Most car engines are up to 6 cylinder in length – most larger engines are in a V formation – V8 and V12, which are 4 and 6 in length. These big Vs are sadly being phased out due to stricter emissions controls and at the other end of the scale, there have been two and three cylinder engines in smaller post war cars however in the last 40 years, most engines have been 4, 6 or 8 cylinder motors with straight, flat and V formations. I’ll do articles on W and H formations in the future.
5 cylinder engines aren’t new – like many technologies or concepts in motoring, the 5 cylinder engine was first seen in aircraft engines before migrating to cars. Engineers like Henry Ford developed motors in the 1930s, but in those days small engines and US consumers didn’t mix, so they were never built! Lancia built 5 cylinder truck engines during the Second World War, however it was the German manufacturers in the 1970s that really brought them into mainstream cars.
The 5 cylinder motor provides a nice mix of the benefits of the 4 and 6 motors – the fuel efficiency of the 4 and the power advantage of a 6. However, having an odd number means that the motor is unbalanced so needs to be designed to give a smoother delivery.
An interesting thing about engines is when the power stroke happens. In a 4 cylinder engine the crank receives a power stroke every 180 degrees, so two power strokes a revolution in a four stroke motor. When one cylinder finishes a power stroke, another one is starting. In a 5 cylinder engine, there is a slight overlap – the power stroke is every 144 degrees rotation of the crankshaft and so the power of the stroke causes low and high speed vibrations – the unbalancing I spoke of earlier. So like large capacity 4 pots, the engine needs a balancing shaft.
Balancing shafts were invented in 1904 by Frederick Lanchester of the Lanchester Car Company, and on large 4 cylinder motors the engine needs 2 balancing shafts however on a 5 cylinder engine only one is needed to counter the fact that the engine vibrates due to the firing order and where the pistons are at any time. However, the balancing shaft cannot be fitted in the same place as the 4 cylinder motor and it is slightly off-centre which reduces the efficiency of the counter weights.
5 cylinder engines have been built by General Motors, VW/Audi, Honda, Volvo, FIAT and Mercedes. Volvo and VW/Audi are the current users of this formation. The engines have been designed as a modular design, which means that they can be built on the same production lines as their related 4 or 6 cylinder motors.
For example, the VW/Audi V5 is essentially their V6 with one cylinder missing and it isn’t a true V formation, being at an angle of just 15˚ instead of the normal 60˚ and because of this the cylinders share the cylinder head rather than having two.
However, saying that only a handful of manufacturers build 5 cylinder motors doesn’t mean that only a few cars have them. VW shares its motors with Audi, Seat and others, Volvo being owned for a while by Ford, shared the motor between their S40 and some Ford Focus models and General Motors used theirs in the Hummer and several Chevrolet models. Many of the current motors are now being supplied with turbochargers to increase the power and efficiencies.
And to finish off, the V5 really made it’s mark in MotoGP racing with the Honda RC211V that won many World Championships. This engine had three forward facing cylinders and two rearward at 75.5˚ and produced 220hp from 990cc.