Have you ever wondered what is a V8 or an Overhead engine or a Supercharged or Turbocharged engine? Well, this is what we are going to discuss today.
In this article, we’ll see in detail the 31+ Different types/classifications of engines. Some of which you might never have heard of…
You can download the PDF on the Different types of engines at the end of the article.
What is an I.C engine?
An I.C.E ( Internal Combustion Engine) is a type of heat engine which is popularly used to power automobiles for decades. An I.C engine works by combustion of fuel inside an enclosed cylinder that causes the expansion of the air-fuel mixture, thereby pushing the piston downwards to get useful mechanical work.
The first successful and modern I.C engine working on petrol was developed in 1876 by Nicolaus Otto.-Source Wikipedia
We know that the petrol or SI engine operates according to the otto cycle. This cycle that we know is named after “Nicolaus Otto”
Now, let us take a look at the different types of automobile engines.
|Classification on the basis of||Types of Engines|
|1) Type of fuel used||a. Petrol engine|
b. Diesel Engine
c. Gas engine
|2) Type of Ignition||a. Spark Ignition |
b. Compression ignition
|3) Type of operating principle||a. Otto cycle|
b. Diesel cycle
c. Dual cycle
|4) Number of strokes||a. 2 stroke engine|
b. 4 stroke engine
|5) Number of cylinders||1,2,3,4,6,8,12 and 16 cylinders|
|6) Type of cylinder arrangement||inline engine|
|7) Type of air intake|| a. Naturally aspirated engine|
b. Supercharged engine
c. Turbocharged engine
|8) Type of cooling system used||Air-cooled engine|
Evaporation cooled engine
|9) Type of valve arrangement||L head|
|10) Type of engine speed||Low-speed engine|
Now that we have taken a glimpse at the classification, let’s deep dive into each of the topics mentioned above.
#1. Types of engines based on fuel used.
1a.) Petrol engine
As the name suggests, the petrol engine works by combustion of the petrol/gasoline. The petrol engine receives a chemically correct mixture of air & fuel from the carburetor during the suction stroke. How much air and how much petrol should be allowed is decided by the stoichiometric ratio.
The stoichiometric ratio for a petrol engine is 14.7:1, which means that you will require 14.7 kg of air to burn 1 kg of fuel This air-fuel mixture is then compressed by the piston during the compression stroke.
A spark plug is used to ignite the mixture and useful work is obtained. After that, the leftover exhaust gases are forced out of the engine during the exhaust stroke. This is in short how the petrol engine works.
Petrol engines are widely used in passenger cars, scooters, bikes, etc.
1.b) Diesel engine
Diesel engines use diesel as the fuel for their operation. These engines work in a little different manner as compared to petrol engines. This has to do with the different properties of the two fuels. Unlike petrol engines where the air-fuel mixture is ignited with the help of a spark plug, diesel engines rely on the heat generated by the compression only.
Instead of a spark plug diesel engines have a fuel injector that sprays diesel into the cylinder. In diesel engines, only air is sucked in. And due to high compression ratios, diesel engines can compress the air hot enough for combustion.
At this point, the fuel injector sprays diesel in the cylinder, and the hot air causes the fuel to ignite. That is how combustion is achieved in diesel engines.
After that, the exhaust stroke forces out the flue gases from the engine. This is how the diesel engine works.
Diesel engines are widely used in heavy machinery, automobiles, farming equipment, trucks, buses, etc.
1.c) Compressed natural gas (CNG)
The CNG engine is similar to the petrol engine, however instead of petrol CNG is admitted to the engine for combustion.
The gas used in a CNG engine is methane gas which is compressed at a pressure of 196 to 245 bar. The working of a CNG engine is similar to that of a petrol engine.
A CNG engine produces fewer pollutants and greenhouse gases as compared to petrol engines resulting in it being more environmentally friendly as compared to petrol and diesel engines.
Along with a CNG tank, a petrol tank is also provided in these cars just in case the automobile runs out of CNG the driver can switch it to Petrol and drive a few more kilometers.
#2 Engine types based on type of ignition
2.a) Spark ignition
Commonly, Petrol engines are called spark-ignition engines. As the name suggests spark-ignition engine uses a spark to ignite the fuel and air mixture, which then expands in the engine cylinder to give work output.
The cost of maintenance of a SI engine is low. Since SI engines have a low compression ratio, their thermal efficiency is less.
2.b) Compression ignition
Commonly, diesel engines are known as Compression ignition (CI) engines. In a CI engine, only air enters the cylinder through the inlet valve.
