Can a car have 5 cylinders?
The Advantages And Disadvantages Of The Inline Five-Cylinder Engine
Five cylinder engines have managed to sneak themselves under the bonnets of some of the all-time greats in the realm of performance cars. Well-known uses of this configuration include the Audi Ur Quattro, the second-generation Ford Focus RS and the Volvo 850R. Quite a roster.
Five-cylinder engines are still in production and feature most prominently in the Audi TT RS and RS3. Despite their rarity, it’s worth looking at the pros and cons of such engines to see why some manufacturers swear by them and why others would never touch them, sticking with a standard in-line four.
Five cylinders have a bespoke firing order that can even its power strokes throughout the crankshaft’s rotation. The four-stroke, five-cylinder setup leads to a firing interval of 144 degrees of crankshaft rotation. In comparison to a four-cylinder engine which fires every 180 degrees, there will be a 36 degree overlap, meaning another power stroke has occurred before the crankshaft rotates to the 180 degree mark. This results in a power delivery is smooth, instead of the relative jolting action of an inline-four.
The crankshaft journals are spaced out in a fashion to cater for the five cylinders. Relative to the first piston being at top dead centre, the second journal sits 144 degrees counter-clockwise around the crankshaft, the third journal at 216 degrees, the fourth at 288 degrees and the fifth at 72 degrees (or 432 degrees from the origin). With the respective firing interval, this makes for a firing order of 1-2-4-5-3 in most five-cylinder engines. This means the piston reciprocation hops from one side of the engine block to the other before finishing its full cycle with the central third piston.A five-cylinder engine with a slightly different firing order of 1-4-2-5-3, again finishing with the central cylinder
As with three-cylinder engines, the behaviour of the reciprocation due to the journal spacing and firing order leads to a balance of the vertical forces within the engine. Unfortunately, there is a torque imbalance along the horizontal plane of the engine, meaning a five-cylinder is constantly trying to twist or flip over its length. This rocking motion will often need a balancing shaft to cancel out that twisting force which will improve overall refinement. That intrinsic inertial behaviour is then enhanced by the length of the engine compared to an I4, leading to an engineering complexity that many manufacturers decide to shy away from.
For those willing to engineer their way around these problems however, there are multiple reasons why a five-cylinder is a viable option as a powertrain. For starters, Being shorter in length than an in-line six, they can be mounted transversely much more easily. This opens a window for the implementation of a five-pot in smaller cars within a manufacturer’s range.
As discussed previously, the delivery of power is smoother than that of an inline-four which makes for the silky-smooth ascent in revs that the five-pot is renowned for. This is further enhanced by the vertical balance of the reciprocating pistons and when combined with the added potential displacement over a four-cylinder engine, there are plenty turn-ons that justify the choice of these powerplants by the likes of Audi.
Sounding like miniature V10s, five-cylinder engines seem to have naturally grown a respect within the automotive community. Possibly stemming from past motorsport success, cars featuring five-pots are still holding on, unlike their V10 cousins.
We’ll soon be testing the Audi RS3 saloon which features the same 395bhp five-cylinder 2.5-litre engine as the Audi TT RS, a car that CT is already rather fond of. With Audi cancelling a 400bhp+ version of its EA888 inline-four due to the fact the existing five-pot is a cheaper option, this engine should be around for a while longer.
Add in the fact that Mercedes is re-joining the in-line engine game this year with its new straight-six plus Jaguar set to follow, we could be on the cusp of a renaissance of the inline performance engine. Exciting times!
The straight-five engine (also referred to as an inline-five engine; abbreviated I5 or L5) is a piston engine with five cylinders mounted in a straight line along the crankshaft.
Although less common than straight-four engines and straight-six engines, straight-five engines have occasionally been used by automobile manufacturers since the late 1930s, particularly the Mercedes Benz’s diesel engines from 1974 to 2006 and Audi’s petrol engines from 1979 to the present. Straight-five engines are smoother running than straight-four engines and shorter than straight-six engines. However, achieving consistent fuelling across all cylinders was problematic prior to the adoption of fuel injection.
