It has taken four years, but Isuzu’s much-awaited 1.9-litre diesel engine has finally come to Malaysia powering the updated 2019 D-Max.

136PS, 280Nm; those were the outputs of the previous-generation Isuzu D-Max 3.0 phased out less than a decade ago. Even by the standards of the time, they were hardly competitive numbers – every one else, bar the Toyota Hilux, had smaller engines that were comfortably faster.

That comparative lack of performance had never troubled Isuzu or their loyal customers, however, as the D-Max was renowned for its strength in other areas, namely mechanical robustness, ease of maintenance, and parsimonious fuel economy. These traits are made possible because Isuzu deliberately gave their engines highly under-stressed tunes allowing them to operate in extremely relaxed fashion.

Pushing out 150PS and 350Nm from its diminutive capacity, the new D-Max 1.9 is comfortably faster than the 2.5-litre model it replaces. Apart from the Ford Ranger’s aggressively-tuned 2.0-litre Puma mill, no other powerplant in the segment pushes out more horsepower or torque per litre of displacement than Isuzu’s cili padi engine.

Such gains don’t come easily, of course, especially not if Isuzu’s reputation of bomb-proof durability is to be maintained. Extensive efforts were made to lighten, strengthen, and smoothen every inch of the engine to ensure that it meets Isuzu’s targets for both performance and reliability. The block, for example, is 13% stiffer than that of the outgoing 2.5-litre, whilst the pistons are coated with graphite along its sides to minimize cold start wear.

Redefining Expectations

They are also known to be highly over-engineered. Alongside Toyota, Isuzu’s engines are known to be amongst the toughest in the business, easily tuned to double its factory-rated outputs on stock internals without incurring any reliability issues.

So, whilst the likes of the Ford Ranger and Mitsubishi Triton earn plaudits for their technology and passenger car refinement, the D-Max majors on being the workhorse you can count on even after prolonged and unrelenting abuse.

This tried and tested formula has served Isuzu well for many years, so it came as a major surprise when the company rolled out a 1.9-litre engine to replace the proven 2.5-litre 4JK1 powerplant. Like every new engine in this era of downsizing, the new Isuzu mill comes with all the usual promises of small engine fuel economy without sacrificing big engine performance.

Being the smallest engine in the market and by a significant margin over the accepted average of 2.4 to 2.5 litres, the Isuzu 1.9 breaks new ground for both the company and the pick-up truck segment as a whole. Even the engine code – RZ4E – follows a changed convention to imply its significance.

The new engine, … no, wait, it’s not exactly new. It has actually been four years since its launch, but the reason it has taken Isuzu this long to introduce it to Malaysia is a combination of overwhelming demand and additional engineering work needed to adapt it for our local conditions. There is the dirty fuel to contend with, for one, and Isuzu also wanted to run extra tests on the engine’s performance and durability over our hilly roads.

Thanks to a combination of reduced sizing and more advanced construction materials, Isuzu was also able to make the 1.9 a full 56kg lighter than the outgoing 2.5. According to Isuzu, those weight savings immediately translate to higher payload, meaning the new D-Max 1.9 will carry up to 50-60kg more stuff than its predecessor. More interestingly for us, with 56 fewer kilos pressing on the front axle, it promises a more nimble handling and better-balanced weight distribution.

And it shows.

Through sweeping bends, the D-Max 1.9 demonstrates impressive athleticism, changing direction with astonishing eagerness. The typical understeering tendencies of a pick-up charging into corners is instead replaced by an alert front end that goes the way you point the steering without complaint or fuss.

Of course, the most pressing question this truck needs to answer is, can it convincingly play ball with the bigger engines in the segment? Can you really get 2.5-litre performance for just half the road tax?

For the most part, the tiny motor copes with its demands admirably, and it does so without the typical feeling of thrashiness you get from overworked, undersized engines. In other words, it burns with a smoothness that is almost reminiscent of a bigger engine. Overall, I’d say Isuzu’s claim of improved refinement is absolutely legit.

Are there moments that expose the engine’s lack of size? Moments reminding us of the futility of replacing displacement? Because the engine is still just a 1.9 and there are places on the tachometer that the turbocharger can’t work. There are, but they are fleeting, and mostly mitigated by some clever engineering on Isuzu’s part.

Helping the engine to better exploit its taller but narrower torque curve is a pair of new transmissions; both manual and automatic, with six forward ratios as opposed to just five that the 3.0 is still making do with. They help the driver keep the engine boiling and on-boost as much as possible. With the manual, Isuzu even built in a feature that amplifies throttle input on slopes for smoother take-off.

As a whole, the new 1.9 engine turned out to be more than an adequate replacement for the old 2.5 4JK, and it managed to exceed expectations despite overwhelming anticipation. It is far from the fastest truck in the market, but it has more than enough for you to get by responsibly.

There are certain situations and usage where you will find yourself needing a bigger engine, but these are conditions for which we would have recommended the 3.0 anyways. For most of us, the new D-Max 1.9 offers all the performance you’ll need from a pick-up and puts a smile on your face every year to the tune of RM399.20.

Words Kon, Pictures TJ