Honda did not invent variable valve timing or variable valve lift. In fact, Cadillac had a driver-operated variable valve timing system in production in 1903, three years before Soichiro Honda was born. Alfa Romeo and Nissan also had variable valve timing in the Eighties, but it was the 1989 Integra and its 1.6-liter VTEC four-cylinder that created a legend.
So much of automotive engineering is about minimizing compromise, and doing so while also minimizing cost. With a conventional valvetrain, valve lift (how much the valve opens), valve timing (when the valve opens), and duration (how long it opens) is defined by the camshaft profile, the shape of the individual cam lobes on the shaft. Before variable valve timing and lift, auto engineers had to select a cam profile that provided a desirable compromise between performance and efficiency across a wide powerband. Engines want different things depending on load and operating speed. A camshaft profile that gives you good fuel economy when puttering around town isn't optimal when you're wide-open-throttle at high revs. By changing valve timing, duration, and lift, you can optimize for all sorts of different running conditions. The trick is to do it reliably and cheaply.
The benefits of such a system were obvious even to the first automotive engineers. At the 1989 SAE international congress, a pair of Stanford professors presented a paper which noted that at least 800 patents around variable valve timing had been granted since 1880. By examining these patents, the researchers created 15 classifications for different variable valve timing systems, but concluded "VVT has much potential, but that very little of this potential has yet been realized. Serious difficulties have limited the application of variable valve timing to date. Virtually all VVT mechanisms proposed until recently suffer from high cost and complexity, limited variability, and high impact velocities."
That very next SAE paper was written by three Honda engineers, detailing a prototype VTEC system as fit to a 1.2-liter DOHC engine. It is the classic VTEC system as we know it today, with two low-speed cams on either side of a high-speed cam. The two low-speed cam profiles operate as normally at lower engine speeds, acting on rocker arms that press on the valve stems. The third cam profile is essentially freewheeling at this point, acting on a separate rocker arm not attached to the two acting on the valve. At a certain engine speed, the ECU triggers a solenoid, which opens an oil passage that forces a piston to lock the three rocker arms together. Now, the larger cam profile is at work, increasing valve lift and duration.
This paper may have described a prototype system, but just two months later, VTEC made its debut in the second-generation Integra. (The U.S. would have to wait two years for the launch of the NSX to get its first VTEC engine.) The engine was a marvel. Initially, the target for the new Integra's was 140 horsepower from a 1.6-liter, but that was just 10 better than its predecessor. According to a history from Honda, Ikuo Kajitani, the engineer in charge of Honda's four-valve engines, didn't think this was enough for a car entering a new decade. Honda R&D chief Nobuhiko Kawamoto suggested that Kajitani aim for something that seemed illusive among naturally aspirated engines—100 horsepower per liter. Absent an increase in displacement—undesirable for the Japanese market—that sort of power meant more revs. Eight-thousand to be exact, well into racing territory, and far higher than any other mass-market four-cylinder of the time. Hitting that number while also achieving good fuel economy and drivability around town would require more flexibility from the valvetrain. VTEC was the obvious solution, if not the simple one.
Work on the engine, the B16A, started in 1986, so there wasn't a ton of time to get it into production. Its high-revving nature also meant materials selection was a huge challenge, as parts needed to be both lightweight and strong, thus expensive. The abbreviated timeline also meant engineers needed to be militant about which components were necessary and which weren't for making the VTEC system work, and work reliably. When all was said and done, the 1989 Integra XSi offered 160 metric horsepower (152 of our imperial horsepower) at 7600 rpm.
In R&T's August 1989 issue, Japan Editor Jack Yamaguchi noted that the engine was expensive, adding around 15 percent of cost compared with the 1.6-liter SOHC Integra. The forged and polished crankshaft apparently had more than a passing resemblance to the company's F1 cranks. This was Japan's price-asset Bubble Era, when money seemed to be endless and automakers flexed their engineering muscles to create some of the greatest cars of the modern era. An 8000-rpm twin-cam four in a sporty mass-market hatchback seems batty now, but just look at the other Japanese cars of the era. This is when Toyota went after Mercedes, when Nissan tore apart a Porsche 959 to develop an all-wheel drive super coupe, when Mazda decided to single handedly revive the roadster. On-the-limit technology was allowed to proliferate, so why not put an engine with more power per liter than the ultra-specialized E30 M3 into what was essentially a fancy Civic?
Yamaguchi declared the B16A "sweetest power unit the house of Honda has ever put on four wheels," and promptly ordered an Integra XSi. Honda president Tadashi Kume was so impressed by VTEC, he ordered the V-6 in development for the NSX be reengineered to accommodate the system. It was an expensive endeavor that came late in the car's production, but one that gave Honda's supercar power to match the Ferrari 328 with two fewer cylinders.
