Diesel Develpoments

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2014 Audi A8 TDI
2014 Audi A8 TDI

Everyone knows that the days of noisy, clattering, and smoking diesel engines are over. What you may not know about are the latest performance developments regarding diesel propulsion.

Modern technological advancements have allowed diesel fueled engines to reach horsepower ratings which rival their gasoline powered counterparts while achieving markedly superior fuel efficiency numbers.


Diesel engines are known for their remarkable torque and have, for many years, been regarded as the workhorse of commercial logistics. With the emergence of today’s quieter running, cleaner burning, turbocharged diesel engines many luxury and sports car manufacturers have taken to offering diesel engine options in select models.


There are primarily three factors which have contributed to the recent advancements in diesel propulsion technology. They can be categorized thusly:

  • Turbochargers and intercoolers
  • Cleaner, more efficient diesel fuel
  • Alternative injection methods and substances


The addition of turbochargers is possibly the greatest event in the history of diesel propulsion. Turbochargers increase horsepower by forcing massive amounts of air into the induction system of the engine.

The greater the amount of air that is forced in, the greater the gain in horsepower; then there are other factors, such as intake air temperature, turbocharger impeller RPM, and fuel mixture which further enhance engine power and torque.

Modern sports cars and luxury sedans, equipped with diesel engines, utilize the function of two separate turbochargers. A low RPM turbo provides the punch at take-off and is typically a smaller, less inductive unit. A larger, high RPM turbo unit is activated as RPM levels increase. This system delivers smooth acceleration, crisp throttle response, and minimal turbo-lag.

One way to think of an intercooler is to imagine it as the radiator of the turbocharger.

Intake air, destined for the turbocharger, is routed through the intercooler where it is (as the name implies) cooled. This is accomplished by utilizing the air which rushes across the intercooler face at cruising speed, or is drawn across the surface by using either a mechanical or electric cooling fan.

The cooler air is then forced into the engine where it can be burned more efficiently than warmer air.

The introduction of cleaner more efficient fuels has changed the way consumers look at diesel propulsion. Modern diesel automobiles, and over the road tractors, use what has been named ultra-low-sulfur diesel (ULSD) fuel.

As of 2007 all diesel propelled vehicles which are operated on the highway, in North America and much of Europe, are required to burn the ULSD fuel. This has resulted in a much cleaner, more efficient, and less odorous era of diesel propelled automobiles; including passenger cars and light trucks.

High absorbency catalytic converters and specialized high-performance exhaust systems have also helped to enhance the overall cleanup and performance capabilities of today’s diesel powered automobiles.

Diesel fuel additives are nothing new, however the method for delivering these additives has become more proficient and reliable.

Computerized aftermarket injection systems are being offered which are capable of delivering a precisely metered water and methanol injection, directly into the air intake system significantly boosting horsepower by decreasing intake air temperature.

The Mercedes-Benz BlueTEC diesel engine makes use of a selective catalytic exhaust system, which uses exhaust fluid for increased efficiency, while Audi and Volkswagen use the TDI clean diesel system to spray atomized fuel directly into each cylinder.


S.M. Darby

S.M. Darby

I am a freelance author with over 25 years of experience as a professional, ASE certified automotive technician and shop owner, muscle car enthusiast, avid street racer, and classic car restoration specialist.