This air is then compressed by the piston such that its temperature as well as the pressure increases.
When the temperature and pressure of the air are at their maximum, diesel is sprayed with the help of a fuel injector.
This results in combustion & expansion of the fuel due to the very hot air and high pressure caused by compression and finally work is obtained.
The cost of maintenance of a CI engine is high. Since CI engines have a high compression ratio, their thermal efficiency is more.
Must read : Difference between S.I and C.I engines
#3 Based on the cycle it operates
3.a Otto cycle
The Otto cycle is also known as the constant volume cycle. It is an ideal thermodynamic cycle that tells us about how a Spark Ignition engine works.
It tells us about how much heat is added or removed to a mass of gas and also what is the pressure, temperature, volume of the gas at a given point.
Given below is the P-V diagram of the otto cycle:
|The Otto cycle consists of 4 main processes|
|Process 1-2 Adiabatic compression|
Process 2-3 Addition of heat at constant volume
Process 3-4 Adiabatic expansion
Process 4-1 Rejection of heat at constant volume
3.b Diesel cycle
The diesel cycle is also known as the Constant pressure cycle was introduced by Dr. Rudolph diesel in the 18th century.
Diesel engines are based on this cycle.
|4 main processes of the Diesel cycle are|
|Process 1-2 Isentropic compression|
Process 2-3 Addition of heat at constant pressure
Process 3-4 Isentropic expansion
Process 4-1 Rejection of heat at constant volume
3.c Dual cycle
The mixed or dual cycle is the combination of both the otto cycle as well as the diesel cycle. In this cycle, the heat is added partly at constant volume as well as constant pressure. Whereas when the heat is rejected only at constant volume.
Therefore, in the dual cycle, there are 2 ways of heat addition (at constant pressure and volume) and a single way of heat rejection (at constant volume)
|The following are the main processes of the dual cycle|
|Process 1-2 Isentropic compression|
Process 2-3 Addition of heat at constant volume
Process 3-4 Addition of heat at constant pressure
Process 4-5 Isentropic expansion
Process 5-1 Heat rejection at constant volume
#4. Based on Number of strokes
4.a) 2 stroke engine
A Two-stroke engine is an engine that completes 2 strokes in one revolution of the crankshaft, out of which one stroke is a power stroke.
The 2 stroke engine on the other end is simple in construction, without any inlet outlet valve instead it has ports. The two-stroke engine has a smaller flywheel and is light in weight as compared to 4 stroke engine.
2 stroke engine produces 1 power stroke in 1 revolution of the crankshaft. Whereas, a 4 stroke engine produces 1 power stroke in every 2 revolutions. This type of engine has less mileage as compared to 4 strokes.
4.b) 4 stroke engine
A Four-stroke engine is simply an engine that completes 4 strokes of the piston in 2 revolutions of the crankshaft.
|The following are the Four strokes:|
|Stroke 1: Suction stroke|
Stroke 2: Compression stroke
Stroke 3: Power stroke
Stroke 4: Exhaust stroke
A four-stroke engine’s thermal efficiency is high as 4 stroke engine gives 1 power stroke every 2 revolutions instead of one power stroke in 1 revolution as in the 2 stroke engine.
You might also like to read: What is meant by VVT, i-VTEC, or VTVT engine?
#5. Based on number of cylinders
5.a) 1 cylinder engine
Just as the name suggests, this type of engine uses just 1 cylinder and piston arrangement. It is used for low power applications like scooters, go-karts, radio-controlled vehicles, portable tools, and garden machinery like lawnmowers, etc.
5.b) 2 cylinder engine
A 2 cylinder engine or a twin-cylinder engine consists of 2 cylinders and pistons. These types of engines are quite popular in the two-wheeler industry. Other applications include snowmobiles, jet skis, driving pumps and different types of air compressors, etc.
5.c) 3 cylinder engine
The 3 cylinder engine is not quite popular like the 2 or 4 cylinder engines but has been used in quite a few notable automobiles like the 2004-present Triumph Rocket III engine, 1969-1975 Kawasaki H1 Mach III, Alfa Romeo 33, etc.
5.d) 4 cylinder engine
These are one of the most common and popular types of engines. If you own a compact to the mid-range car there’s a high probability that the car you own is a 4 cylinder engine.
Maruti Suzuki Swift, Wagon R, Hyundai Grand i10, Honda City, Hyundai Creta, etc are some of the popular cars with 4 cylinder engines.
5.e) 6 cylinder engine
From here on the lets talk real horsepowers, shall we?
