Secrets of the C8 Corvette Z06’s Outrageous 5.5-Liter V-8 Engine

Overview

The LT6 is an all-new engine and doesn’t share anything with the small-block V-8 that we’re familiar with. It has its origins in the Corvette C8.R race engine. However, while the race engine has to contend with things like homologation and restrictor plates, the engine used on the streetcar doesn’t, to the extent that this new V-8 outperforms the engine in the race car.

The Spec

• An all-new aluminum cylinder block with a new dual-overhead-camshaft cylinder head design
• Dual-coil valve springs, and CNC-machined combustion chambers
• Forged aluminum pistons
• Forged titanium connecting rods
• Aluminum harmonic balancer that helps minimize rotational inertia
• Active split intake manifold with twin 87mm throttle bodies
• New six-stage dry-sump oiling
• Stainless steel exhaust headers
• Edge Red camshaft covers.

The result? The new Z06 produces 670 horsepower and 460 pound-feet of torque, which according to General Motors makes it the most powerful naturally aspirated V-8 engine to ever be fitted to a production car.

Why a Flat Plane Crank?

Typically, crankshafts have to deal with the angle throws, commonly known as journals. In a Cross plane crankshaft, this is typically 90 degrees, whereas, on a flat plane crankshaft that the new Z06 uses, it is 180 degrees.

One of the primary drawbacks of a Crossplane crankshaft is that it requires heavy counterweights to help it stay in balance, barring which, you’d have excessive engine vibrations. As a result, engines with this type of crankshaft can’t rev as high. But the benefit here is torque. Muscle cars generally use this type of crankshaft, which is why you hear that deep rumble.

The new 5.5 liter LT6 V-8 engine meanwhile, revs to a phenomenal 8600 rpm, and this is because it uses a flat-plane crankshaft instead, which don’t use counterweights. This type of engine tech is typically used on European exotics, which is why they make their power so high up in the rev band.

A Soundtrack like no Other Vette

This is also why the new C8 Z06 has a truly distinctive engine note and doesn’t sound like any other Corvette to hit the road, before it. The flat-plane crank also posed another challenge. The Engineers had to relocate the mufflers to the corners of the car with pipes exiting the car in the center. Developing the centrally mounted reverse megaphone exhaust cost GM, millions, but I’m sure everyone will agree that it was money well spent, given how good it sounds.

GMs Take on the Flat Plane Crankshaft

In the end, between the two types of crankshafts out there, it’s the flat plane that tends to vibrate more. So how exactly did Chevy manage to curtail the issue on the new LT6? Well, the engineers accomplished this by specifying a big 104.3 mm Bore and a short 80.0 mm Stroke for the cylinders. This helps in reducing the piston speed, which in turn reduces the secondary vibrations.

A new sophisticated oiling system, also borrowed from racing ensures that the engine performs well under load. It uses a six-bay oil pump that runs the length of the engine and by itself, requires 14 horsepower to operate.

To Sum it Up

With the new C8 Corvette Z06, it looks like GM finally has an answer to the old saying ‘There is no replacement for displacement. Chevy really has tinkered with where they want to take the Corvette name. This began first with the introduction of the mid-engined C8 and now, a new flat-plane crank, on the Z06.

The new engine does sound nothing short of evocative and will definitely put a smile on your face. In fact, this one factor alone might be enough to compel you to get one. But this powertrain is so much more than just the sound, what Chevy has achieved here with the new LT6 is truly staggering, because extracting 670 horsepower from a naturally aspirated V-8 engine is no joke.