RZ4E vs RZ4F: ISUZU Diesel Engine Differences

ISUZU diesel engines have long earned a solid reputation for outstanding durability and consistent performance, securing a vital position across both commercial and passenger vehicle markets. As global environmental awareness grows and emission standards become stricter, alongside rising consumer demands for stronger power, better fuel efficiency and superior ride comfort, Isuzu has unveiled its newly developed 2.2L turbocharged diesel engine, the RZ4F. Part of the MaxForce series, this new powertrain is designed to replace the well-received 1.9L RZ4E engine, bringing comprehensive upgrades to core performance and technical specifications that set it distinctly apart from its predecessor.

RZ4F Diesel Engine

The RZ4F is an all-new 2.2L turbocharged diesel engine developed by Isuzu and initially fitted to the two-wheel-drive mu-X and D-MAX models.

Core Performance Parameters

Maximum power output: 120kW (163HP)

Peak torque: 400N·m, available across the 1600–2400rpm range

Key Technical Upgrades

1.Fuel injection: Equipped with 250MPa high-pressure injectors for improved diesel atomization and more complete combustion.

2.Turbocharging system: Featured with an electronically controlled Variable Geometry Turbocharger (VGT), which dynamically adjusts vane angles to match driving demands instantly.

3.Transmission system: Mated to an Aisin 8-speed automatic transmission (8AT). It delivers a wider gear ratio spread and refined shift logic for smoother driving and more enhanced fuel economy.

RZ4E Diesel Engine

The Isuzu RZ4E is a 1.9L diesel engine widely deployed on Jiangxi Isuzu D-MAX, mu-X , as well as various commercial vehicles including light trucks, buses and specialized work vehicles.

Core Performance Parameters

Maximum power output: 110kW (163HP)

Peak torque: 350N·m

Rated engine speed sits at 3600rpm, delivering steady robust power from 1500rpm to 3700rpm.

Key Technical Highlights

1.Structure: Long-stroke layout (80mm bore × 94.4mm stroke), reducing operating engine speed to boost fuel economy.

2.Turbocharging system: Matched with a Variable Geometry Turbocharger(VGT), paired with a 2000-bar high-pressure common rail system. The combination optimizes fuel atomization and combustion efficiency to boost power while cutting emissions.

3.Transmission system: Paired with a 6-speed automatic transmission.

Built upon the 1.9L RZ4E engine, the RZ4F features upgraded core components and an all-new 8-speed automatic transmission, marking a dual breakthrough in performance and technology. Its maximum power is raised by 10kW compared to the older 1.9L unit, while peak torque gains an extra 50N·m, with cranking torque increased by 56%. The torque delivery range is revised to 1600–2400rpm, offering more responsive low-speed power for greater practicality. Technically, the RZ4F integrates advanced components such as low-friction pistons, attaining a fuel consumption figure as low as 5.6L per 100 kilometers — a roughly 10% improvement over the previous generation. It not only elevates overall vehicle performance and fuel efficiency but also fully complies with increasingly stringent emission regulations.