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Modern day diesel engines have come a long way from Rudolf Diesel’s peanut oil sipping invention in 1893. Historically, diesel engines have been smelly, noisy and dirty. But with the advent of new technology in engine management, emerging economies, and even Europe for a time, adopted diesel motors for their efficient power production and range per given liter of fuel.
As work horses, diesel-powered trucks have been the logistic backbone of many countries around the world. Here in the Philippines, diesel engines remain a mainstay because of the relative lower prices of diesel fuel versus gasoline. Jeepneys, buses, trucks, even boats and heavy equipment such as excavators, forklifts, tractors and generators mostly run on diesel fuel, or what we affectionately call, “krudo.”
In the pickup and commercial vehicle markets, diesel engines have continued to power both industry-leading segments, albeit with better environment-friendly credentials and superior performance compared to diesel engines from even a decade ago.
One company that has led the evolution of diesel engines around the world is Isuzu. Originally known as Ishikawa Automotive Works, Isuzu’s expertise in diesel engine manufacturing stems from its early collaboration with DAT Automobile Manufacturing Incorporated (a predecessor of Nissan) in 1933. Three years later, the joint venture would yield the company’s first two diesel engines models – the DA6 and the DA4.
The DA6 was Japan’s first air-cooled diesel motor for practical applications. And since the company, Tokyo Automobile Industries, was designated by the government as the sole diesel engine manufacturer in Japan, it enjoyed a headstart and a strong foundation to lead the development of diesel engine technology in the country, and around the world.

After World War II, the company, now renamed Isuzu Motors, the name of which was derived from a famous river in Japan, developed the DA80 diesel engine. This also happened to be Japan’s first V8 mill.
Through these early years, Isuzu was also able to develop pre-combustion chambers for its diesel engines. And from this method of indirect injection to the precursor of today’s direct injection, Isuzu was at the forefront of these technologies honed during the post-war era.
Isuzu’s leadership in diesel-engine technology continued on through the 1960s as well. Japan’s first diesel engine for passenger cars, the DL201 was developed by Isuzu in 1961. And in 1964, the DL200 engine powered the Elf, Japan’s first cab-over light-duty truck. This combination has earned a solid reputation for the Elf as a reliable, fuel-efficient workhorse, a reputation it holds to this day.
The global financial and oil crises in the 1970s saw a further evolution of the diesel engine under Isuzu’s charge. With emerging concerns on engine noise and emissions and the demand for energy-saving measures at the time, Isuzu released the low-emission, light-weight and high output PA diesel engine for trucks and tractors.
By 1981, Isuzu launched the high-torque, fuel-saving turbo-charged 8PB1-T and 6RA1-T engines as its answer to the growing public demand for low pollution, high output and good fuel economy engines. And in 1983, Isuzu introduced advanced diesel technologies in the electronically controlled 6RA1-TC turbo-charged model which incorporated intercooled design.
A familiar sight in the Philippines during the early ‘80s was the Isuzu Gemini. This and the Isuzu Florian were the company’s response to the demand for diesel-engine passenger cars. Because of their durability and fuel economy, the Isuzu Gemini became a mainstay in the taxi and fleet services in the Philippines during that era.
Isuzu would continue to develop and adopt more groundbreaking diesel engine technologies as the years went by. In 1981, Isuzu introduced the direct-injection design, which features both high output and low fuel consumption, to all diesel engines installed in two-ton payload trucks. It was also Isuzu that developed the world’s first full-scale electronically controlled diesel for both light- and heavy-duty trucks.
The company would also lead the development in ceramics technology for diesel. This led to the world’s first Ultra Quick on Start system introduced also in 1981. With the use of a ceramic glow plug with high heat resistance and electronic control, Isuzu eliminated the practice of preheating time during start-up. Something we take for granted in diesel-fed engines today.
Isuzu’s diesel-engine prowess has led to many collaborations with various manufacturers. General Motors, Land Rover, Toyota, Mazda and even fellow diesel-expert Cummins, have come to rely on Isuzu’s expertise.
One Isuzu model that has benefitted strongly from this body of diesel engine knowledge is the all-new Isuzu D-MAX pickup. Isuzu’s latest engine, the RZ4E, powers the latest iteration of the D-MAX 4X2. It is a mere 1.9-Liters in displacement but produces power more efficiently than its 2.5-Liter predecessor.


Combining Isuzu’s diesel technology honed over the years, the D-MAX 4×2 now enjoys the benefits of a 62-kilogram engine weight loss, redesigned swirl-inducing combustion chamber, graphite coated pistons for reduced piston wear on cold starts, and Diamond Like Carbon (DLC) coated piston pins.
Isuzu also poured its know-how on reducing vibration and noise, two common issues with older diesel engines, in the RZ4E. A lighter, high-stiffness, long-skirt design cast-iron cylinder block, along with a cylinder head camshaft cover crafted from resin, provide a more refined operation while increasing performance.
Designed for increased durability, the RZ4E also makes use of connecting rods and their caps forged from a single piece of metal. This Fracture-Split manufacturing method ensures precise fit between the cap and its corresponding rod, leading to improved reliability.
Combined with the latest in Variable-Geometry Turbo technology, performance in slow and high-speed scenarios have likewise been improved with the RZ4E. Along with maintenance innovations such as paper filter cartridge replacement in lieu of oil filter canisters, the use of Hydraulic Valve Lash Adjusters which eliminates manual valve clearance adjustments, and a Single Accessory Drive belt, which takes away multiple drive belts from the early diesel engine designs, all contribute to ease of ownership over the long run.
From its smallest 1-Liter diesel engine used in a mini-backhoe, to its largest, a 30-Liter house-sized engine used in heavy-duty tractors, Isuzu has become synonymous with reliable, eco-friendly, durable and technologically-advanced diesel power. And its latest D-MAX is the prime example of how far Isuzu diesel technology has come over the last 90 years.
With more than 28 million diesel engines produced today, Isuzu’s dominance in the realm of diesel engine technology and manufacturing is a reassuring fact that underlies every Isuzu pickup and 7-seater SUV, as well as its range of light and heavy-duty trucks around the world. There are only a handful of companies around the world that can claim expertise in this evolving technology. Isuzu just happens to be top of mind.

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