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DOHC Vs. SOHC Engine - What's the difference?

6th January 2021
"Although the DOHC has more top-end power, the SOHC has stronger low-end torque and the two retain the same number of valves."

You may have heard manufacturers using acronyms such as SOHC and DOHC when looking at a motorcycle's specification board. It's called a SOHC (Single Overhead Camshaft) engine if the engine has a singular camshaft, and it's called a DOHC (Double Overhead Camshaft) engine if the engine has double camshafts. Each engine, either air-cooled or liquid-cooled, includes camshafts that are specifically designed to open the inlet and exhaust valves. The camshafts were mounted below the engine block in earlier versions and were recognized as OHVS or Overhead Valve Engines. In OHV, with the aid of pushrods and rockers, the valves on the engine were controlled and were also called pushrod engines. There are also fewer moving elements in OHCS compared to OHVS.

sohc-vs-dohc

SOHC Engine:

As we already know, SOHC engines only have a single camshaft and both the inlet and exhaust valves are powered by the singular camshaft. SOHC engines generate less power than DOHC engines in comparison. But the benefit of providing a configuration for the SOHC engine is that it is faster and easier to build, as well as lighter than DOHC engines. Also, since this design requires fewer components, maintenance costs are usually lower than the DOHC engines.

Also Read: CARBURETED VS FUEL-INJECTED ENGINE

DOHC Engine:

Two camshafts are available in DOHC engines, one that controls the inlet valves and the other that operates the exhaust valves. As they have more direct control over valve lift and timing, DOHC engines are known to be more flexible in design and are usually the go-to for multi-valve engines. Engineers can position the intake and exhaust valves as far apart as required in such multi-valve systems, as each set of valves is operated by its own cam. In a SOHC configuration, this choice is minimal.

Also Read: LIQUID COOLED ENGINES VS. AIR COOLED ENGINES? WHAT'S THE DIFFERENCE?

Which should you choose? DOHC Engine or SOHC Engine

Based on different variables, such as fuel efficiency, valve function, and general operation, we will evaluate them. 

Valve Timing  

In DOHC, valve timing can be conveniently optimized. The synchronization of the valves is important for the engine's output and efficiency. To maximize the operation of valves, the majority of modern car engines are fitted with variable valve timing technology. Since SOHC has a single camshaft for both the inlet and exhaust valves, the valve timing is much less controlled, whereas the timings can be more optimized in DOHC since there are different inlet and exhaust valve shafts.

Fuel efficiency

You have a double-set of valves in each DOHC head. Improved valve management leads to the better use of fuel and this, in essence, increases performance. However, when it comes to fuel economy, other considerations play a part, such as the age of the vehicle, the driver's expertise, and gear transmission.

The SOHC was simply referred to as the OHCC until the DOHC's introduction (overhead camshaft). In the SOHC, with the valves above, the camshaft is positioned above the cylinder head. The shim situated between the stem of the valve and the lobe of the cam controls the valves' opening and closure.

There are always two or three valves per cylinder in traditional SOHC engines. You have two camshafts in the DOHC that equate to two cams per head of a cylinder. You will have four valves per cylinder in this situation. The downside to having two camshafts and more valves is that it provides the vehicle with more weight.

Spark plugs

In DOHC vs. SOHC, another aspect is that the spark plugs can be located in the middle of the combustion chamber. Fuel quality by increased combustion is the result. In SOHC, both the intake and exhaust are powered by the camshaft and must therefore be mounted in the center of the combustion chamber.

This means that the spark plugs are not strategically placed, and their output is hampered by this.

Performance

Due to the DOHC engine's increased weight, a SOHC engine with 16 valves generates greater torque than a DOHC with the same number of valves. But at faster speeds, the DOHC can produce more horsepower. Although the DOHC has more top-end power, the SOHC has stronger low-end torque and the two retain the same number of valves.

The DOHC motor favors technical development in valve timing. Studies suggest that the number of valves does not greatly affect output at low rpm, but an engine with more valves performs better with a transition to the next gear.

