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At the moment when you tell your friend that you want to purchase car he will ask you a counter question: Why you want to purchase car? Let me answer it. I purchase it for two reasons: Comfort and Safety.

  • I want to save myself/family from hot summer and cold winters.

  • I want to save myself/family from waiting in ticketing queue at bus or railway stations.

  • I want to save myself/family from dieing due to accident.

We will sustain all problem on us but won’t like our family suffer due to same problems. Loss of family member is most painful in anybody’s life.

Following are the points which need to be considered in mind before purchasing car

  1. Engine performance

  2. Safety features

  3. Mileage

  4. Infotainment

  5. Comfort

  6. Style

Engine performance

Engine is the heart of any car. When we talk about engine then two terminologies emerges out: Engine power and Engine torque. Both are designated as HP @rpm and N-m @rpm. Different automobile companies uses different notation in it. You will hear “This car produces Y HP or Y PS of power”. What is meaning of it? If I say in single statement then it means “Y horses are pulling this car”.

History of Engine Power

James Watt from England invented steam engine and thought to compare its power producing capacity with popular power producer of that time, a horse. He founded that horse can pull 180 lb (What is lb? It is used to represent pound and stands for Libra) mass at distance of 181 feet every minute. Finally he declared that a horse can pull 33000 lb mass at distance of 1 foot in 1 minute or 550 lb mass at 1 foot distance withing 1 second and he named it Horse Power (HP). This is how horse power born. This concept of comparing power generation with horse became popular in entire Europe and later, French, Italian, German, Scandinavian, Dutch came out with similar names.

  • French and Italian CV (Cheval Vapeur)
  • Scandinavia HK (HesteKraft)
  • Netherlands PK (PaardenKracht)
  • Germany PS (PferdeStrke)

All these represents same meaning, horse power. The only diference was German believed horse can carry 32500 lb mass at distance of 1 foot within 1 minute. Later, all new system of units based on decimal came in use.

So,

British Horse Power = 33000 lb mass at distance of 1 foot within 1 minute

=33000*1/60

=550 lbf-ft/s

=550 *0.456*1*0.3048 kgf-m/s

= 76.11 kgf-m/s

=76.11*9.81 N-m/s

=746 watts.

German Horse Power =32500 lb mass at distance of 1 foot within 1 minute

=32500*1/60

=541.67 lbf-ft/s

=541.67 *0.456*1*0.3048 kgf-m/s

= 75 kgf-m/s

=75*9.81 N-m/s

=735 watts.

German horse power is also popularly known as Metric Horse Power. HP is 1.4 % (76.11/75=1.014) higher than PS and both are interchanged frequently. Use of PS gives psychological advantage. If British says I have 200 HP then a German will say I have 203 PS, 3 horses more than your engine !!!

Torque

Torque is simply accelerating power of the engine. More torque means more acceleration and greater pick up speed. Engine will be running at 900 rpm when starts. Revolutions will increase as you apply accelerator. So, if maximum power and torque are designated at lower revolutions, it means greater power and torque will be achieved at lower revolutions. Imagine the thrill when you reach 0 to 100 kmph speed in single digit of seconds!!!

Two Valves (2v) or Four valves (4v)

The only tipping point between the two is cost v/s performance. Machining cost of 8v will be lesser. Power and torque production of engine directly depend on combustion which ultimately affected by how effectively fuel air is mixed. At low engine speeds, one intake valve gives increased velocity, hence better gas mixing and better cylinder filling. If you open a second intake valve at low engine speed, the velocity drops dramitically, leaving poor intake filling and a lean intake charge. The result is engine knock and less torque. On the other hand, at high revolutions, breathing is the name of the game. The valves are open such a short length of time you need the maximum available intake area. Therefore 2 intake valves work better at high revolutions. However, turbochargers have improved mixing of air fuel and 16v are no more required for better mixing at higher revolutions. So, low cost will tend to favour 8v and better performance will tend to favour 16v – and there is a compromise here: the 12v 4-cyl engine with 2 intake ports and one exhaust port per cylinder. Noise is not an issue here.

Safety

Airbags (driver and passenger both), ABS (Antilock Bracking System), childlock etc are standard safety features.

Mileage

There is myth that diesel engine is more efficient because it gives more mileage. The statement is partially true because of higher thermal efficiency of Diesel cycle than Otto cycle and not due to its mileage difference. Calorific Value (CV) of petrol is 45.8 MJ/kg, slightly higher than that of diesel which is 45.5 MJ/kg. However, diesel is denser and has volumetric energy density of 36.9 MJ/lit, 16% higher than that of petrol which is 33.7 MJ/lit. For same volume diesel will give 16% more mileage than petrol. For example Maruti Suzuki Swift petrol mileage is 20.4 kmpl and you can roughly expect diesel mileage to be 20.4X1.16=23.6 kmpl. Claimed mileage of Swift diesel is 25.3 kmpl.

Infotainment

Music player, Movie player, Techometer, Trip meter, Fuel warning, Instant mileage display, Bluetooth, Mobile connectivity, GPS navigation, touch screen etc are standar infotainment systems.

Comfort and convenience

AC, AC rear vent, front and rear wiper, front and rear defogger, rear leg space, head rest, driver seat adjustable, rear seat folding, boot space, cup, bottle etc holder, USB connection, charging point, etc are standard comfort features.

Style

Colour, curves, chrome content, handle, interior design, dual tone, shape of car etc makes car stylish.

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