SOHC vs DOHC which is faster

SOHC Vs DOHC Which Is Faster? (Differences Explained DOHC Vs SOHC)

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Last updated on July 11th, 2023 at 05:47 pm

Have you wondered what the difference between SOHC vs DOHC which is faster if you can convert SOHC to DOHC or maybe you thought Which engine is better DOHC or SOHC? Well, the truth is the technical specs of a car engine, such as DOHC or SOHC, are very perplexing. But it’s quite simple. So please continue reading to learn everything you need to know about it. If you’ve been looking for a new car and have looked at the engine specifications, you’ve seen that SOHC and DOHC are frequently used. Related Article:

In his article include we will touch on the following topics: 

  • DOHC meaning and SOHC meaning
  • SOHC vs DOHC, which is faster?
  • SOHC and DOHC Engines: What’s the Difference?
  • How do I know if I have a SOHC or DOHC car
  • Which engine is better, DOHC or SOHC
  • DOHC vs. SOHC advantages and disadvantages

what exactly do these symbols imply? Both terms refer to the Camshaft. There are a few key distinctions between these two sorts of configurations. Before deciding between a DOHC and a SOHC engine, it’s important to know what they mean and how they work. Let’s get started.

DOHC Meaning

DOHC stands for dual overhead cam, which implies two cams control the exhaust and intake valves. Although the engine has only one header, it has two cam rods. The DOHC, unlike the SOHC, has one Camshaft that controls the intake valves and another that controls the exhaust valves. 

A short chain usually connects the camshafts; however, the timing belt can sometimes loop around both gears.

Features

As the name implies, a double overhead cam engine is a gasoline combustion engine with two camshafts situated over each row of cylinder heads. 

DOHC engines are frequently compared to overhead valve (OHV) engines, which have the cylinders above the camshafts, single overhead cam engines, or SOHC, which have only one Camshaft driving the valves.

Identification

Multiple inlets or exhaust valves on each cylinder do not require two camshafts, and not all DOHC engines have multi-valve cylinder heads. For example, the first two-valve-per-cylinder double cam engines had only two valves. Most modern cylinders, on the other hand, contain three to five valves per cylinder. 

Engines with eight or more cylinders, such as the Bugatti 16-cylinder engines, have more than one bank of cylinder heads, but because each cylinder head has two camshafts, they are classified as DOHC engines despite having more than two camshafts in total.

Types

DOHC engines began with two-cylinder engines and progressed to the straight-8 and current V6 and V8 engines. Many designs are available in various configurations, with single cam types having exactly half as many total valves and appearing in lower-performance models. 

Engines with five valves per cylinder will have two camshafts with two valves each and three camshafts with three-valve each. 

The difference between the sedan and family versions of Dodge and Chrysler, which utilize a single overhead cam version of the Mitsubishi Cyclone V6, and the 3000GT and Stealth980s, which use a DOHC version of the same engine to generate more horsepower, is an example of the enhanced power of DOHC engines.

SOHC Meaning

A single overhead cam is abbreviated as SOHC. There is only one Camshaft in the engine head of this sort of engine. One intake valve and one exhaust valve are the most common configurations for SOHC engines.

Because camshafts are normally centered in the cylinder head, the SOHC has two valves. The entering fuel is regulated by one valve, while the exhaust gas output is regulated by the other. The valve’s open-close configuration is controlled by a rocker arm that is directly connected to the camshafts. There are, however, SOHC engines with four valves on the market presently.

Keynote:

A SOHC 4 valve engine would have better torque towards the low end because the valve train mass is lower in this form. On the other hand, a DOHC arrangement will produce less torque initially with the same number of valves due to the larger mass of the valve train but will have better top-end performance. 

Another benefit of using two valves per cylinder is that the number of parts is reduced, which reduces cost and complexity. 

Because the airflow is faster at lower engine speeds due to the more restricted flow, the design is also superior for low and mid-range torque. However, in a SOHC engine, the Camshaft is normally positioned in the center of the head, preventing the spark plug from being in its ideal location.

SOHC vs DOHC, which is Faster

What you’re looking for will determine this. DOHC is superior in terms of performance since it produces more horsepower. SOHC has a higher level of reliability. A SOHC engine has a less number of parts, making it more reliable.

DOHC engines are more powerful, have higher performance, and can run at faster speeds. In addition, because the engines have less inertia, they can run at greater speeds with more severe cam profiles. 

Keynote:

The engine speed and torque are multiplied to calculate power. It simply implies that when the crank spins faster, you will generate more power. This engine also has separate exhaust and intake valves, allowing for continuous cam phasing while in operation. This makes it possible to tune a single engine for both high and low rpm power.

When more air enters the cylinder, the engine produces more power, and when the exhaust is easily pumped out of the cylinder, the engine wastes less power. In addition, the DOHC engine’s four valves allow it to inflate enough air to run and produce good power at high speeds.