"A lot of the engine guys came from our F1 program," Kurt Antonious, Honda's longtime PR lead, remembers of the early VTEC days. "They learned so much in F1 racing as far as getting the most performance, you know, with the least amount of weight in the engine." Honda's culture was conducive to fostering such a technology, too. Then, as now, it is a company made in Soichiro Honda's image, and Mr. Honda was an engineer first and foremost. Antonious points out that in the late eighties and early nineties, R&D received huge investment, creating what he considers a "magical era" for the company.
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If you've ever driven a classic VTEC engine, a B-series derived from that original Integra mill, a later naturally aspirated K-series, the NSX's V-6, or the F20C from the S2000, you won't forget the experience. The changeover in cam profiles is very obvious. Take the above video of a K20-swapped 1993 Civic from AutoTopNL on YouTube as an example. Right around 5500 rpm you can see and hear the switchover, with the sound getting more buzzsaw, and the car suddenly pulling harder to its 9000-rpm redline. Other VTEC cars don't make the changeover quite so obvious, but it's still noticeable. In an S2000, you don't really hear the change, but you feel the difference, especially beyond the 7000-rpm mark. The viral "VTEC just kicked in YO" video exaggerates the difference, with the driver going to wide-open-throttle only around the point where the profiles shift. Still, though, it's a sound burned into many car enthusiast heads.
What's interesting is that not many variable valve-timing and lift systems behave quite like this. Honda might've been the first to push this sort of thing into the public consciousness with such an excellent system, though it's hard to say it alone was the spark that kicked off the revolution. Recall that both Alfa Romeo and Nissan had variable timing systems in production before Honda launched the 1989 Integra XSi. That SAE paper from the Stanford professors notes that of the 800-plus patents examined, over 110 were granted between 1985 and 1987, so it's clear variable valve timing and lift was on the minds of far more than just some engineers at Honda.
Two years after the Integra XSi, Porsche debuted a revised version of the 944, the 968, which featured the first continuously variable valve timing system. As Total 911 explains, VarioCam, as it's called, uses a tensioner to vary the amount of slack in the chain between the intake and exhaust cams, changing the intake valve timing. Given that most cars are developed on a four-year timeline, Porsche was assuredly working on VarioCam before VTEC reached the public. BMW's VANOS variable-valve timing system, which uses a helical gear on the camshaft to change the timing, also arrived in 1992 with the company's much-loved M50 straight-six
VTEC isn't necessarily the simplest way to boost an engine's performance and efficiency either. At least where timing is concerned, VTEC uses a lot of parts to achieve what others—like BMW and Porsche—achieved with simpler mechanisms. In modern times, most engines with variable valve timing use some sort of camshaft phaser controlled by oil pressure (as is the case with VANOS) or electric motors to adjust the timing relative to crankshaft position.
Turbocharging has also changed the equation. With much greater control over the air going into the engine, there isn't nearly as much of a need to have complicated valve gear on the intake side. Honda's VTEC Turbo engines, like the 2.0-liter in the Civic Type R, use a VTEC system on the exhaust camshaft to deal with all the extra air forced in by the turbo at higher engine speeds.
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For a great example of a modern engine with variable valve timing and lift, we should look to one of the most ubiquitous, the Volkswagen Group's EA888 turbocharged four-cylinder. The above video from YouTubers Engineering Explained and Humble Mechanic looks at the head from a 2009 Audi A4 2.0, though what's here is broadly applicable to applications of the "triple-eight" including the Mk7 and Mk8 VW GTI. On the exhaust side, the camshaft can be moved to one of two positions, one with low-lift profiles, one with high-lift profiles. On the intake side the common oil-pressure driven cam phaser adjusts valve timing.
What separates the classic VTEC from all of this really is the driving experience. This was an example of a technology that made a very apparent change to how a car felt. Your modern car probably has some sort of variable timing/duration/lift system, but you probably don't notice it at work—you just get good performance and economy across a wide powerband. In a 2001 Integra Type R at 5500 rpm and wide-open-throttle, you got the sound and the fury. Following that original Integra XSi, plenty of automakers introduced variable valve timing and lift. Few did so with such panache.
A car enthusiast since childhood, Chris Perkins is Road & Track's engineering nerd and Porsche apologist. He joined the staff in 2016 and no one has figured out a way to fire him since. He street-parks a Porsche Boxster in Brooklyn, New York, much to the horror of everyone who sees the car, not least the author himself. He also insists he's not a convertible person, despite owning three.
