Chevrolet LT6

General Motors' 5.5 flat-plane-crank V8 — the LT6 — in the C8 Corvette Z06.

⚑ It is unlike every other GM V8 in this catalogue. The others are pushrod cross-plane engines with two valves per cylinder; this is dual overhead camshafts, thirty-two valves, a flat-plane crankshaft and 8,600 rpm. Nothing about the LS or LT small-block families transfers to it — not the parts, not the service intervals, and not the diagnostic habits.

A flat-plane crank is inherently unbalanced in a V8, which is where its sound comes from and why it vibrates more than an owner stepping out of a LT2 expects. That is design, not fault.

It is dry-sumped and it is very new, so there is no settled long-term record and saying so is more useful than repeating early reports. What can be said is that oil grade, level and interval on an engine making this much power per litre are not routine advice.

The LT7 is its turbocharged relative and is refused as a designation in this catalogue's own tooling — GM used those three characters for a 1980s Buick diesel V6 as well.