When designing an internal combustion engine there are three different designs to choose from. Each and every one of them has its own pros and cons.
Inline Engines where all cylinders are being placed next to eachother. This design is not used in F1 since the 60s, as the engines tend to be long thus needing up the need for a heavy cranckshaft.
Boxer engines where there are two cylinder rows opposing eachother. It is like having a V Engine with a 180° angle. This engine has been very popular during the 70s, as it helps a lot in lowering the center of gravity, before they would be replaced by V-angle engines as they where having trouble whitstanding the car's G-forces during cornering.
V-Angle Engines where the two cylinder banks are being separated by a geometrical V angle. This is the type of engines used to all modern F1 racing cars. Determining the optimum angle for every engine has been subject to extreme testing and research, before the FIA determined that all cars will be using 90° V8 engines. In the past there had been used V8, V10, and V12 engines with the V angle at 60°, 72°, 90°, 112°, and 120°.
Today the engine of an F1 racing car is a stressed member of the chassis. This was first introduced by Ford Cosworth DFV. It means that nowadays the engine is an integral part of the F1 racing car. In older times the mechanics used to built the chassis as a cube frame where the engine were put. Today the engine is bolted in between the monocoque at the front and the gearbox in the back. All other engine types would compromise the weight of the chassis and limit the options the aerodynamisists have when designing the car.
So how is the V-angle determined? Choosing the right angle is essential to the performance of any given engine. It has to do with the firing sequence and primary balance. A circle has 360° and the included angle*number of cylinders must be a function of 720° as one rotation of the crankshaft is 360° and every complete combustion cycle takes two turns. So the optimum included angle has to do with the number of cylinders, in order to achieve evenly spaced cylinder firing and primary balance.
Ferrari have been using 60° and 120° V12 engines in the past. If you divide 720 with 12 you will see that 60° is the optimum angle. The same comes if you think of a V12 engine as two aligned V6 engines.
Renault used the same equilibrium when designed its highly successful V10 engine with a 72° included angle.
Today FIA regulations have the included angle fixed at 90°. All teams are using this angle not only because FIA regulations say so but also because it is the optimum one for a V8 engine.
Few years ago Renault had constructed a V8 engine with a 112° angle, in an effort to be revolutionary. This design was abandoned soon after, despite the gains in terms of low center of gravity, as the performance was low and the engine could not reach high rpms due to uneven firing order introducing unwanted vibrations which in turn had their part on the life span of the engine.
