Engines keep changing. New technologies emerge that make them more fuel efficient while producing more horsepower. Today, we even have hybrid ones that run on both fuel and electricity.
But, one of the most confused part in buying a car is whether to go with the Dohc or Sohc engine. Arguments arise as to which is the better one.
In this article, we will delve into the various features that differentiate the Dohc and the Sohc engine. We also look into some of the pros and cons that characterize these engines.
SOHC
Sohc stands for single overhead camshaft and is one of the most popular engines in the market. In this case the camshaft is over the engine cylinders. The ignition of the fuel/air mixture moves the internal combustion engine.
This moves the pistons which are connected to the crankshaft through connecting rods. The camshaft rotates as the crankshaft moves through a system of valves and pulleys. On the camshaft are intake and exhaust valves.
Everything is timed in the camshaft so that fuel goes to the cylinders at the right time and the exhaust gases are gotten rid of through the exhaust system.
The Sohc work in conjunction with the pushrods meaning you will not experience instances of bent or floating rods. To keep everything in sync you have a timing belt that connects the crankshaft and the camshaft.
You maybe asking why should I get a Sohc engine. For one this engines are simple to assemble hence their popularity. Due to their simplicity repairs are easier to fix. You also do not have many variable parts making the Sohc have low maintenance costs.
DOHC
Dohc stands for dual overhead cam engine. Unlike the sohc where we have one camshaft here we have two camshafts. You can place the dohc in either a inline or V-shaped engine.
In the sohc you have alternating intake and exhaust valves but in the dohc you have a separate camshaft for the exhaust valve and another for the intake.
This arrangement gives you better control over the exhaust and intake process hence making the engine more efficient. The engine is complicated but all the valves open and shut in perfect timing.
What makes the dohc more outstanding is that the engine is more efficient and produces more power. It is also quieter even during high rpm. Due to the many restrictions on carbon emissions, the engines are more popular.
In fact, most modern cars are coming with dohc. Due to their complexity, they are owners are bound to incur more repair costs unlike the sohc.
How dohc and sohc engines compare on several factors
Operation
One of the key differences between the sohc and the dohc is how they operate. In the sohc you have one camshaft that runs the intake and exhaust valves. In the dohc, you have two separate camshafts that handle both valves.
This key difference influences how both engines operate. The dohc has the benefit of being more efficient and is quieter. The result is you have a smoother ride.
Valve timing
The internal combustion engine operates primarily by the ignition of the air/fuel mixture. The explosion is intense and moves the piston up and down. The piston ring is connected to the crankshaft via the connecting rod.
Since the camshaft has the intake and exhaust valves and there is need for perfect timing with the crankshaft various timing belts/chains connect the two.
The angle of the camshaft is what influences the opening and closing of the intake and exhaust valves. This timing has to be perfect. Dohc camshafts have better control over valve timing than the sohc ones. This flexibility makes for more horsepower.
Fuel efficiency
The dohc produces more power due to optimal valve timing. When you have a double set of valves per camshaft more fuel is released to the cylinders. This leads to more horsepower at the cost of more fuel.
While the sohc are marketed to be more fuel efficient than the dohc it will depend on the car design and the driving skills of the driver. How you maintain the car will also affect fuel efficiency.
Maintenance costs
The dohc has double camshafts which means you have more valves. This has a direct bearing on the maintenance cost as you have more movable parts. The sohc is less complicated making it more production friendly. The engine is cheaper than the dohc.
The use of one camshaft means going forward you will be experiencing lower maintenance costs than the dohc. The dohc complicated nature means that you have higher production and maintenance costs. However, the need for new car technologies favors the production of the dohc engines.
Spark plugs
The spark plugs for the dohc are located at the center and this means they operate both the exhaust and intake valves. This centering of the valves results to better combustion and enhanced performance. The spark plugs are not centered but located elsewhere. This makes the sohc engine less efficient.
Which should I purchase – Dohc or Sohc?
When it comes to the dohc you can integrate four valves per cylinder. Two are used as intake valves and two as exhaust valves.
This arrangement enables the dohc to be more efficient in the flow of gases in the combustion chambers. The spark plugs are located at the center which makes them more efficient in the combustion process.
You may also want to consider how much power you need for your car. Due to the less chances of inertia in the dohc engines it means they produce more horsepower than the sohc.
If the crankshaft moves faster you experience more torque hence speed. Since you have double camshafts you can alter how the intake and exhaust valves operate. A singe dohc engine can produce both low and high rpm.
Your decision as to which to choose will also depend on the potential maintenance costs. Sohc engines are easy to operate and manufacture. This means they have less engine parts hence making them more affordable. They are also more fuel efficient.
But, if you are looking for power and do not mind the maintenance cost then go with the dohc engine. Today, we have more fuel efficient dohc engines as car designers change the engine design.
You will also find most V6 and V8 engines are equipped with dohc camshafts. At the end of the day, what you choose to go with will largely depend on your unique needs. It will also be a factor of your budget – how much are you willing to spend.
Conclusion
Sohc engines have one camshaft that controls the intake and exhaust valve. These engines are easy to manufacture and are more energy efficient. The dohc uses two camshafts for both valves.
This means you can have two intake and two exhaust valves per cylinder. The benefit of all these is you have more horsepower. The sparkplugs for the dohc are centered. Dohc engines are quieter than the sohc but consume more fuel than the sohc.
Choosing between the two engines is largely about preference. While you have increased maintenance costs with the dohc you also get more power. When it comes to pricing dohc engines are more expensive to produce than the sohc.
