Back in 1876, a talented German engineer by the name of Nikolaus August Otto created what is considered to be the first commercially viable internal combustion engine. He would have been an extravagantly proud man today had he seen what his prized invention has become now. Modern internal combustion is nothing short of a technological marvel. However, despite its qualities and advancement over the years, the Internal Combustion engine still does suffer from some inherent shortcomings. But thankfully, technology has provided useful solutions for many of these shortcomings through various compensatory devices. Today we will be discussing two popular forced air induction devices, a Supercharger and a Turbocharger. We will also learn why they are used and take an in-depth overview of their functioning.
Understanding Forced Induction: Why does the Engine Need a Supercharger and Turbocharger?
To sum it up as simply as possible, a supercharger and turbocharger are used to add power and torque to the engine. Before we dwell into the intricate details of this topic, let’s first list out the 5 major factors that the power output of an engine depends on:
- Amount of air entering into the engine
- The efficiency of the utilization of that air
- Engine RPM
- Engine Size (Displacement in CC)
- Quantity and quality of fuel supplied
- Thermal efficiency of the engine
So the question arises now if you are a car manufacturing company which method will you use to add more power to the engine? The last two are almost never considered because optimizing thermal efficiency will require an extravagantly massive R&D budget dedicated just for that purpose and is not suitable for mass production.
Will Increasing the Engine Displacement Help?
For a very long time, carmakers across the world had been building upon the performance envelop through the 3rd and 4th factors. Increasing the operating RPM of the engine or increasing the displacement of the engine were the primary methods that manufacturers used to boost the car’s power output. But this process also has a lot of disadvantages. Adding more CC means you are increasing a lot of things like raw material usage, more weight, more complex engine design and higher manufacturing costs which translate to higher pricing for the vehicle. Also, the larger your engine is, the more your fuel economy is going to take a hit. Hence, this method is suitable only for luxury/premium cars which are far away from the reach of the masses.
Is RPM the Answer?
Increased Engine RPM also has a similar set of disadvantages just like increasing displacement. As you increase the RPM, you also have to take into consideration several other limiting factors such as friction and heat. The faster you make your piston move inside the engine, the frictional force and thereby the operating temperatures will also increase.
So you have to construct an engine with stronger materials which will drastically increase both the manufacturing and product costs. Secondly, for road use, no one prefers revving to atmospherically high RPMs just for the sake of power. This strategy works perfectly for purpose-built race-cars where the engines need to only last a couple of races. But for road-going normal cars, there’s a very strict limit you need to follow for setting operational RPM levels. I guess it’s fairly obvious now that the first two factors were the actual correct answers to the question and this is exactly what a Supercharger and Turbocharger help
Air is the Answer!
In broad terms, both these devices are used to force a larger quantity of air into the engine with a stronger push (Hence the term, Forced Induction). The actual characteristic here is air density. A denser air charge not only equates to a higher volume of air but also allows delivery at higher pressure. Basically, a supercharger and turbocharger help the engine breathe more freely. By letting in more air at a high-pressure level, you can program the engine to use more fuel and thereby have stronger combustion. The stronger this combustion is, the more is the force exerted on the piston which in turn exerts more torque and power to the wheels. So in simple terms, this process can be summed up as follows: More Air -> Stronger Boom -> Stronger Push on Piston -> Stronger Force on Wheel.
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At atmospheric pressure, air is induced into the cylinder at 14.7 psi (pounds per square inch). As a case example, the new Ford EcoSport’s 1.0-liter EcoBoost engine comes with a 24 psi Turbocharger. So air is being sucked into the engine at nearly 39 psi, which is almost thrice the value of a naturally aspirated engine!
Advantages of Supercharger and Turbocharger vs Natural Aspiration:
- Smaller Engine Same Power: The primary utility of incorporating a supercharger and turbocharger is that you can you can get the same payload of a naturally aspirated engine with a much smaller cubic capacity. This has multiple advantages like lesser material usage, more space in the engine bay, lighter overall car weight etc.
- Easy Driving in Higher Altitudes: If you have ever taken your car for a trip to the hills, you would have certainly felt a lack of power as the altitude increases. This happens because atmospheric air’s density decreases as the altitude increases. So your naturally aspirated engine, in higher altitudes won’t get air at the required amounts for optimal combustion. This problem will never occur in the case of a supercharger and turbocharger since air is inducted at a much higher pressure than normal air pressure. So a supercharged or turbocharged engine will never suffer from power loss in hilly areas.
- Increased Fuel Economy: This is a tad situation dependent but still does apply for supercharger and turbocharger powered engines. With a forced induction engine, you can keep the engine size much smaller than a naturally aspirated engine for the same output. This naturally imparts the engine with higher fuel efficiency. However, fuel consumption in a forced induction engine can be higher than a naturally aspirated engine when you are giving full throttle input. But for city driving, idling and traffic situations, a forced induction engine due to its smaller size will always consume less fuel than a bigger, naturally aspirated engine.
Disadvantages of Supercharger and Turbocharger against Natural Aspiration:
- Necessity of Stronger Materials: A supercharger and turbocharger induce air at roughly 2 or more times than its natural pressure. In order to withstand the increased forces arising out of the higher air pressure and stronger combustion, the internal components have to be made of stronger materials. Till these materials are put to mainstream use, their cost will naturally be higher than the normal materials, which will also reflect in the vehicle’s on-road costs.
- Higher Operating Temperatures: It is a well-established fact that pressure is directly proportional to temperature. Similarly, when atmospheric air is compressed at high pressures, it tends to get really hot. This drastically increases the operating temperature of the engine for every combustion cycle. In the long run, the engine’s life takes a serious hit. Hence in order to mitigate this problem, forced induction engines need to be compulsorily fitted with a separate intercooler solely for the supercharger or turbocharger. Apart from that, the cooling requirements of parts like the piston and valves are also increased due to the same.
So, with this, we come to the end of our blog on superchargers and turbochargers? What do you think of forced induction? Also, do you plan to sell off your car to upgrade to a CNG model? In case you do, we are glad to inform you that CARS24 not only offers you a great platform to assist you with the sale of your used vehicle online but even enables you to obtain the best price for your old car. In fact, CARS24 even takes care of all the documentation, including the RC transfer, totally free of cost. Not just this, you can even make use of our free old car value calculator to know the correct resale value of your car.