OCTANE AND CETANE NUMBER EXPLAINED !!

Octane and cetane number are standard measure of performance of a fuel.

Octane number is related to petrol and cetane number gives quality of diesel.

Higher the octane number, better the quality of petrol, and hence the vehicle gives higher efficiency.

Octane number (octane it means eight carbon atoms )

Octane number is used in petrol engines. It determines how much compression ratio a petrol mixture can withstand. If the limit is crossed the fuel will spontaneously ignite and its called knocking.

Generally octane numbers range from 87 - 90 . If that number is high then the petrol can withstand higher compression ratio. But it comes with more cost.

The number 87 denotes 87 % of octane and rest is heptane ( it can withstand only very lower compression ratio) , that's why as octane number increases the engine can have higher compression ratios.

Octane the name comes because its major composition of petrol.

Cetane number ( 16 carbon atoms )

Its for diesel engine due to composition of diesel has mostly 16 carbon atoms. Its just opposite of octane number.

It determines how fast the fuel will enter combustion stage. It signifies the time gap between time of injection and time of ignition of a diesel. Higher cetane number means this gap is less.

So why you need higher cetane fuel

Fuel is generally injected few degree of crank before piston hits TDC. If cetane number is less the fuel will combust at a time when the pistion would have already left far from TDC. So you dont get enough torque and milegae will be less. So if fuel ignites earlier there will more time for expansion.

Cetane numbers are between 40 - 48

RELATION BETWEEN TORQUE & HORSEPOWER EXPLAINED !!

Horsepower and torque are very useful when you buy a vehicle of a rotary machine. Before discussing on this topic, first you should learn about the meaning of torque, horsepower and RPM. 

What are Torque, RPM and Horsepower?

Torque:

Torque is measure of rotary force. It is works as force works in linear motion. When a torque is applied on a shaft it rotates or tends to rotate if the torque is not sufficient. In simple words, the rotary force applied on a shaft to rotate it is known as torque. 

In mathematically torque is the product of tangential force applied on a shaft and the radius of shaft. The SI unit of torque is N-m (Newton meter). 

RPM:

RPM is the unit or measure of speed in rotary motion. The rpm is stand for rotation per minute. If a shaft rotate 50 cycle per minute mean it has 50 rpm speed. Larger rpm means larger speed. 

Horsepower:

Horsepower is the unit or measure of power. Power is the capacity of do work. Larger power means, more work can do in smaller time. 

Mathematically work done per unit time is called power or product of force and velocity is called power. But in rotary motion Torque is stand for force and RPM for velocity so the product of torque and RPM is called power. The SI unit of power is Watt ( J/s). It is equal to the power needed to move 1N weight bar to one meter in one second. Watt is a very smaller unit so we used KW and Horsepower (HP) to specify a machine power. One horsepower is equal to the 735 Watt. 

Horsepower vs Torque:

As we know that horsepower is a unit or measure of power and torque is measure of force in rotary motion. In any rotary machine power is measured at highest rpm and the torque is at lowest rpm. If a vehicle is specified 400 HP @ 2000RPM means its maximum power is 400HP. If The same engine is specified as 2000 N-m @ 1300rpm means it give maximum torque is 2000 N-m.

The torque is measure of force applied to move the vehicle and the Horsepower is measure of rate of work done. 

Torque plays a very important role while choosing a vehicle. Suppose two vehicles one is a truck and other one is a sports car. Both have same Horsepower 400 HP but both vehicles are with different each other. Sports car can't pull a heavy load like 1MT or a truck can't run on speed like 200Kph. The main difference between these machines is torque. A truck has a higher torque compare to sport vehicle so it can pull more load but due to power is function of product of torque and RPM so it has low RPM or speed. In the other hand the sport car has high RPM but low torque which gives it high speed. Both machines have same power but gives different uses. 

It is seen like that a 1 kg block is move 10 meter or a 10 kg block is move one meter. Both have same power but have different pull force. These are key difference between them.

The more torque gives high starting power or gives more pickup to vehicle. So next time, when you go to buy a vehicle considered both Horsepower and torque and remember torque is pulling force and power means product of torque and RPM.

NITROGEN IN TYRES: PROS AND CONS EXPLAINED !!

A few years ago, the use of nitrogen in tyres had been introduced. The idea was to replace the free air provided at petrol pumps with Nitrogen gas for a nominal charge. The concept did not gain much mileage and nitrogen gas providers shut down at some places.

But today, there are many 250cc bikes available in the market. The price of high speed bikes is well within the reach of the middle class consumer. At continuous high speeds, the tyres in these bikes can inflate quickly. Here, tyres filled with nitrogen gas prove their superiority over tyres filled with air. Let’s have a look at the benefits and shortcomings of nitrogen in tyres.

Advantage of nitrogen in tyres:

–    Nitrogen is lighter than air. So, the bounce you feel sometimes at high speeds is reduced to a very great degree. This translates into a smoother ride for you.

–    Nitrogen gas remains cool, which is a characteristic trait of the element. So the temperature of the tyres while riding at high speeds also remains cooler compared to air.

–    The tyre pressure remains constant at different speeds regardless of heavy / light load on the vehicle. It remains quite stable regardless of the temperature of the tyre.

–    The life of the tyre gets an extension. Since the wear and tear has slowed down, the durability of the tyre increases.

–    There is also a noticeable reduction in rusting of the rims or wheel as nitrogen is chemically inactive.

–    The rate of nitrogen pressure leaking from the tyre is 10 times less than the compressed air. So one can fill the tyres with nitrogen gas and then check the pressure again after 3-4 months or even more.

There are not many disadvantages of nitrogen in tyres but those that exist cannot be ignored.

–    The process is expensive. When it was introduced, it cost approximately Rs.100 for a two-wheeler and the cost was double for a four-wheeler.

–    Even today the gas is not available widely. Only a handful of tyre dealers provide it.

–    It’s useful for high speed bikes. Compared to the amount of commuter bikes the ratio is fairly low.

–    If a tyre gets punctured, after repairing the puncture, you have to repeat the process of filling nitrogen in the tyre.

Despite the shortcomings one can still opt to fill their bike tyres with nitrogen and get rid of the risk of tyres running at high temperatures. Perhaps you can even save your tyre from getting burst due to inflation. These advantages surely outweigh any cost disadvantage that nitrogen gas may have.