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The Ingenuity Behind VTEC: Honda’s Variable Valve Timing and Lift Electronic Control

Honda’s reputation is deeply tied to best-selling models like the Civic, a sedan revered for its practicality and versatility. These characteristics are at the heart of every Honda Civic for sale, but they do little to convey Honda’s ongoing efforts to deliver more horsepower and capability in its lineup. For Honda, practicality and performance aren’t mutually exclusive, and it’s apparent in revolutionary designs like the VTEC engine, which has been around since the 1980s. But what is it, and how has it impacted the industry?

The Demand for More Power and Better Efficiency

The demand for more power has always defined the automotive industry. Yet, that demand is often associated with performance-oriented models like sports cars and trucks that require more horsepower and torque for heightened capability and smoother off-the-line acceleration. Honda’s VTEC engine proves even modest sedans like the Civic can benefit from the pursuit of power, debuting in the 1980s as a more practical option in a fleet already ingrained in practicality.

Honda launched its New Concept Engine (NCE) program in 1984 to find a feasible way to increase the power output from its small displacement engines. Engineers realized the give-and-take relationship between horsepower and torque in a traditional engine. A higher-revving engine compromises low-end torque, but retuning the engine to produce more low-end torque limits its horsepower output. The Honda NCE program found a solution, developing a four-valve per cylinder double overhead cam (DOHC) engine with Variable Valve Timing and Lift Electronic Control (VTEC).

VTEC: How It Works

The relationship between the timing and lift of the intake and exhaust valves is intricate and integral to an engine’s power output. The relationship typically yields high-end torque or low-end horsepower, but not both simultaneously. Once Honda recognized the relationship, the automaker found a way to alter the timing and lift of the valves to balance the horsepower and torque output. The solution was VTEC, the first commercially-successful variable valve timing and lift technology for a production car.

Honda’s earliest iteration of the VTEC engine debuted with the 1989 Integra in Japan, eventually arriving in the United States with the 1991 NSX. The engine is unique because it features three cam lobes for each valve pairing, with specific assignments for the cams. The center cam is larger and tuned for high-revving horsepower, and the smaller outer cams are tuned for smooth idling and low-end torque.

Each cam in the VTEC system has a rocker arm, with the center rocker arm paired with the center cam. This setup lets the outer rocker arms press against the valves. When the center cam is inactive at lower speeds, it allows the outer cams to open and close the valves. Then, as the revs increase, the engine’s computer releases a spool valve, directing oil pressure to lock the two outer rocker arms to the center arm. This optimizes the lift and timing to deliver high-end horsepower without compromising low-end torque.

The Proof of Success: It’s in the Numbers and the Evolution

The 1993 Prelude was the first Honda-branded model in America to feature a DOHC VTEC engine, and the difference was notable. The Prelude’s standard 2.3L engine produced 160 hp, but with VTEC, the Prelude saw an increase to 190 hp and 158 lb-ft of torque from a smaller 2.2L engine. The power output climbed even higher with the fifth-generation 1997 Prelude, which came standard with a 2.2L VTEC engine that produced 200 hp and 156 lb-ft of torque.

Honda capitalized on the revolutionary VTEC system, building its reputation for providing a more affordable and manageable alternative to turbocharged power. Drivers responded quickly, realizing small displacement engines could pack a heavy punch in Honda models. This success inspired the automaker to finetune its design, leading to the VTEC’s evolution and widespread use in the Honda fleet.

SOHC VTEC

With a keen eye for practicality, Honda looked for ways to use the VTEC system across its lineup. In 1992, the automaker debuted a single overhead camshaft (SOHC) VTEC engine in the best-selling Civic. Models like the Civic Si hatchback garnered widespread praise as its power output increased from 108 hp to 125 hp with the addition of VTEC, and its fuel economy climbed to 29 MPG in the city and 36 MPG on the highway. It was hard to imagine a vehicle could produce more power and use less fuel, but Honda proved the unimaginable feat was possible.

VTEC-E

While the demand for more balanced power was at the heart of the VTEC system, Honda also acknowledged its fuel-saving potential. VTEC-E capitalized on this characteristic, debuting in the 1992 Civic VX via a 16-valve 1.5L SOHC engine with a 12-valve mode. With one intake valve remaining closed during normal driving, the VTEC-E system generates a charge in the combustion chamber that moves the more concentrated part of the fuel-air mixture near the spark plug. As a result, VTEC-E is more efficient, with the 1992 Civic VX getting 48 MPG in the city and 57 MPG on the highway. Even later models, like the sixth-generation Civic, benefited from this development, saving fuel while producing more power.

VTEC Options With VTC and VCM

VTEC’s applications are widespread, with Honda updating the technology as i-VTEC in the new millennium to reflect its more advanced and intelligent design. The modern system offers more versatility and is compatible with Honda’s four-cylinder and V6 engines. It also pairs seamlessly with Honda’s Variable Timing Control (VTC) and Variable Cylinder Management (VCM) technologies, yielding an ideal balance of power and outstanding efficiency.

Most notably, Honda now applies its VTEC design to the very thing that inspired Honda engineers in the early 1980s––the turbocharger. After decades of fine-tuning VTEC, Honda took its 1.5L turbocharged four-cylinder engine, altered the valve timing and lift, and incorporated Variable Timing Control Technology. In doing so, Honda optimized the timing of the cams to enhance performance and responsiveness without dramatically reducing efficiency. For example, when accelerating, the design of the VTEC Turbo optimizes low-end torque because of the broader valve overlap. Alternatively, when the engine is revving higher or at full throttle, the VTEC Turbo closes that gap to ensure optimal horsepower.

That’s the VTEC Kicking In

Honda’s VTEC system is revolutionary because it seamlessly transitions between low-end torque and high horsepower output. This transition is well-known among Honda enthusiasts as “the VTEC kicking in.” It’s noticeable from the difference in speed and the sound of the engine between casually driving around town to engaging the accelerator to merge onto the highway. That shift is VTEC kicking in to give you the necessary power for the situation without compromising your control or the practicality guaranteed with the Honda name.

For many, VTEC’s benefits are best enjoyed from behind the wheel of a Honda with a manual transmission. A manual transmission provides a physical connection to your vehicle, letting you shift gears as needed. In doing so, you can reap the full benefits of the VTEC’s performance because you’re more aware of the engine’s RPMs and the power at your fingertips. That, however, isn’t to say other drivers looking to reap the rewards of Honda’s automatic transmissions can’t benefit from a boost in power, an engaging driving demeanor, and excellent efficiency.