WHY V-SHAPED ENGINES ARE USED ?

A V engine, or Vee engine is a common configuration for an internal combustion engine. The cylinders and pistons are aligned, in two separate planes or 'banks', so that they appear to be in a "V" when viewed along the axis of the crankshaft.The primary reason to use a V-engine is largely packaging. They're shorter and more compact than an inline engine.

The first thing to consider is an engine as a purely rotational system. Imagine a one cylinder engine; the rotating crankshaft is massively out of balance. Even if the actual crankshaft was perfectly balanced, the motion of the piston and the forces it applies will never cancel out. This is why most one cylinder engines run a balance shaft; a weighted shaft geared into the crankshaft to mitigate the out-of-balance effects. A balance shaft can be run on other out of balance engines as well.

A V-engine, on the other hand, can be made to be inherently balanced. This means that no matter what speed the engine's running at, the forces from the rotating assembly will always cancel out. Most notably, a 90 degree V4 or V8 engine can be easily balanced and many race motorcycle engines use this configuration (Honda and Ducati in MotoGP). V6s and V12s run balanced at 60 degree bank angle.

Apart from this other advantages of V configuration are as follows:

1. Dimensions are compact - which are appreciated either in construction of road cars or race cars
2. The compact dimensions mean that more cylinders can be packed in, as comparable to an inline/straight engine of similar dimensions.
3. Can accommodate higher displacement cylinders, and therefore that extra power
4. Its a strong engine - which makes it ideal for racing applications
5. Can accommodate higher compression
6. High levels of refinement.

An interesting note: because a V12 is essentially two inline 6 engines stuck together they're naturally balanced regardless of bank angle. This is why V12 Jaguars have a reputation for smoothness. V6s, being two 3 cylinders stuck together, are inherently out of balance.

Talking about the limitations of V configuration engines,there are few yet they play and important role.These are mentioned below:

1. Contains more moving parts, resulting in higher cost/complexity
2. Weight. The same technicality above makes a V-engine heavy.