13-02-2013, 08:18 PM
VTEC (Variable Valve Timing and Lift Electronic Control) is a valvetrain system developed by Honda for improve the volumetric efficiency of four-stroke internal combustion engine . This system uses two camshaft profiles and electronically selects between the profiles. It was invented by Honda R&D engineer Ikuo Kajitani It can be said that VTEC, the original Honda variable valve control system , originated from REV ( Revolution-modulated valve control ) introduced on the CBR400 in 1983 known as HYPER VT EC
The camshaft uses rotating lobes that push against the valves to open and close them. Since engines valves play a major role in how air gets in an out of the combustion chamber, it makes sense to focus on them when looking to increase horse power and efficiency.
When you increase the rpm however this configuration for the camshaft does not work well. If the engine is running at 4000 r/min the valves are opening and closing 2000 times every minute. When the intake valve opens at the top of the intake stroke, it turns out that the piston has a lot of trouble getting the air moving into the cylinder in the short time available. Therefore, at a higher rpm ranges you want the intake valve to open prior to the intake stroke-actually back in the exhaust stroke-so that by the time the piston starts move in downward in the intake stroke the valve is open and air moves freely into the cylinder during the entire intake stroke. For maximum engine performance at low engine speeds the valves need to open and close differently than they do at higher engine speeds. If you put in a good low-speed camshaft, it hurts the engineâ„¢s performance at high speeds, and if you put in a good high-speed camshaft, it hurts the engineâ„¢s performance at low speeds.
VTEC (which stands for Variable Valve Timing and Lift Electronic Control0 is an electronic and mechanical system in some Honda engines that allows the engine to effectively have multiple camshafts As the engine moves into different rpm ranges the engines computer can activate alternate lobes on the camshaft and change the camâ„¢s timing. In this way, the engine gets the best features of low-speed and high-speed camshafts in the same engine
MIVEC (Mitsubishi Innovation Valve timing and lift Electronic control) which is used on the Mitsubishi engines.
VVT-I (Variable Valve Timing with Intelligence) and now VVTL-I ((Variable Valve Timing with Intelligence AND Lift with Intelligence) which is being used on the current Toyota and some Lexus engines
VVL (Variable Valve Lift ) which is used on the Nissan engines, The cam VVL, Nissanâ„¢s new variable lift
VTEC (Variable Valve Timing and Lift Electronic Control) is a valvetrain system developed by Honda for improve the volumetric efficiency of four-stroke internal combustion engine . This system uses two camshaft profiles and electronically selects between the profiles. It was invented by Honda R&D engineer Ikuo Kajitani It can be said that VTEC, the original Honda variable valve control system , originated from REV ( Revolution-modulated valve control ) introduced on the CBR400 in 1983 known as HYPER VT EC
The camshaft uses rotating lobes that push against the valves to open and close them. Since engines valves play a major role in how air gets in an out of the combustion chamber, it makes sense to focus on them when looking to increase horse power and efficiency.
When you increase the rpm however this configuration for the camshaft does not work well. If the engine is running at 4000 r/min the valves are opening and closing 2000 times every minute. When the intake valve opens at the top of the intake stroke, it turns out that the piston has a lot of trouble getting the air moving into the cylinder in the short time available. Therefore, at a higher rpm ranges you want the intake valve to open prior to the intake stroke-actually back in the exhaust stroke-so that by the time the piston starts move in downward in the intake stroke the valve is open and air moves freely into the cylinder during the entire intake stroke. For maximum engine performance at low engine speeds the valves need to open and close differently than they do at higher engine speeds. If you put in a good low-speed camshaft, it hurts the engineâ„¢s performance at high speeds, and if you put in a good high-speed camshaft, it hurts the engineâ„¢s performance at low speeds.
VTEC (which stands for Variable Valve Timing and Lift Electronic Control0 is an electronic and mechanical system in some Honda engines that allows the engine to effectively have multiple camshafts As the engine moves into different rpm ranges the engines computer can activate alternate lobes on the camshaft and change the camâ„¢s timing. In this way, the engine gets the best features of low-speed and high-speed camshafts in the same engine
MIVEC (Mitsubishi Innovation Valve timing and lift Electronic control) which is used on the Mitsubishi engines.
VVT-I (Variable Valve Timing with Intelligence) and now VVTL-I ((Variable Valve Timing with Intelligence AND Lift with Intelligence) which is being used on the current Toyota and some Lexus engines
VVL (Variable Valve Lift ) which is used on the Nissan engines, The cam VVL, Nissanâ„¢s new variable lift
