Corvette Engineer Reveals More About C8 Z06 LT6 Engine, One Takes 3.5 Hours To Build


Many prospective customers and Corvette diehards were afraid it won't be as powerful as the LT4 in the previous-generation Z06. But as opposed to the 6.2-liter supercharged small block of yesteryear, the 5.5-liter engineering marvel is 20 hp more powerful and 14 kilograms (31 pounds) lighter.

A free-breathing affair that features center-mounted exhaust outlets in the United States and corner-mounted exhaust outlets for export models, the LT6 is the most powerful naturally-aspirated engine ever fitted to a series-production car. Equipped with hollow camshafts to keep the weight low, this lump fires evenly in the following order: 1-4-3-8-7-6-5-2. The Ferrari 458 Italia that Chevrolet benchmarked against the new Z06 is listed with 1-5-3-7-4-8-2-6 while the Mustang Shelby GT350 fires 1-5-4-8-3-7-2-6.

The LT6 makes over 150 horsepower more than the LT6.R in the C8.R endurance racer, which is hindered by a 44.3-millimeter inlet restrictor. “Through the course of development of the Z06, we literally borrowed parts from each other. From the production team and race team, to help develop the engine simultaneously,” highlighted Josh Holder at the NCM Bash.

Nora Roper is much obliged to explain that the LT6 is solely built in the Performance Build Center in Kentucky, hand-assembled by a single builder from beginning to end, every 3.5 hours. Each cylinder head is made up of 140 pieces, and the first measurement gauges the gap for the correct shim to be selected. Each head receives a unique set of shims that are picked, measured, and installed by a robot. The increment between the 33 shim sizes is 0.025 millimeters, which converts to 2.5 microns or 0.00098 inches.

Another unique feature of the LT6 compared to dime-a-dozen engines from GM comes in the guise of select fit main bearings and connecting rod bearings. In other words, every LT6 is unique. The block assembly, crank, and rods are measured at the supplier, then this information is laser etched for the smart bench workstation to calculate which bearing to select.

A clever robot applies room-temperature-vulcanizing adhesive to the lower crankcase, then another robot utilizes vision technology to validate the height, width, conformity, lower main and thrust bearings, and gaskets.

Every LT6 is validated through visual inspection, engine weight, torque count, and all that jazz. The next step sees every LT6 shipped to a dyno facility in Bowling Green, where the flat-plane crankshaft V8 is put through its paces. Every LT6 goes through a post-test oil and filter change and a black light inspection before heading to the Chevrolet Corvette’s assembly plant.

Last but certainly not least, a personalized placard is applied by the LT6’s builder to signify their stamp of approval for this high-revving engine.

Expected to enter production this month alongside the Stingray, the Z06 features lightweight forged titanium con rods and low-profile forged pistons that enable high engine speeds and quick engine speed changes.

Dual-coil valve springs also need to be mentioned, together with titanium intake valves, sodium-filled exhaust valves, triple tuning valves in the intake, CNC intake ports and combustion chambers, and two throttle bodies.

Gifted with a six-stage dry-sump lubrication system that boasts individual crank bay scavenging, the 5.5-liter mill breathes out through four-two-one headers constructed from stainless steel. Designed for cornering rather than straight-line thrills, the Z06 is much obliged to accelerate to 60 miles per hour (97 kilometers) in 2.6 seconds with the Z07 performance package.

Three tenths quicker than the Stingray Z51, the Z06 Z07 produces up to 734 pounds (333 kilograms) of downforce at its top speed of 186 miles per hour (nearly 300 kilometers per hour). The quarter-mile takes 10.6 seconds.