best diesel engines.

While the 6.7L Power Stroke and 6.7L Cummins share the same displacement, the 6.6L Duramax is a pretty close match. Both the 6.7L Power Stroke and 6.6L Duramax are V8 engines, with the 6.7L Cummins being an inline six-cylinder diesel engine.

Horsepower and torque numbers are similar between the three diesel engines, but the Cummins engine leads the pack with its torque rating breaching the four-figure threshold. Other differences include engine cylinder and blockhead construction, bore and stroke, the compression ratio, along with the firing order. Still, they share similar fuel systems.



Cummins vs Powerstroke vs Duramax

Specs 6.7L Cummins Diesel I6 6.6L Duramax L5P V8 6.7L Power Stroke V8
Displacement 408 cubic inches, 6.7 liters 403 cubic inches, 6.6 liters 409 cubic inches, 6.7 liters
Configuration I6 V8 V8
Valvetrain OHV – 24 valve, 4 per cylinder, solid lifter camshaft OHV – 32 valve, 4 per cylinder, mechanical roller lifters Pushrod OHV – 32 valve, 4 per cylinder, cam-in-block
Bore x Stroke 4.21 x 4.88 inches 4.055 x 3.897 inches 3.90 x 4.25 inches
Firing Order 1-5-3-6-2-4 1-2-7-8-4-5-6-3 1-3-7-2-6-5-4-8
Compression Ratio 16.2:1 16.0:1 16.2:1
Horsepower 400 horsepower 445 horsepower 450 horsepower
Torque 1,000 lb.-ft. 910 lb.-ft. 935 lb.-ft.
Fuel Ultra-low sulfur diesel and B20 biodiesel Ultra-low sulfur diesel and B20 biodiesel Ultra-low sulfur diesel and B20 biodiesel
Engine Block Compacted graphite iron Cast Iron Compacted graphite iron
Cylinder Heads Cast Iron Cast Aluminum Aluminum
Fuel System Direct injection with high-pressure common rail Direct injection with high-pressure common rail Direct injection with high-pressure common rail

What is the Best Diesel Engine Ever Made?

The most reliable diesel engine ever made was the 5.9L Cummins 12-Valve 6BT. This unit has million-mile durability, and it arrived factory with a 230 horsepower, 440 lb-ft of torque, and an inline P7100 injection pump. Diesel enthusiasts from the era of the 6BT could boost horsepower to over 500 horsepower with ease.

The engine had an outstanding performance and fuel efficiency rating. It’s almost guaranteed to last over 500k miles. Its fuel consumption rate was about 20 mpg on the highway.

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