The excess weight is the hindrance to making more valves. You ought to adjust the springs of the valves to make them stiffer. This, in essence, produces more friction from the valve, meaning that the energy is used to overcome the extra pressure. At low rpm, smaller valves induce lower intake velocity since a large valve ensures that the valves experience less strain.

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Compiled by : Upasana Poudel Upasana Poudel

Petrol vs Diesel car: 5 things to look before you choose

29th August 2020
"Choosing petrol or diesel engine car is one of the first decisions you’ll have to make before buying a new car"

After being in a position to buy your own car, choosing a petrol or diesel engine car is one of the first decisions you’ll have to make before buying a new car. From a financial perspective, there’s now less and less difference between petrol and a diesel car. It is still true that if you look at pure fuel running costs, diesel will cost less. You will, though, have to have high annual mileages and use motorways more often to get the financial benefits.

This is because newer diesel vehicles now have higher tax, which can cost almost as much as the fuel savings you could make in a year, and there are also concerns over air pollution caused by diesel. That means that if most of your journeys are local and your mileage is lower, a small petrol car might be more suitable for you, especially if you’re looking to change vehicles in the next five years. 

Here are some points to compare petrol vs diesel cars: 

Cost of Petrol Vs Diesel Car

The diesel variant of cars cost more than the petrol variant. A diesel engine needs to maintain a higher compression ratio and handle greater vibration than the petrol engine, so the construction of the diesel engine is more rugged and are costly than the petrol engine. For example, cars which cost less than 10 Lakhs, the showroom price between diesel and petrol variants differs from 2 to 2.5 Lakhs. The difference in the on-road price of petrol and diesel car variants will be even more. This higher initial cost has a major significance in the overall economics of choosing a model and depending on the cost of the vehicle and where it is purchased.

Mileage of Petrol vs Diesel 

Diesel engines tend to return more kilometres per litre than a similarly sized petrol motor.so we can say the mileage of the diesel engine is more than that of a Petrol engine. This factor tends to be the sole reason the majority of us tend to go for a diesel variant.  A diesel engine does not need a spark plug and thus has higher compression. This makes the diesel engine utilise more fuel as compared to a petrol engine. The better mileage of a diesel engine makes it easy to cover the extra cost of the car paid initially, but with the increasing cost of cars, the time required to recover this cost has increased. 

Smooth Drive

Apart from a fact that diesel engines are more powerful than petrol engines, they also have higher torque and hence they give a smoother drive. On the other hand, the harshness, noise, and vibrations in diesel-driven cars are way higher than that of a petrol-driven car which is a big reason for concern. In petrol engines, the power developed is low due to compression ratio whereas, in diesel engines, the power is more.

Maintenance Cost of Petrol vs Diesel Car 

The maintenance cost of diesel cars is higher than petrol cars. This is because consumables like engine oil and spares used in diesel vehicles are more expensive. Also, keep in mind that newer diesel has a special filter fitted to help prevent pollution. It’s called a diesel particulate filter (DPF). These can clog if the vehicle isn’t used regularly on a motorway, and is costly to fix or replace. This means if you don’t use motorways often, a diesel might not be for you. The resale value of a used diesel car is higher than that of a petrol car. However, the life of a petrol engine is more than a diesel engine.

The price difference between Petrol vs Diesel 

Since last one year, the prices of diesel and petrol have seen a big hike in Nepal. Fluctuation in price shows that the difference between both is reducing day by day, the difference in both is about 14 Rs per litre and is further decreasing day by day. The lower diesel price is a reality, with the price difference between a litre of petrol and diesel generally hovering 14 rupees. However in the long run, if you have to drive for a longer distance in a smaller span of time choosing Diesel engine car will be more beneficial.

Choice, it’s a personal thing

In the end, it's not possible to say which is better, petrol or diesel engines, because it's very much a case-by-case, or car-by-car thing, and it also comes down to personal preference. Some people just can't stand the sound that diesel engines make, particularly under strain, so they'll never buy one. Although some high-end brands, now make diesel that are so quiet you can barely tell which engine you're driving without putting the windows down.

Besides that, there are now many alternatives to petrol and diesel cars. Technological advances are beginning to make alternative energy vehicles a realistic alternative to petrol and diesel ones. With hybrid, electric, hydrogen fuel cell and LPG powered vehicles, there’s more choice than ever, some opportunities to save money, and there are of course significant environmental advantages to using this kind of vehicles.

