under the hood

What engine is in the Isuzu mux?

The new engine from Isuzu, which can be found under the hood of the D-MAX pick-up and the mu-X SUV, is truly interesting. It’s tiny by the standards of the class but has the performance not only to keep pace with the competition but lead. 

How did Isuzu perform this feat of automotive engineering and what makes this RZ4E the undeniable pound-for-pound champion of diesel engines? 

Adding options for car-buyers is a great move for a brand, as it gives the consumers choices that will fit their wants and needs. Isuzu Philippines Corporation (IPC) recognizes that and brings in the mu-X 1.9 RZ4E to the local showrooms. Its arrival came just in time, as it’s bound to replace the non-Euro 4-compliant 2.5 variants in IPC’s lineup.

Those who are shopping for a mu-X are now facing a tough choice — should they go for more power with the 3.0 or the smaller but more frugal 1.9? If you’re eyeing the latter, IPC gave us the chance to review both its manual and automatic transmission LS-A variants before its official launch. Here are our thoughts.

Sophisticated in every way

There was a time when most of us needed a desktop computer to get a job done; devices that were big, heavy, and not mobile. Today’s smartphone can do more, achieving the feat with sophisticated technology and design, and they can all fit in our pockets. The RZ4E follows that same idea of innovation. 

As early as the 2000’s, Isuzu was already pursuing technology that would make their engines more powerful, more efficient, more environmentally-friendly, and more compact. To do so, they designed an engine that was just 1.9-litres in displacement surpassed the performance of the 2.5L 4JK1 engine.

Isuzu’s extensive history and expertise in the design and production of diesel engines was focused upon the development of the RZ4E engine.

Utilizing Isuzu’s original analytical technology, Isuzu engineers redesigned the combustion chamber to achieve the most efficient mixture of the air and fuel as well as creating the optimum swirl to maximize engine performance while reducing fuel consumption and exhaust emissions.

The RZ4E engines have “graphite coated” pistons, which dramatically reduce piston wear during cold engine starting. The piston pins (gudgeon pins) are coated with Diamond-Like Carbon (DLC), which is a human-made anti-friction material, designed to be effective under high temperatures and high pressure.

All these features and more, coupled with a 6-speed transmission that assists in improving fuel efficiency and lowering CO2 emissions, make the RZ4E one of the most sophisticated turbo diesels in the market

Light makes right 

One key difference of the RZ4E engine is its weight or lack of it.

Even with its many features and sophisticated technologies, the RZ4E is much lighter than the larger Isuzu 4JK1 engine by 62 kilos.

Let’s put that in perspective. You know those 5-gallon jugs of water we commonly have at home? If you’ve lifted one, you’ll know that each one is heavy: about 20 kilograms. So, Isuzu was able to reduce the weight equivalent of three 5-gallon jugs full of water. We don’t even have to look further than the weight of the average Filipino male: which is just at 61.3 kilograms according to the National Nutrition Survey. 

Less weight means better performance and better overall fuel efficiency.

Smoother and quieter

Diesels of the past have been known for being much louder than their gasoline counterparts. They were also known for their vibrations, and contrary to the popular song, not the good kind. But Isuzu is changing all those perceptions with the RZ4E. 

Being the specialists of diesel engines, Isuzu used all of their decades of experience, as well as new technologies put forth by their research and development departments for the RZ4E. Being a smaller and lighter engine -and featuring advances in diesel engine design and development- Isuzu was able to make the RZ4E run smoother and quieter than larger engines like the 4JK1.

A resin cylinder head camshaft cover and high-stiffness cast iron cylinder block results in reduced noise, vibration, and improvements in structural damping of the cylinder block. The RZ4E cylinder block is manufactured from cast iron and utilizes the “Long Skirt” design. These two features result in a light, rigid and stiffer cylinder block. The customer benefit is reduced noise, vibration, and harshness. A lighter cylinder block means an increase in payload and an increase in performance.

Stronger and more durable

A key aspect of the RZ4E is that it’s engineered to have increased engine life, increased performance, and a lower cost of ownership.

The components are made stronger -therefore, more durable- than before. Conventional connecting rods and their adjoining end caps are separately forged and machined. The RZ4E, however, has Fracture-Split connecting rods and are manufactured quite differently. The connecting rod is forged as a single piece of metal. Next, using specialized equipment, the cap is then literally “snapped” from the rod. This process results in an uneven fracture surface on the rod and cap parts. This uneven surface allows for a more precise, durable cap-to-rod fit versus the conventionally manufactured connecting rods. The Fracture Split method improves engine reliability and decreases power loss because the accuracy of the inside diameter of the big end is improved due to the improvement in the positioning accuracy between the cap and the rod.

