THE ENGINE DISPLACEMENT OR CC

The car engine it’s a life and soul as the power and the fuel efficiency of the car will be determined by the car engine. The car engine can be naturally aspirated or a turbocharged engine. They are many complicated mathematical formulas involved in making the engine and some technical complexity on making the best engine possible. The engine may work seamlessly but in truth, it is the technical expertise of the car engineer to make a complex engine to works in one simple motion. They are many aspects of the car engine that can determine the car performance like the horsepower, torque, valve timing and much more. One of the most important aspects of car engine apart from mentioned above is the engine displacement or popularly known as CC.

The CC is the abbreviation from the word cubic centimeters. The CC or the engine displacement means the swept volume of the piston inside the cylinder of the engine in a single movement from the piston Top Dead Centre (TDC) to the Bottom Dead Centre(BDC) of the engine piston. The displacement of the engine does not include the total volume of the combustion chamber. They are a mathematical formula to determine the displacement or cc of the engine via the bore and stroke of the engine cylinder. The bore is the diameter of the circular chambers cut into the cylinder block.

Examples: The 427 Chevy bore is 4.312 in, and the stroke is 3.65 in, therefore the displacement for this eight-cylinder engine is:

3.1416/4 × (4.312 in)2 × 3.65 in × 8 = 426.4 cu in

or:

(4.312 in)2 × 0.7854 × 3.65 in × 8 = 426.4 cu in

If the bore is 10 cm and the stroke is 5 cm with four cylinders, the calculation is:

3.1416/4 × (10 cm)2 × 5 cm × 4 = 1,570 cm3 = 1.57 litres

In the real world, how does the CC works? For describing this we will take the Honda Accord 2.4 as an example. When the engine had been started and with the crankshaft also been started, each 4 pistons of the engine movement will inhale a total of 2.4 liters of air and fuel mixture in the engine. However, another thing that can mislead is that without rounding the figure the actual number of the engine displacement will just be 2,398 and not exactly 2.4. It’s something that is like the computer Random Access Memory (RAM) where the actual number is different than the number advertised.

The engine displacement is one of the crucial factor in the determining the engine power output, fuel efficiency and in some country like for example in our country, it can be used to determine the price of the road tax. How can the engine CC determine the engine power? The engine that has higher CC will draw more of the air and fuel mixture in the engine resulting in a better performance but a higher fuel consumption. In the engine that has lower CC meanwhile may draw less air and fuel mixture resulting in the higher fuel efficiency but provide the least performance although, with the forceful induction via the turbocharged engine, the lower CC can squeeze more power and increasing the torque power of the engine. This is one the reason on why the turbocharged had least horsepower but more torque if compared to the naturally aspirated engine where it can have more horsepower but least amount of torque.

Speaking of the road tax, in our country the CC will be used to determine the road tax price regardless of the car age. The road tax of a car that has 1.5 cc engine will cost only RM90.00 where the road tax for the car that has 3.5cc can cost RM4380.00. Countries like Japan meanwhile will use CC and also use the vehicle weight to determine the road tax price. However not all country will use the CC to determine the road tax price as in Britain they are using the vehicle emission level to determine the road tax. In Holland, they will use the region, weight, and fuel type as a factor to determine the road tax.

The car manufacturer like to encode the engine CC in their car model like for example Honda Accord 2.4, Nissan Teana 3.5, Toyota Camry 2.5 and much more. BMW loved to use the engine displacement as their vehicle model name especially in their sedans like BMW 318i, BMW 320i, BMW 520i, BMW 730i, and much more. For BMW 320i, the name and displacement is an exact match however in their model 318i the displacement of the engine is just 1.5cc. Similarly, for their model 330i, the engine displacement is not 3.0cc but it is 2.0cc. Due to this, this can be a misleading figure for the car lovers.

Since in our country the road tax will be determined by the engine displacement, the car manufacturer will only sell a car that has higher CC in their highest range model like the Audi A8, Mercedes Benz S Class, and BMW 7 Series. The Japanese model like the Honda, Toyota, and Nissan will only sell higher CC car in their highest variant sedan. The ultra-premium model like Bentley and Rolls Royce usually have a very high engine displacement starting from 5.0cc and above and for the sports car like Ferrari, Buggati Veyron, Lamborghini and much more who built for performance it too has a higher CC engine displacement.

From here we can know that the engine displacement is not just a number but a factor in the power output, fuel efficiency and to determine the road tax price. This is a testament to the car engineer is making the best engine displacement in the car as it involved in some complicated mathematic and the complexity of the engine parts. The engine is the life and soul of a car hence it must build in the best way possible to give the life to the car as expected by the car engineer, car manufacturer and for the car lovers. In the simple term, they are more to CC or engine displacement than just number encoded in the car brochure or in the car model.