The AMG M104 engine

The Mercedes-Benz M104 is a automobile straight-six engine produced from 1988 through 1999. It has a double overhead cam design with 4 valves per cylinder, and used a crossflow cylinder head. It replaced the M103 and was replaced by the M112 V6 starting in 1997. Renowned for its performance, reliability, and technological advancements, the M104 has left a lasting impact on both the Mercedes-Benz lineup and the broader automotive landscape. This article delves into the performance characteristics of the M104, its development journey, various configurations and engine sizes, the Mercedes models that utilized this engine, competing engines from the same era, and the most valuable model featuring the M104.

The M104 engine is a 3.0 to 3.2-liter inline-six engine that showcases impressive performance metrics. With a design that emphasizes both power and refinement, the M104 produced between 185 to 220 horsepower depending on the variant, making it a strong contender in its class.

Key performance characteristics include:

• Power Output: The engine’s power ranged from 185 hp in the base models to 220 hp in more performance-oriented versions.

• Torque: The M104 delivered substantial torque, peaking at around 295 Nm (217 lb-ft), which provided smooth acceleration and a responsive driving experience.

• Technology: The engine featured a DOHC (Double Overhead Camshaft) design with 24 valves, improving airflow and overall efficiency. Some variants included a variable intake manifold for better performance at different RPMs.

• Smoothness and Refinement: Known for its smooth operation, the M104 engine’s inline-six configuration contributed to reduced vibrations, enhancing the overall driving experience.

The M104 engine was developed in the late 1980s as part of Mercedes-Benz’s efforts to modernize its engine lineup. The need for a more efficient, powerful, and environmentally friendly engine was critical, especially with increasing competition in the luxury automobile market. The development process included:

• Emphasis on Efficiency: The engineers focused on creating an engine that delivered better fuel efficiency and lower emissions while maintaining high performance.

• Modular Design: The M104 was designed with modularity in mind, allowing it to be adapted to different models and configurations.

• Advanced Materials: Utilization of lightweight materials in construction enhanced performance and efficiency.

The M104 engine was produced in various configurations and sizes:

• M104.94x: 2.8 liters (169 hp/125 kW)

  • Mercedes-Benz E 280 (W124, W210)

  • Mercedes-Benz 280 CE (C124)

• M104.98x: 3.0 liters (188 hp/138 kW)

  • Mercedes-Benz E 300 (W124, W210)

  • Mercedes-Benz 300 CE (C124)

• M104.99x: 3.2 liters (231 hp/172 kW)

  • Mercedes-Benz E 320 (W124, W210)

  • Mercedes-Benz 320 CE (C124)

  • Mercedes-Benz SL 320 (R129)

These configurations allowed the M104 to be versatile across different Mercedes-Benz models while catering to various market segments.

The M104 engine was installed in several key models during its production run, including:

• Mercedes-Benz E-Class (W124): One of the most iconic models to feature the M104, particularly in the E320 variant.

• Mercedes-Benz S-Class (W140): Used in the S320, this model emphasized luxury and performance.

• Mercedes-Benz C-Class (W202): The C280 variant showcased the M104 in a more compact form.

• Mercedes-Benz SL (R129): The M104 was integral to the SL lineup, particularly in the SL320 variant.

These models not only benefited from the M104’s performance but also contributed to its reputation for reliability and engineering excellence.

During the M104’s production, several competitors emerged in the luxury inline-six market. Notable rivals included:

• BMW M50 Engine: BMW’s M50, a 2.5 to 3.0-liter inline-six, was known for its smooth performance and high-revving nature, appealing to driving enthusiasts.

• Jaguar AJ6 Engine: The AJ6 was celebrated for its performance and refinement, utilized in models like the XJ6.

• Nissan RB Series: While more performance-oriented, the RB series offered competitive power and tuning potential.

These competitors contributed to a vibrant market, pushing manufacturers to innovate and enhance their engine offerings.

Among the various models equipped with the M104 engine, the Mercedes-Benz 300SL (R129) stands out as the most valuable. The combination of iconic styling, performance, and the M104’s reliability makes the 300SL a sought-after collector's item. With a well-maintained example fetching premium prices at auctions, it embodies the pinnacle of the M104’s legacy.

The Mercedes M104 engine is a testament to the brand’s commitment to engineering excellence and innovation. Its performance characteristics, diverse configurations, and application across numerous models underscore its significance in automotive history. As collectors and enthusiasts continue to appreciate the legacy of the M104, its impact on the luxury car market remains undeniable, solidifying its place as a classic engine in the annals of automotive engineering.