DOHC 16V – What Is A DOHC 16 Valve Engine?

One of the most important aspects to consider in a vehicle’s engine is air and fuel distribution into its combustion chamber. The smoother this distribution happens, the better. You probably already know that the component that distributes the gas in the engine is the valve. But have you ever heard of DOHC?

In this post, I’ll walk you through everything you need to know about the DOHC 16v engine or otherwise known as the Dual Overhead Camshaft 16v engine. But first, let’s look at how a car engine works.

dohc 16v engine

How A Car Engine Works

At a high level, a gasoline engine can be thought of somewhat like an air pump, except that the exhaust coming out is more of a side effect. This pump’s real purpose is to rotate an internal shaft which in turn rotates the vehicle’s wheels. It does this by connecting that shaft – called a crankshaft to pistons that move due to a mixture of air and gasoline combusting inside their cylinders, which creates a sort of chain reaction that keeps the engine turning.

The two main parts of an engine are the Block and the Head. The Block, which is at the bottom is home to the pistons, cylinders, and crankshaft. The crankshaft sends the engine’s power out to the transmission and wheels.

The head which is above contains the top of the cylinders and manages their airflow and combustion through valvetrain, fuel injection, and ignition systems. You can see this post to learn about a particular type of head – the 862 LS heads.

What is DOHC 16V?

DOHC 16v refers to a 4-cylinder internal combustion engine with 4 valves in each cylinder and two camshafts. The reason for the use of two camshafts is that the engine uses four valves in a cylinder – 2 valves for the intake and the other 2 valves for the exhaust. As a result of this number of valves, the air distribution is faster so that the engine RPM can easily reach its maximum.

A camshaft is driven by the crankshaft of the engine and it opens the intake and exhaust valves so that the engine can take air in and expel the exhaust gases. It is installed on the cylinder head so that it will directly press the valve.

In some types of DOHC 16v engines, Rocker Arms are used in adjusting the valve gap. DOHC mechanisms that use Rocker Arms have a hydraulic lash adjuster system to automatically adjust the valve gap. For those without Rocker Arms, the valve gap is adjusted manually using a ring that is placed inside the valve lifter. To change the valve gap, this ring must be replaced.


Both SOHC and DOHC represent the valve configuration inside an engine head to control the action of the valves. Though these configurations are renowned for their superior performance, both have some significant differences.

SOHC stands for single overhead camshaft. This type of valve configuration utilizes only a single camshaft for operating both intake and exhaust valves.

DOHC or dual overhead camshaft on the other hand utilizes two independent camshafts for the operation of the intake and exhaust valves.

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The DOHC 16v or Dual Overhead Camshaft 16v is an internal combustion engine type with a 4-valve mechanism within the 4 cylinders – making up a total of 16 valves. It is different from the SOHC or Single Overhead Camshaft in the sense that it has two camshafts while the SOHC has just one camshaft.