How Cosworth Develops V-12s From Tiny Three-Cylinder Engines

Cosworth is engineering two naturally aspirated V-12s currently—a 6.5-liter for the Aston Martin Valkyrie, and a 3.9-liter for Gordon Murray’s new T.50. For both, the legendary British engineering firm started with three-cylinder mules to test combustion characteristics on a smaller scale before going through the trouble of making a V-12. These mighty triples are a great way to speed up development work, and ensure that the big V-12s can meet modern emissions regulations.

As Drivetribe’s Mike Fernie explains in this video, Cosworth originally came up with the three-cylinder mule idea when working for Nissan. The Japanese company wanted a V-6 for its GT-R LM Nismo race car and gave Cosworth very little time to do it. Rather than start completely from scratch, Cosworth took a four-cylinder it designed for the Jaguar C-X75 concept car and cut off a cylinder. This three cylinder took just five months to go from idea, to test mule on the dyno, and soon after, its design was adapted into a powerful V-6.

Developing a V-12 from a three-cylinder makes a lot of sense. A V-12 is essentially two inline-sixes with a common crankshaft, and an inline-six is basically two conjoined triples. So, a three cylinder gives you a pretty good idea of what to expect from a straight-six, and by extension, a V-12.

It’s especially important to do this sort of development work for road cars. To meet emissions regulations, you have to be exacting when creating a combustion system. With a three-cylinder, Cosworth can ensure that fuel and air is combusting exactly as it should, tweaking various parameters until emissions and performance targets are hit without going to the trouble of putting together a V-12. Once the three-cylinder achieves the desired numbers, you can make a V-12 and have a very good idea of how it’ll perform.

Fernie says that Cosworth based the Valkyrie V-12 on an older engine, but couldn’t disclose which engine. A while back, Top Gear reported that the V-12 is based on a V-8 Cosworth made for the Williams F1 team in 2010.

The funny thing is that you can’t simply double or quadruple the power figure of these three-cylinder mules to figure out how much horsepower your V-6 or V-12 will make. You actually get a bit more horsepower because there’s less parasitic loses from pumping and and cam gear. So that’s how a 240-horsepower three-cylinder becomes a 1000-hp V-12.

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