Yes, you read that right. As far back as 1994 GM was toying with the idea of building a V-10. Mopar and Ford had one, so it should come as no surprise that GM would be interested in doing an engineering study on it. Instead of spending money to continually upgrade the big-block V-8 and make it comply with emissions, a V-10 based on the same platform had many advantages.
From a performance perspective, a 10-cylinder also has advantages, thanks to an increase in piston area (at the same displacement), that could help push the platform to new heights. Had it come to fruition, there would have been an iron truck block and an aluminum Corvette version. The proposed GM V-10 was essentially a Generation III LS engine with two extra cylinders, a 90-degree block with uneven firing cylinders like the Mopar V-10.
According to a GM HighTech Performance story by David Vizard, GM spent $310,000 on prototype tooling for two iron blocks that were ordered
and “still floating around the bowels of Powertrain Advanced Engineering in Pontiac, MI.” With so many changes over the years, including the newly opened Global Powertrain Engineering Center built at the same location, some of these old relics have a tendency to walk out the door. This brings us to today. The folks at VC Fabrication in Kansas City, Kansas, have one of these engines in their possession, and it was recently rebuilt with new pistons. Check out this video of the crank being balanced.
Lee Masters at VC Fabrication says this engine was in an Escalade before it was tossed in the trash. We can probably assume this powerplant was not one of the original Gen III V-10s, though, because it has DOD — Displacement on Demand, with cylinder deactivation that turns the V-10 into a five-cylinder for better fuel mileage — and variable valve timing like the Gen IV engines, as well as an LS3/L92style rectangular port head. Those advancements did not exist until much later than 1994. The Gen III V-10 supposedly used an LS6 style, cathedral port head.
According to Lee’s research on the date codes, the engine dates to 2004. A 4-inch bore and stroke puts displacement around 502 cu-in, quite a bit larger than the original 455 that was proposed. The crankshaft uses an eight-bolt flange like the LSA to handle the extra torque going to the flexplate. Lee says the camshaft measures 24.88 inches in length, rides on six journal bearings, and has .48-inch lift. The intake manifold and valley cover are also unique to the V-10.
The intake manifold uses twin throttle bodies with no crossover between banks. The oil pan resembles the all-wheel-drive GM truck’s V-8, as does the front accessory drive, which supports the theory that it was previously used in an Escalade to explore its use in the truck market.
VC Fabrication will be dropping this engine in a 1964 Impala two-door hardtop with fabricated valve covers, intake manifold, and headers. The headers may be used to feed a custom twin-turbo system in the future, built in house.
A custom wiring harness and aftermarket EFI will be the final touches to get this beast running with a 4L80E four-speed to handle the power. More updates to come, so stand by.
This story originally appeared in Hot Rod.