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Celebrating 20 Years of LS Engines

Time flies when you’re building huge horsepower

Barry Kluczyk Nov 20, 2017
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Gravity affects space-time. That’s basically what Einstein was getting at, and it means that time on Earth passes differently than if you were, say, doing the Star Trek thing out in the vacuum of space.

That’s all very well and good for Kirk and his crew, but it doesn’t quite explain how we were all watching the “Festivus” episode of Seinfeld for the first time and then, as quickly as the “Macarena” came and went, we’ve passed the 20-year mark with LS engines.

It’s true. It’s been two decades since the groundbreaking LS1 engine was first launched in the C5 Corvette, then in Chevy trucks and, finally, the fourth-generation Camaro. The significance of its development is difficult to overstate, because in a very real way, it saved the classic American V-8 by reinventing it. And the effects of that will reverberate for years to come.

Engine development takes time, and General Motors’ decision to pursue the architecture that would officially become the Gen III small-block started in the early-’90s. The decision wasn’t an easy one. In fact, it was more of an existential dilemma brought on by the seismic shift in consumer tastes and technological advances during the previous decade.

In 1980, the best-selling car in America was the Olds Cutlass Supreme, which was as old-school Detroit as it got: rear-wheel drive, body-on-frame sedan, either a pushrod V-6 or V-8 engine. By 1989, the Honda Accord—a front-drive import with a fuel-injected four-cylinder—had claimed the best-selling crown. Talk about a shift in the space-time continuum.

GM officials knew the future for the original small-block was limited. There were performance, efficiency, and emissions targets it wouldn’t be able to achieve by the end of the ’90s. The question wasn’t so much when the small-block would be replaced, but what would replace it. With the industry already largely changed to overhead-cam designs, it seemed like the logical direction. Even Ford would dump its stalwart Windsor V-8 platform for the “modular” overhead-cam engine family that spawned the 4.6L V-8 introduced in the 1994 Mustang GT.

And while the march toward an overhead-cam replacement for the small-block seemed inevitable. A story described by Will Handzel in his book How to Build High-Performance Chevy LS1/LS6 V-8s, illustrates the objectivity that ultimately changed fate. It was mid-1992 and a bunch of GM execs were at the company’s Milford Proving Ground, near Detroit, to review different vehicles and engine technologies.

The reviews included blind tests of C4 Corvettes featuring different engines. The execs didn’t know what was under the hood of the respective cars, but they included an early version of the warmed-up LT1 engine that would become the 330-horsepower LT4 offered in the 1996 Grand Sport model. There was also a car with the C4 ZR-1’s DOHC LT5 engine, albeit connected to an automatic transmission.

Despite the LT5’s refinement and high-rpm horsepower, the consensus after driving the cars back-to-back was the one with the small-block simply seemed more responsive. That would be thanks largely to the inherent low-rpm torque of its nearly 40-year-old cam-in-block design. In a brave move that bucked conventional wisdom, the decision was made to pursue a new V-8 architecture that retained the overhead-valve design of the original small-block.

With a clean-sheet design, the new Gen III small-block enabled the development team to build a modern engine designed not only for tougher performance and emissions targets, but with the refinement contemporary overhead-cam engines offered.

Among the items on the engineers’ wish list was a deep-skirt block with cross-bolted main caps, which would serve as a more rigid foundation than the Gen I/II-style block. They also needed to reduce friction wherever possible in the engine, to enhance efficiency, and reduce emissions. Along those lines, the cylinder heads needed to deliver mixture motion that would optimize combustion for port fuel injection. That meant larger, longer intake ports and a change in the valve angle from the existing small-block’s 23 degrees to 15 degrees. A traditional distributor would also be eliminated in favor of a contemporary coil-near-plug design.

Additional elements that would help define the new engine included a raised camshaft to make room for a larger-diameter crankshaft, a larger-diameter camshaft with commensurately larger cam bearings, and—in performance applications for the Corvette and Camaro—an aluminum block.

There was one more thing: the centerlines between the cylinder bores would be 4.40 inches, the same as the original small-block design.

When the LS1 finally saw the light of day in the C5 Corvette, it was a small-block, all right, but with a powerband completely unlike its predecessors. Owing to its new, deep-breathing heads, the horsepower and torque peaks moved up significantly on the tachometer. In the 1997 Corvette, the LS1 was rated at 345 horsepower, a significant 15-percent jump over the previous LT1 with comparable displacement. The LS1 debuted in the 1998 Camaro Z28, where it was rated at 305 horsepower.

It was the first time a regular-production Camaro had exceeded the 300-horsepower mark since 1970 (the 305hp 1996-’97 SS models were “second-stage” conversions by SLP).

