What is the difference between V12 and W12 engines?
4 Answers
Difference between V12 and W12 engines: 1. Different structures: The V12 engine has a simple structure, good operational balance, and compact size; the W12 engine has a more compact structure, can accommodate more cylinders, and has a larger displacement. 2. Different arrangement methods: The V12 engine is arranged in a V shape; the W12 engine is arranged in a W shape. An engine is a machine that can convert other forms of energy into mechanical energy, including internal combustion engines (reciprocating piston engines), external combustion engines (Stirling engines, steam engines, etc.), jet engines, electric motors, etc.
Having driven my friend's Bentley and S-Class, the difference between the V12 and W12 is quite noticeable. The V12 is like two teams of soldiers arranged in a V-shape, with 6 cylinders symmetrically distributed on each side, making the engine bay look very neat but taking up more longitudinal space. The W12 is more like combining two rows of V6 engines, with the 12 cylinders arranged in four staggered rows, making the entire engine more compact and flat. When I drove the W12-powered Audi A8, I clearly felt that the front end could be designed more aerodynamically, with a significantly lower drag coefficient. However, the W12's structure is more complex, and the mechanics were sweating profusely during repairs. For ultimate smoothness, the V12 still has a slight edge, especially at high RPMs with that silky sensation, but the W12 has already reached a level where ordinary drivers can hardly tell the difference. Both engines are costly, and they've become even rarer with the rise of electric vehicles.
As a mechanical engineer, the structural design is quite fascinating. A traditional V12 engine features two banks of cylinders at a 60-degree angle, with each connecting rod operating independently. In contrast, the Volkswagen Group's W12 engine is essentially a combination of two VR6 engines with a 72-degree angle, utilizing a three-layer chain drive. This design shortens the engine length by approximately 30%. For instance, when a W12 is fitted into an Audi A8L, the front overhang can be made exceptionally short, allowing for a more spacious cabin. However, there are drawbacks: the W12's intake and exhaust manifolds are labyrinthine, offering less modification potential compared to a V12. During one disassembly, I noticed the W12's spark plugs are buried deep within the cylinder block, making them three times harder to replace than those in a V12. In terms of fuel consumption, both are gas guzzlers, but the W12 excels in lightweight construction, with its all-aluminum block weighing around 150 kg less than a V12 of equivalent horsepower.
Having worked on cars for over a decade, the W12's biggest headache is its compact structure. The cylinders are nested in a W configuration, with camshafts needing to pass through four rows of cylinders—timing alignment is an absolute nightmare. Last time I dealt with an ignition issue on an Audi W12, just removing the intake manifold required dismantling the entire wiper assembly and front bulkhead. In contrast, while the V12 is larger, its layout is far more orderly; at least you can actually work in the engine bay of a Mercedes S600. The W12's advantage lies in vibration control—the four rows of cylinders cancel each other's vibrations, making its engine mounts simpler than a V12's. But when it comes to reliability, many older V12 models undergo major overhauls after 500,000 km, whereas W12s typically start leaking from the valve cover gaskets by 300,000 km. Nowadays, car enthusiasts would rather choose a supercharged V8 than touch these engines.
