In thermodynamics you might get confused with various thermodynamic processes like isobaric, isochoric, isothermal, isetropic. This video explains various tricks to remember the meaning of various thermodynamic processes.


The 4WD and AWD are pretty much same, but have some variations each works best under certain conditions.

Four Wheel Drive:

  • It’s the oldest one, which has two options in terms of how and when torque is supplied to each wheel called Full time 4WD and Half time 4WD. Power from the engine goes to transfer case, which splits the power between the front and rear axles so that torque is evenly applied to each wheel
  • It’s axles doesn’t rotate at the same speed, the option is available to choose what we need whether the torque needed for 2 wheels or 4 wheels.
  • It’s good for Off road vehicles, Pickup trucks, terrain running vehicles where torque plays major role.
  • It has locking differential option which gives more traction power to the wheels in off roads.
  • This rugged technology has an option to turn off the drive to improve fuel economy.
  • It might be dangerous once back on Tarmac from off road.
  • Used in Jeeps, Landrovers, Pickup trucks.

All wheel drive:

  • AWD is a car system while 4WD is a truck system, the recent innovation which is AWD drive system is on all the time used in all the cars like Audi, Nissan GTR, Mercedes-Benz E63 AMG .These are all good examples for AWD.
  • ECU(Electronic control Unit) Plays a major role in the AWD system sensors on each wheel monitor traction, wheel speed, and several other data points and decide to send the power to which wheel depends to maximise the grip and driveability.
  • This best AWD sends the power to each wheel using a front rear torque - split system cutting the power from the wheel to the least traction. Most of the time rear wheels have the power to move the vehicle forward and from front wheels moves freely to improve fuel economy.
  • The latest technology in AWD use variable torque distribution system.
  • Provides increased grip and control under all road condition, gives sportier handling and traction to a broader range of cars. Good in snowy roads, performance oriented cars.
  • Not good for off road and fuel economy is less.


1) Important Air Conditioner Terms

SEER: Seasonal Energy Efficiency Ratio. Just remember this, higher the SEER, more will be the efficiency of unit, resulting in a lower operating cost.
Blower (Blower Motor): The motor and fan assembly mounted near the evaporator that draws air over the evaporator. In automotive applications, the blower motor may draw outside or inside air, depending on control settings.
Charging: Adding refrigerant to a system.
Flushing: A process of cleaning the internal components of an A/C system. This process requires the removal of refrigerant. This process is used to remove contamination and corrosion from the system.
Compressor: The pump that moves the refrigerant from the indoor evaporator to the outdoor condenser and back to the evaporator again.
Refrigerant Oil: Highly refined oil that is free of contaminants. Used in the A/C system for the sole purpose of maintaining compressor lubrication.
Ductwork: A pipe or conduit through which air is supplied.
Evaporator coil: It is the network of tubes that are filled with refrigerant. It is located inside the home within the indoor unit and takes heat and moisture out of the indoor air when liquid refrigerant evaporates.

2) How Air Conditioner Works?

Air conditioners use the basic refrigeration process to cool indoor air. However, conditioning is different from refrigeration as it also regulates air humidity, quality, and speed besides the temperature. When a liquid (refrigerant) converts into gas, it absorbs heat, and this is called evaporation or phase conversion. This occurs in the evaporator part of the system. Whereas, when the refrigerant is condensed, it turns back into liquid, and this happens in the condenser. Other key components include expansion valve, compressor, and the collector. Air conditioners use phase conversion by forcing refrigerants to evaporate and condense in a closed system of coils repeatedly.

3) Purpose Of Air Conditioner Filters

Filters remove particles from the air to keep the dust out of your car AC’s air ducts. Make sure you change your ‘dirt air filter’ every 1-3 months depending on your surroundings and usage. Not changing your air filters can bring problems like dirty air, reduced airflow, increased fuel consumption, low quality of cooling, and frozen coils.

4) Maintenance Of Air Conditioner

Your air conditioner becomes less efficient, weak, and unreliable when it is not taken care of. This will cause headaches for you and probably increase repair bills in case you ignore it up to the point of busting it.
Just like the rest of your car, your air conditioner needs regular service. If the air conditioner is not running properly, it may be working too hard. This could result in inconsistent air temperatures, heating of the car, and reduced comfort.
If you need more convincing, most manufacturers require routine maintenance for their warranty on the air conditioners to remain valid. So go get your car AC checked up in case you feel it is not working up to the mark.

