The internal combustion engine is a marvel of engineering; its design hundreds of years old yet its modern iterations powering a multitude of vehicles ranging from automobiles, motorcycles, ships, and even locomotives. ICE power plants have revolutionized transport and forever changed our world, all in a package that can fit inside your engine bay.Naturally, the internal combustion engine has evolved and improved, commensurate with the constant development of engineering and design capabilities. Modern ICE power plants come in a wide variety of cylinder configurations, mainly: straight (or inline), V, and flat (or boxer). Less common configurations such as W, X, U, and H engines exist as well.Now you may be wondering, what is the need for different cylinder configurations when I4 engines are the most common design? This is an excellent question to ask. The simple answer is that different cylinder configurations each have their distinct advantages and disadvantages. The longer answer is a little more complex.
STRAIGHT OR INLINE
As the name suggests, straight (otherwise known as inline) engines have their cylinders arranged in one row, each cylinder right after the other. Common modern variants include I4 and I6 engines, although Audi produces an I5 (in its RS3) and Volvo ceased production of their own I5 as recently as 2016.Hundreds of millions of cars with straight engines (specifically of the straight four or I4 variety) are driving on today’s roads across the globe. They’re simple in construction, inexpensive to produce, reliable, and compact. These characteristics lend themselves to their widespread appeal and ubiquitous usage.
V
V engines utilize two banks of cylinders arranged at an angle to each other. When viewed from the front or back, V engines resemble the letter “V”, hence the name. V6, V8, V10, and V12 engines all continue to be popular choices for performance automobiles, while V4s are used by some motorcycle manufacturers such as Aprilia.V engines are relatively compact, which means they can be used in a wide variety of applications even as small as motorcycles. For example, Chevrolet’s LS series of V8 small-block engines are a common swap among enthusiast circles, with dedicated enthusiasts performing LS swaps on all manner of cars ranging from Mazda Miatas to Mini Coopers.
FLAT OR BOXER
Because their cylinders are positioned in two horizontally opposed banks located on either side of the crankshaft, flat or boxer engines have a flat profile when viewed from the front or back (along the axis of the crankshaft). Flat engines commonly have each pair of opposed cylinders reciprocating inwards and outwards at the same time. This is referred to as a boxer design.Modern applications of flat engines—specifically boxer engines—include the ever popular Subaru WRX and WRX STI and the mighty Porsche 911 family of sports cars. These cars take advantage of the balance, low center of gravity, and smooth power delivery of flat engines; characteristics which are quite favorable for sports cars.
W
Here’s where it starts to get a little more complex. W engines utilize three or four banks of cylinders connected to a single crankshaft, thus resembling the letter “W” when viewed along the axis of the crankshaft. W engines are quite rare, with very few production automobiles employing this design.Volkswagen Auto Group is the only manufacturer which has used cars with W engine configurations in recent years; among them are a select few Audis, Volkswagens, and Bentleys which use W12s. Additionally, Bugatti has famously employed a thunderous quad-turbocharged 8.0-liter W16 in its record-breaking Veyron and Chiron models.
OTHER CONFIGURATIONS
Internal combustion engines do not exclusively utilize reciprocating piston designs. Wankel rotary engines are one such notable exception, instead utilizing at least one unidirectional rotor in place of reciprocating pistons. In essence, rotary engines fulfill the same function as reciprocating engines—converting pressure into rotating motion.Although reciprocating engines are by far the most popular ICE design in the world, Wankel rotaries have seen limited use in production vehicles. Mazda notably made use of Wankel designs in its RX-3, RX-7, and RX-8 models, with the RX-8 being discontinued in 2012. Mazda has remained mostly tight-lipped about the future of its future development of rotary engines.Even with an estimated 1.4 billion automobiles on the road, we can safely assume that the vast majority of them employ ICE designs. Internal combustion engines are durable and efficient, with a proven design that has stood the test of time. Do you know what kind of cylinder configuration your ICE vehicle has, or are you an electric vehicle lover? Comment down below!
