How the Mid-Engine Corvette Helped Chevy Make a Better Small Block

Chris Perkins
Photo credit: CAMDEN THRASHER

From Road & Track

Chevy's main reason for making the C8 Corvette mid-engined was improving traction. Putting more weight over the driven wheels gives the new Stingray furious straight-line performance and ferocious traction exiting a corner. But there were other benefits to the move that you might not have expected.

Chevy invited journalists to the GM Performance and Racing Center in Pontiac, Michigan, for a deep dive into the drivetrain powering the C8 Stingray. There, we learned about the many ways that the Small Block has evolved for its role in the mid-engine Vette.

If you've driven a C7 Stingray, you've probably appreciated the car's surprisingly low hood line, which gives great forward visibility. GM's pushrod engines are shorter than the typical overhead-cam engine, allowing for a nice low hood. The C7's designers augmented this by tightly packing the engine compartment, using a compact low-rise intake manifold on the naturally aspirated LT1 V-8.

Photo credit: Steve Fecht/Chevrolet

There's no such packaging compromise with the LT2 powering the C8. Because the mid-engine Vette situates its engine so low in the chassis, Chevy had more space above the engine block. The C8's intake manifold has a volume of 14.1 liters, compared to 11.1 liters on the C7's LT1. And where the LT1 had smaller intake runners on cylinders two and seven (to make room for engine-mounted fuel pumps), the LT2 has equal-length runners on all cylinders.

The result is that the LT2's new intake manifold allows the engine to make roughly 3 percent more peak power than the same engine fitted with the LT1 intake, with increased torque at the top of the power band. The catalytic converters are closer to the exhaust ports, helping to reduce cold-start emissions. The new catalysts allowed Chevy to increase exhaust valve lift by 1mm and duration by 18 degrees, for more exhaust flow.

Photo credit: Chevrolet

A few engine components carried over, like the pistons and rods, but this philosophy of small changes defines the evolution from LT1 to LT2. All in all, when equipped with the optional performance exhaust system, the LT2 in the C8 Stingray makes 495 hp and 470 lb-ft of torque, improvements of 35 hp and 5 lb-ft over the C7's LT1.

All C8 Stingrays use dry-sump lubrication, a feature that wasn't offered on base-model C7s. The LT2's oil tank holds 2.25 quarts less than the dry-sump LT1, but improvements to the system mean that less of that oil is caught up in the pumping system at any given moment—Chevy says there are 2 more quarts of oil flowing through the engine at max RPM.

Photo credit: Chevrolet

Many of the new components designed for the LT2 are lighter than those they replace, but overall, the LT1 and the LT2 weigh the same, 472 pounds with fluids. The extra weight comes in part from the block-mounted oil tank and the redesigned crankshaft, which has a slightly longer nose to accommodate the scavenger pump.

Even with all these improvements to the LT2, it's still a GM V-8—the valvetrain architecture is the same as every other small block, and the cylinder heads are shared with all GM 6.2-liter V-8s. Mike Kociba, assistant chief engineer for small blocks at GM, told Road & Track that using a familiar engine family helps Chevy to sell the C8 Stingray at a relatively low base price.

Photo credit: Chevrolet

Learnings from the LT2 will trickle down into other small blocks. "Running the Corvette durability schedule, you're beating the shit out of it, you're simulating track conditions," Kociba said. "Everything I learned to make it better, you get on a truck for free."

The Stingray is unique among its competitors for sticking with natural aspiration.

Photo credit: Chevrolet

The Stingray is unique among its competitors for sticking with natural aspiration—nearly every performance car today is turbocharged. Ostensibly, downsized turbo engines offer better fuel economy, but Kociba argued that those benefits are only apparent in laboratory testing. In a turbocharged engine, "exhaust valves get really hot, and as a result, you end up having to go richer than [stoichiometric] to protect components," he said.

"With a large displacement V-8, we don't have to do that. So, with every gram of air flow, we're adding just enough fuel to burn that amount of airflow. We don't have to go rich." Add in cylinder deactivation, and like the LT1, the new Stingray engine should offer impressive fuel economy for a large-displacement engine. (EPA fuel economy ratings have not yet been finalized.)

We asked Kociba if this means the Corvette will never go turbo, but he declined to comment. What he did confirm is that his small-block team is the same group that developed the new naturally aspirated 5.5-liter DOHC flat-plane V-8 powering the C8.R race car. Based on FIA homologation requirements, a version of that engine will have to find its way into at least 300 production road cars, but neither Kociba nor anyone else at Chevy was willing to comment on that.

Photo credit: CAMDEN THRASHER

Like many mid-engine supercars, the C8 shows off its engine under a glass lid. Because of that, the engineering team worked with GM designers to dress the engine for the occasion. Tom Peters, head of design at GM Performance Car, personally specified the design of each visible bolt on the engine. The rocker covers are painted Edge Red, with the Corvette crossed-flags logo molded in. Production cars will wear an engine-bay badge paying tribute to the Tonawanda, New York workers who build the LT2—an exact recreation of the badge placed on big-block V-8s made there in the 1950s and '60s. GM president Mark Reuss specified the badge, inspired by a big-block rebuild project of his own.

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