To summarize, a four-valve-per-cylinder SOHC engine with a lighter valve train mass would perform better at the lower end of the power band.

With its increased valve train mass and as many valves per cylinder, a DOHC configuration will provide more peak torque and horsepower at higher engine speeds. For more information on disc brakes, could you take a look at our comprehensive blog?

Is it better to have SOHC or DOHC?

What you’re looking for will determine this. DOHC is superior in terms of performance since it produces more horsepower. SOHC has a higher level of reliability. A SOHC engine has a less number of parts, making it more reliable.

So, now that you understand the differences between a SOHC and a DOHC engine, which one should you choose and the advantages and disadvantages of each? There are numerous distinctions amongst these that you should be aware of.

Performance

The performance of DOHC and SOHC engines differs significantly. Dual camshafts create higher horsepower, which is why they are commonly used in modern cars. This is because DOHC engines typically have four valves per cylinder rather than the one intake and one exhaust found in SOHC engines.

Because older cars had less of a requirement for performance, they could get by with just one Camshaft.

Fuel Efficiency

A dual camshaft engine will often have superior fuel efficiency than a single camshaft engine due to the number of valves per cylinder. However, when it comes to performance, more often than not, more power equates to less fuel efficiency. This is due to the engine’s increased efficiency when it is allowed to breathe properly.

Smoothness

Because the DOHC engine has more power, you’ll notice that it runs considerably smoother and with fewer misfires. This is due to the efficiency and ease with which valve timings may be controlled.

If engine smoothness is crucial to you, you should choose a DOHC engine.

Costs of Repair

The disadvantage of a DOHC engine is that more valves, camshafts, and parts fail. For the engine to perform properly, a single camshaft requires much fewer parts. If you want a reliable engine without sacrificing performance, the SOHC is probably the way to go!

DOHC and SOHC Engines: What’s the Difference?

The differences between SOHC and DOHC are numerous. For example, the SOHC has a single camshaft above the engine’s head, but the DOHC has double camshafts. Aside from the outward differences, their performance differs as well. The following are the distinctions between the two engines:

  1. DOHC: There are two camshafts in the Double Overhead Cam. One is utilized just for the intake, while the other is only used to control the output. In addition, there are two sets of inlet and exhaust valves on the engine.

SOHC: A single camshaft controls the exit and input of gasses in a single overhead cam engine. There are only two exhaust valves on this engine.

  • DOHC: DOHC has double camshafts, which allows for more adjustability and optimal valve timing. This raises the highest horsepower possible.

SOHC: Because SOHC engines have only one Camshaft, valve timing is less precise. When the air and fuel mixture ignites, the internal combustion engine starts. For the ignition process to work, the timing of fuel injection and exhaust gas removal must be precise. The angle of the Camshaft influences the timing of the exhaust and intake of gasses. When you have better timing, you will have greater horsepower.

  • DOHC: Because the valves are better controlled, DOHC uses more energy. When you use a lot of electricity, you use a lot of gasoline. However, various elements such as the gear transmission, the driver’s experience, the engine design, and the car’s age influence fuel efficiency.

SOHC: Because of its low power consumption, SOHC is more fuel-efficient.

  • DOHC: Because it functions in both the exhaust and intake, spark plugs in DOHC engines are located in the combustion chamber center. As a result of the improved combustion, fuel efficiency improves. In addition, the spark plugs are precisely placed, resulting in greater efficiency and performance.

SOHC: The spark plugs aren’t in the cylinder’s middle. They aren’t strategically placed, and as a result, the SOHC engine’s performance suffers.

  • DOHC: DOHC has a higher peak power. DOHC delivers better top-end power at higher speeds with the same number of valves. Its performance is also improved since more valves can be attached to individual cylinders.

SOHC: The low-end torque of SOHC engines is superior. A SOHC engine with 16 valves delivers more torque at low speeds. However, the performance is significantly lower, particularly at high speeds.

  • DOHC: Both the outgoing and incoming gases are handled differently by DOHC. It contains two valves, which makes it more difficult and thus more expensive to make. When it comes to repairs and upkeep, it’s also more expensive. The DOHC engines benefit more from technological advancements in valve timing.

SOHC: It is less expensive since it only has one cylindrical rod to manage the exit and intake gases. Because the design is simpler, the manufacturing costs are lower. In addition, the costs of maintenance and repair are very inexpensive.

  • DOHC: Multiple valves control the intake and exhaust in the DOHC. As a result, the ride is quiet and comfortable.

SOHC: In SOHC engines, only a single set of valves controls the inlet and outlet, resulting in some noise.

How do I know if I Have a SOHC or DOHC Car?

The best way to tell if your automobile is still OHV is to look at the ends of your valve covers. You might, however, have a SOHC.