Ironically, the LS platform made tremendous horsepower thanks to its high-flow heads, but it didn’t come with a corresponding jump in torque. In the 1997 Corvette, the LS1’s peak torque was only about 5 percent greater than the previous LT1 and it came higher in the rpm band.

If the LS1 lacked a little in low-end grunt, it more than compensated for it with high-revving capability. The old small-block simply ran out of breath by 5,000 rpm, while the LS1 kept pulling. Again, it was all thanks to those deep-breathing heads, which helped the engine offer a unique balance between the attributes of a traditional pushrod engine and the characteristics of an overhead-cam design.

A Performance Revolution
Just as the LS architecture saved the classic American V-8, it’s no stretch to suggest it also revitalized the performance industry. The exceptional capability of the LS engine to make huge horsepower established a new niche in engine and parts development that continues to grow. It has also changed expectations in ways few could have predicted.

“Twenty years ago, a 300-horsepower small-block was a very respectable street engine and anything more than 400 horses was something to talk about,” says longtime engine builder Brian Thomson, who spent much of the last 20 years on the leading edge of LS engine performance. “Today, building a 1,000-horsepower supercharged LS street engine with daily driveability is not only possible, it’s commonplace.”

Thomson should know. That’s what’s powering his ’72 Chevelle.

“The great thing about LS engines is their capability for making really strong horsepower with only a few basic upgrades,” he says. “You don’t have to go crazy with a big supercharged combination. An LS3 with the right camshaft will make well over 500 horsepower. You can’t go wrong.”

In fact, you can order such an engine right out of the Chevrolet Performance parts catalog. It’s called the LS376/525 crate engine, and Scoggin-Dickey, Summit Racing, and Jeg’s offer it for right around $8,300.

“When it comes to bang for the buck, there’s great value in LS crate engines,” says Bill Martens, special programs manager for Chevrolet Performance. “New swap kits make installing LS engines in vintage vehicles easier than ever, making them increasingly popular with enthusiasts.”

Martens is quick to point out the vintage small-block that inspired the LS continues to hold its own. “Chevrolet Performance recently made an investment in tooling that will keep the classic small-block in production long into the future,” he says. “But the LS has the potential to be the classic small-block for a whole new generation. If you’re building a project, you’ve never had more choices.”

With hindsight, it’s easy to call GM’s decision to stick with pushrods a prescient one, but it was undeniably gutsy, given the prevailing trends at the time. In fact, the LS1’s introduction is arguably second to only the original small-block’s 1955 introduction in importance to Chevrolet performance history.

Its influence continues, as the Gen V “LT” engine family introduced in the C7 Corvette and sixth-gen Camaro traces its architectural roots to the groundbreaking engine, proving pushrods still have a place in the modern world. Happy Festivus—and happy 20th anniversary to the LS! CHP

002 20 Years Of The Ls Engine Corvette 2/20

First came the C5 Corvette in 1997. That’s when the LS1 was born, ushering in a new era of factory performance and laying the groundwork for a revolution in aftermarket high-performance. The new engine was rated at 345 horsepower in the Corvette.

003 20 Years Of The Ls Engine 3/20

Although some blocks for truck applications were made of iron, the LS engines used in Corvettes, Camaros, and other performance models featured strictly aluminum blocks. And while they shared nothing physical with the original small-block casting, all LS engines feature the small-block’s signature 4.40-inch bore centers.

004 20 Years Of The Ls Engine Y Block 4/20

One of the most important design elements of the LS1 was the change to a deep-skirt block design—also known as a Y-block—that extended below the centerline of the crankshaft. Along with increasing the block’s rigidity, the design allowed the use of cross-bolted main bearing caps, which further strengthened the assembly and enhanced refinement.

005 20 Years Of The Ls Engine Fourth Gen Camaro 5/20

The LS1 brought a dramatic change in performance to the fourth-gen Camaro. Horsepower in the Z28 jumped from 285 in 1997 to 305 with the 1998 introduction of the LS1. Likewise, the SS model jumped from 305 horses in 1997 to 320 in 1998, and increased to 325 horses by 2001. More than greater power, the LS1 was roughly 90 pounds lighter than the previous small-block.

006 20 Years Of The Ls Engine Cathedral Ports 6/20

The key to the LS architecture’s performance capability is all the breathing. Early engines, including the LS1, LS6, and LS2 featured high-flowing cathedral port heads that were so-named for their tapered tops. And while they aren’t considered the best for maximum performance these days, thanks to later rectangular port designs, they still out-flowed the best factory small-block heads by a long shot, enabling the LS1 to rev higher.

007 20 Years Of The Ls Engine C5 Corvette 7/20

The hiatus of the Camaro’s production after 2002 left it solely up to the Corvette to advance the LS’s burgeoning performance legacy. The LS6-powered C5 Corvette Z06 upped the ante with a 40-horse leap to 385 horsepower, at first, and then another jump to 405 horsepower, matching the output of the vaunted C4 ZR-1’s DOHC LT5 engine.

