Let’s take a moment to reflect on the pure insanity that is the 2015 Chevrolet Corvette Z06’s supercharged LT4 V8. Rated at 650 horsepower, this is not an engine one wants to disrespect.
To date, the most powerful car I’ve driven was the Chrysler 300 SRT8. As I learned way back then, the old Spider-Man quote carries real weight: “With great power comes great responsibility.” Disrespect 470 horses, and they’ll disrespect you back.
But it’s hard for me to even wrap my head around the idea of having 650 horsepower, especially in a fiberglass car. The difference in power between the Chevrolet Corvette Z06 and the Chrysler 300 SRT8 is more than the entire engine power in my Ford Ranger.
The interesting details of how GM got all that power out of 6.2 liters of pushrod V8:
Well, first of all, supercharging
I mean, duh, right? Slap a supercharger on any engine, and its low- and midrange pickup will be vastly improved.
GM Powertrain Engineering Vice President Steve Kiefer said, “The LT4 Small Block sets a new benchmark for power and torque at GM. The engine also puts the new Corvette Z06 on par with the most powerful supercars offered in America, while delivering performance with impeccable manners that make it suitable for daily driving.”
The press release from GM said the Chevrolet Corvette Z06’s V8, true to most supercharged engine designs, makes a meaty lump of torque low in the rev range. That helps it stand out from other high-performance cars, GM said:
Compared with other supercar engines, the LT4 is a veritable fountain of low-end torque, producing 457 lb-ft (619 Nm) just off idle and 625 lb-ft (847 Nm) by only 2,800 rpm. The V-12-powered Ferrari F12 Berlinetta, for example, produces about 28 percent less torque than the Z06, despite offering about 12 percent more horsepower – and its peak torque isn’t achieved until 6,000 rpm. The LT4 maintains 90 percent of its peak torque, or 592 lb-ft (802 Nm), from 2,500 to 5,400 rpm.
The new LT4 engine eclipses the Porsche 911 Turbo S engine’s peak power levels by 90 horsepower (67 kW) and 134 lb-ft of torque (182 Nm).
So obviously, supercharging isn’t the entire story here. To build what Chief Engineer of Smallblock Engines Jordan Lee called “one of the smallest and lightest 650-hp engines in the industry” requires more tech know-how than just strapping on a scroll above the Chevrolet Corvette Z06’s intake, right?
Here’s GM’s nitty-gritty on how the engineers squeeze every last pony out of the V8 engine:
The new LT4 engine is based on the same Gen 5 small block foundation as the Corvette Stingray’s LT1 6.2L naturally aspirated engine, incorporating several unique features designed to support its higher output and the greater cylinder pressures created by forced induction, including:
- Rotocast A356T6 aluminum cylinder heads that are stronger and handle heat better than conventional aluminum heads
- Lightweight titanium intake valves
- Machined, forged powder metal steel connecting rods for reduced reciprocating mass
- High 10.0:1 compression ratio – for a forced-induction engine – enhances performance and efficiency and is enabled by direct injection
- Forged aluminum pistons with unique, stronger structure to ensure strength under high cylinder pressures
- Stainless steel exhaust manifolds and an aluminum balancer that are lighter than their LT1 counterparts
- Standard dry-sump oiling system with a dual-pressure-control oil pump.
A new 1.7L supercharger spins at up to 20,000 rpm – 5,000 rpm more than the supercharger on the Corvette ZR1’s engine. The rotors are smaller in diameter, which contributes to their higher-rpm capability – and enables them to produce power-enhancing boost earlier in the rpm band. That boost is achieved more efficiently via a more direct discharge port that creates less turbulence, reducing heat and speeding airflow into the engine.
“The Small Block’s cam-in-block design heritage has always enabled very high performance and responsiveness in a small, compact package – an attribute amplified by the performance of our new supercharger’s design,” said Lee.