The Evolution of VTEC

Saturday, February 16, 2008

By Tobi Connell (aka "HONDA GHANDI")- 02.11.2008

In the beginning, there were the incredible days of cheap gas and even cheaper insurance. Boy, those were the days weren’t they? The fuel crisis of the late 70’s flipped our world upside down. Gas guzzlers were heading for the crusher in record numbers, and the newly emerging import market was on the horizon. In the early days, Hondas were roaming the streets in limited numbers with even more limits in style. The first Hondas widely sold in the US were quirky and strange, but they got nearly 50 mpg giving them a slight edge in the US market. Thus, the economical import car market was born, and Honda would be forever known as the weird little car that saved you some cash at the pump and lasts forever.

The early 80’s marked booming business for Honda in the US. Gaining ground on Detroit meant higher sales, new models and the realization that the old CVCC engine was showing its age. In true Honda fashion they began working on a completely new engine instead of redesigning a classic. The goals were simple: It has to have power on the low and high rpm range, it had to have economy, and it had to produce 100 hp per liter. In 1982 this was a very bold statement when the typical 4-cylinder engine was producing in the range of 50-60 hp per liter. Honda engineers were asked to present several ideas and designs to be selected as the new foundation for Hondas engine program. The end result would ultimately become what we know as VTEC (Variable Valve Timing & Lift Electronic Control System). The concept of variable camshaft profiles at the time was not a new idea, but the technology was still years away. Honda was dedicated to fast-tracking the technology needed to get it into production.

In 1984 Honda formed a special engine group called NCE (New Concept Engine). NCE’s purpose was to take VTEC from an idea to production in four short years. The initial idea was to use a 4-valve engine in a 3-valve mode closing one valve at low rpm and during cruise speeds. This eventually became the economical version of VTEC known as VTEC-E. It made respectable power on demand as well as incredible fuel economy at highway speeds upwards of 45 mpg in the Civic VX. Among other ideas, a dual profile camshaft with floating rocker system was being finalized. This system would revolutionize the sport compact performance market for years to come. The design was simple, lightweight and could produce high revving sports car type excitement as well as economy car drivability and economy. Honda’s Integra in 1989 would be the first production car to come with this revolutionary power plant. The US would still have to wait until 1991 to get its first taste of VTEC in the form of Acura’s NSX supercar. The average Joe would have to wait until 1993 to get its own version of the four cylinder monster in the 1993 Integra GSR made by Acura, and the Del Sol VTEC which was met with mixed reviews in the US market. In 1994, Acura redesigned the Integra and upgraded the VTEC engine to 1.8L forever changing the face of 4-cylinder performance. It has been referred to as the “Small Block Chevy” of the 1990’s.

In design, the VTEC principle was simple and effective. A trio of rocker arms follows the camshaft’s matching trio of lobes. The two outer lobes would drive the valves during idle, low speed operation and cruise speeds. When more power was demanded from the engine, a solenoid activated by the ECU would provide hydraulic pressure down the rocker shafts locking all three rocker arms together forming one large rocker arm that would follow the center cam lobe. It would effectively increase the airflow and volume of the cylinders creating a significant jump in power and torque. When the throttle was lifted, it would revert back to its previous state using spring loaded pins in the rocker arms to allow the rocker shafts to unlock. All of this can take place in the blink of an eye at upwards of 6000 rpm. The result is a rush in power that lasts all the way to 9000 rpm in some engines.

By the late 1990’s the VTEC engine had been adapted, modified, beefed up and stuffed in every possible car combination you could imagine. Some tuners were making nearly 1000 hp with turbocharged versions of the 1.8L 4-cylinder engine and racing them on the track smashing track records. No one could have predicted the success and limitless opportunities presented to the motor sports community by the little 4 cylinder engines produced by Honda. That was all about to change in 2001 when Honda discontinued the Integra and Civics along with all the glorious VTEC DOHC cam engines that came with them. Again, a need for larger, faster, more luxurious models and strong competition for higher fuel mileage and emissions standards was about to bring a whole new generation of power plants from the Honda camp. Its name would be i-VTEC, and it would revolutionize the Honda tuning scene yet again.

In 2001 Honda introduced the 2002 Acura RSX-S with the newest version in the VTEC camp aptly named i-VTEC. The “i” stands for “intelligent”. Improving on an aging system proved to be well worth the 12 year wait. The new i-VTEC system had a much lighter and more compact roller rocker system resulting in less parts and a smaller upper end package. The roller rockers allowed for a decreased valve angle and higher flow through the cylinder head resulting in higher torque and top end power. In accordance with the new i-VTEC system which activates the VTEC lobes by calculating load instead of RPM, Honda added a totally new device on the intake cam which allowed the ECU to alter the intake camshaft timing up to 50 degrees. This allowed for increased low end torque, smoother acceleration and very good cruise speed economy. In effect, they have achieved the best of both worlds in an engine that can tune itself as it drives.

By 2003 the aftermarket machine had embraced the new Honda engines like one of its own children. Custom cams, pistons, and a myriad of engine parts were flying off the shelves as well as the earliest forms of swap mounts and turbo kits for what would be known simply as “The K” because of the engine codes K20 and K24. In a few short years, performance tuners had figured out that almost all of the K series engines had interchangeable parts and could be mixed and matched. 2.4L lower halves were mated to the coveted K20A2 cylinder head to make a very potent street killer. By 2006 tuners were approaching the 300 whp mark with bored and stroked versions of this amazing power plant. A feat that the original engineering group that designed the VTEC engine, just 20 short years earlier, would have never thought possible.

So what does Honda have left in the stable for its next generation VTEC engine? All roads point to a totally new version of VTEC that allows for variable cam timing, variable valve lift, and possibly direct injection. With a valve mechanism that can be controlled electronically, it can fine tune the engine’s characteristics to the point of deleting the throttle plate and several other antique engine technologies for a hyper-clean burning engine that can deliver horsepower previously thought impossible from a 4-cylinder gasoline engine.

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