008 20 Years Of The Ls Engine 8/20

The introduction of the C6 Corvette in 2005 included the Gen IV engine dubbed LS2, which featured a larger 6.0L displacement over the 5.7L LS1/LS6. That was achieved with a new block casting that accommodated larger, 4.00-inch bores versus the LS1’s 3.89-inch bores. In the Corvette, the LS2 was rated at 400 horsepower and 400 lb-ft of torque.

009 20 Years Of The Ls Engine Cathedral Port Heads 9/20

The LS2 continued to use a cathedral port head design, but it was based on the higher-flowing heads used on the LS6, minus the LS6’s unique, lightweight, sodium-filled exhaust valves. The LS2 head’s combustion chambers were also a little smaller than the LS1, which increased the compression ratio.

010 20 Years Of The Ls Engine C6 Corvette 10/20

Things got real in 2006 with the introduction of the C6 Corvette Z06 and its take-no-prisoners LS7 engine. Rated at 505 horsepower, it was performance from Detroit the likes of which hadn’t been seen since the days of original COPO Camaros and L88 Corvettes four decades earlier.

011 20 Years Of The Ls Engine Ls7 11/20

The LS7 was all about technology transfer from the Corvette Racing program, with straight, Lincoln Tunnel-sized intake ports, lightweight titanium intake valves, a high-flow intake manifold, high-flow exhaust manifolds, and even a factory dry-sump oiling system. The engine would also find its way to the fifth-generation Camaro Z/28.

012 20 Years Of The Ls Engine 12/20

Chevrolet upped the displacement and output of the LS engine again in 2008, with the 6.2L LS3. Picking up where the LS2 left off, it featured even larger 4.06-inch bores while retaining the 3.62-inch stroke that was used on the LS1, LS6, and LS2. Horsepower increased to 430 in the Corvette.

013 20 Years Of The Ls Engine Rectangular Port Heads 13/20

Notably, the LS7, LS3, and other Gen IV LS variants, such as the L92 engine used in some truck and SUV applications used a new rectangular port head design that supported the larger-displacement engines’ airflow requirements. The LS3 and L92 used a similar port size/shape, while the LS7’s ports were slightly wider and a little shorter. LS3 and L92 can be used on other LS engines with at least a 4.00-inch bore, such as the LS2, but the LS7’s heads are not interchangeable, thanks to their use on the only 7.0L displacement engine in the LS family.

014 20 Years Of The Ls Engine Fifth Gen Camaro 14/20

The re-introduction of the Camaro in 2009 as a 2010 model brought with it the LS3 engine in SS models. LS performance technology had taken a quantum leap since the fourth-gen cars bowed out seven years earlier, enabling owners to quickly get their fifth-gen cars up to speed, figuratively and literally.

015 20 Years Of The Ls Engine Lsa 15/20

The fifth-generation Camaro ZL1, introduced in 2012, leveraged the supercharged 6.2L LSA engine from the Cadillac CTS-V. The Camaro version carried some unique features, including specific plumbing for the heat exchanger mounted above the supercharger. It also used unique exhaust manifolds, accessory drive system, and more. It was rated at a stunning 580 horsepower.

016 20 Years Of The Ls Engine C6 Zr1 Corvette 16/20

The pinnacle of LS performance came with the C6 Corvette ZR1, which featured the supercharged 6.2L LS9 engine, rated at a stunning 638 horsepower and 604 lb-ft of torque. As the most powerful production vehicle ever from Chevrolet and General Motors, it topped out at more than 200 mph—pushrods and all.

017 20 Years Of The Ls Engine Ls9 17/20

Everything about the LS9 was unique, from the intercooled Eaton supercharger with high-helix (160-degree) four-lobe rotors to the forged titanium connecting rods and roto-cast aluminum cylinder heads.

018 20 Years Of The Ls Engine Ls9 Block 18/20

The LS9’s aluminum cylinder block was also unique, with an enhanced alloy that made it stronger than the standard 6.2L cylinder block.

019 20 Years Of The Ls Engine Lsx 19/20

Chevrolet has supported LS performance right from the start and even developed the LSX line of factory-engineered high-performance parts and crate engines designed for the rigors and pressures of power-adders. This LSX454R crate engine is a high-compression drag engine rivaling the output of big-blocks, with more than 600 horsepower and nearly 600 lb-ft of torque.

020 20 Years Of The Ls Engine 20/20

Beyond the production line, LS swaps have become arguably the biggest trend in hot rodding and high performance. A proliferation of swap kits has made it easier than ever to retrofit LS power into vintage vehicles. It’s a trend that will only accelerate in the years to come.

Photos by Barry Kluczyk and Courtesy of General Motors

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