Variable Geometry Turbocharger System (VGS) works to precisely and efficiently control the turbocharger system, based upon intake air volume. The VGS overcomes the lack of turbocharger performance associated with low engine rpm when there is very little exhaust flow from the engine. The turbocharger’s turbine is made from a high-temperature resistant material for longer life. The turbocharger’s central body is water-cooled for reliability, longer component life, and low cost of ownership

Easy Serviceability

The Hydraulic Valve Lash Adjuster maintains the correct valve lash clearance without the need for adjustment. This also improves performance and reduces service costs. A Single Engine Accessory Drive-belt eliminates the need for multiple drive-belts for components such as the alternator and air-conditioning compressor. The auto-tensioner maintains the correct drive-belt tension to ensure correct operation and minimizes drive belt wear for increased component service life.

The Cartridge-type Oil Filter is an ecological feature. Instead of discarding a metal canister with fixed paper element “spin-on” type oil filter when changing the engine oil filter, the RZ4E oil filter is a paper cartridge type. When replacing the RZ4E oil filter, only the paper element is replaced.

As for emissions, the RZ4E has Blue Power technology, making it conform to cleaner Euro-4 emissions standards.

Do just as much, with less

The key thing about RZ4E is its performance and efficiency. It is normal to think that such a small engine will be unable to produce the power and torque required by the D-MAX and mu-X, but thanks to Isuzu’s advanced engineering, that is not the case.

When compared to the 2.5-litre 4JK1-TC which produces 136 PS and 320 Newton-meters of torque, the smaller 1.9-litre RZ4E produces more power at 150 PS and 350 Newton-meters of torque. 

Perhaps the best part about the RZ4E is its fuel efficiency. Previously, the 4JK1-TC was the most efficient engine in certain variants of the D-MAX and mu-X, but the RZ4E takes that same fuel economy several steps further.

During a fuel economy test conducted by Isuzu Philippines Corporation to conform to Department of Energy (DOE) standards and verified by the Automobile Association Philippines (AAP), the new RZ4E-equipped mu-X models proved to be a force for fuel economy runs. The Isuzu mu-X RZ4E 6-speed manual did much better, able to achieve 37.27 kilometres to a litre, a 14.3% improvement over the manual gearbox variant of the 2.5L 4JK1 model. The Isuzu mu-X RZ4E LS-A 6-speed automatic variant was able to deliver an even better fuel economy of 35.8 kilometres per litre, a 48% improvement over the previous 2.5-litre 4JK1 5-speed automatic variant.  

This sophisticated 1.9-litre RZ4E is truly a revolution for turbo diesel engines. Isuzu gave it the performance of much larger engines through technology. They made it smoother, quieter, and lighter. They even gave it an outstanding fuel economy and far better eco-friendliness to match. Like a pound-for-pound champ, Isuzu built the RZ4E to punch way above its weight class. 

Innovative Engine Technology

Totalling four years of test and development, the Isuzu RZ4E engine has a displacement of 1.898-litres, capable of producing maximum power of 150 PS at 3,600 rpm and a maximum torque of 350 N-m from 1,800-2600 rpm – and is EURO 4 compliant.

New technological features include a well-design combustion system, composed of Diamond-Like Coated (DLC) piston pins, coupled with a clothoid curve combustion chamber, new fracture-split design connecting rod and DLC fuel injector needles – which are all put together to decrease engine friction thus promoting improved fuel economy and lesser exhaust emissions.

Aside from the combustion system, the RZ4E also has a new water-cooled Variable Geometry Turbocharger system, that ensures that the engine has excellent throttle response even at low rpm. The turbocharger’s turbine is made from high-temperature resistant material while the central body is water-cooled for durability.

For ease of maintenance, the new RZ4E engine has a Hydraulic Valve Lash Adjuster (HVLA) which keeps the correct valve lash clearance, a Single Engine Accessory Drive-belt for the alternator and air-conditioning compressor and a cartridge-type oil filter, which is another one of its ecological features that eliminate discarding of the metal canister by replacing only the paper element of the filter.

Under the hood of the Isuzu mu-X RZ4E is a new 1.9-litre, 4-cylinder in-line Blue Power turbo diesel engine that is capable of producing 150 PS of power and 350 Nm of torque. These figures are mated to a 6-speed automatic transmission with Sequential.

The suspension set up is made of Independent Double Wishbone with Coil Spring and Stabilizer at the front, and the back is equipped with Five-link Coil Spring and Stabilizer Bar. For the brakes, the variant we have here comes with four-wheel ventilated disc brakes, so there’s no worry putting the car at a stop without a fuss.

