I Prefer Cars!

Let’s kill two birds with one slingshot shall we? Horsepower and Speed! I am by no means a gear-headed girl although I must say that I hold an avid interest in fast cars that are not just sexy but are powerful, elegant and aerodynamically efficient.

A while back I had a conversation with one of my gear-headed male friends who not only is a car enthusiast but also has a keen eye on motorbikes, owns one and can hold a conversation for hours about our mutual love for automotives, hydrocarbon burning and in his own words “environment ruining machinery” which he brushes off languidly and carries on about how the environment factor could not take away his affection for some of the fine pieces of art (cars) produced by different automotive companies and their designers over the last years.

I digress a bit there. But the reason why I mentioned him forms the grounds for this article; which is to really understand the horsepower that the car produces. It is through our discussions and other research that I have been able to grasp at least some level of understanding of it. So coming back to the topic of horsepower and whether it makes the car go faster or in fact whether it has anything to do with a car being faster or not is what I want to shed light on.

The more horsepower the car has the faster it is? No. In simple words really, that is the answer. Now, if you asked the more horsepower the car has the more powerful it is? The answer to that would be ‘Yes’. But what is horsepower? How does it impact the car’s performance? Firstly, power on its own does not equal speed. When it comes to car performance, horsepower is simply the amount of power that the engine produces against a certain load and the more horsepower it produces the more powerful it is. You could measure this power by hooking up the engine to a dynamometer. Apply certain mass to the engine and see how much load it can take at different speeds. In mechanical terms this measurement is called “Torque output”. The measure of horsepower then can be derived from this output; amount of torque x rpm (revolution per minute)/5252=HP or in simple English power equals force multiplied by speed.

Torque can tell you a lot about how fast the car can accelerate but having said that on its own, it doesn’t necessarily tell how fast or fast-er the car IS. How fast the car can travel is dependent on a combination of things which I will touch on a bit later. But in order to understand the notion of car’s speed, let me briefly touch upon the topic of what produces velocity in terms of car wheels. How do the car wheels spin and therefore allow the car to ‘move’. The car as my dear friends puts it “is a made up of various parts; tyres, wheels, engine car’s body etc” and it is the engine, the core that holds “everything” in a car together. Its cylinders combusts fuel and release heat energy which is converted to kinetic energy which in turn makes the wheels go round i.e. that kinetic energy is the source of car’s wheels motion that is along with other factors related to the velocity of the car. Bear in mind I have failed to even attempt at explaining how this kinetic energy reaches and therefore makes the wheels spin.

Coming back to what make the car faster is a heap of things, that include its mass, its horsepower, its average acceleration time (usually measured to see how quickly a car can accelerate to 60 miles per hour), the gear ratio produced by engine torque and wheel torque, the quality of the tyres, the aerodynamic efficiency of the car’s body (how it’s built, what material has been used to build it etc) and even the skills of the driver of the car; how efficiently he can throttle and maneuver the car. Other things, that also impact the car’s speed are the technology that’s used; the ECU (engine control unit) of the car that “determines the amount of fuel, ignition timing and other parameters”, what type of gearbox has been built in the car; whether it’s a sequential manual gearbox (used in motorcycles and high performance cars usually used for racing) or manual gearbox or manumatic gearbox (Automatic transmission that provides some manual gearbox functions). That’s what may explain why some 4 cylinder 3 or 4 liter cars with a turbocharger that make less power are faster than cars that have more cylinders say, V8 with 6 liter because they are lighter in weight and may be more efficiently built (along with various other factors).

There it is kids, a spill on power and speed. In a nutshell power does not equal speed and what makes the car powerful and fast is a realm of nuts and bolts so complex that it wouldn’t fit under the umbrella of one discussion. I am sure I would be returning soon with another topic because I do believe I mentioned “turbocharger” and “cylinder” somewhere.
Over and out!

Asima S.

References:
Sameer Sharma
http://en.wikipedia.org/wiki/Main_Page
http://auto.howstuffworks.com/