There’s as much drama as there is romance when it comes to twelve cylinders firing in a V formation. Whether that comes down to the sheer grunt of the thing, or the fact that modern-day V12s tend to show up only in supercars like the Ferrari LaFerrari or Pagani Huayra, were not quite sure, but we know nothing gets hot and hungry like a V12 in anger.
Which made it all the more painful when we were recently reminded that GMC, yes GMC, produced a V12 at one point in time. And yes, it came from the factory.
It’s true, though it’s been more than five decades since one last rolled off any assembly line.
Back in 1960, GMC Trucks designed its own unique V12 engine, comprised of two 351 ci V6 GMC engines united by a single block and crankshaft. Aside from that, most of the innards were comprised of the main parts from the V6 engines, which also appeared that year in light-duty and heavy-duty trucks. GMC even used the 351 ci V6 to help design the V12.
Marketed as the “Twin Six” V12, the mighty V12 was produced through to 1965 in the heavy-duty truck line, with a 702 ci (two 351s) capacity that produced 275 hp and a mighty 630 lb-ft of torque from 1,600 rpm to 1,900 rpm. A narrow power band, sure. But it acted more like a rumbling diesel engine than a screaming engine from Italy.
Today, you’d have a better chance at catching SARS than finding one these precious V12 engines. Enthusiasts quickly realized its potential and soon all the best examples were snatched up, refinished and rebuilt.
However, if you’re really set on shoving on of these ultra rare V12s into your donor car, we’d be remiss if we didn’t direct you over to thunderv12.com, which stocks GMC V12 1960-1965 engine cores that have been have disassembled and graded. The company then uses them to create the “ThunderV12” engine. Though, to be clear, they say the “goal is not to rebuild GMC V12 engines, but to create ThunderV12 engines.”
Oh, and if you decide to play doctor Frankenstein and shove one of those V12s in a GMC Sierra, please let us know. ‘Cuz that’s something we need to see… and hear… and drive.