Characteristics [ edit ]
Animation of the 1-2-4-5-3 firing order
MAN B&W 5S50MC 1,865 litre marine diesel engine
Straight-five engines are typically shorter than straight-six engines, making them easier to fit transversely in an engine bay.  They are also smoother than straight-four engines,  and are narrower than V engines  and flat engines.
Engine balance and vibration [ edit ]
Five-cylinder engines have a crankshaft with 72 degree angles.  Amongst four-stroke engines, an advantage of engines with five or more cylinders is that the power strokes are overlapping (if the engine has an even firing order). 
On the other hand, the odd number of cylinders in a straight-five engine results in imperfect primary and secondary engine balance (unlike a straight-six engine). Counterweights on the crankshaft (also used in straight-four engines) can be used to reduce the vibrations from these imbalances.  
Firing order [ edit ]
Most four-stroke straight-five engines use a firing order of 1-2-4-5-3.  This firing order results in the minimal primary (crank speed) rocking couple, and is used by the Volvo Modular engine, VW/Audi straight-five engine, General Motors Atlas engine and Honda G engine. Straight-five engines typically have a 72 degree crankshaft design. 
All two stroke straight-five engines are limited in having a single firing order for a given crank configuration; because a complete cycle occurs every 360 degrees, there is no chance to share piston phases without having simultaneous ignitions, so the straight-five is at no disadvantage in this case. Some two-stroke outboard engines, e.g. the Mercury Marine Force 150 engine use a firing order of 1-5-2-3-4. 
Carburettors and fuel injection [ edit ]
The use of straight-five petrol engines in mass production cars only became truly viable with the advent of reliable fuel injection. This is because of the unavoidable problems of a carburettor supplying an odd number of cylinders and the length of the inlet manifold between the carburetor varying greatly between cylinders at the ends of the engine and those nearer the carburetor. Unlike other engine layouts, these problems are not easily solved by using multiple carburettors.
Diesel engines have always used fuel injection, therefore large displacement straight-five diesel engines were commonly seen decades before straight-five petrol engines.
Usage in automobiles [ edit ]
Diesel engines [ edit ]
The 1938 Lancia 3Ro trucks introduced a straight-five diesel engine to replace the previous straight-three engine. Built for the Italian and German armed forces during World War II and later for civilian usage, the truck remained in production until 1950. 
The first mass-production straight-five passenger car engine was the 1974 Mercedes-Benz OM617, a naturally-aspirated 3.0 L (183 cu in) engine introduced in the Mercedes-Benz 300D (W114/W115) models. In 1978, a turbocharged version was introduced in the Mercedes-Benz 300SD Turbo models. Mercedes-Benz continued to produce straight-five engines for the next 28 years, until the Mercedes-Benz OM647 engine ended production in 2006.
In 1978, the Audi 2.0 R5 D engine was introduced in the Audi 100 sedan. In 1983, a turbocharged version was introduced, initially for the U.S market Audi 100. Several Volvo cars were produced with Audi straight-five diesel engines, prior to the introduction of the Volvo D5 turbo-diesel engine; this engine was produced from 2001 to 2017 and was used in several diesel hybrid applications (marketed as «twin engine» models).  
Other mass-production straight-five diesel engines include the 1999-2001 VM Motori 531 turbo-diesel engine,  the 1998-2007 Land Rover Td5 turbo-diesel engine, the 2006-2019 Ford Duratorq 3.2 turbo-diesel engine and the 1998-2009 Fiat JTD 2.4 turbo-diesel engine.
Petrol engines [ edit ]
An Audi 2.3 NG engine, mounted longitudinally
A Volvo B5244S engine, mounted transversely
Henry Ford had an inline-five engine developed in the late 1930s to early 1940s for a compact economy car design, which never saw production due to lack of demand for small cars in the United States. 