Let’s go to the mu-X’s exterior features.

At a glance, it’s worth noting that the mu-X comes with an aggressive and modern design. The grille houses a set of angular Bi-LED Headlamps with Auto Leveling Function and DRL, giving the front fascia of the mu-X that tough touch. Meanwhile, the rear is highlighted by a pair of Horizontal Rear Combi Lamp with LED Positioning Lamp. These 18-inch Aluminum Alloy Wheels complete the whole look of the mu-X.

Inside, it looks as modern as the outside. It’s evident that Isuzu has slightly tweaked some details. Aside from the new colours and materials, these new Blue Ambient Lamps on the door panels allow the car to be cozy for passengers. Also, for a seven-seater, the mu-X has ample space for everybody to move comfortably. For the seats, our model here is equipped with Bucket Seats with back pockets and adjustable headrest in the first row. Meanwhile, in the second row, it comes with a 60/40 split-folding bench type with centre armrest and three-adjustable headrests. The third row gets a 50/50 split-folding bench type with two-adjustable headrests.

At the heart of the mu-X’s interior is the infotainment system. Comes equipped with an 8-inch touchscreen display that is available with CD, DVD, Aux-in, USB, MP3, and Bluetooth connectivity, entertainment is not a problem when aboard the mu-X. Moreover, audio is an enjoyable courtesy of 6 speakers. There’s also a 10-inch Roof Mounted Monitor with Remote Control for the passengers at the back.

Excellent Fuel Economy

Given its new design and quite a number of new engine parts installed, the new RZ4E performs efficiently which has been proven in the recent fuel-efficient testing conducted by the company.

During their testing, IPC conducted their test using the Isuzu mu-X RZ4E LS-A variants running alongside its current Isuzu mu-X 2.5L variants which presently runs economically based on the previous testing.

The Isuzu mu-X RZ4E LS-A MT records 37.27 km/l which is up to 14.32% improvement from the 2.5-litre variant (32.60 km/l), while the Isuzu mu-X RZ4E LS-A AT logs a total of 35.80 km/l that is up to 48.36% higher than the 2.5-litre variant (24.13 km/l).

The test is conducted under the supervision and verification of the Automobile Association Philippine (AAP) following the Department of Energy (DOE) testing parameters and standards.

“Our 2.5-litre engine as it is, is already fuel-efficient, but with the introduction of the new Isuzu RZ4E engine, our Isuzu mu-X model now is made smarter by performing at a higher capacity under lower fuel consumption,” said Koso.

New Smart & Functional Variants

The new Isuzu RZ4E Blue Power engine is set to replace Isuzu’s existing 2.5-litre variants and will be made available for both the Isuzu mu-X and D-MAX models.

As an entry-level SUV, IPC will offer the Isuzu mu-X RZ4E LS 4×2 MT, which is ideal for fleet or as a company vehicle, carrying with it standard SUV features. This variant is designed to give you comfort and convenience without breaking the bank.

Together with it, the new Isuzu mu-X RZ4E 4×2 LS-A MT and AT variants, which are packed with top of the line SUV features, will be perfect for urban duelers who need to move seven people, and more comfortable and efficient. Dubbed as a smart and functional variant, these units give you the styling of a high-end SUV but is still easy on the pocket to drive.

Similar to the mu-X, the Isuzu D-MAX will have its own smart and functional variants – the Isuzu D-MAX RZ4E 4×2 LS MT and AT. Ideal for urban drivers, these two new variants offer comfortable driving experience while maintaining its cargo truck capabilities.

When it comes to safety and security, the mu-X has features that cater exactly to that department. It’s equipped with the standard features such as the anti-lock braking system with electronic brake-force distribution, anti-theft alarm system, reverse camera and rearview mirror, and reverse sensing system, among others.

On top of that, the mu-X also comes with features that focus on added convenience for the driver and passengers.

Not only that, IPC tweaked things under the new variants’ hood to make its maintenance painless for the buyer — a Hydraulic Valve Lash Adjuster (HVLA) to keep correct valve lash clearance, a Single Engine Accessory Drive-belt for the air-conditioning and alternator compressor, and a Cartridge-type Oil Filter for easy oil filter maintenance.

With these, the mu-X 1.9 may not only be the better choice when shopping for mu-X per se; it can be the smart alternative when you’re lost at the sea of SUV options in the market.

That was the 2019 Isuzu mu-X, complete with an engine and other powerful features that ensure a good drive. That’s it for our Car Review this week.


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