Updated at: 23-04-2022 - By: micdot

Have you ever wondered what the difference is between SOHC and DOHC? If you can convert SOHC to DOHC, which engine is better, the DOHC or the SOHC? Well, the truth is that the technical specs of a car engine, like DOHC or SOHC, can be very hard to understand. But it’s very easy. I hope you’ll keep reading to find out more. So if you’re looking for a new car and have looked at the engine specs, you’ve seen that SOHC and DOHC are used a lot. The following is a link to another article:

What do these symbols mean? Neither of them is a word for the Camshaft. There are a few important differences between these two types of setups, like: You need to know what a DOHC and a SOHC engine are before you make a decision. They both have valves that open and close at the same time. Let’s start now.

DOHC Meaning

It’s called DOHC because two cams control the exhaust and intake valves by moving them up and down. Even though the engine only has one header, it has two cam rods, so it can do two things. There is one Camshaft that controls the intake valves, and another one that controls the exhaust valves. This is different from the SOHC.

It is common for a short chain to connect the camshafts. However, a timing belt can sometimes wrap around both gears and connect them together.


This type of engine has two camshafts on top of each row of cylinders.

These engines are often compared with those with overhead valves (OHV) and those with single overhead cams (SOHC), which have only one Camshaft that drives the valves. DOHC engines have the cylinders on top of the camshaft.


Not all DOHC engines have multi-valve cylinder heads. Multiple inlets or exhaust valves on each cylinder do not need two camshafts, and not all have multi-valve heads. Among other things, the first 2-valve engines with two valves per cylinder had only two valves at each cylinder. If you look at the most recent cylinders though, they have three to five valves in each one.

A DOHC engine is a type of engine with eight or more cylinders. Each cylinder head has two camshafts so the engine is classified as DOHC even though it has more than two camshafts in total.


DOHC engines started with two-cylinder engines, then moved on to straight-8 engines, V6 and V8 engines, and the V6 and V8 engines that are now used in cars and trucks. Most of the designs come in a wide range of configurations, with single cam types having only half as many total valves and being found in lower-performance models.

People who drive engines that have five valves in each cylinder will have two two-valve cam shafts and three three-valve cam shaft, so they will have five camshaft.

This is an example of how DOHC engines can make more horsepower than single overhead cam engines. The Dodge and Chrysler sedans and families use a single overhead cam version of the Mitsubishi Cyclone V6. The 3000GT and Stealth980s use a DOHC version of the same engine to make more horsepower, which is why they have more power.

SOHC Meaning

It is called SOHC if there is only one overhead cam in the car. One Camshaft is in the engine head of this kind of engine. One intake valve and one exhaust valve are the most common configurations for SOHC engines, but there are many other ways to build them.

There are usually two valves in a SOHC cylinder head because the camshafts are usually in the middle. One valve controls the amount of fuel that comes in, and the other controls how much gas comes out of the car. An arm called a rocker arm that is connected to the camshafts controls how the valve opens and closes, and it does this by moving it. It’s still possible to buy SOHC engines with four valves in them on the market now.


A SOHC 4 valve engine would have more torque at the low end because the mass of the valve train is less in this form. However, a DOHC arrangement will make less torque at first because the valve train is heavier, but it will also make more power at the end of the race.

Using two valves per cylinder is also a good idea because it cuts down on the number of parts, which saves money and makes things easier.

For low- and mid-range torque, the design is better because the airflow is faster due to the more restricted flow. However, in a SOHC engine, the camshaft is usually in the middle of the head. This means that the spark plug won’t be in the best place for it to be.

SOHC vs DOHC, which is Faster

This will depend on what you want. In terms of performance, DOHC is better because it makes more horsepower. It is more reliable because SOHC is made of steel. There are fewer parts in a SOHC engine, which makes it more durable and less likely to fail.

It’s better to use DOHC engines because they are more powerful, have more performance, and can go faster than other engines. The engines can also run faster with more severe cam profiles because they have less inertia, so they can go faster at a faster pace.


Power is the sum of the speed and torque of the engine. In simple terms, this means that when the crank moves faster, you will make more power. This engine also has separate valves for both the exhaust and the intake. This allows the camshaft to move in the same direction while the engine is running. This means that a single engine can be tuned for both high and low power.

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When more air gets into the cylinder, the engine makes more power, and when the exhaust can be easily pumped out, the engine wastes less power. With its four valves, the DOHC engine can also inflate enough air to run and make good power at high speeds.

An engine with four valves per crankshaft would be better at the lower end of its power range if it had less weight in its valve gear.

Having a DOHC configuration means that the engine will have more peak torque and horsepower at higher engine speeds because it has a heavier valve train and more valves per cylinder, which means that it will have more peak torque and horsepower. Take a look at our blog to learn more about disc brakes!

Is it better to have SOHC or DOHC?

This will depend on what you want. In terms of performance, DOHC is better because it makes more horsepower. It is more reliable because SOHC is made of steel. There are fewer parts in a SOHC engine, which makes it more durable and less likely to fail.

How about this: now that you know the difference between a SOHC and a DOHC engine, which one should you choose and what are the benefits and drawbacks of each one? If you want to know more about these, you should pay attention.

Fuel Efficiency

There are a lot of differences in how well DOHC and SOHC engines do. Dual camshafts make modern cars more powerful, which is why they are often used. The reason for this is that DOHC engines usually have four valves per cylinder instead of the single intake and exhaust valves found in SOHC engines.

Because older cars didn’t need to be very fast, they could get by with just one Camshaft.

Reduce the amount of fuel that you use by

The number of valves in each cylinder makes a dual camshaft engine more fuel efficient than a single camshaft engine. However, when it comes to performance, most of the time, more power means less fuel efficiency. This is because when the engine is able to breathe properly, it is more efficient.


This is because the DOHC engine has more power, and it runs much smoother and has fewer misfires because of that. Due to the ease and efficiency with which valve timings can be changed, it is this way.

You should choose a DOHC engine if the smoothness of your car’s engine is very important to you.

Costs of Repair

An engine that has DOHC is bad because it has a lot more valves, camshafts, and parts that break down. For the engine to work properly, a single camshaft needs a lot fewer parts than a double camshaft. If you want a long-lasting engine that doesn’t sacrifice performance, the SOHC is probably the best way to get it.

Conclusion on SOHC or DOHC, which is better?

The difference between SOHC and DOHC engines is very big, and it’s important. Because of this, the type of engine you choose should be based on your needs.

In the SOHC, there is one camshaft on top of each cylinder head. In the DOHC, there are two camshafts on top of each cylinder head. So, when compared to SOHC, it is more efficient at high speeds when it comes to using fuel.

People who used older cars had SOHC engines, and people who used newer cars have DOHC engines. There is less noise and less heat in the engines when they’re moving because of the DOHC valve timing, which is very good. The extra valves make the vehicles heavier, but they make them run very well.

It makes the same amount of power at low torque with the DOHC and SOHC engines, but when the rpm goes up, the DOHC makes more power than the SOHC does. If you want to move from SOHC to DOHC, you can do some engine swaps to get the new car.