What is in this article?:
- New GM V-8 Proves Pushrods Still Rock
- Efficiency Targets Toughest Challenge
The 6.2L LT1 is physically smaller and lighter than a twin-turbo 4.4L V-8, but it makes more power and torque with better fuel efficiency.
Efficiency Targets Toughest Challenge
Key suppliers include Nemak for the aluminum blocks and head castings;for valves, lifters and the LT4's supercharger; Mahle for the pistons; and Stanadyne for the high-pressure fuel pump.
The toughest challenge was meeting the efficiency objectives. "We had lofty goals and achieved them with a lot of painstaking work and analysis. The classic image of a V-8 is big and thirsty, so we wanted to dispel those notions by making our Gen V engines extremely efficient. Refinement was a big deal for us as well."
Lee adds that direct injection, the key technology that all the others were built around, allowed engineers to raise the compression ratio to improve power, torque and fuel efficiency. "Coupling that with AFM," he says, "we can run in 4-cylinder mode a lot more than in past generations because we have a significant improvement in low- and midrange torque."
And he asserts GM is one of the very few manufacturers in the world to combine DI, VVT and AFM in all variants of an engine family. "We were adamant that we needed all three technologies in all of the engines because we wanted to offer the best fuel economy without customers having to pay extra for it.
"The hallmark of the small-block engine is its power density in a small package size, and we are extremely proud to have one of the smallest and lightest 460-hp engines in the world today. Compared with the4.4L twin-turbo V-8, for example, our LT1 is 40 lbs. (18 kg) lighter and 4 ins. (102 mm) shorter in height, with more power and torque and better fuel efficiency."
And he says there is a lot of "headroom" left in this architecture for future improvements in both output and efficiency: "We're working on new designs and technologies as we speak, including higher compression ratios, further combustion-system improvements, the ability to blend more AFM time and maybe even more cylinders in AFM."