The first production straight-five petrol engine was the Audi 2.1 R5 introduced in the Audi 100 in 1979. Audi has continued use of straight-five petrol engines (in both naturally aspirated and turbocharged versions) to the present day. The Audi TT RS and Audi RS3 currently use straight-five engines.  In motorsport, the first car to use a straight-five engine was the Audi Quattro rally car;  other racing cars which used straight-five engines include the 1985-1986 Audi Sport Quattro E2 and the 1989 Audi 90 Quattro IMSA GTO.     For the year 1987 factory team tested a 1000 hp version of the inline-5 powered Audi S1 Sport Quattro. 
Several Volkswagen-branded straight-five engines have been produced, beginning with the Volkswagen WH/WN 1.9 litre 10v engine used in the 1981 Volkswagen Passat. The final Volkswagen straight-five petrol engine was the Volkswagen EA855 2.5 litre 20v engine used in the North American Passat models until 2014. 
The Volvo Modular engine was introduced in the 1991 Volvo 850 sedan and was used in various Volvo models, along with the Ford Focus ST and Ford Focus RS models. All of the straight-five petrol engines used by Volvo and Ford were built at the Volvo Skövde engine plant in Skövde, Sweden, until their discontinuation in 2016.
Other straight-five petrol engines include
- 1989-1998 Honda G-series 2.0-2.5 litre 20v engines
- 1995-2006 Fiat Family C 2.0-2.4 litre 20v engine
- 2004-2012 General Motors Vortec 3500/3700 3.5-3.7 litre 20v engines
In recent years the engine has been falling out of favour, with Volvo announcing in 2012 it would discontinue building them, for example. 
Usage in motorcycles [ edit ]
See also: List of motorcycles by type of engine § Straight five
Very few motorcycles have used five-cylinder engines. However, the 1965 Honda RC148 and 1966 Honda RC149 125 cc four-stroke racing motorcycles used straight-five engines based on the 50 cc straight-twin engine from the Honda RC116 Grand Prix racing motorcycle.   These straight-five engines were an unusual design in that they were configured as a straight-six engine with one of the middle cylinders removed. 
See also [ edit ]
Wikimedia Commons has media related to Straight-5 engines .
References [ edit ]
- ^ abc«The Advantages And Disadvantages Of The Inline Five-Cylinder Engine». Car Throttle . Retrieved 20 August 2022 .
- «Inline vs V Engine — Why High End». www.whyhighend.com . Retrieved 20 August 2022 .
- «Gimme Five». www.hemmings.com . Retrieved 21 August 2022 .
- ^ Robert Bosch GmbH, Bosch Automotive Handbook, 6th edition p. 459-463, Professional Engineering Publishing 2004,
- ^ Bednar, Fundamentals of Combustion, 1989
- «Firing Order of Cylinders (Automobile)». what-when-how.com.
- ^https://www.hemmings.com/blog/article/gimme-five/ [bare URL]
- «150 H.P. (1989-1992) Force Outboard 1989-A THRU 1992-C CRANKSHAFT — PISTON Diagram and Parts». Archived from the original on 2015-12-08 . Retrieved 2015-12-02 .
- Storia Illustrata del Camion Italiano (in Italian). Edizione Neri. ISBN978-88-900 955-8-0 .
- «V60_GBen». Ipaper.ipapercms.dk . Retrieved 2018-05-17 .
- «History of the Volvo 5 Cylinder». 11 October 2017.
- «VM Motori 3.1 531 OHV engine». AutoManiac . Retrieved 24 August 2022 .
- «Henry Ford’s Weird Old Engines», Popular Science, Bonnier Corporation, p. 195, August 1960
- Sutton, Mike (2017-10-16). «400-HP 2017 Audi RS3 Tested!». Car and Driver . Retrieved 2023-01-17 .
- Graham Robson (2008-06-15). Audi Quattro. p. 12. ISBN9781845841416 .
- «Audi 90 quattro IMSA-GTO». www.classicdriver.com.
- «Detailed specs review of 1989 Audi 90 Quattro IMSA-GTO model for North America racing/rallye». www.automobile-catalog.com.
