Toyota VVT-i system:

VVT-i is Toyota’s proprietary valve timing system – “Variable Valve Timing with intelligence”, which means intelligent change in valve timing.

This is the second generation of Toyota’s variable valve timing system. Installed on cars starting from 1996.

Operating principle: the main control device is the VVT-i clutch. Initially, the valve opening phases are designed for good traction at low speeds. After the speed increases significantly, and at the same time the oil pressure increases, which opens the VVT-i valve. After the valve is open, the camshaft rotates at a certain angle relative to the pulley. The cams have a certain shape and, when turning the crankshaft, they open the intake valves a little earlier and close later, which has a beneficial effect on increasing power and torque at high speeds.

Toyota VVTL-i system:

VVTL-i is TMC’s proprietary valve timing system – “Variable Valve Timing and Lift with intelligence”, which means intelligent change in valve timing and valve lift.

Third generation of VVT system. A distinctive feature from the second generation VVT-i lies in the English word Lift – valve lift. Now the camshaft not only rotates in the VVT clutch relative to the pulley, smoothly adjusting the opening time of the intake valves, but also, under certain engine conditions, lowers the valves deeper into the cylinders. Moreover, valve lift is implemented on both camshafts, i.e. for intake and exhaust valves.

If we look at the camshaft, we will see that for each cylinder for each pair of valves there is one rocker arm, along which two cams operate at once – one normal and the other enlarged. Under normal conditions, the enlarged cam runs idle, because in the rocker arm there is a so-called slipper underneath, which fits freely inside the rocker arm, thereby preventing the large cam from transmitting the pressing force to the rocker arm. Underneath the slipper is a locking pin that is operated by oil pressure.

Operating principle: under increased load at high speeds, the ECU sends a signal to an additional VVT valve – it is almost the same as on the clutch itself, with the exception of minor differences in shape. As soon as the valve has opened, oil pressure is created in the line, which mechanically acts on the locking pin and moves it towards the base of the slipper. That’s it, now the slipper is blocked in the rocker arm and has no free movement. The moment from the large cam begins to be transmitted to the rocker arm, thereby lowering the valve deeper into the cylinder.

The main advantages of the VVTL-i system are that the engine pulls well at the bottom and shoots at the top, and fuel efficiency improves.

The disadvantages are reduced environmental friendliness, which is why the system in this form did not last long.

Toyota Dual VVT-i system:

Dual VVT-i is TMC’s proprietary valve timing system. The system shares the same operating principle with the VVT-i system, but is extended to the exhaust camshaft. VVT-i couplings are located in the cylinder head on each pulley of both camshafts. In fact, it is a conventional dual VVT-i system.

As a result, the engine ECU now controls the timing of the opening of the intake and exhaust valves, allowing for greater fuel efficiency at both low and high speeds. The engines turned out to be more elastic – torque is distributed evenly across the entire engine speed range. Considering the fact that Toyota decided to abandon the valve lift adjustment as in the VVTL-i system, the Dual VVT-i therefore does not have the disadvantage of being relatively low in environmental friendliness.

The system was first installed on the 3S-GE BEAMS engine in the Toyota Altezza RS200 in 1998. Currently installed on almost all modern Toyota engines, such as V10 LR series, V8 UR series, V6 GR series, AR and ZR series.

Toyota VVT-iE system:

VVT-iE is TMC’s proprietary valve timing system. From English Variable Valve Timing – intelligent by Electric motor, which translated means intelligent change of valve timing using an electric motor.

To date, this is the most technologically advanced Toyota system designed to change the valve timing of modern engines. Its meaning is exactly the same as that of the VVTL-i system. The difference lies in the implementation of the system itself. The camshafts are deflected at a certain angle to advance or retard the sprockets using an electric motor, and those oil pressures are the same as on previous VVT models. Now the operation of the system does not depend on engine speed and operating temperature, unlike the VVT-i system, which is not capable of operating at low engine speeds and without reaching the engine operating temperature. At low speeds, the oil pressure is low and is not able to move the VVT clutch blade.

VVT-iE does not have the above disadvantages, because independent of engine oil. It also has the additional advantage of being able to accurately position the offset of the camshafts depending on the operating conditions of the engine. The system begins its work from the start of the engine until it stops completely. Its work contributes to the high environmental friendliness of modern Toyota engines, maximum fuel efficiency and power.

Operating principle: the electric motor rotates together with the camshaft at a speed equal to the speed of the camshaft. If necessary, the electric motor either slows down or accelerates relative to the camshaft sprocket, shifting the camshaft by the required angle, advancing or retarding the valve timing.

The VVT-iE system first debuted in 2007 on the Lexus LS460 installed in the 1UR-FSE engine.

Here’s a good video showing how the VVT-i system works: