HONDA UPDATES THE VTEC
More power and economy from high-tech engine
Honda has revealed an update to its VTEC engine technology that makes the engine more efficient. The company said that the 1.8-litre version produces as much power as a 2-litre as a result but returns fuel economy figures akin to those of a 1.5-litre lump.
According to Honda, the engine employs an intelligent VTEC system that switches the valve timing for maximum efficiency during startup and acceleration to achieve powerful, torquey performance, then delays intake valve closure timing during cruising and other low-load conditions for improved fuel economy.
Use of the valve timing control system results in off-the-line acceleration performance equivalent to a 2.0-litre engine, fuel economy better than the current 1.6-litre Civic engine, making it one of the world’s most efficient 1.8-litre engine designs. During cruising, the new engine achieves particularly high fuel economy, on a par with that of a 1.5-litre engine.
How it works
Under low-load conditions on conventional engine, the throttle valve is normally partly closed to control the intake volume of the fuel-air mixture. During this time, pumping losses are incurred due to intake resistance, and this is one factor that leads to reduced engine efficiency.
With Honda's new i-VTEC engine, however, intake valve closure timing is delayed to control the intake volume of the air-fuel mixture, allowing the throttle valve to remain wide open even under low-load conditions for a major reduction in pumping losses of up to 16 per cent. Combined with comprehensive friction-reducing measures, this results in a significant increase in fuel efficiency for the engine itself.
A drive by wire system provides high-precision control over the throttle valve while the valve timing is being changed over, ensuring smooth driving performance which, according to Honda, leaves the driver unaware of the resulting torque fluctuation.
Other innovations include a variable-length intake manifold that delivers optimum inertia effect to further improve intake efficiency and piston oil jets that cool the pistons to suppress engine knocking, for powerful torque at rpm ranges typical in normal driving.
While the 1.8-litre engine only delivers some 138bhp and maximum torque of 128lb-ft, it is not hard to see how a bigger engine could deliver some meaty numbers. It also delivers cleaner emission performance, employing a two-bed catalytic converter positioned immediately after the manifold and high-precision air-fuel ratio control to achieve low emission levels.
In addition, lower block construction resulting in a more rigid engine frame, aluminium rocker arms, high-strength cracked connecting rods, a narrow, silent cam chain, and other innovations make the engine more compact and lightweight.
The engine will find its way first into the new Civic.