三菱4A91T发动机的结构及使用的技术方法

The 4A91T engine is based on the Japanese MITSUBISHI engine technology, jointly developed by Shenyang Aerospace and MITSUBISHI, and was mass-produced in 2013. It gained recognition as the "2014 Power Pioneer" for its strong power and low fuel consumption in the same displacement class. The engine has a maximum torque of 215 N·m and a power output of 115 kW.

This engine is an upgraded version of the MITSUBISHI 4A91 engine. Although it may not be considered highly advanced in today's market, it is still considered a mid-to-high-end configuration in domestic models. Known for its compact size, high performance, low fuel consumption, and environmental compliance (meeting Euro 5 emissions standards and upgrading to Euro 6), it holds a significant position in the Chinese market. Its reliability is widely acknowledged in the industry, with a saying that "the car can be scrapped, but the engine won’t need a wrench."

Below is an introduction to the structure of the 4A91T engine:

1. Turbocharger: The 4A91T uses MITSUBISHI's original turbocharger technology, with core components such as the turbine, high-speed bearings, and pump wheel assembly imported from Japan, while only the turbine housing is produced and assembled domestically. It uses exhaust gas to drive the turbine, which increases intake pressure, thereby improving engine efficiency and performance. Compared to naturally aspirated engines, this model achieves a 30% increase in power and 40% increase in torque, while maintaining similar fuel consumption. For example, the DX3 and DX7 models equipped with the 4A91 and 4A91T engines have similar fuel consumption of 5.8L and 5.9L per 100 km, respectively.

The engine's external characteristics refer to the maximum torque at each speed. The higher, the better. From the graph, we can see that the turbocharger begins to take effect even at idle speed, contrary to the common belief that turbochargers start working around 2000 RPM. By around 1400 RPM, the turbocharged engine’s torque already exceeds the maximum torque of the naturally aspirated engine, delivering a noticeable power boost. Additionally, the range of maximum torque for turbocharged engines expands to 2000–4500 RPM, offering more flexibility in driving conditions.

Developing good driving habits is essential for both performance and fuel efficiency. Here are some tips to help you save fuel while enjoying better power:

(1) Master the timing of gear shifting, keeping the engine running in the most efficient RPM range. Shifting between 2000–2500 RPM is a great choice.

(2) When starting or driving at low speeds, gently press the accelerator to allow the engine to run at a higher RPM, which provides more torque and smoother acceleration, while also improving fuel efficiency.

(3) Avoid sudden acceleration, as this puts the engine into an over-rich condition, where extra fuel is used to cool the engine and prevent detonation, leading to lower combustion efficiency and increased emissions.

(4) Avoid driving in high gears at low RPMs, as this reduces efficiency and increases carbon buildup, which can degrade engine performance over time.

(5) If you often drive in the city, occasionally taking a trip on the highway helps clean carbon deposits and improves overall engine efficiency.

2. Dual Overhead Camshaft (DOHC) and MIVEC Variable Valve Timing Technology: The MIVEC system used in the 4A91 engine optimizes both the timing and lift of the valves, increasing air intake and achieving low fuel consumption, low emissions, and high performance across a wide RPM range. This technology outperforms VTEC and VVTI, which do not offer both functions simultaneously.

3. Aluminum-Magnesium Alloy Pressure-Cast Cylinder Block: Using an aluminum alloy block reduces the engine’s weight, enhances heat dissipation, improves acceleration, and boosts fuel economy. However, it also increases manufacturing costs and lowers production yield.

4. Resin Intake Manifold and Rocker Cover, Reverse Exhaust Manifold: Most conventional engines use aluminum or cast iron intake manifolds and forward-mounted exhaust manifolds. The 4A91 engine uses a resin intake manifold and reverse exhaust design, helping to reduce weight and fuel consumption.

5. Timing Chain Drive: Unlike most older engines that use timing belts, which require replacement every few tens of thousands of kilometers, the timing chain in the 4A91T engine lasts the entire lifespan of the vehicle. This can save users 5,000–10,000 yuan in maintenance costs over the vehicle's lifetime.

6. Electronic Throttle: Paired with an electronic throttle pedal, the ECU controls the DC stepper motor on the throttle body based on sensor input, adjusting the engine's airflow and RPM. This system not only improves fuel efficiency but also reduces harmful emissions. The 4A series engine easily meets the strictest Euro 5 emission standards.

7. Independent Ignition System: The 4A91 engine features an independent ignition system, with one ignition coil per cylinder. This results in higher ignition energy, more precise timing control, and more complete combustion.