Well I decided that I might as well add this for discussion. Some are familar with these types of set ups, but for those who aren't here's a quick overview. The idea is to have the best of both worlds, low end grunt & top end power. A few companies out there have produced twincharger kits & some manufactures even used this technology on factory offered cars. I have pulled some facts on the subject, for us to read.
Twincharger refers to a compound forced induction system used on some piston-type internal combustion engines. It is a combination of an exhaust-driven turbocharger and an engine-driven positive displacement supercharger, each mitigating the weaknesses of the other. Any forced-induction system puts more oxygen into the cylinders than would be available without force, allowing more fuel to be burned, producing more power. Engines with relatively small displacement can thus be used for a given power output, these smaller-displacement engines being more fuel-efficient in typical real-world vehicle designs than their normally-aspirated counterparts (those without forced induction) of equivalent power.
The term twincharger is a misnomer, as the two "chargers" of the system are of radically different designs. The advantages of this system over other forced induction systems are, in fact, due to the differences between the two.
A twincharging system combines a supercharger and turbocharger in a complementary arrangement, with the intent of one component's advantage compensating for the other component's disadvantage. There are several different twincharging configurations. The two most common are series, and parallel.
Series systems, the more common of the two, are plumbed such that one compressor's output feeds the inlet of another. It is a sequentially-organized Roots type supercharger, connected to a medium- to large-sized turbocharger.[citation needed] The supercharger provides near-instant manifold pressure (eliminating turbo lag, which would otherwise result when the turbocharger is not up to its operating speed). Once the turbocharger has reached operating speed, the supercharger can either continue contributing air to the intake (yielding elevated intake pressures), or it can be bypassed and mechanically decoupled from the drivetrain via an electromagnetic clutch (increasing efficiency of the induction system).
Other series configurations exist where no bypass system is employed and both compressors are in continuous duty. As a result, compounded boost is always produced as the pressure ratios of the two compressors combine. This form of series twincharging allows for the production of boost pressures that would otherwise be unachievable with other compressor arrangements. A significant advantage of this method is the reduction in charge temperature for a given pressure output versus that of a single compressor producing the same output.
Parallel systems typically always require the use of a bypass or diverter valve to "select" which compressor is feeding the engine. Parallel systems are not compounded by design, and maximum manifold pressure will be equal to the maximum output of the compressors, whichever is greatest. Parallel systems often employ complex electronics to control bypass valves selecting which compressor is utilized depending on several engine parameters, driver inputs, and environmental factors. Mechanically-controlled parallel twincharged systems typically cannot provide a transparent and seamless switch between compressors. As a result, power delivery can have abrubt spikes.
The concept of twincharging was successfully used by Lancia in the 1980s on the Lancia Delta S4 rally car. The idea was also successfully adapted to production road cars by Nissan, in their March Super Turbo [1]. Additionally, multiple companies have produced aftermarket twincharger kits for cars like the Subaru Impreza WRX, Mini Cooper S, Ford Mustang, Nissan Skyline GT-R, Toyota MR-2, Acura Integra, as well as the GM 3800 Engine, as in the Pontiac Bonneville SSEI, Pontiac Grand Prix GTP among others.
The Volkswagen Golf TSI has a 1400 cc engine that utilises both Turbocharger and supercharger. The power output for the European model is 170 bhp (127 kW; 172 PS).
I have seen some of these set ups & spoke with some owners. All seemed to be happy with the combo of designs. Here's a few pics.
Sun Jan 03, 2010 4:01 pm
