But the engine is real, built by a guy named Ray and his partners in a shop in Seattle, WA. Ray said they wanted to make a V12 engine for a plane, and after experimenting with Buick 215 engine blocks they got around to the LS. With a stock stroke and a 4.4-inch sleeve, the result is a 545 cubic inch motor (8.9 liters) that fires like a V16 short of four cylinders. Their first two LS12 builds went into a 3/4-scale P51 Mustang, and a Chevrolet Tahoe two years ago. The Tahoe engine, only the second build, was said to get around 525 horsepower.
They now have the parts to make five more LS12s and are refining their technique, working on simpler solutions for the crankshafts - they machined the first crankshafts from a solid piece of steel, but that's crazy expensive. One of the engines is already slated to receive a massive Littlefield supercharger and "might find its way into a long-nosed 240Z." That Z, mind you, will also be getting its own chassis since the decades-old original item couldn't begin to handle the power.
Check out EngineLabs.com for more on the build, and a brief walkaround of the engine in the video below. For the long story, the link to LS1 forums is where the story begins - and where you'll discover that the V4 is apparently the perfect size for a Harley-Davidson.