6 cylinders engines are used in some of the most popular car names like the Audi A6 , Porshe Panamera, the iconic Porsche 911, Ford GT etc.
One can find 6 cylinder engines from SUVs to Sedans to Supercars to heavy-duty trucks.
Must check out this article on The different types of cars
5.f) 8 cylinder engine
The V8 form of the 8 cylinder engine were once used in various motorsports including Formula 1, NASCAR, IndyCar etc.
During world war 1, V8 Engines were also used in airplanes. Modern-day cars like the Chevrolet Corvette Stingray, Aston Martin Vantage, Ford Mustang Shelby GT, Porsche Cayenne GT turbo, etc are some notable automobiles with 8 cylinder engines.
5.g) 12 cylinder engine
Talking about 12 cylinders, we enter the hypercar territory. Most ultra high-end cars you see would most probably be sporting either a 12 cylinder or a 16 cylinder engine.
Some iconic names come under this category like the Aston Martin DB11, Bentley Continental GT, Ferrari 812 Superfast, Pagani Huyara, Rolls Royce Ghost and Rolls Royce Phantom to name a few.
5.h) 16 cylinder engine
How is it possible that you talk 16 cylinders and not talk Buggati? Yes my friend, be it a Buggati Veryon to the Buggati Chiron both of them come equipped with a powerful W16 engine.
16 cylinder engines were also used in the locomotive as well as aircraft field.
#6. Based on cylinder arrangement
The inline type of engine is a simple mechanical engine that gets its name because of all the cylinders placed in a straight line, one after the other. Inline engines are also called straight engines.
These engines have only one cylinder head and fewer moving parts.
The advantages of inline engines is that they are simple in construction, they are cheaper as well as their maintenance costs are also low.
The inline engine with 6 cylinders is used in some notable cars like the Volvo V60 Polestar and BMW S55.
6.b) V type engine
The most popular type of cylinder arrangement is the V type. It is made up of 2 cylinder banks with a common crankshaft at the bottom.
This engine gets its name because when seen from the front, the cylinders resemble the shape of the letter “V”.
Since the V-type engines have 2 cylinder heads therefore for engines having more cylinders, they are shorter in length but are wider than their inline counterpart.
V twin engines have 2 cylinders arranged in V shape and are popular in motorcycles like the Kawasaki Ninja 300 and Yamaha R3.
The V6 engine that comes with 6 cylinders in V arrangement is widely used in sports cars like:
- Porsche Cayman 718 GT4,
- Nissan GTR
- Chervolet Camaro
- Jaguar F type,
- BMW M3 (2018)
- Honda NSX etc.
Do you know?
The Caterpillar 797 is the world’s largest and highest capacity dump truck in the world and has a 3700 horsepower V20 engine.
Then comes the V8 and V10 engines with 8 and 10 cylinders respectively. V12 engines can be perfectly balanced and are used in luxury cars like Rolls Royce and Bentley to Boats and aircraft.
6.c) W type engine
W engine is made up of 3 or 4 cylinder banks with a common crankshaft and when seen from the front it resembles the letter “W” and hence the name W engine. The W-type engine is more compact than the V-type engine arrangement.
The following images above show a W engine with 3 banks and a W engine with 4 banks.
“Broad arrow” engines is term referred to W engines with 3 banks of cylinders, because of their resemblance to the British government broad arrow property mark.
The W engine comes in a variety of arrangements ranging from W3 (i.e with 3 cylinders) to W30 (i.e with 30 cylinders).
The Buggati Veryon and the Chiron come equipped with W16 engines churning out 987 and 1479 horsepower respectively.
The 3-cylinder W3 engine was intended for motorcycle use, whereas the W30 engine was used in tanks. Though, only W6 to W24 engine type is used in automobiles.
6.d) Boxer engine
Unlike the V-type engine, the boxer engine has the cylinders placed flat i.e the cylinder banks are placed 180 degrees apart. So instead of moving up and down as in V & W Type engine, the pistons in the boxer engine reciprocate left and right horizontally.
These engines are naturally more balanced and are easier to cool than V or W engine type arrangements.
The advantages of boxer engine include:
- The boxer engine has a low center of gravity which increases stability & handling.
- Boxer engines are evenly balanced.
- They are wider and flatter that helps in spreading the weight of the engine more evenly.
- These engines have a smooth operation along with reduced vibrations.
Do you know?
Boxer engines were first invented in 1897 by Karl Benz. They are termed as “boxer” engines as each pair of pistons moves in and out just like the gloves of a boxer.
