The OHC V12 That Cadillac Almost Built
In the mid sixties, Cadillac gave very serious thought to replacing its aging V8 engine with an OHC V12. And blog.hemmings finally convinced Cadillac to send them some detailed pictures and more information. Looks mighty production ready, but that air cleaner sure makes it looks a lot less sexy than a Ferrari with a bank of Webers.
Six prototypes were built in 1963 and 1964, all with a 60-degree bank, chain driven camshafts and hydraulic finger followers. The initial displacement was 7.4 liters, but an 8.2 was also built, which corresponds exactly to the size of the new V8 engine that eventually was built instead of the V12. Various induction systems were tried, including single four-barrel, dual two-barrel, and triple two-barrel carburetors, as well as fuel injection. Output was between 295 to 394 horsepower, and from 418 to 506 lb.ft. of torque.
The engines were planned to make their appearance in the new FWD Eldorado in 1967. Ironically, one of the main reasons they were canceled is because GM drivetrain engineers were still considering a transverse orientation for the FWD system. That would have made the V12 too long. In the end, a longitudinal FWD system was used, which would have accommodated the V12. So the V12 appears to be a victim of poor GM planning.
One of the prototype engines is now available for your viewing pleasure at the GM Heritage Center.
More by Paul Niedermeyer
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GM is like Budweiser. They *can* make anything. I've tasted some AB experimental brews that stand up to anything in the world. The reason they (and GM) sell low quality to the masses is simple. They can make it cheap and market it to death. GM is famous for shorting the Fiero, fixing it and killing it. There are far too many examples of good ideas from engineering getting squashed in the accounting department. Save the 'Vette (still with crappy interior) and a few Caddys, they still sell lowest common denominator cars. GM CAN make just about anything....they choose not to.
GM did an aweful lot of experimenting with new ideas up until the late 60's. Even still there was still quite a bit of powertrain experimentation that took place. A lot of the reason why GM, and many other companies stopped was the onslaught of emissions and safety regulations that tied up so many of their resources. However they worked with and developed systems that allowed them to not only work with the regulations, but have engines that produced more power, met CAFE standards and met emissions standards. Cadillac introduced digital electronic self diagnostic engine controls in it's 1980 models. It's a system that every powertrain management system built since is pattered after. This engine is an interesting study, and one that maybe should have seen production. It looks to be made of mostly aluminum, which would make it light. A 60 degree V-12 is incredibly smooth, which would have added to Cadillac's reputation of building powerful, smooth and silent engines. And I think some of this technology was used with the much later HT4100. Note the long head bolts. But there is the question of the cylinder construction. Were they wet liners like the HT4100 used, or were they to use the Reynolds 390 process that used electrically charged silicon particles in the casting process to create very hard cylinder surfaces? that was under development in the big Chevrolet Can Am engines in the mid to late 60's. It also appears to be die cast. That technique was used with the Vega engine, and later the HT4100. The '67 Eldorado was designed to carry a long engine. Cadillac even experimented with a V-16. The hood was very long to showcase such an engine. However the 472 that was being developed concurrently with the V-12 eventually won out. And it was a very good engine. It was light (63 pounds heavier than a small block Chevrolet), even though it was all cast iron, remarkably efficient (if tuned properly) very powerful and bullet proof durable. That basic engine lasted through the early 80's in 368 cid guise.