The Story of Honda VTEC

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Do you recognize this sound?
If you said “Honda’s VTEC” then you’re right! But what is “VTEC” exactly?
Though it's been called many things, the VTEC acronym really stands for Variable Valve Timing and Lift Electronic Control. But, VVTLEC doesn't sound quite as sexy as the more well-known abbreviation.
It may also surprise you to know that the technology behind VTEC originated from Honda’s motorcycle division and none of it had anything to do with their automobile engines. Early on, Honda's engineers knew that four-valve engines made great top-end power, but that two-valve variants were much more capable at the low rpm range and idle.
Let’s dive deeper into what this means exactly. In a standard four-stroke engine, the intake and exhaust valves are actuated by lobes on a camshaft. And the shape of the lobes determines the timing, lift, and duration of each valve. Timing refers to the angle of measurement of when a valve is opened or closed as it relates to the piston’s position - either TDC or BDC. Lift refers to how much the valve is opened. And duration refers to how long the valve is kept open.
Additionally, air-fuel mixtures behave differently before and after combustion which impacts the physical limitations on their flow. Coupled with ignition spark, optimal valve timing, lift, and duration settings under low RPM operation are very different from those under high RPM conditions.
For example, the optimal low RPM valve timing lift and duration settings would result in an inefficient air-fuel mixture inside the cylinder at high RPM, thus considerably limiting engine power output. Conversely, optimal high RPM valve timing lift and duration settings would result in very rough low RPM operation and difficult idling.
The ideal engine would have fully variable valve timing, lift, and duration, in which the valves would always open at exactly the right point, lift high enough and stay open just the right amount of time for the engine speed and load in use.
This sparked the quest for a 500cc engine that would rev effortlessly to 11,000 rpm but could also hold a smooth idle at 1,000rpm.
The result was what Honda internally labeled "HYPER VTEC". Which was introduced on the CBR400 in 1983. The technology allowed for only one intake and one exhaust valve per cylinder to operate below certain engine speeds but for another pair of intakes and two exhaust valves per cylinder to function above that threshold.
The evolution of this new technology continued when.
In March 1984, Honda launched the NCE (New Concept Engine) program, which aimed to push the limits of top-end torque performance without sacrificing low-end power. The result of this particular project materialized in the 1985 Civic and Integra engines released exclusively in the Japanese market.
The success of the New Concept Engine project convinced Honda’s engineers that a dual-camshaft profile-or a mechanism that could dynamically alter camshaft timing-must be a part of the company's next generation of engines.
The goal would be to have better fuel economy and a higher output across the entire powerband. Initially, this goal was set specifically for 90 hp per liter. However, based on the suggestion of then Honda R&D president Nobuhiko Kawamoto, a higher goal of 100 hp per liter was set.
This was considered a lofty proposition considering conventional engines in those days could only produce 70 or 80 hp per liter. Honda engineers knew this wasn’t going to be an easy task since an engine becomes subjected to a higher load as rpm increases. Also adding the complication of a quality-assurance target of 15 years, or 250,000 km, for a mass-production engine.
After all that, another goal was officially set that the new VTEC engine would make 160hp and have an 8,000 rpm redline. This all led to disagreements among Honda engineers on whether or not such an engine was even possible. After three months, the lead engineer of the project put it all on the line, ordering his team to move forward.
The aim to push the limits of top-end torque production without sacrificing low-end performance eventually would be realized when the new VTEC technology was official and featured in the 1989.5 Integra XSi which used the 160 bhp DOHC B16A engine.
The same year, Europe saw the arrival of VTEC in the Honda Civic and Honda CRX 1.6i-VT, using a 150 bhp B16A1 variant. The United States market saw its first VTEC system with the introduction of the 1991 Acura NSX which used a 3-liter DOHC C30A V6, outputting 270 bhp. DOHC VTEC engines soon appeared in other vehicles, such as the 1992 Acura Integra GS-R making 160 bhp, and later in the 1993 Honda Prelude VTEC producing 195 bhp and the Honda Del Sol VTEC which made 160 bhp.