The technical journal ‘Automotive Engineering International’ (AEI) published in the USA has honoured the VarioCam Plus technology applied in the 911 GT2 and 911 Turbo with the ‘AEI Tech 2001 Award’ within the framework of a readers survey. The readers of the internationally renowned journal regard VarioCam Plus as one of the most outstanding technical innovations which have been presented at the ‘SAE-Congress’ (Society of automotive engineering) in Detroit in March. Approximately 1000 engineers and technicians of the international automobile industry meet there annually to keep themselves informed about the latest technical developments in their field.
Dr. Ing. h.c. F. Porsche AG in Stuttgart first introduced the VarioCam Plus in the 911 Turbo. The new engine technology has contributed substantially to the fact that the fuel consumption could be reduced by 18 percent in comparison to the predecessor model and the emission values could be reduced by an average 50 percent in the European standardising process.
VarioCam Plus combines a new valve tilting position through switchable flat-base tappets with a phase adjustment of the inlet camshaft and therefore unifies two completely different engine operating modes in one engine. One operating mode can be characterised as city traffic mode with which the VarioCam Plus is set exclusively for low consumption, low toxic emissions and optimal comfort performance of the engine. Among other things, this requires small valve strokes of three millimetres which only allow driving performances for typical secondary roads or city traffic.
If the driver demands increased performance by actuating the accelerator, the other operating mode, the so-called ‘driving perfomance mode’, is activated into within milliseconds. This mode is designed with large valve strokes exclusively for maximum torque and peak performance. More than treble the torque is available within fractions of a second. The fact that the economical city traffic engine changes into a sprinting peak performance engine is only noticeable to the driver via the accelerator. This comfort demands extensive interventions in engine management. Besides the throttle position and the fuel preparation, the ignition and control of the switchable inlet valves also change. So far this is the most extreme intervention in the gas exchange for optimising the engine for standard engines world-wide.
Porsche is deliberately concentrating on these two engine operating modes. On the one hand, because a simple technical implementation of the VarioCam Plus is possible and because a very high degree of reliabilty is guaranteed against failure in hard everyday operation. On the other hand, additional engine types can also enjoy the modular-structured valve drive and engine control concept without difficult adaptation.