The valve structures of the eighth generation Accord 2.0 and 2.4 are SOHC and DOHC respectively. What do they mean? Which is better?

SOHC: single overhead camshaft stands for single overhead camshaft engine, namely an intake valve and an exhaust valve. At low speed, the torque is greater and the explosive force is better than that of the same displacement DOHC engine.

DOHC: Twin-cam stands for double overhead camshaft engine. Generally, each cylinder has multiple valves, generally four valves (i.e., two intake valves and two exhaust valves). The multi-valve engine burns more fully, allows more fresh air to enter the engine, and has better emission efficiency (the structure is more complicated than SOHC). Generally speaking, DOHC does have strong high-speed power, but the fuel economy and low-speed torque are far from those of SOHC engines with the same displacement.

What is the function of the engine ignition system?

The automobile ignition system is a spark-ignition engine. In order to work normally, according to the ignition sequence of each cylinder, high-voltage electricity with high enough energy (about 15000 ~ 30000 V) is regularly supplied to the spark plug, so that the spark plug can generate strong enough sparks to ignite the combustible mixture. When the engine is working normally, only 1~5mJ spark energy is needed because the compressed temperature of the mixture is close to its auto-ignition temperature. However, when the mixture is too rich or too lean, when the engine starts, idles or the throttle valve opens sharply, higher spark energy is needed.