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Things to consider while buying a motorcycle

10th December 2020
"Enjoy your big step with ease!"

Buying your first motorcycle can be a thrilling experience. Whether you are buying a new bike or a second-hand bike, we will guide you on what to consider while buying your first ride. It takes passion, some patience, and a lot of research. So read this motorcycle buying guide before buying one!

Find the bike that suits you

suits-you

Adjustable elements such as the seat, steering wheel, etc do not come with motorcycles. That is why you need to see what suits you and what looks right while buying a motorcycle. Remember, what feels right for one minute in the showroom might not feel good on a long trip around town.

Standard, or “naked motorcycles” are great beginner motorcycles because the rider is in an upright position without having to lean and reach too far forward so naked bikes are a bit better for beginners than a sports bike.

Research, Research, Research

research

Whatever bike you want to purchase, make sure you read what you can about the manufacturer, the model, and when and how you can service it and if possible, get parts in the future. Basically, after all, you are going to be the owner, and this is not a minor investment, you should make an effort to know more about your bike inside and out.

Power is not everything

Why should I buy a 250cc bike instead of 600cc?

The answer is 600cc bike has more power and you cannot control the power if you are a beginner. Start from a humble beginning, Even experienced riders have problems with 600cc bikes.

You should start from 200cc above bikes, Many manufacturers are even specifically designing bikes in this class for new riders like yourself. Our advice: start with something smaller and trade up for something bigger later on.

Bike weight

average-motorcycle-weight.

You should also worry about the weight after you settle on the kind of bike you want. Usually, the weight of the bike goes up with displacement, but that is not the case with all motorcycles, since some cruisers weigh a lot for a more moderate displacement. It is more convenient and simple to ride a lightweight motorcycle, and you can also ride it at much higher and quicker speeds which is fun. So the lighter your bike weights, the more fun you get while riding it.

Think for long term

Another tip that we can give you is to think about the long term, buy the beast you dreamed of, the kind that can go on the city and long trips with ease. Always go for what makes you happy but let your brain decide what’s best for you and if you're buying it for day-to-day functioning, go for things like high mileage, lightweight, low servicing cost, affordable, and the one best for you. Do not settle for cheaper motorcycles as you're going to need them for a long time and compromise is not a factor!

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Things to Consider while buying a Riding Jacket

1st January 2021
"Everyone looks good in a Riding Jacket."

A good riding jacket is among the most essential aspects of riding equipment. It not only offers protection from the weather and lets you prevent severe injury in the event of a collision, but also makes you appear stylish as you ride your favorite two-wheeler. Although selecting the right riding jacket needs little information, here are some basic tips that can be more than just a cosmetic enhancement to your riding gear with the aid of your jacket.

riding-jacket

Fit:

As critical as its safety capability, a comfortable fit for a riding jacket is, The jacket should not be too tight or too loose, both in summer and winter, so that it can be worn easily. In addition, the arm length should be perfect since longer sleeves will make riders struggle while gripping the handlebars.

 

Number of Pockets:

To carry specific items, like cell phones, wallets, etc., a riding jacket must have at least a few pockets. This can be a handy way of holding essential things during a journey, and without any hassle, you can conveniently hold any of the above-described utilities.

 

Air Vents:

A riding jacket that is made up of leather must have air vents. Make sure that the leather riding jacket that you are buying comes with air vents. Since leather has poor air passage with the absence of air vents the rider will end up sweating during summer days. So, air vents are important.

 

Reflectors:

Essentially, a riding jacket must have reflectors. The theory is that it helps to boost vision in the dark since riding at night can be risky. This is when a rider needs to get noticed by other vehicles. They can shine in the light of some other car if you have reflectors on your riding jacket to make you extremely noticeable. Hence, riders can be spotted from a distance by other vehicles.

 

Thickness:

Bear in mind that the thickness of the leather should be at least a millimeter thick or more when selecting a leather jacket. In the event of a collision, this can be very beneficial as your skin will not get affected due to this dense coating of leather on it.

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