Applying the Technology to All Honda Models

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The V6 3.0-liter DOHC/VTEC engine powering Honda's flagship NSX sportscar



<< 1. Variable Valve Timing... for Power and Fuel Economy
<< 2. Designing a Dream: A Hundred Horses per Liter
<< 3. An Open Invitation to Participate
<< 4. Discerning Genuine Technologies
<< 5. Pursuing Excellence Through Trial and Error
<< 6. Applying the Technology to All Honda Models
<< 7. The Confidence Needed to Innovate
 


The VTEC engine had finally revealed its complete performance profile. However, the success of D-development only meant the start of a critical phase. In order to ensure absolute reliability in mass production and introduce the engine to the market with confidence, the team had to guarantee the functions of all mechanisms and parts. In addition to a significant responsibility for product reliability, the team had special expectations regarding the VTEC engine. Said Kajitani, "We all shared the determination to apply these technologies to every Honda model."

The team's view of it was that VTEC technology shouldn't be limited to the Integra alone but further improved it could be adapted to Honda's future model developments. As such, the initial specification would have to meet customer expectations. In fact, the team had gone through a repeated process of trial and error designed to eliminate all possible problems, however minor they might have been. Actually, at the onset of engine development their greatest concern was the assurance of engine functions. They knew how difficult it would be to guarantee a complex switching mechanism.

For example, the selector pin had a thickness of only 10 mm, so its operation was affected by wear of just several microns. So, in many cases the more delicate the task the more worrisome it was.

"That's why we so thoroughly carried out our malicious tests," said Kajitani. "We were very near the point of overdoing it."

A malicious test is one designed to verify a mechanis-m's reliability and performance by subjecting it to conditions far in excess of those anticipated during actual vehicle operation. In case of VTEC, numerous tests were repeatedly carried out for all parts, including the timing belt, camshaft, rocker arm and selector pin, to meet the target switching performance of 400,000 events. The team even analyzed the effect of changing loads on the control of low- and high-speed valve timing. Fail-safe(1*) measures were further incorporated in the hydraulics and electrical systems. In this way the development staff not only eliminated its initial fears but achieved a degree of reliability that was well beyond the target value.

Note(1*): Fail-safe feature: An auxiliary device or system is used to ensure continued operation in the event that a system failure occurs.
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