- «ableitet.no — Audi 90 IMSA GTO». www.ableitet.no.
- «Retrospective>> Quattro Firepower: The Imsa Audi 90 Gto — Speedhunters». 26 May 2009.
- «Secret Rally Car: Audi Group S Prototype». Archived from the original on 2015-01-18 . Retrieved 2015-01-16 .
- «2014 Volkswagen Passat». www.cars.com . Retrieved 24 August 2022 .
- Herriott, Richard (21 August 2014). «Theme – Engines: Throbby, Thrummy Quints». Driven To Write. Archived from the original on 2022-06-25.
- «Honda’s two-wheeled glory years». www.goodwood.com . Retrieved 23 August 2022 .
- «The 1966 Honda RC149». Cycle News . Retrieved 23 August 2022 .
- «RC 148 / RC149» (in Japanese) . Retrieved 25 October 2019 .
The Best Audi Engines Have Five Cylinders
Though Audi wasn’t the only automaker to produce a five-cylinder gasoline powertrain, they were actually the first. Throughout the ’80s and ’90s, this unconventional engine demonstrated its effectiveness many times over, in the crucible of motorsports. Among enthusiasts, the format has developed a following for its smooth yet ample power, durability, and truly unique sound.
Why did Audi make a five-cylinder engine?
In 1976, Audi introduced the world’s first gasoline five-cylinder engine in a production car. The number of pistons wasn’t an arbitrary decision, but one of necessity according to Peter Leitner, who designed the original engine at Audi. Endeavoring to make more power than its four-cylinder motors allowed, the company’s engineers ran into a problem. German laws had very specific requirements when it came to engine building.
“They had a cylinder distance – was very long-time strict law – it was 88 millimeters said Ulrich Baretzky, Audi Sport Head of Engine Development. “And 88 millimeters didn’t allow you to make a very big bore, so the only way to make a larger capacity of an engine was to add a cylinder or two.”
With the available space, adding two cylinders wasn’t optimal, so they decided to add just one to the EA827 inline-four. The result was a 2.1-liter five-cylinder with 136 hp in its original naturally-aspirated form. As time went on, the need for even more power led Audi to apply the latest 1970s fad: turbocharging.
Inline-fives and quattro AWD shake up the racing world
With forced induction, the Audi inline-five really came into its own. Power jumped to 170 hp, with 195 lb-ft of torque, in the flagship 1979 Audi 200 5T. About the same time, the company was perfecting its revolutionary quattro all-wheel drive coupe. With turbocharged and intercooled inline-fives now making over 200 hp, Audi entered the World Rally Championship in 1980.
By 1982, Audi won the manufacturer’s title and one year later Hannu Mikkola drove the quattro to a WRC driver’s championship as well. At the end of its stage rally career in 1986, the turbo inline-five was making nearly 600 hp with an improved DOHC 20v cylinder head. Audi developed the engine further in road racing, where the 200 Trans-Am and IMSA 90 GTO made as much as 720 hp. All the while, engine displacement never went above 2.2 liters.
Meanwhile, production cars like the Audi S2, S4, and S6 were also using the improved 20v turbo inline-five. It was under-stressed and hardly broke a sweat at 227 factory hp. With a performance ECU tune, exhaust, and intake 300 hp was easily attainable on the stock K24 turbo. The ultimate version came in collaboration with Porsche, on 1995’s RS2 Avant. Sporting a larger turbo, injectors, and upgraded cams, the RS2 wagon made 315 hp and did 0-60 in 4.8 seconds. After ending production of the 20v AAN motor with the S6 in 1997, Audi took a break from inline-fives.
Does Audi still make a five-cylinder?
Thankfully, the company revived the format in 2009 with the TT RS, which received a new 2.5-liter variant with 340 hp. Since then, Ingolstadt has continued to produce the five-cylinder and the latest version in the 2022 RS 3 is making over 400 hp. Because engineers kept the original 1-2-4-5-3 firing order, the new ones have even retained the signature engine note so beloved by Audi fans.