The VTEC breakthrough as of October 2004 : solving a century-old dilemma

Not all technologies depicted are used in all markets.

What is VTEC?

Born some 100 years ago, the engine was, until VTEC,
a clever balancing of compromises.

Improvement in one area was always achieved at the expense of another area.

Until VTEC, privileging ease of use affected outright performance. On the other hand, the pursuit of performance meant reduced drivability in everyday use.

Combining drivability in everyday situations with outright performance is what VTEC is all about.

VTEC: an entirely new approach to engine design

A 4-stroke engine goes through induction, compression, combustion and exhaust strokes to generate power. Before the advent of VTEC, the valves controlling the intake and exhaust strokes were operated according to fixed rules.

If the intake valves were made to open a relatively small amount to privilege drivability at low engine speeds as used in normal driving conditions, the engine would not be allowed to intake enough air at higher engine speeds, sacrificing outright performance. On the other hand, if the intake valves were made to open wide to privilege breathing at higher engine speeds, performance at low engine speeds would be compromised. This is a dilemma that has plagued engines for over a century.

VTEC operation

The new approach was to regulate valve operation to optimize performance at all engine speeds: opening the valves a small amount at low engine speeds, opening the valves wider as engine speed increases. That’s the breakthrough we named VTEC.

Optimizing engine breathing: how VTEC works

An elegant, simple mechanism
Switching between high and low valve lift using two cam profiles and two rocker arms per cylinder.

The switch is made using hydraulic pressure to push/release the sliding pin, locking/unlocking the middle rocker arm and the other rocker arm.

At low engine speeds, the pin is retracted, disengaging the middle rocker arm. The valves are operated by the two outside, low-profile cams for a low valve lift.

At higher engine speeds, increased hydraulic pressure pushes the pin, engaging the middle rocker arm. The valves are operated by the middle, high profile cam for high valve lift.

VTEC: a deceptively simple mechanism that uses hydraulic pressure to switch between different cam profiles.

100 years after the engine was born, VTEC technology finally reconciles drivability in everyday use and outright performance, creating the first uncompromising engine.

The 1989 Integra XSi/RSi were the first models powered by VTEC engines. They combined superior everyday drivability with a specific output of 100PS per liter of engine capacity, at the time an unheard of feat in a production engine.
1.6-Liter DOHC VTEC, Max. Power 160PS/7,600rpm (net)

The 2004 Legend is powered by a 3.5-Liter VTEC engine, the biggest engine in Honda’s line-up. It combines impeccable manners in everyday driving together with an outstanding maximum output of 300PS.



Page Top

Honda Worldwide site

Home | Site Map | Site Index | About this Site

Copyright, Honda Motor Co., Ltd. and its subsidiaries and affiliates. All Rights Reserved.