The Difference Between DOHC and SOHC in Cars, Which One is More Fuel Efficient?

Many automotive enthusiasts are still unaware of the difference between DOHC and SOHC. In fact, if you pay attention, the differences can be seen quite easily. To make it easier, you can learn about some of the differences below.

Definition of DOHC and SOHC

Before discussing the details of the differences, it would be better if you first understand the definitions of these two terms. DOHC is a type of camshaft engine that has a double overhead.

This engine usually has two pairs of overhead in one piston. That is why in a DOHC engine you will find four valves, with two valves regulating the fuel and the other two valves regulating the gas that will be expelled through the exhaust.

On the other hand, SOHC is a camshaft used in an engine. If observed, SOHC will have valves on each cylinder known as exhaust valves and intake valves.

The intake valve has the function of absorbing or sucking in the air-fuel mixture. Meanwhile, the next type of valve has the function of sucking in the combustion remnants and channeling them to the exhaust.

Some Differences Between DOHC and SOHC

The differences between DOHC and SOHC can be seen from various aspects. For more clarity, please refer to the discussion in the following sections.

1. Viewed from the camshaft

The first difference can be seen from the camshaft they have. In SOHC, you will only find one camshaft in the engine. Usually, this camshaft is located in the middle of the cylinder head.

Then, what about DOHC? Quite differently, DOHC has two camshafts that can be maximized. Each camshaft will directly operate two valves. However, there are also those that operate more than that.

2. In terms of function

Next, you can see the differences between the two in terms of their functions. DOHC has the function of rotating the air and fuel mixture in the engine. The intake valve will regulate the incoming air and fuel, while the exhaust valve expels the combustion remnants.

Meanwhile, SOHC is a cylinder head that has a single camshaft. Its general function is to regulate the intake and exhaust valves.

3. Based on the way they work

When viewed from the way they work, DOHC and SOHC are indeed different. The DOHC engine works by moving the piston from the top dead center to the bottom dead center with the exhaust valve closed while the intake valve is open.

With this condition, the air will eventually be sucked into the vehicle's fuel chamber. Then, the piston will move towards the top dead center with all valves closed.

On the other hand, in SOHC, the camshaft is located at the top of the cylinder. This camshaft is driven by a mechanism that rotates it. Next, the cam will press the rocker arm and then move the intake and exhaust valves in the combustion chamber.

4. Based on advantages and disadvantages

Each type will certainly have its own advantages and disadvantages. For example, the DOHC engine has a relatively lighter rotation than SOHC. This is because the intake and exhaust valves have their own camshafts.

In addition, DOHC also has the advantage of having four valves. These valves function to regulate the entry of fuel and gas to be expelled.

However, DOHC also has a disadvantage, namely the repair costs tend to be high. Not only that, but the spare parts for DOHC engines are also more numerous, making them generally heavier compared to SOHC.

This is different from SOHC. SOHC has the advantage of a simple engine construction and can open and close the valves. Then, the low rotation results from using a single camshaft can save fuel expenses.

So, now you know some of the differences between DOHC and SOHC from various aspects. If it is still unclear, you can look for other reference sources.