VTEC: How Honda’s Smart Solution Gives Your Car the Edge on the Road

If you are a fan of fast cars, you have probably heard of Honda’s VTEC system. VTEC stands for Variable Valve Timing and Lift Electronic Control, and it is a clever trick that Honda invented to make their engines more powerful, more efficient, and more fun to drive. But how does it work, and why is it so special? Let’s find out.

The Story of VTEC

The VTEC system was born in the late 1980s, when Honda engineer Ikuo Kajitani had a brilliant idea. He wanted to create an engine that could combine the best of both worlds: the low-end torque and the high-end power. He was inspired by a system that Honda used on their motorcycles, called REV, which changed the shape of the camshaft at high speeds to increase the valve lift and duration.

The camshaft is a metal rod that rotates with the engine and pushes the valves open and closed. The valves are the gates that let the air and fuel into the combustion chamber, where they are ignited by the spark plug and produce the power. The shape of the camshaft determines how far and how long the valves open, which affects how much air and fuel can get in and out of the engine. The more air and fuel, the more power.

The problem is that there is no one perfect shape for the camshaft. If you want more power at high speeds, you need a camshaft that opens the valves more and longer, to let more air and fuel in. But if you do that, you lose torque and efficiency at low speeds, because the valves open too much and too early, and some of the air and fuel escape without being burned. On the other hand, if you want more torque and efficiency at low speeds, you need a camshaft that opens the valves less and shorter, to keep the air and fuel in. But if you do that, you limit the power at high speeds, because the valves don’t open enough and long enough, and the engine can’t breathe properly.

Kajitani’s solution was to create a camshaft that could change its shape depending on the engine speed and load. He designed a camshaft that had three different lobes for each pair of valves: a small one for low speeds, a big one for high speeds, and a medium one for the transition. He also devised a mechanism that could lock and unlock the lobes together, using a solenoid, a spool valve, a locking pin, and a rocker arm. The rocker arm is a metal lever that connects the camshaft to the valve, and it has three parts: one that follows the small lobe, one that follows the big lobe, and one that follows the medium lobe and pushes the valve.

The mechanism works like this:

• When the engine is running at low speeds, the solenoid is off, and the oil pressure is blocked from the locking pin. The locking pin is pulled back, and the three parts of the rocker arm are separated. The valve is only moved by the part that follows the small lobe, which opens the valve less and shorter.
• When the engine reaches a certain speed and load, the solenoid is turned on, and the oil pressure is allowed to the locking pin. The locking pin is pushed forward, and the three parts of the rocker arm are locked together. The valve is now moved by the part that follows the big lobe, which opens the valve more and longer. The part that follows the medium lobe acts as a bridge between the other two parts, and the medium lobe is ignored.
• When the engine slows down and the load decreases, the solenoid is turned off again, and the oil pressure is blocked from the locking pin. The locking pin is pulled back, and the three parts of the rocker arm are separated again. The valve is now moved by the part that follows the small lobe, which opens the valve less and shorter.

The VTEC system can switch between the small and the big lobes in a blink of an eye, without any interruption or delay in the engine performance. The switch-over point is variable, depending on the engine conditions and the driver’s demand. The VTEC system also has a hysteresis effect, which means that the switch-over point is higher when going from low to high than when going from high to low. This prevents the engine from constantly switching back and forth between the two lobes, which could cause instability and wear.

The first VTEC engine was the B16A, a 1.6-liter engine that debuted in the 1989 Honda Integra XSi. The B16A produced 160 horsepower and 111 lb-ft of torque, making it the most powerful naturally aspirated engine per liter at the time. The VTEC system gave the B16A a smooth and linear power delivery, as well as a high-revving capability of up to 8,000 RPM.

The VTEC system soon became a trademark of Honda’s performance-oriented engines, such as the B18C in the Integra Type R, the F20C in the S2000, and the K20A in the Civic Type R. These engines were loved for their responsiveness, flexibility, and thrilling sound. The VTEC system also made its way into Honda’s mainstream engines, such as the D15B in the Civic, the F23A in the Accord, and the J35A in the Odyssey, where it improved the fuel economy and emissions without compromising the power output.

The Magic of VTEC

The VTEC system offers several benefits for the engine performance, fuel efficiency, and emissions, such as:

• More power and torque at high speeds, by allowing the engine to breathe more freely and burn more fuel and air.
• Better fuel economy and emissions at low speeds, by reducing the pumping losses and the residual gas in the combustion chamber.
• More responsiveness and flexibility at all speeds, by providing a smooth and linear power delivery and a wide power band.
• Less engine weight and size, by eliminating the need for multiple camshafts or variable valve timing systems.

The VTEC system is one of the most advanced and successful engine technologies that Honda has ever developed, and it has earned a loyal fan base among car enthusiasts and drivers around the world. The VTEC system is not only a technical achievement, but also a symbol of Honda’s passion and dedication to creating the best engines possible.