Recently, I've seen many of my buddies and others were much confused between the two entirely different system known as Variable Valve Lift (VVL) and Variable Valve Timing (VVT). Honda has implemented this system first in their cars. And then by seeing its efficiency, many other manufacturers started to use this system in their four wheelers as well as in their two wheelers. Now in this post, let's break out this confusion and I try to simply explain out the differences between the both of them.
As I said, VVL and VVT is not the same one. Firstly, let's see about VVL and then we land onto VVT. Variable Valve Lift (VVL) is mainly used to improve the overall performance of the vehicle. We can able to see where the manufacturers gives different acronym for their models. For example, Yamaha's R15 V3 have a VVA motor which is expanded as Variable Valve Actuation and BMW Motorrad in their S 1000 RR offers a ShiftCam technology. Both the Yamaha's VVA and BMW's ShiftCam plays a same role of Variable Valve Lift. To know about how these two mechanisms work, check out my posts where I've clearly explained about it. In normal engines, single cam lobe will be present in the intake camshaft for operating the inlet rocker arms and single cam lobe for operating the exhaust rocker arms. But the engine comes with VVA or ShiftCam technology have two intake cam lobes in the intake camshaft for operating the inlet rocker arms or valves. First cam lobe will be having a smaller profile which provides medium valve lift and lift duration which suits for lower RPM bands. Second cam lobe have larger profile providing higher valve lift and lift duration which suits for higher RPM bands. Instead of using same cam lobe in all rev range, this bigger cam lobe will provide that additional boost which is required in higher RPMs by letting in more fuel air mixture inside the combustion chamber. The purpose is the same one but the actuating mechanism differs from one manufacturer to the other one. Yamaha uses the sliding pin to interlock the both normal and high profile cam lobe's rocker arms. In the other hand, BMW uses the mechanism where they pulls the camshaft itself to make the high profile cam lobe comes to contact with the rocker arms. So we can say Variable Valve Lift (VVL) plays an important role of varying the valve lift and lift duration which very much helps in proving good power output in all rev range.
As I said, I've clearly explained about the both VVA and ShiftCam technology which comes under VVL in previous posts. Now, let's see about VVT. Here, let's see the overview and I'll post about it explaining completely in my upcoming posts. Variable Valve Timing (VVT) system is used to alter the flow of air going into the engine. Unlike VVL engines, it adjusts the profile of the intake cams but with the same cam profile instead of using a separate cam lobe. Yeah.. Manufacturers like Suzuki and Ducati use this VVT in their engines. Suzuki calls it as a Mechanical VVT where Ducati calls it as a Desmodromic Variable Timing (DVT). In both the cases, the camshaft contains no additional lobes for operating under high RPMs. Instead, the camshaft will move back and forth inside the head of the engine. One direction will advance the valve timing where the other one retards it. By providing the air earlier or later adjusts the combustion process to match the needs of the engine at given speed and engine temperature. This VVT is all about advancing and retarding the valve timing which very much helps in controlling the emission and this is done with the help of centrifugal force which pushes the steel balls outwards which changes the position of the camshaft in Suzuki's mechanical VVT system. In Ducati's DVT, the oil pressure is used to change the position of the camshaft to rotate either side in order to advance or retard the timing.
Now I believe surely you would have understood the difference between Variable Valve Timing and Variable Valve Lift. In future, will let you know about how VVT system works and to know about more technical contents and to feed your mind with more mechanical stuffs, make sure that you are following my posts regularly.
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As I said, VVL and VVT is not the same one. Firstly, let's see about VVL and then we land onto VVT. Variable Valve Lift (VVL) is mainly used to improve the overall performance of the vehicle. We can able to see where the manufacturers gives different acronym for their models. For example, Yamaha's R15 V3 have a VVA motor which is expanded as Variable Valve Actuation and BMW Motorrad in their S 1000 RR offers a ShiftCam technology. Both the Yamaha's VVA and BMW's ShiftCam plays a same role of Variable Valve Lift. To know about how these two mechanisms work, check out my posts where I've clearly explained about it. In normal engines, single cam lobe will be present in the intake camshaft for operating the inlet rocker arms and single cam lobe for operating the exhaust rocker arms. But the engine comes with VVA or ShiftCam technology have two intake cam lobes in the intake camshaft for operating the inlet rocker arms or valves. First cam lobe will be having a smaller profile which provides medium valve lift and lift duration which suits for lower RPM bands. Second cam lobe have larger profile providing higher valve lift and lift duration which suits for higher RPM bands. Instead of using same cam lobe in all rev range, this bigger cam lobe will provide that additional boost which is required in higher RPMs by letting in more fuel air mixture inside the combustion chamber. The purpose is the same one but the actuating mechanism differs from one manufacturer to the other one. Yamaha uses the sliding pin to interlock the both normal and high profile cam lobe's rocker arms. In the other hand, BMW uses the mechanism where they pulls the camshaft itself to make the high profile cam lobe comes to contact with the rocker arms. So we can say Variable Valve Lift (VVL) plays an important role of varying the valve lift and lift duration which very much helps in proving good power output in all rev range.
As I said, I've clearly explained about the both VVA and ShiftCam technology which comes under VVL in previous posts. Now, let's see about VVT. Here, let's see the overview and I'll post about it explaining completely in my upcoming posts. Variable Valve Timing (VVT) system is used to alter the flow of air going into the engine. Unlike VVL engines, it adjusts the profile of the intake cams but with the same cam profile instead of using a separate cam lobe. Yeah.. Manufacturers like Suzuki and Ducati use this VVT in their engines. Suzuki calls it as a Mechanical VVT where Ducati calls it as a Desmodromic Variable Timing (DVT). In both the cases, the camshaft contains no additional lobes for operating under high RPMs. Instead, the camshaft will move back and forth inside the head of the engine. One direction will advance the valve timing where the other one retards it. By providing the air earlier or later adjusts the combustion process to match the needs of the engine at given speed and engine temperature. This VVT is all about advancing and retarding the valve timing which very much helps in controlling the emission and this is done with the help of centrifugal force which pushes the steel balls outwards which changes the position of the camshaft in Suzuki's mechanical VVT system. In Ducati's DVT, the oil pressure is used to change the position of the camshaft to rotate either side in order to advance or retard the timing.
Now I believe surely you would have understood the difference between Variable Valve Timing and Variable Valve Lift. In future, will let you know about how VVT system works and to know about more technical contents and to feed your mind with more mechanical stuffs, make sure that you are following my posts regularly.
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