Supercharged Diesels

Turbocharger + Supercharger = Lag Free Performance

Super Turbo ChargedThe same technology used to provide blistering performance on gassers has been adapted to give diesels an edge as well. We're talking about supercharging, a method of forced induction that runs off the engine via a belt drive. Supercharger kits are currently available for select generations of Duramax, Cummins, & Power Stroke diesels. Empire Diesel Performance is a major pioneer of the concept and offers bolt-on supercharger kits for Duramax and Power Stroke engines.

 

Superchargers vs. Turbochargers

Before we get into the science behind supercharged diesels, it is important to understand the difference between superchargers and turbochargers. A turbocharger has a compressor wheel connected to a turbine wheel via a common shaft. Exhaust gases directed at the turbine wheel force both the turbine and compressor to rotate. As the compressor wheel rotates, air is drawn in, compressed, and forced into the engine. The boost that a turbocharger creates is relative to engine load.

 

Superchargers feature a compressor or screw rotors that are driven off the engine crankshaft via a belt drive - as the crankshaft spins, the compressor spins. The supercharger draws in ambient air, compresses it, and feeds it to the engine. The boost that a supercharger creates is relative to engine speed (RPM).

 

 

Turbocharger

Supercharger

Advantages:

• Highly efficient, powered by engine waste heat (exhaust).
• Capable of providing high volume and boost pressures.

 

• Instant boost - no lag since system operates relative to engine RPM. If the engine is spinning, the supercharger is creating boost.

Disadvantages:

• Turbo lag - boost pressures dependent on engine load. Turbochargers do not spool instantly and provide very little boost under light load.

• Requires power from engine to operate, less efficient.
• Limited boost/airflow characteristics.

 

 

Supercharged Diesel

By playing on the advantages of both turbochargers and superchargers, a system can created that provides instant throttle response and higher boost in low-load driving situations while meeting the airflow requirements of the engine, even at high engine loads/RPM. On a supercharged diesel, the supercharger compresses air and feeds it into the intake side of the turbocharger, where it is further compressed and sent through the intercooler and into the engine. The result is a combination which yields instant throttle response at any speed (no lag, since the supercharger is creating boost anytime the engine is running, even at idle), more horsepower/torque, and significant improvements in fuel economy.

 

 

Supercharged + Turbocharged Diesel

Advantages:

• Instant throttle response at any engine speed, since the supercharger creates boost at any RPM.
• Meets airflow requirements under high engine load or speed (RPM).
• Boost available at cruising speeds and light load conditions.
• Increased horsepower, torque, & fuel economy.

Disadvantages:

• Supercharger uses engine power to operate, higher parasitic loss compared to compound (twin) turbochargers.

 

 

While a compound turbocharger setup remains better suited for all-out performance (sled pulling, drag racing engines), a supercharged + turbocharged diesel is an intriguing option for streetable trucks and tow rigs. Additionally, manufacturers offer a range of sizes to meet your performance needs. Can you imagine never having to wait for the turbo spool?

 

 

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