Len Gilmore, owner and operator of German Auto Center, has over 30 years plus working with German made vehicles. In the past decade alone, the industry has been taken by storm with many new and revolutionary engineering breakthroughs. German engineering advances of the past ten-years have included numerous engine and power-train modifications. In this post, we share the Top 5 German Engine & Power Train Management Innovations in the past Decade:
1. Variable camshaft timing. Most German manufactures including BMW, Mercedes Benz, Audi, Porsche, Volkswagen and Mini Cooper all make use of variable camshaft or valve timing to improve performance and engine efficiency. This allows a vehicle engine to be tuned and balanced between engine performance and engine economy (fuel mileage). Your BMW, Mercedes Benz, Audi, Porsche, Volkswagen or Mini Cooper has programming built into the engine control module (ECU/DME) that changes the engine valve timing – when the valves open and close – based on driving conditions. This is accomplished by changing the position or timing of the camshafts.
By moving the camshaft timing advanced, valves will open sooner on the lobes of the camshaft. Retarding has the opposite effect. This optimization automatically and continuously adjusting the valve timing to suit operating conditions (rpm/load), and can either increase fuel efficiency or engine performance depending on how the vehicle ECU/DME is programmed. Although implementations vary by manufacturer, these systems use continuously variable camshaft controls – typically an oil solenoid valve that is controlled from the ECU/DME and the position of the cam is detected and adjusted using the cam position sensors and actuators. Earlier implementations of variable valve timing controlled just the intake camshaft(s) position, while current systems control both the intake and exhaust camshaft position allowing when air enters the combustion chamber and when exhaust is let out independently.
One of the most recognized systems is BMW’s VANOS (abbr. from German variable Nockenwellensteuerung) system for controlling both intakes and exhaust camshaft timing. In 1999, BMW first introduced the single VANOS system controlling the intake valves. Current technology utilizes a double VANOS system controlling both the intake and exhaust valves. This is effectively changing the timing of the crankshaft and the camshafts (four-camshafts in the double VANOS system). By adjusting the valve timing electronically based on system demands, torque and can optimized when needed keeping a flat performance torque curve at a variety of rpms and loads.
Although all manufacturers utilize variable valve and camshaft timing technology to gain better and more efficient performance, it does come with a price. It is critical that you maintain the specified engine oil and change your oil regularly. Oil and dirt deposits will become lodged in the timing control actuators causing check engine lights and poor operating performance. On the BMW VANOS system, this is also commonly followed by a “rattle” noise at the front of the engine.
Whether you drive a Porsche, Mercedes Benz, BMW, Volkswagen or Audi, It is important to remember that today’s German performance vehicles can only perform to their optimum specifications if they are properly maintained and service. Remember to service your engine and have the oil professional changed by an expert every 7,500 miles (5,000 for turbo charged and super charged engines).
2. Variable valve lift. Variable valve lift physically changes the height that a valve opens to directly effect performance and fuel economy. Although differing by manufacturer, the height of valve is controlled by a hydraulic lifter that rides between the camshaft and the valve. By increasing the height of the lifter, the valve will travel a greater distance. When used with variable camshaft timing, engine management systems offer a level of fuel efficiency and engine performance control not previously available through purely mechanical engine designs. Please see post on the BMW VANOS for additional information about variable timing systems.
3. Direct injection. Direct injection is used to deliver fuel directly into the engine’s combustion chambers as opposed to into the intake manifold or plenum. With the advent of piezo injectors, engine developers can now inject fuel into a cylinder’s combustion chamber in just 0.2 milliseconds. This allows the engine management system to make multiple fuel injections during a single combustion cycle improving fuel efficiency and controlling engine performance real time. One example of this technology is BMW’s N53, N54 and its successor, the N55 engines.
Although this design has many benefits, there have been significant drawbacks related to direct injection. Most notable as the camshaft timing overlaps, there is a tendency to pull carbon deposits from the combustion process into the engine ports. With older injections systems the fuel delivered into the intake manifold would wash away these deposits. With direct injection, there is no way to wash out ports. Clogging of the intake and exhaust ports can lead to poor performance due to reduced air and poor valve seating. Some engine designers are now experimenting with adding a traditional style injector for the sole purpose of cleaning the ports.
4. Diesel engines. Pioneered by the Volkswagen Group (including Audi, Porsche and Volkswagen) the TDI diesel engine has gained wide appeal due to its high-torque and improved fuel economy. The Turbocharged Direct Injection or TDI engine is a turbocharged diesel engine which also makes use of direct fuel injection (see technical blog on direct fuel injection). The TDI engine makes use of forced induction through the turbocharger moving more air into the engine combustion chamber increasing torque and horsepower. Although similar technology is used in the Mercedes Benz BlueTEC Diesel and the BMW turbocharged DOHC 12-valve diesel inline 4-cylinder engine, TDI is proprietary to the Volkswagen Group including Audi, Volkswagen and Porsche.
5. Dual clutch and sequential shifting transmissions. Electrohydraulic sequential manual transmissions are a type of semi-automatic transmission designed to provide effortless and rapid shifting improving upon the average driver’s abilities. This design uses an automated clutch controlled by vehicle electronics and hydraulic solenoids. Unlike a traditional manual transmission, vehicle electronics and precisely match engine RPMs, and engine management systems to create a smoother and more rapid shifting process. To change gears, the driver selects the desired gear with a shift lever or paddle, and the system automatically operates the clutch and throttle to match engine speed and engage the clutch. Most of these transmissions such as the BMW SMG transmission operate in sequential mode where the driver can only upshift or downshift by one gear at a time.
A dual-clutch transmission, such as the Porsche PDK transmission is another type of semi-automatic transmission (Also referred to as an automated manual transmission such as the BMW SMG transmission). This transmission is designed to use two separate clutches for odd and even gear sets. This design allows for rapid and smooth shifting across the entire range of the gearbox. As with the SMG transmission, the use of electrohydraulics allows the transmission to operate in an automated mode provide more rapid shifting than a driver can typically perform manually.
Although not making our top 10 list, honorable mention should be given to the emerging hybrids being developed by Audi, Porsche, Volkswagen, BMW and Mercedes Benz. These include both gas and diesel hybrid designs.
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