Over Head Valve (OHV) engines have a camshaft above the crankshaft but below the valves. At neither end, there is no sign of a wheel-like spherical item. Instead, this is a valve-over-cylinder engine.

However, if you have a D or S OHV engine, you’ll notice a cover at the end of your valve covers. There are one or two sprockets or pulleys beneath it that are connected to the crankshaft by a chain or belt. In addition, a bar of silver and black casing can be seen at the end of the valve cover to the right. This is a valve-over-cylinder engine.

SOHC (Single Over Head Cam) vs. DOHC (Dual Over Head Cam) can be difficult to distinguish. First, you’ll need to figure out what the cover is all about. Because the cover is too boxy and lengthy to cover one tire merely, this engine is unmistakably a DOHC.

In comparison, there’s a small round black cover on the right side of the engine that’s too small to cover two wheels; this is a single overhead cam engine (SOHC).

Which Engine is Better DOHC or SOHC

Each variety has characteristics that distinguish it from the others. So let’s take a closer look at the differences between SOHC and DOHC to assist you in making a better decision.

A SOHC is a single camshaft that regulates the inlet and outflow of gases, whereas a DOHC is a double camshaft with a specialized inlet and outlet configuration. In comparison to a SOHC, this means that a DOHC has two inlet and exhaust valves. 

As a result, the engine runs cooler with an even distribution of operations, resulting in a smooth, noise-free, and efficient ride. The working of the engine is known to be activated by valves. The shape and angle of the Camshaft also affect the timing of the intake and outtake of gases. 

Variable valve timing is essential when the breathing process needs to be improved, which improves the maximum horsepower achieved. In addition, due to the single camshaft availability, SOHC designs have less control over valve timing than DOHC designs, making DOHC more flexible in terms of tuning.

Keynote:

A DOHC, as previously stated, has a two-valve layout per head. As a result of the improved control over the valves, more power will be consumed. And, as power increases, so does fuel consumption. As a result, when comparing SOHC vs. DOHC fuel efficiency, a SOHC is more efficient. 

However, it should be noted that a DOHC engine’s fuel efficiency is determined by the driver’s skills and the engine’s design. You could check for maintenance recommendations to understand how to maintain engine efficiency properly.

When you’re wondering, “What is SOHC?” remember that it features a single rotating cylindrical rod that regulates gas intake and exit. This necessitates cost-effectiveness over DOHC, which has a unique configuration for both entering and leaving gases. 

When opposed to SOHC, a DOHC has twice as many valves, making it a less complicated and thus less expensive design.

DOHC vs. SOHC Advantages and Disadvantages

Advantages of DOHC (DOHC engine advantages)

The DOHC has twice as many valves as the SOHC, allowing them to be optimally positioned for improved performance. DOHC engines will have four or more valves, depending on the manufacturer and model. This contributes to a better wind stream and, as a result, a smoother, clamor-free ride.

  • In DOHC, valve timing can be easily optimized. The timing of valves is a crucial component in determining engine performance and efficiency. Variable valve timing innovation is included in the most recent versions of motors to improve valve activity.
  • In DOHC, valve timing can be easily optimized. The timing of valves is a crucial component in determining engine performance and efficiency. Variable valve timing innovation is included in the most recent versions of motors to improve valve activity.

Disadvantages of DOHC

  • The engine’s complexity and weight are increased when compared to cam-in-block plans. Design and manufacturing costs are also higher than the norm.
  • In comparison to SOHC engine designs, DOHC engines have a more complex chain or belt drive system, reducing overall performance and increasing maintenance costs.

Advantages of SOHC

  • A single overhead camshaft arrangement is a less complicated and easier-to-use version of a dual overhead camshaft motor.
  • As the name implies, a double overhead cam uses two camshafts for each bank of chambers to improve valve control, resulting in an overall increase in engine weight.

Disadvantages of SOHC

  • The engine’s complexity has increased. This increases the expense of the plan and assembly. In addition, in comparison to cam-in-block designs, there may be a general increase in motor weight.
  • Camshaft drives that use a chain or a belt can provide unwavering quality and maintenance options that aren’t typically found in cam-in block motors.

Conclusion on SOHC or DOHC, which is better?

The difference between SOHC and DOHC engines is significant. Therefore, the type of engine you select should be determined by your requirements. 

The SOHC has a single camshaft on top of each cylinder head, but the DOHC has two camshafts on top of each cylinder head. Therefore, when compared to SOHC, it has superior fuel efficiency at high speeds.

SOHC engines were used in previous automobiles, while DOHC engines were used in newer vehicles. Because of the DOHC’s efficient valve timing, the engines are quieter and cooler when in motion. The extra valves make the vehicles heavier, but they provide excellent performance.

The DOHC and SOHC create the same amount of power at low torque, but the DOHC produces more power as the rpm rises. If you want to upgrade from SOHC to DOHC, you can do some engine swaps.

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