Variable Valve Timing Complexity for Motor Oils

Matt erickson | Technical Product Manager - Passenger Car

Matt erickson
Technical Product Manager - Passenger Car

Driven by increasingly strict emissions limits and higher fueleconomy requirements, vehicle makers are adding new technology to engines and making advancements to present systems. The setup used to vary the time of intake and exhaust valves opening and closing is just one area receiving tons of curiosity.

Like people, engines must "breathe." An ordinary engine needs approximately 10, 000 gallons of air, to combust one-gallon of petrol. Getting the absolute most from the fuel-air mixture is vital for top engine functionality. This involves precise regulation of valve train components, including the, camshaft and valves. Valves are opened and closed to evacuate exhaust gases from the cylinder after burning gas and to control the delivery of fuel and fresh air for the cylinder. Valves are pushed open by cams (lobes) and closed by springs. Valve timing is controlled by the contour of the cam lobe and position of the camshaft relative to the crankshaft. In traditional engine designs, the time of every valve is locked and can't be altered without physically changing the camshaft. The task is making a method that performs economically at both low engine rpm and high engine rpm. Enter variable valve timing systems.

Variable valve timing presents yet another complexity for motor oils to overcome.

Variable valve timing (VVT) is just a decades old technology that has been introduced to defeat the constitutional limitations of fixed valve train systems. Its use has steadily grown since the late1990s, and VVT can now be found in virtually all 2011 and later vehicles. VVT allows the opening and closing activity of the valves to occur sooner, or be delayed, in accordance with the place of the plunger. This can help you reach optimal fuel economy and performance at low speeds and when passing someone on the freeway. It also results in lower emissions.

There are many VVT methods used by OEMs, and there were recent developments in the control of the methods. Many systems use oil-pressure - used mechanical devices to change valve timing (as soon as the valve opens and closes), valve duration (how long the valve is open) and valve lift (how far the valve opens). For instance, the Honda i-VTEC system utilizes oil pressure to lock the motion of intake valves together via pins and transfers their motion to another cam profile to correct for the increase in performance needed above 4500 rpm.

Now more than ever, quality motor oil is key to engine longevity.

Other systems, like Toyota's VVT-i, vary the valve motion by adjusting the time of the camshaft in relation to engine speed. Oil pressure-actuated devices, generally called cam phasers, are used to control that motion.