The Boxer engine is sometimes called the “Flat engine” or the “Horizontally opposed engine“.
The Porsche 911 is one of the famous cars using a Boxer-type engine. Other popular manufacturers of the boxer engine include Subaru and Toyota.
6.e) Radial type engine
The radial type engine has a circular cylinder arrangement with the crankshaft in the middle. This engine was quite popular among aircraft during the world war, however, as the demand for power increased and with the gas turbines being launched, the radial type engines have become less popular.
Image source – Andy Dingley (scanner), Public domain, via Wikimedia Commons
This type of engine is shorter as well as it produces fewer vibrations as compared to engines with cylinders arranged in a row.
6.f) X type engine
The X engine has 4 cylinder banks and a common crankshaft between them placed in such a manner that when viewed from front, the engine resembles the letter “X”.
The X engine is shorter in length when compared with a V type engine having the same number of cylinders.
However, this type of engine is rarely used because of its heavyweight and complex construction.
6.g) H type
When seen from the front this engine looks like the letter “H” and hence the name H engine. The H engine has 2 separate crankshafts, unlike the V, W, or radial engines that have a single crankshaft. The H engines have two cylinder banks above and two below.
The H engine is a relatively rare form and was mainly used in aircraft engines in the 1930s and 1940s. The 1966 Lotus 43 Formula 1 racing car had a 16-cylinder H engine and an 8-cylinder engine was used in Speedboat racing in the ’70s.
As there are 2 crankshafts rotating in opposite directions in an H engine the gyroscopic effect produced is canceled out by one other. This is a smooth engine operation.
#7. Based on Type of Air Intake
7.a) Naturally aspirated engine
The Naturally aspirated engine is a type of engine that relies only on the air intake at normal atmospheric pressure and it does not have a forced air induction as in the case of Superchargers or Turbochargers.
A Naturally aspirated engine depends on the natural circulation of air to carry out the combustion process.
Advantages of Naturally aspirated engine
- Naturally aspirated engines are more reliable.
- These type of engines are easier to maintain.
- They have less parts as compared to turbocharged or a supercharged engine.
- Power delivery is smooth without lag.
Limitations of Naturally aspirated engine
- Naturally aspirated engines are not as fuel efficient as Turbocharged engines.
- Their size is larger as compared to a turbocharged or supercharged engine of the same power.
The reason why supercars like Ferrari 812 Superfast, Lamborghini Aventador S, Porsche 911 speedster, Audi R8, etc. use a Naturally aspirated engine is that it sounds good, gives instant power and there is no lag.
7.b) Supercharged engine
The function of the supercharger is to compress & increase the density of the air before it enters the engine for combustion.
The supercharger is a type of air compressor that may be either of Centrifugal, Roots-type or a Twin-screw type.
The increased density of air supplied by the supercharger results in increases amount of air available in the combustion chamber.
The more the amount of air in the cylinder, the more fuel can be added and the more powerful explosion can be obtained resulting in increased horsepower.
Superchargers help increase the horsepower as well as the torque developed by the engine to quite some extent.
As the R.PM of the compressor increases, the temperature of the air exiting the supercharger also increases. This hot air is not desired. Thus it needs to be cooled. Therefore, in between the supercharger and the engine, an intercooler is placed in order to cool the air and increase its density even more.
Advantages of using a Supercharger
- Supercharging gives a high power output
- It increases the mechanical efficiency of the engine.
- Complete and smooth combustion is possible.
- Fuel and air can be properly mixed.
- Smoke is reduced.
Limitations of using a Supercharger
- The supercharger requires a cooling apparatus that increases cost and space.
- Due to bigger explosions, stresses are induced in the engine material. Thus, good engine construction is needed.
7.c) Turbocharged engine
The Turbosupercharger or in short the Turbocharger that compresses the air before it enters the engine.
As you can see in the above figure, the part painted in black is the one connected to the exhaust and within which the turbine is placed. The turbine and the impeller of the compressor are mounted on the same shaft. And the light silver portion is the compressor that compresses air before sending it to the engine.
Isn’t it similar to the supercharger?
Well, it is a little bit. Unlike the supercharger where it is driven by the engine, the compressor of the turbocharger is driven by a turbine mounted on the same shaft of the compressor. This turbine is powered by the hot exhaust gases coming from the engine.
What is Turbo Lag?
As the turbocharger operates on the exhaust gases, it doesn’t quickly start working in its full capacity. As the exhaust increases so do the capacity of the turbocharger. Therefore, when you accelerate suddenly, the speed won’t increase at the same rate instead it would be gradual. This delay is known as “Turbo lag“
Advantages of Turbocharger
- Turbochargers help increase the fuel economy.
