SOHC i-VTEC vs DOHC i-VTEC info and comparison

Single Over Head Camshaft i-VTEC

4cylinder engine created by Honda, it comes out with L-series engine and R series engine.

The new SOHC i-VTEC implementation is an entirely new implementation that was first introduced on the 2006 Honda Civic's R-series four cylinder SOHC engines. This implementation uses the so-called "fuel economy cam" and "high output cam" on one of the two intake valves of each cylinder (another intake valve is fixed). The "fuel economy cams" are designed to retard the closure of one intake valve and are activated between 1000-3500 RPM and under low load conditions. When "fuel economy cams" are activated, the intake valve closes well after the piston has started moving upwards in the compression stroke. During this time, the drive-by-wire throttle valve is open wider than normal. Due to the delayed closing of intake valve, a part of the intake mixture that has entered the combustion chamber is forced out again into the intake manifold. That way, the engine "emulates" a lower displacement than its actual one, which reduces pumping losses thus reducing fuel consumption and increases its efficiency. VTEC-off on means it can be considered to be running "high output cams". When the right conditions are achieved for fuel economy, VTEC engages the 2nd set, the 'low' or 'economy' cams. Thus VTEC-on on means it is running low cams.

Double Over Head Camshaft i-VTEC

VTECValve lift and duration are still limited to distinct low- and high-RPM profiles, but the intake camshaft is now capable of advancing between 25 and 50 degrees (depending upon engine configuration) during operation. Phase changes are implemented by a computer controlled, oil driven adjustable cam gear. Phasing is determined by a combination of engine load and rpm, ranging from fully retarded at idle to somewhat advanced at full throttle and low rpm. The effect is further optimization of torque output, especially at low and mid-range RPM.The engine is 10 per cent lighter and more compact than conventional 2.0-litre engines due to a new engine structure.

Sohc and Dohc both installed with Honda technology.They both have their own benefits. For example, Honda Accord 2400cc ( DOHC model ) and Honda Accord 2000cc (SOHC model).

SOHC honda engine provide the better fuel consumption, it is more lighter and more simple engine. Inside the SOHC engine, the valve-train is lighter also. In the end, a SOHC engine would have better torque on the low end where the DOHCvalve train’s weight results in lower torque. But at high engine speeds, the DOHCengine’s peak torque and horsepower would be greater. That’s the trade-off. With the amount of valves being equal, SOHC has better low-end torque because thevalve-train package is lighter while DOHC has better top-end power

That why Honda introduced 2 different engine in the same model and same chassis of vehicle. SOHC i-VTEC more cheaper price than DOHC i-VTEC, and more suitable to drive in the city due to the good low end torque. DOHC i-VTEC is to produce max horsepower.

Honda Technology used in engine VTEC ( Variable Valve Timing & Lift Electronic Control ) is to increase the power output , it was a successful engine system in the market before. When the revolution of engine reaches certain speed ( commonly about 5500rpm ) , the computer activate the lobes on the camshaft and change the cam's timing. So, it has a feature of low speed and high speed camshaft in the same engine. Its idea is to increase the torque power when high speed rotation of engine. So that, no decrease of power when the engine meets the red line. The main idea is providing BIG amount of power in a SMALLER engine.

AND

i-VTEC and ''i'' stand for Intelligence. It utilizes Honda's proprietary VTEC system and adds VTC (Variable Timing Control), which allows for dynamic/continuous intake valve timing and overlap control.

The demanding aspects of Fuel economy, ample Torque, and Clean Emissions can all be controlled.