American Honda Motor Co., Inc., has announced it will introduce a new 1.8-liter i-VTEC engine this fall in the upcoming 2006 Civic designed to achieve both more powerful performance and enhanced fuel economy. The engine employs an "intelligent" i-VTEC system that switches the valve timing for maximum efficiency during takeoff and acceleration to achieve powerful performance with excellent torque output, and then delays intake valve closure timing during cruising and other low-load conditions for enhanced fuel economy. Use of the valve timing control system results in off-the-line acceleration performance at low rpm equivalent to that of a 2.0-liter engine, and efficiency that is up to 6 percent better than the current 1.7-liter Civic engine, making it one of the world's most efficient 1.8-liter engine designs. During cruising, the new engine achieves particularly high fuel economy, on a par with that of a 1.5-liter engine.
With the new i-VTEC engine, intake valve closure timing is delayed to control the air intake volume, allowing the throttle to open wider under low-load conditions for a major reduction in pumping loss of up to 16 percent.
Under low-load conditions on a conventional engine by comparison, the throttle opening is small to control the intake volume of the air-fuel mixture. During this time, pumping losses are incurred due to increased intake resistance through the small throttle valve opening, a significant factor that leads to reduced engine efficiency. The new i-VTEC engine minimizes this pumping loss effect to increase efficiency.
Combined with comprehensive friction-reducing measures, the delayed intake valve closing results in a significant increase in fuel efficiency for the engine itself. A DBW (Drive By Wire) throttle control system provides precise control over the throttle valve while the valve timing is being changed, ensuring smooth driving performance. Other innovations include a variable-length intake manifold that delivers optimum inertia effect to further improve intake efficiency for powerful torque delivery at rpm ranges typical in normal driving. Piston oil jets reduce piston operating temperatures, which help suppress the possibility for engine knock in an engine with a 10.5:1 compression ratio.
Overall, the new engine delivers a high level of performance with maximum output of 140 horsepower and maximum torque2 of 128 lb-ft. It also delivers enhanced emissions performance by employing a 2-bed catalytic converter positioned immediately after the manifold and high-precision air-fuel ratio control to achieve ULEV-2 / Tier 2 Bin 5 emission levels in all 50 states.
The more powerful engine is both lighter and shorter than the current Civic 1.7-liter engine, and quieter as well. The engine's lower block construction results in a highly rigid design. Innovations that help make the engine more compact and lightweight include aluminum rocker arms, high-strength cracked connecting rods, and a narrow, silent cam chain.
1Honda internal data
2Horsepower and torque calculations reflect new SAE J1349 procedures revised August, 2004.
Specifications* for the 1.8-liter i-VTEC engine
|Engine type and number of cylinders||Water-cooled in-line 4-cylinder|
|Bore x Stroke (mm)||81 x 87.3|
|Max. Output (horsepower/rpm) 2||140|
|Max. Torque (lb-ft./rpm) 2||128|
*All values according to Honda in-house calculations