- Increased engine power output.
- They produce less pollutants.
- Turbochargers can be used on a variety of vehicles like cars, trucks, buses etc.
- These engines produce more power as compared to a naturally aspirated engine.
- Turbochargers run on the exhaust gases, so no power is consumed by it as in the case of superchargers that run on engine power.
Disadvantages of Turbocharger
- Turbochargers are subjected to the problem of Turbo-lag especially large turbochragers.
- Turbocharged engines are more complex and have more parts than naturally aspirated engines.
- They are expensive as compared to normal engines.
#8. Type of cooling system used
8.a) Air cooled engine
As the name suggests the air-cooled engine is dependant on the natural air circulation for the dissipation of heat produced by the engine. Air-cooled engines are used in motorcycles, scooters, and other machines with small engines.
There are fins attached to the cylinder block and cylinder head of the engine that increase the surface area that helps in heat dissipation.
When the vehicle is in motion, the air flows between these fins and helps cool down the engine. This is why this type of engine are known as “Air-cooled engine”
8.b) Oil cooled engine
The oil-cooled engine makes use of the engine oil to dissipate the heat produced by the engine. This type of cooling is better than the air-cooled engine type.
These types of engines have fins like the air-cooled ones but along with it, the engine oil is also cooled. When the engine is running, the engine oil lubricates the moving parts as well as absorbs the heat produced by the engine.
Now this heated oil is then passed to an oil cooler placed outside the engine. The oil cooler is similar to the radiator within which the hot oil coming from the engine is cooled. The cooled oil is then further circulated through the engine.
8.b) Liquid cooled engine
The liquid-cooled engine makes use of a coolant that is a mixture of water and concentrated coolant in a fixed proportion. This type of cooling process is better than the oil-cooled as well as air-cooled engines.
The coolant used in the engine has desirable properties like anti-corrosion, low freezing point, high boiling point, anti-fouling.
This coolant is passed through water jackets that surround the engine. After passing through the jacket, the heated coolant is then passed through the radiator in order to lower its temperature. It is then recirculated through the jacket and the process goes on.
#9. Based on Types of valve arrangement
This type of classification is based on the position of the inlet and outlet valves and the spark plug with respect to the combustion chamber.
In order to remember the classification on the basis of valve arrangement, simply remember the word “LIFT” which stands for L head, I head, F head, and T head engine respectively.
9.a) T head
The T head type arrangement was used during earlier times. In this arrangement, the inlet and exhaust valves are placed at either side of the combustion chamber which resembles the letter “T”.
The vertical part of the letter “T” represents the combustion chamber whereas the inlet and exhaust valves are represented by the two ends of the horizontal line.
Since the valves are on either side, they need separate camshafts to drive them. The main limiting factor of this type of valve arrangement is that it is difficult to manufacture as well as the chances of knocking also increase.
9.b) L head
The L head type valve arrangement helps solve some of the problems found in the T type arrangement. In this arrangement, the inlet and exhaust valves are on the same side, one behind the other. This eliminates the need for 2 separate camshafts as they can be operated using the same camshaft.
As you can see in the above figure, the head looks like an inverted L and hence the name L head type valve arrangement.
You may notice that the spark plug is placed not at the center of the cylinder instead it is placed above the valves.
This is because the valve is a little far which causes the air to travel more distance and loss of velocity that results in knocking. So in order to prevent this, the spark plug is placed above the valves.
Do you know?
The design of placing the spark plug was made by Ricardo which is a global engineering, environmental and strategic consultancy, operating across a range of market sectors.
The advantage of the L head arrangement is that it is simple in construction and therefore easy to maintain.
9.c) I head
The I head valve arrangement consists of the inlet and outlet valves at the top of the cylinder whereas the spark plug is at the side.
The I head type of engine is also known as “Overhead valve engine” or simply an “Overhead engine“.
The advantages of the I type engine / Overhead engine are:
- This type of engines can be easily accessed for maintenance
- They are suitable for higher compression ratios
- There is less knocking in the I head engine.
- It requires a shorter and simple timing chain.
9.d) F head
The F type valve arrangement share similarity with the L and I type engine. It has an inlet valve at the top just like in the case of the I-type engine, whereas the exhaust valve is at the side just like the L type.
This was a brief on the Different types of engines. Have you learned about an engine that you never knew existed? We would love to hear about it in the comments.
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Till then Keep learning!