Owning a vehicle and not knowing what exactly its internals are made of puts you in quite a vulnerable position: you wouldn’t want to get scammed at the workshop by mechanics telling you that you drive a V8 Engine in your Toyota Prius, neither would you want to be embarrassed in front of your geek car guys.
Knowing what engine your car has is essential for you to be able to take care of it, ensuring its longevity, satisfactory mileage to save some gas money and understanding its limits. Here are all types of Engines that may exist in your car and a guide on how to understand what it is:
Inline (Straight) Engines
Inline engines are where the cylinders in the engine are arranged in one single row, and the pistons in the cylinder are connected at the bottom to one rotating crankshaft. This type of engine layout is quite common and relatively compact due to the lesser number of cylinders to a V or Flat shaped layout. However, as the number cylinders increase, the length of an Inline engine may become impractical, eventually having to consider wider engines over longer ones to fit into an engine bay.
A few common types of Inline Engines are:
I2 (Inline 2/I-twin) Engines
Two cylinders in line with each other with the pistons attached to a common crankshaft. The crankshaft angle between the two pistons can be 180, 270 or 360 degrees, where any configuration may cause the engine to vibrate vigorously due to which balance shafts and counterweights may need to be used.
These are mostly used in Motorcycles due to its compact size and fuel efficiency.
I3 (Inline 3) Engines
3 Cylinders in line with each other with the same basic principle. The crankshaft angle between each piston is usually 120 degrees allowing for an even firing interval. This makes the I3 engine less prone to vibrations than its 1 cylinder less forerunner.
The I3 engines are still used in many compact family micros, sedans and hatchbacks, however, with a solid build and the support of turbos coupled with the engine, it is still used in various compact high performing cars: among the big names there are the Koenigsegg Gemera Twin Turbo Inline-3, Toyota Corolla GR Yaris, BMW I-8 and more.
These engines are also used in more high-end luxury/sports bikes.
I4 (Inline 4) Engines
One of the most, if not the most common type of engine to be used in modern day family sedans, SUVs, hatchbacks and more. If you own any mid sized family car that gives you a good mileage and minimal engine problems, chances are it’s an I4 engine. I4 engines are very well balanced as their pistons move in pairs: as one pair (piston 1 and 4) moves down, another pair (piston 2 and 3) moves up, reducing vibrations.
Most modern day 4 cylinder engines are I4s, however, its durability allowed it to be used in racing and Formula 1 cars too throughout the 1900s. Smaller, more compact versions of an I4 are used in MotoGP racing as well by many motorcycle brands.
I5 (Inline 5) Engines
Following the same principles of the previous inline engines, I5 just adds a fifth cylinder in one row all attached to one crankshaft with a 72 degree configuration. Most I5 engines have a firing order of Piston 1-2-4-5-3 causing it to be a bit imbalanced, however, as the pattern you may have noticed, the more cylinders you add, the more you can counteract the vibrations caused by the pistons moving.
I6 (Inline 6) Engines
Ever heard about the 2JZ-GTE or the RB26-DETT engine? Inline 6 layouts have given the world some of the most resilient, power-generating and power-handling engines of this generation. However, as the inline engines began to grow longer, it became just as difficult to fit them into modern engine bays shared with all the new technologies. So, soon, V6 engine layouts replaced I6 engines due to a smaller size and better efficiency in fuel economy and manufacturing.
Inline 6s are 6 cylinders arranged in a straight line, perfectly balanced with a suitable firing order (1-5-3-6-2-4). The pistons move in balanced pairs too causing lower vibrations (1 and 6, 2 and 5, 3 and 4).
Above the Inline 6 engines, any other inline engine becomes too long to fit into any car’s engine bay, requiring us to choose an alternative layout, mostly V Engines.
V Engines
A V shaped layout introduces a twin cylinder head layout where the pistons are still connected to a common crankshaft. These cylinder are arranged at an angle to each other making the V shape and the number (#) after the letter V# denotes the total number of cylinders of that engine.
Generally as the number of cylinders exceeds 4, V shaped engines become more preferable and efficient over Inline engines due to their shorter length with the same number of cylinders.
Common V engines include:
V2 (V-twin) Engines
Two cylinder configuration shaped in a V where the piston movement is offset by 180 degrees using a common crankshaft. This is a relatively small engine commonly used in motorcycles. Usually, a 90 degree angle between the pistons is used to achieve the greatest possible balance for the engine and produce the least vibrations.
V4 Engines
Although its Inline 4 cylinder layout counter-engine is more commonly used and mass produced for commercial vehicles, V4 engines are still a better balanced version at 90 degree piston angles. Not many cars use this type of engine, however a majority of MotoGP manufacturers still use V4 engines for their bikes.
V6 Engines
V6s become far more prominent in commercial use as Inline engines become too long to fit (that’s what she said). 6 Cylinders, 3 on each bank of the engine, basically shaped like 2 inline 3 engines slapped onto each other with a certain V-angle. Due to the odd number of cylinders, it is quite imbalanced and causes significant vibrations which need to be counteracted using balance shafts.
A 60 degree V angle is the most appropriate for a V6 as long as the firing interval/Piston movement can be kept at 120 degrees to each other.
V6 Engines are very popular among many modern day cars from manufacturers like Toyota, Mazda, Mitsubishi, Audi, Ford, Honda, etc.
BMW is probably the only manufacturer who, instead of shortening their perfect Inline 6s into V6s, actually modified their car chassis to be able to accommodate a longer inline 6 proving how much BMW values a ‘driver’s’ car.
V8 Engines
With the same analogy, V8s are just 2 inline 4s slapped together by the side. Mostly, all pistons are connected by a common crossplane crankshaft; flat-plane crankshafts were also used after the early introduction of V8s which produced high vibrations and imbalances.
