The History and Impact of Detroit Diesel Superchargers on Diesel Engines

An Introduction to Detroit Diesel Superchargers

The Detroit Diesel supercharger has played an important role in the history and development of diesel engines. Supercharging is a method of increasing the power output of an internal combustion engine by forcing more air into the combustion chambers. This allows more fuel to be burned, generating greater engine power. The supercharger was a key technology that helped diesel engines become a viable and powerful engine for heavy duty vehicles in the 20th century.

History of Detroit Diesel Superchargers

The Detroit Diesel Engine Company was an early pioneer in supercharging diesel engines in the 1930s. Under the leadership of chief engineer Charles F. Kettering, Detroit Diesel conducted research into supercharging as a way to increase the power and efficiency of diesel engines. Kettering adapted mechanical supercharger technology from the aviation industry for automotive use.

In 1938, Detroit Diesel introduced their first supercharged diesel engine model, the 6-71. The 6-71 featured a Roots-type blower system and could produce up to 170 horsepower, a significant increase over naturally aspirated diesels of the time. This made it an ideal engine for World War II era tanks, trucks, boats, and heavy machinery. Detroit Diesel continued to develop improved supercharger systems through the 1940s and 50s.

The most iconic supercharged Detroit Diesel engine became the popular 8V71 model introduced in 1957. The 8V71 featured a two-stroke design and a twin screw supercharger that could generate up to 350 horsepower. This versatile engine was installed in everything from buses and boats to heavy duty trucks and off-highway vehicles. Millions of Detroit Diesel V71 supercharged engines were built over several decades.

How Detroit Diesel Superchargers Work

The supercharger is an air pump that increases the air density and pressure delivered to the engine's cylinders. It provides a boost of additional air to allow more fuel to be injected, creating a more powerful combustion. There are two main supercharger designs:

• Roots type blowers: Early Detroit Diesel superchargers used this design. Two rotors spin in opposite directions, trapping air in pockets and pushing it into the intake manifold.
• Twin-screw compressors: Later Detroit Diesel superchargers like the 8V71 and 12V71 used a more efficient Lysholm twin-screw design. The rotating screws compress the air as it moves through them.

The compressed air from the supercharger is forced into the engine's cylinders after being cooled by an intercooler. At the point of combustion, an increased mass of oxygen allows around double the amount of diesel fuel to be injected and burned compared to a naturally aspirated engine. This boost in power output is proportional to the increased air density.

Benefits of Detroit Diesel Supercharging

There were several major benefits of supercharging for Detroit Diesel engines:

• Increased power density: The supercharger dramatically boosted power output from a given engine size through forced induction.
• Improved torque: Supercharging engines delivered stronger torque across a broad RPM range.
• Better efficiency: Supercharged engines achieved better fuel efficiency than equivalent displacement naturally aspirated engines.
• High reliability: Detroit Diesel's supercharger designs were engineered for durability and long service life.
• Altitude compensation: Supercharging prevents power loss at higher altitudes through boosted intake pressure.

Thanks to these benefits, supercharging became standard in most Detroit Diesel engines by the 1950s. This gave them a major competitive advantage in the trucking, construction, marine, and industrial engine markets.

Supercharger Maintenance

Like any engine component, Detroit Diesel superchargers require periodic maintenance to keep performing at their peak. Here are some important supercharger maintenance practices:

• Change supercharger oil at prescribed intervals to reduce wear and prevent corrosion inside the unit.
• Inspect drive belts and pulleys for wear - replace as needed to prevent slippage.
• Check intake piping for leaks - inspect clamps and seals.
• Clean rotors, casing, inlet, and discharge ports to prevent buildup of dirt.
• Check supercharger clutch, gears, bearings for tightness and wear.
• Follow OEM guidelines for rebuilding or replacing supercharger components.

Neglecting maintenance will lead to reduced performance, accelerated wear, and possible supercharger failures. Follow the manufacturer's maintenance schedule for your specific Detroit Diesel engine model.

Detroit Diesel Turbocharging vs. Supercharging

In the 1960s, Detroit Diesel began adopting turbochargers in addition to superchargers for their engines. Both turbo and superchargers perform the same basic function of increasing intake air density. However, there are some key differences:

• Superchargers have instant boost response since they are directly mechanically driven. Turbochargers take momentary spool up time to deliver boost.
• Superchargers typically have more linear power delivery. Turbos are subject to lag and surge.
• Turbos can potentially be more efficient by recovering waste exhaust heat energy.
• Superchargers are simpler systems with potentially higher reliability.

Later Detroit Diesel engines often utilized a combined turbocharging and supercharging system to achieve maximum power and fuel efficiency. The turbo delivers initial low RPM boost while the supercharger provides high RPM power.

The Legacy of Detroit Diesel Supercharging

The supercharger was a vitally important technology that allowed Detroit Diesel to build extremely powerful yet compact engines. It gave Detroit Diesel an edge in the heavy duty engine market in the middle 20th century. Many iconic Detroit Diesel models like the 6-71, 8V71, and 12V71 achieved legendary status thanks to the rugged reliability of their supercharger systems.

Today, the core concepts pioneered in those original Roots type and twin-screw superchargers live on in modern diesel engine designs. Turbocharging has mostly overtaken supercharging, but the idea of forced induction to increase diesel engine performance remains fundamentally the same. The Detroit Diesel supercharger left an enduring legacy that helped shape diesel history.

FAQs

When did Detroit Diesel first introduce supercharging?

Detroit Diesel first introduced supercharging in 1938 with their 6-71 engine model, which featured a Roots-type blower system.

What are the main types of superchargers used by Detroit Diesel?

Early Detroit Diesel superchargers were Roots-type blowers. Later models used more efficient Lysholm twin-screw compressors, such as the 8V71 and 12V71 engines.

How does a supercharger increase engine power?

By forcing more pressurized air into the cylinders, a supercharger allows more fuel to be injected and burned, increasing combustion power output.

What kind of maintenance do Detroit Diesel superchargers require?

Important maintenance includes changing supercharger oil, inspecting drive components, checking for intake leaks, cleaning rotors and ports, and rebuilding/replacing worn parts as needed.

What are the main differences between supercharging and turbocharging?

Superchargers have instant boost but can be less efficient. Turbos have lag but can recover more energy. Later Detroit engines used both systems together.