5) Importance Of Air Ducts

It is important to have your car’s air ducts cleaned and checked for leaks. Sometimes dust or leaves get stuck up in the air ducts, wrecking havoc with your cooling system and the blower. A clean air duct system will help your car AC last longer by removing contaminants that decrease your system’s efficiency and consume more fuel.

6) Increasing Air Conditioner Efficiency

Keeping your air conditioner maintained and tip top is the best thing you can do for its performance and your wallet as well. Sealing leaky ducts, keeping the right refrigerant charge, increasing your thermostat by a few degrees, replacing filters, cleaning coils, using car window tinting, parking in the shadow, insulating the air ducts are all great ways that help to increase the energy efficiency of air conditioner.


Electric irons and certain other kinds of heating appliances have a high risk of the power cord being exposed to very high temperatures, by direct contact with the heating element. Plastic or rubber materials work great as electrical insulators, but many of them acts very poorly and fail in undesirable ways when exposed to high temperatures.
In order to prevent this kind of hazardous failure, the cord is sheathed with a material that has:
  • good resistance to high temperatures
  • low thermal conductivity, to protect the rubber electrical-insulating layers inside
  • high flexibility
This kind of woven/braided fabric meets these requirements pretty well. The kind of kinking failure shown in the picture results from poor handling, and specifically too small of a bend radius.Also in case of direct contact with the heating element by mistake they do not fail (melt)immediately as in case of plastic or rubber.


Many times we have heard that, this car is supercharged or this is turbocharged. When we heard this, one question arises in our mind 
what is supercharged and what is turbocharged engine. Which one is  better between them. What are functions of these units. Today we will discuss all these answers and the main differences between them. -

Before discussing about these unit, first we should know about what is charge. When we talk about an engine the charge is used to identify amount of air and fuel mixture sucked into the cylinder during the intake stroke. So the charge is refereed as the mass of air-fuel mixture taken into the cylinder during intake stroke.

When we require more power than we need more charge into the cylinder. There are two ways of increasing charge of an engine. 

1. First one is to increase the engine size or cylinder size, so more air fuel mixture sucked and generate more power.

2. The other one uses a compressor which increase the density of charge and  draws more charge into the cylinder at high pressure so the more mass of air fuel mixture comes into the cylinder which generate more power. 

The second one is more convenient because it uses an smaller size engine to generate same power as the big one. And the other benefit is that this can be implemented in the old cars by adding a compressor unit. Both supercharger and turbocharger are  worked on same principle i.e. by using compressor. Turbocharger and supercharger both compresses the air and forces this compressed air into the engine cylinder. According to the air, large amount of fuel is injected into the cylinder, which produces more power. It is the basic principle of both turbocharger and supercharger. 

The main difference :-

Supercharger :-

Supercharger is an air compressor which is used to increase the power of an engine. Basically supercharger is a rotary compressor which is driven by  the crankshaft through a belt drive. This compressor is connected at the inlet manifold of the engine. As the engine rotate it rotate the supercharger which forces compressed air into cylinder. So the supercharger takes power from crankshaft to drive its compressor.


Turbocharger is basically a combination of a turbine and a rotary compressor. The turbine is connected to the compressor and driven by the hot exhaust gases of the engine. So a turbocharge is a compressor which is driven by exhaust gases of engine which forces the compressed gases into the cylinder. 

So the main difference between supercharger and turbocharger is that supercharger takes power from the engine to drive its compressor whereas turbocharger takes power from exhaust gases to drive its compressor.


Not everyone can afford to buy a new motorcycle in their fist year of joining a job that pays them on the basis of a fresher who has just entered college finishing their high schooling and it is also not always about new bikes being better than the used ones. Blame the perception here for an instance.
In India although used bikes doesn’t strike the right chord with the buyers as it’s mostly seen negative, there are several instances where a used bike has proven itself a lot worthier for the money spent on it rather than a shiny one parked in the showroom waiting to be rolled down the ramp. 

