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Development of the LS1 Engine Changed Everything

Two Decades of the LS Engine: 1997 saw the introduction of arguably the most successful V-8 ever fielded in a Chevrolet

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As the saying goes, “time flies when you’re having fun.” It must be true because we were in shock when it dawned on us that the LS1 was introduced two decades ago. Yep, 20 years that seemed to go by way too quickly. We remember when the new mill was introduced for the 1997 Corvette. It was a radical departure from the previous Gen II LT1, but kept many of the facets we were familiar with. At 345 horsepower it beat the LT1’s output by 45 hp, but with the aluminum block it was also quite a bit lighter (12 percent lighter than the Gen II LT4). The LS1’s 319 heat-treated aluminum block tipped the scales at just 107 pounds, 53 pounds lighter than the Gen II LT1 block! The tried-and-true 4.4-inch bore center-to-center measurement was kept but the overall design really was a huge evolutionary step for the GM V-8.

As Jordan Lee Chief Engineer – Small-Block Engines explained, “The transition going from Gen III to Gen IV and Gen V was a natural progression. The Small Block team has always been guided by the principles of the original small-block team. Keep the technology employed relevant and beneficial to the customer, maintain low mass and compactness, strive for every drop of efficiency and, of course, always improve power density. Interesting to note is that with each iteration we thoroughly evaluated all options and always validated the design genius of the original small-block.

Today’s small-block continuity with the original is in its use of pushrod valve actuation, 90 degree V, and 4.4 inch bore centers. It’s almost as if Ed Cole and the original team envisioned something that would live well beyond themselves—as it has. Key design features that carry over from the legendary Gen III LS design include the deep skirt block with six-bolt mains, single plane sealing surfaces, composite intake, coil-near-plug ignition, and the crank driven oil pump. The Gen III also brought us to our current firing order of 1-8-7-2-6-5-4-3. The team today is grateful to be able to build off of the smart, forward looking design decisions made with the Gen III LS.”

Many people were surprised the new engine stayed with the single cam pushrod configuration. After all, dual overhead cams and other technologies were becoming more prevalent, so staying with this architecture seemed odd to some. We asked GM about this and the reply was simple. It was all about packaging. It would be challenging and expensive to fit a huge double overhead cam engine under the low hood of the C5 Corvette. The C4 ZR1 Corvette did have the double-overhead cam LT5, but that was a limited production halo car, and at the time the most expensive Corvette sold. The design of the LS1 kept the Gen III small-block compact and able to squeeze into the C5’s tight engine bay, affordably.

But that really wasn’t why the LS1 was developed. The engine it was replacing, the Gen II LT1, debuted in the 1992 Corvette. It displaced 350 inches and made 300 hp at 5,000 rpm. That was a 55hp improvement over the L98 small-block it was replacing, but GM knew that with stricter emissions and CAFE standards this platform wasn’t going to carry them very far into the future. So, around 1993 work began on what would become the LS1. Aluminum was chosen to drop the weight, aiding both performance and fuel economy. This balancing act between performance and other factors, like fuel economy and emissions, led to an engine that seemed familiar to small-block fans, but was vastly different internally. In addition to keeping the size down, staying with a pushrod design kept the manufacturing costs down as well.

We went back and dug up a 20-year-old press release from GM, which turned out to be pretty prophetic. “Until the introduction of the LS1 in the C5 Corvette, almost every V-8 engine used for high performance or for racing dated back to designs that originated in the mid-1950s,” said Herb Fishel, director of GM Motorsports.

“The most famous example is the small-block Chevy. First introduced in 1955, millions have been built and can be found powering everything from production cars and trucks to the cars and trucks raced at just about every racetrack across North America. But now, with the introduction of the C5’s LS1, General Motors will begin to phase out the small-block Chevy that has been the backbone of America’s high-performance and racing industry for more than 40 years,” continued Fishel. “It will be replaced by derivatives of the LS1, which has the highest specific output of any production V-8 engine GM has ever built. In every sense the LS1 is truly the high-performance engine of the future.”

“Few people yet realize the long-term effect that the C5 LS1 engine is going to have on the performance industry,” says Joe Negri, manager of IRL and Road Racing Groups for developing the C5-R racing version of the LS1. “What is really remarkable is that the very high specific output of the production Corvette’s LS1 engine has been achieved at reasonable cost and weight while meeting both emission and fuel economy standards. It is a fantastic engine on which to base a modern-day racing program.”

Wixom LS Build Center 2/4

The LS line of engines kept evolving over time, to the point where some of the higher-performance variants, such as the LS7 and LS9, were hand assembled in specialized build centers like this one in Wixom, Michigan.

Corvette engine developers looked to the future and realized that performance had to be based on new designs that produced engines that were fuel, weight, and emissions efficient; cost effective; and environmentally acceptable to a changing world. These would be engines where electronics and vastly improved cooling, oiling, and sealing systems would contribute to the increased performance goals.

“In the 1970s and 1980s the manufacturers and the performance industry were on divergent paths,” says Herb Fishel. “For most of the ’70s and ’80s, the manufacturers’ focus was on fuel economy and emissions. It was left mostly to aftermarket suppliers to develop performance components for small-block V-8s. This led to the cost of racing engines, for example, increasing dramatically since the performance was being added on to an aging design rather than being built in to a modern design.”

Chevrolet LSX375 15B CrateEngine 0021 3/4

The LS engine became so popular that Chevrolet Performance (as well as other aftermarket companies) began offering non-factory blocks that pushed the size and performance of LS engines to new levels. This Chevrolet Performance LSX iron block was designed to go big (over 500 cubic inches with the tall deck version) and handle big power as well as loads of boost.

“It’s fitting that this new design of engine was introduced in the C5 Corvette,” says Negri. “It was Zora Duntov’s vision in 1953 that Corvette should lead the way with ‘ready-engineered’ parts and designs. And I think he would be proud of what has been achieved with the LS1. It is the leading edge of V-8 technology as we enter the 21st century. And there’s absolutely no question that a good portion of racing in the 21st century is going to be built around the engine that the world first saw in the C5 Corvette.”

It wasn’t long after the introduction of the LS1 that gearheads started figuring out how to graft them into classic Chevys and it all snowballed from there. Now the aftermarket makes it nearly painless to do an LS swap. Shortly after the introduction of the LS1, GM came out with an iron-based-block design for their truck/SUV line and constant improvements led to other milestone engines like the LS2, LS3, and LS7. Even though GM has moved on to its new direct-injected LT line of engines, the popularity of the LS engine shows no signs of slowing down. “The LS3 is currently our bestselling crate engine in the LS family,” said Rocko Parker, Chevrolet Performance Parts Engineer. “When we introduced it in 2008, its 430 horsepower and 6.2L engine drew a lot of interest. Today, its combination of technology, uncompromising performance and accessible price point, make it a popular option.” So, happy birthday to an engine that changed hot rodding, we look forward to the next two decades of performance.

Chevrolet Engineers Involved With LS1 Design 4/4



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