V8s are much larger displacement engines used in SUVs, performance luxury vehicles, offroaders, supercars, NASCAR and even in Formula 1 racing. Top brands and car models use these engines like: Toyota Land Cruiser V8, Maserati Quattroporte, Ferrari 488, Audis, BMWs and Mercedes.
V10 Engines
V10s are far less common and are mostly used in performance, luxury and sports cars. The crankshaft structure is pretty much the same with 2 extra cylinders at the end as the V8. It is relatively more imbalanced because of its configuration as two banks of inline 5 engines (as I5s themselves are quite imbalanced), because of which balance shafts need to be used to reduce vibrations.
The Dodge Viper introduced the first V10 engine in a commercial vehicle after which Lamborghini, Porsche and Audi started integrating them in their supercars and sports cars. Alongside these, the best commercial car ever (in my opinion) also incorporates a 4.8L V10: The Lexus LFA.
V12 Engines
V12s are two banks of inline 6 engines joined by a common crossplane crankshaft at varying V angles of 60, 120 or 180 degrees. As we’ve seen, inline 6s are primarily and secondarily one of the most balanced engines, which makes the V12 extremely well balanced too, not requiring the extra weights of balance shafts or counterweights.
V12s are more common than V10s because of their smooth delivery of power due to their even firing orders, but the sheer size and weight of a V12 makes it a luxury to be owned; only being found in supercars and luxury vehicles.
Flat Engines
Flat Engines can be divided into 2 main types: a 180 degree V engine or a Boxer engine. If we talk about the 180 degree V angle engine; basically, each oppositely placed piston shares one crankpin along the crankshaft. What does that mean? Let’s say on a Flat-2 Engine (two oppositely placed cylinders), as the two pistons are connected to one crankpin, when one of the pistons moves inwards the one opposite to it moves outwards. So if you increase the number of cylinders, whenever one cylinder moves inwards, the one opposing it moves outwards because the piston’s base is connected to the same crankpin.
Flat engines have their benefits, they have a lower centre of gravity and better primary and secondary balance due to being horizontally arranged. However, they are obviously very wide. Flat Engine variations extend just like the V engines: Flat twin, Flat four, Flat six, Flat eight, Flat ten and Flat twelve.
Although Subaru and Volkswagen have used flat four engines in a few of their cars, Porsche is infamous for its use of Flat Engines in most of their top of the line sports cars, notably the Flat 6 in Porsche 911s and the Flat 12 in the Porsche 917k.
Boxer Engine
How Boxer engines differ from 180 degree V angle engines is that its pistons do not share a crankpin. So, each piston has a different crankpin it sits on causing the pistons opposing/adjacent to each other to move in the opposite direction at the same time. So in a Flat twin boxer, both pistons move outwards together and come back inwards together.
W Engines
The W engine configuration is quite rare. Its introduction into commercial cars came into light when Volkswagen started developing their W8 engine for their W8 Passat, which did not really work out and was short-lived. Audi tried engineering a W12 for their cars too but after testing it seemed their high displacement V8s performed better. The W12 engine started gaining traction after it was placed in the Bentley Continental GT.
Nonetheless, by far, the most properly utilised for its relatively compact size and weight to cylinder ratio W engine has been the W16 engine in the Bugatti Chiron and Veyron. These engines produce over 1000hp and as they are heavy and balanced, the mid-mounted structure helps these cars to have a low and central centre of gravity.
The W engine can be shaped as a stickman’s W; where there is one cylinder bank that is straight upright (like an inline engine) and then 2 other cylinder banks to the side at a V angle. So, it’s like a V engine but another Inline engine slapped in the middle of the V.
Another layout that is used in the bigger W engines (like the W12 and W16) is 2 V shaped engines on top of each other. So, for example, with a W12 engine, there is one cylinder bank to the left with 6 cylinders arranged in a zigzag pattern on a which is then mirrored onto the right side. All these 12 cylinders are still connected to a common crankshaft.
Wankel Rotary Engines
When we hear Rotary engines, we think of the infamous Mazda Rx-7. Mazda was the only manufacturer mass producing rotary engines (which is actually called Wankel engines, actual rotary engines are different) due to its compact size and high power.
The rotary engine is commonly referred to as the spinning Dorito: with a triangular disc rotating inside an oval shaped compartment. What happens inside the compartment? To simply explain the operation: as the triangular disc rotates away from the intake, it sucks in the air from the intake; as rotation continues, the suctioned air is then compressed by the disc and at that compressed state spark plugs are ignited to cause combustion in the chamber; due to that combustion explosion, the disc is forced to rotate again reaching the exhaust pipe where the combustion gas is released; and the process repeats.
A typical rotary engine has 2 rotors on either end delivering a high power to weight ratio and one of the most captivating engine rev noise to ever exist. However, due to the horrible fuel economy and more than standard emissions, rotary engines were taken out of production, now only being a legend in the history books.
Strokes of an Engine
Almost all commercial cars use a 4 stroke engine setup regardless of the type of engine it is: be it a V engine, Inline, flat or even a rotary. Four stroke engine means one cylinder of an engine goes through 4 steps/stroke lengths; 2 strokes = one complete rotation of the crankshaft where the piston moves up once and down once. So 4 strokes = down-up-down-up.
On the first stroke (for a normal cylinder engines, not rotary), the cylinder moves down and does the INTAKE of air – the up stroke does COMPRESSION of the air taken in – then IGNITION occurs causing an explosion and pushing the piston down, the next down stroke – and, lastly, the up stroke causes the ignited air to come out as EXHAUST.
Rotaries do the same thing just with a different hardware operation