The First and foremost thing being the bike itself that takes the centre stage, it is better that the buyer is on his own in inspecting the bike himself for the loop holes and definitely not rely someone who he hardly knows.Some very important pointers to look out for when buying a used motorcycle in your own local region that you belong to;

  • Check the Papers of the vehicle, which to be very specific will be the Registration Certificate and the Insurance papers are valid and have not expired which in a case of an exotic like a Jawa belonging to 1970’s might not be which can be compromised at buyers own risk. Make sure the registration certificate carries the correct engine & chassis no. that is punched onto the bike. As this makes sure that the bike isn’t suffering from illegal issues and ensures that the piece of love that you’ve been looking for is pretty legitimate.

  • Call up the Insurance agency the bike is registered to and with the help of a little Rapport that you create instantly with them, try and track down if any major claims/ accidents have been registered in the name of the owner or in the registration no. of the bike. This will make sure that the owner is not pushing you a troublesome salvage bike that might have its own legal issues once bought.
  • Avoid a modified Motorcycle as modification in India is not as clean as it is seen abroad. Also modified motorcycle can also be a sign of an abused motorcycle that was modified from its original state to take some amount of abuse for whatever reason the owner did it with. Also modified motorcycles will be a Cop/ RTO authority magnet. It’s always better to be subtle than to shout out crying for unwanted attention.

  • The frame, forks, engine casings and the fuel tank are the most expensive parts housed in a motorcycle excluding the engine itself. A detailed inspection of the above said things will save you a lot of money in terms of maintenance as damaged forks or fork oil seals or even a leaky tank that leaks once the kick stand is on will again drill a hole in the pocket after the deal is closed that puts a lot of financial pressure to the potential buyer.
  • After the bike is visually inspected and when you’re satisfied, proceed to firing the engine. For a safer side, request the owner to start the bike. Keep the bike idling in stationary position. Listen to the engine idle, sharp ears and a good knowledge about Motors will be of a great help. If not pls. call your best mentor in the Automotive field whom you can trust with their decisions and rely them for the final verdict. In general, make sure the bike doesn’t let out too much of exhaust smoke in case of a 4 Stroke and if does, be prepared to look out for other options as a damaged cylinder kit will again cost you thousands additionally.
  • If everything goes alright with respect to the engine idle, request the owner to rev up a little and inspect the same. If ok, ask the owner for a small test drive and pls. be polite to take him along if he insists as he would also feel that you are a complete stranger to him. Mutual respect is sincerely advised in this case.
  • If something goes wrong or if you feel something is wrong during the test ride, pls. feel free to ask the owner about the same. With the answers given by the owner one can be clearly judge the intentions of the seller. Either it should be a legitimate sale or pushing off a rusted piece of metal.
  •  The final stage being the owner and the negotiation part, make sure the owner feels as important as the vehicle itself that you’ve been looking out for. With that kind of feeling subjected to, the owner of-course will be very co-operative in answering almost any question that you throw at him right from the free services availed to the last repair and accident history carried out recently.
  • Coming to the negotiations, make sure you enquire the local market price with respect to the year of manufacturing before you offer your deal. Be very polite in the offers and please avoid low balling as much as possible as most of the owners who have kept their machines in spanking conditions wanting to sell do not part them only because of the need for money. They might look out for better homes to put their long trusted steed in.


You might have noticed that motorbikes having same cubic capacity gives different mileage. For Example,Bajaj Platina has cubic capacity of 100 CC and it gives mileage of 104 kmpl,on the other hand Hero Splendor is also having same cubic capacity but it gives the mileage of 81kmpl.

It is mainly because the bikes like Platina has been made keeping in mind mileage.Parts are light to keep bike weight low.Carburetor is tuned to extract mileage though it puts a strain on engine which you can judge from harsh engine note.If you race it will shudder as it puts strain on engine.Also it gives Low torque, low BHP, and leaner air fuel mixture. Tyres are slim for less friction with road.All this saves you petrol but at a high maintenance cost & low resale value.High maintenance cost can be curtailed with regular servicing but if you give less petrol to engine then wear & tear will be more anyway.