Early C8 Z06 LT6 Engines ‘Shook Like Paint Shakers,’ Says Engineer

When developing the C8 Z06 LT6, GM quickly discovered that flat-plane crank engines present one major engineering obstacle.

As most are well aware by now, the C8 Z06 LT6 engine is a true technical marvel, as well as the most powerful production naturally-aspirated V8 in automotive history. The brand new, clean-sheet design shares noting in common with small blocks of the past, which is always a bit of a risk for automakers. After all, making something unlike anything you’ve ever made before means that there are inevitably going to be problems that pop up, oftentimes complex ones. And that’s precisely the fate that befell the C8 Z06 LT6, as Small Block Chief Engineer Jordan Lee explained at the recent NCM Bash in this video from Corvette Blogger.

As Lee explains, GM wanted to achieve a few goals when creating the LT6, aside from making it the most powerful N/A V8 ever. The biggest target was using a flat-plane crankshaft, of course, to give it “a different sound with its own character,” as well as maximize volumetric efficiency. Lee also notes that GM wanted to return the Z06 to natural aspiration following its years with a supercharger during the last generation.

However, there is an engineering problem that is common with flat-plane crank engines, and that’s the extreme vibrations they cause. Most are aware of this fact because of the issues Ford faced with the 5.2-liter Voodoo V8 present in the last-gen Mustang Shelby GT350. GM quickly discovered that it must also find a way to overcome this problem when its discovered that its early LT6 development engine “shakes like a paint shaker,” according to Lee.

“Horizontal shaking forces are horrendous and so difficult to deal with,” he said. “As an example, Ford did a flat-plane 5.2-liter V8 for a number of years, and they had a story on the web where the oil filter was actually spun off the engine from the shaking forces. And we thought, wow, that’s pretty hilarious, we would never make that mistake…until we made that mistake.”

Sure enough, the second LT6 development engine GM created did the same thing on the dyno, a problem engineers didn’t discover until the powerplant lost oil pressure and failed. After adding safety wire to the oil filter on another engine and setting up a camera to watch, the automaker confirmed that vibrations were indeed the culprit here.

“It was then we realized it wasn’t going to be easy,” Lee added. “And so for five years of working on all the vibrations and all the different issues. It was a bear dealing with vibrations. The good news for you that buy a Z06 is that you do not know it when driving your car. The attenuation of the vibrations at the engine mounts is stellar.”

It’s interesting that GM is so candid about this big problem, but at the same time, it makes sense to reassure anyone who’s worried the LT6 will face some of the same issues that GT350 customers have in recent years.

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