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    To some this might be stupid question but I will give it a shot. What are the differences between VarioCam and VarioCam Plus? Can a car use both VarioRam and VarioCam technology together? When were these technologies implemented in Porsche production cars?

    Re: Question

    VarioCam first appeared on the 968 and varies the angle of the intake cam between two extremes by moving the slack of the chain between the intake and exhaust camshafts.
    VarioCam Plus first appeared on the 996TT (I think) and varies the angle of the intake cam continuously/infinitely (not just two angles) with a hydraulically operated helical screw thing on the end of the camshaft. On the GT3 VarioCam Plus varies intake camshaft over (a larger) 45 degrees of crankshaft rotation.
    VarioCam and VarioRam can co-exist and are controlled by the ECU.

    Re: Question

    To some this might be stupid question but I will give it a shot. What are the differences between VarioCam and VarioCam Plus? Can a car use both VarioRam and VarioCam technology together? When were these technologies implemented in Porsche production cars?

    Porsche offers VarioCam Plus on all models throughout the range. Camshaft adjustment on the intake side (VarioCam) is supplemented in this case by valve lift control also on the intake side (Plus). Featured for the first time on the 911 Turbo, this new system is able to optimise output and performance, on the one hand, while at the same time reducing fuel consumption and exhaust emissions, and improving running smoothness and refinement, on the other.

    The valve adjustment system is made up of switching cup tappets on the intake side of the engine operated by an electrohydraulic 3/2-way switching valve. With two different cam contours on the intake camshaft, the engine always runs on the appropriate lift curve, with the cams switching from one to the other. To be specific, the cup tappets are made up of two interacting tappet elements locked one against the other with the help of a bolt. This creates a direct link, first, between the inner tappet and the small cam, and, second, between the outer tappet and the large cam. A hydraulic compensation unit for valve play is integrated in all cases in the tappet's force flow line.

    For all practical purposes VarioCam Plus means two engine concepts in one. As long as the engine is idling, valve lift is controlled by the small cams to a maximum limit of 3.6 millimetres and valve timing is optimised to keep any valve overlap on the engine to a minimum. The small valve lift serves to reduce friction, significantly increases the charge motion thanks to the very short opening times, and reduces emissions from any previous combustion within the combustion chambers. A further advantage is the considerable reduction in fuel consumption and emissions by up to 10 per cent, together with a much higher standard of idling quality. Under part load, in turn, the engine should preferably run with internal recirculation of exhaust gases in order to minimise any throttle effect and to reduce fuel consumption accordingly. To achieve this goal, valve lift is shifted to a large overlap area, that is a long period for drawing in exhaust gases. Under full load, finally, superior torque and output are ensured by a highly efficient gas charge cycle with minimum losses, on the one hand, and an uncompromising cam contour, on the other, with 11 millimetres maximum valve lift and suitably adjusted opening and closing times during the valve cycle. VarioCam Plus also helps before you set out, for example, by considerably improving the engine's starting characteristics when cool and by reducing emissions through the suitable adjustment of VarioCam Plus while the engine is warming up.

    Both of the two VarioCam Plus systems (camshaft adjustment and valve lift control) are masterminded by Motronic ME7.8 designed especially for these particular requirements and offering a high standard of operating and computing capacity. This is indeed important, since the factors required for controlling VarioCam Plus are, in particular, engine speed, gas pedal position, engine oil and coolant temperature, as well as recognition of the gear currently in mesh. The driver's commands in terms of engine power or torque are compared with control maps within the system, the Motronic control unit then deciding within milliseconds how VarioCam Plus should respond.

    Also have a look at the picture.

    Any more questions?

    Re: Question

    I thank you both for explaining the differences and details about the technologies.



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