2023 Chevrolet Corvette Z06 engine detail

It’s surprising how aggressively Chevrolet has approached the latest Z06’s all-new engine design. Excitement over the eighth-generation Corvette’s move to a mid-engine configuration has been bubbling for the past few years. And while this fundamental shift in platform design is cause for excitement, the standard C8 continues to use a V8 engine with a traditional cross-plane crankshaft.

The 2023 Corvette Z06 comes with a 5.5-liter V8 engine that uses a flat crank; it shares nothing with the standard Corvette eight-cylinder. It was developed alongside the racing engine of the Corvette C8.R, a car that has already won multiple championships while fully validating engine performance and durability in extreme conditions over the past three years. We’ve driven the new Corvette Z06 and can confirm the engine’s immediate throttle response, wide torque band, stratospheric redline and gleaming exhaust note.

With 670 horsepower and a claimed zero-to-60 time of 2.6 seconds, the Z06 delivers everything an exotic car promises, at least on paper. And with a starting MSRP of $106,995, it does so at a fraction of the competitive exotic car price. But why does the flat-plane crank design deliver these features for both the C8.R race car and the new Z06? How does this design give the Z06 bragging rights to have the most powerful naturally aspirated production V8 engine ever? And does it all work as well in real-world conditions as the engine specs suggest?

Let’s start with the inherent advantages offered by a flat-plane crank motor design. There’s a physical rabbit hole related to things like primary and secondary vibrations that we could crawl through and probably never get out of, but we’ll keep things light and just state that a flat plane crank has crankpins arranged 180 degrees (or opposite) from each other. This means that all of the joints where the connecting rods attach to the crank are aligned in a single plane – or “flat” – to the 90-degree cross-plane design of a typical V8 engine.

The flat-plane crank layout is usually reserved for racing cars or exotic cars because it is a more sophisticated (read: expensive) design, with cost/benefit trade-offs that are not justifiable in cars. of mainstream performance. However, advances in modern engineering are making this design more cost-effective (Ford used it for its last Shelby Mustang GT350), and Chevrolet felt this generation of Corvette Z06 deserved a no-compromise approach to engine performance.

And what are the specific advantages of a flat-plane crank over the more traditional cross-plane crank used in the majority of V8s? The main benefits are lighter rotating parts and more efficient intake and exhaust loadings, both of which allow the Z06 engine to rev up (rev) faster and rev to a higher top speed (red line ). In the case of the Corvette Z06, the maximum engine speed is 8,600 rpm (revolutions per minute), which is 2,100 rpm more than the 6,500 rpm redline of the standard C8 Corvette.

After driving the new Z06, we spent some quality time with Dustin Gardner, the LT6 V8 assistant chief engine engineer, and he explained some of the key elements that contribute to the engine’s performance characteristics.

“A lot of people think that the flat-plane crank design allows an engine to run at higher speeds. But you can also run a cross-plane engine at high engine speeds; it’s just that double Firing the pistons from each cylinder bank clutters the intake and exhaust charge, so there’s no benefit to spinning it up there – and it’s harder to tune. On a flat-plane crank , when your firing order is equal to each bank of cylinders, it balances vibrational forces while making intake and exhaust gas breathing much more efficient at high rpm,” Gardner said.

These two elements, the self-balancing forces on the crank and the naturally synchronized air flowing in and out of the combustion chamber, allowed the engine team to use lighter materials and air management tools. air for maximum performance.

When it comes to lightweight materials, the Z06 engine crank weighs 33 percent less than the standard C8 Corvette crank. This combines with titanium connecting rods, low-profile forged pistons and a lightweight aluminum viscous damper to make everything running in the LT6 as light as possible. The result is reduced engine vibration and rapid changes in engine speed, whether pressing the accelerator to accelerate or downshifting when slowing down a corner.

On the air management front, the GM team has enhanced the natural breathing advantage of the LT6’s flat-plane crank through an advanced intake manifold design. The manifold uses internal valves to change its volume with engine speed, greatly increasing volumetric efficiency. Gardner told us that above 3,500 rpm the intake manifold has over 100% volumetric efficiency and, combined with the LT6 specific header design and exhaust tuning, the volumetric efficiency engine overall is around 110%.

Normally you can’t get more than 100% volumetric efficiency without forced induction (i.e. a turbo or supercharger), but that’s what the LT6 achieves – a forced induction type boost without use forced induction. That’s why it’s the most powerful naturally aspirated V8 as standard. It’s also why the engine’s throttle response is so immediate and its torque range so wide and flat, pulling hard all the way to the 8,600 rpm redline. And yes, that also helps create the Z06’s exhaust note.

In a track environment, these characteristics manifest themselves in a relentless forward thrust when the Z06 exits a corner. Quick shifts, initiated by the Z06’s steering wheel-mounted paddles, allow the engine to pull seamlessly when accelerating, while lightweight internals allow it to up and then down quickly when braking. and downshift before entering a bend. The accompanying exhaust note gives the new Z06 a Ferrari-like demeanor, helping it achieve the exotic car experience the Corvette has long sought and which, after 70 years, feels fully delivered by this new V8 LT6.

Edmunds says

The flat crank design of the LT6 has given the new Z06 a heart and soul comparable to Europe’s most exotic supercars.

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