Honey, Ferrari Shrunk the V-12

Ferrari is not the first to dream up an oval-piston engine. Honda actually raced and later sold an oval-piston V-4, with each piston having two connecting rods and eight-valve heads. Essentially, it was a kind of V-8 with two pairs of conjoined combustion chambers on either cylinder bank. AutoGuide uncovered a new Ferrari patent for a very different type of oval-piston engine, a V-12 with pistons rotated 90 degrees from their orientation in the Honda image.

A V-12 might be the king of automotive engines, but with six cylinders on either side, they’re long. Ferrari has proposed a design that shortens the V-12, with oval pistons packed closer together than they would be in a circular-piston engine of equivalent displacement. In other words, you could have the same displacement as a traditional engine but shorter bore spacing. 

The pistons themselves are pill-shaped, flat at the longer sides, and circular on the shorter sides rather than being totally round. 

Ferrari also designed a novel rotating assembly that helps shorten engine length. In a traditional V-12, pistons on opposite banks share a crankshaft journal, but their connecting rods are offset slightly, increasing overall engine length. Here, the pistons on the left-hand bank attach to the cap that bolts to the right-side connecting rod. Those left-hand pistons have shorter connecting rods attached to the cap via a separate pin. 

Photo by: European Patent Office

Photo by: European Patent Office

Essentially, the cylinders opposite one another are parallel rather than offset by a couple ofmillimeters, when looking top-down.

This neat arrangement helps further reduce length a bit, and I suspect the rotating assembly—basically, all the stuff that spins in an engine—may be lighter than a traditional V-12’s, having fewer and smaller components. This could lead to more high-rpm performance. Ferrari also says in the patent filing that the pistons, which have shaved-down “cavities” on the skirt, help reduce friction between the piston and the cylinder wall. Cutting friction also helps performance, especially at higher engine speeds.

By having a shorter V-12, Ferrari can cut vehicle size overall, or make more room for hybrid components, like an electric motor between the engine and transmission. Returning to first principles for a second, an engine is effectively an air pump. The more air you get in and out, the more power you can make. Using oval pistons, Ferrari could theoretically use larger or more intake and exhaust valves, either way increasing total valve area. There are no references to the top end of the engine in this patent, so we don’t know what, or if, Ferrari has anything happening there.

Frankly, we don’t know if Ferrari even plans to build an engine of this design. It might just want to protect its design so others don’t copy, at least without paying a licensing fee. 

If it did build this engine, it would represent a huge departure from traditional V-12 design, and there is something to be said for evolving existing designs instead of going for a revolution. But Ferrari also has to meet increasingly strict emissions regulations, and if it wants to keep selling the V-12—its signature engine,—it might need to take a radical approach.