Throughout the years, GM has produced nearly as many iconic engines, as the Corvettes that they have placed them in. GM has developed, and subsequently put into production, some of the most illustrious small-block V8 engines to ever be engineered. Two such famed engines are the LT1 and LS1.
If you are a performance enthusiast, little introduction is needed for either of these engines. Both hold spots of immense value in the storied history of the Corvette’s continual charge toward excellence. Though the years continue to sail by, the LT1 and LS1 engines both prove to be timeless.
It is no secret that small-block V8’s have been the bread and butter of the Corvette’s power plant offerings for the bulk of its existence. While several memorable big-block engines have been placed into Corvettes throughout the years, few held the same legendary status that has been commanded by GM’s small-block lineup.
The Corvette’s first foray into the small-block V8 market came in 1955 with the introduction of its 265 cubic-inch “Turbo-Fire” V8. Just two years later, Chevrolet began offering “fuelie” fuel-injected systems in conjunction with their initial Corvette V-8 small-block.
As the 1950s and 1960s carried on, GM’s small-block offerings continued to grow in displacement. However, in 1969, the 350 cubic-inch V8 entered the market, forever changing the course of the Corvette, and the small-block platform itself.
Numerous renditions of the 350 cubic-inch V8 continued to be produced well into the 1990s, making this engine one of the longest-lived staples in a lengthy history of noteworthy Corvette powerplants.
As the millennium began to draw to a close, the next generation of GM small-block made its way onto the performance scene. With the 1997 advent of the LS platform, everything changed. With this single revelation, the way that individuals viewed their Corvette’s performance began to shift. This latest rendition of the GM small-block not only bolstered the Corvette’s performance to new levels, but also created an engine specific tuning industry all in itself.
LT1 Facts, Figures, and History
The LT1, named as a nostalgic nod toward the ever-noteworthy LT-1 of 1970’s fame, began its time under the hood during the 1992 production year. The LT1 featured a cast-iron block that was topped with aluminum heads and was capable of producing robust, performance figures. With a rated output of 300 HP and 300 ft./lbs of torque, the LT1 proved to be a potent powerplant for the C4 Corvette.
The LT1 also proved to be revolutionary in more ways than one. The engine featured computer-controlled ignition timing, a redesigned camshaft profile, upgraded multi-port fuel injection, and free-flow cylinder heads. The LT1 also incorporated a higher compression ratio, 10.5:1, than its predecessor.
Other improvements to the newly designed LT1, over previous small-block engines in Chevrolet’s 350 cubic-inch platform, were made in regards to the unit’s exhaust system. A new low-restriction exhaust system was mated to the LT1 that featured dual catalytic converters and two bank-specific oxygen sensors. The stainless steel exhaust manifolds of the past were also traded off in favor of revised cast iron assemblies.
The LT1 also came off the assembly line lubed with synthetic oil. The advent of synthetic oil use allowed GM to navigate away from the use of a standard oil cooler, as the use of such oil assisted in reducing friction and minimizing heat. GM’s new small-block also utilized reverse flow cooling. Through this process, the engine coolant was delivered to the cylinder heads before reaching the block. This worked to effectively reduce cylinder temperatures and encourage more efficient combustion.
LS1 Facts, Figures, and History
When the fifth generation C5 Corvette became available to the masses in 1997, the performance world was rife with anticipation, not just in regards to the vehicle itself, but toward the all-new LS1 powerplant that it harbored as well. Not only would the LS1 prove to be one of the most formidable of all GM small-block offerings to date, but it would also go down in history as the beginning of the LS platform that was loathed by many and revered by competitors on the track.
Though the LS1 shared an identical 5.7L displacement, rod bearings, and overall dimensions with its LT1 predecessor, little else remained unchanged between the two small-block offerings. The LS1 weighed in at 45 pounds less than the aforementioned LT1. Much of this weight reduction can be traced back to the LS1’s all-new aluminum block and thermoplastic composite intake. Both of these features were also dual purpose in their design, as both presented functional attributes of note other than their weight reductive qualities.
The LS1’s new thermoplastic composite intake served to shed heat and thereby reduce inlet air temperatures, aiding in more precise and complete combustion. The engine’s aluminum block also proved to be a valuable performance asset, as aluminum shows a propensity for heating to operating temperatures in a more efficient manner, as well as remaining cooler under high load conditions.
Other advancements to the LS1 small-block V8 included a larger 55mm journal hydraulic roller camshaft, redesigned intake port heads, hypereutectic aluminum flat-top pistons, and a nodular iron crankshaft. The new LS1 was designated to run on premium-grade fuel and came filled from the factory with synthetic motor oil for reduced friction and increased internal component longevity.
The LS1 also dumped the standard distributor ignition that had been featured in GM’s previous small-block V8 offerings. In its place, came a new ECU controlled ignition system that utilized individual coils for each respective cylinder. This new system allowed further strides to be made in ignition timing and combustion efficiency.
Not to disappoint, the LS1 proved to be yet another advancement in the direction of pure performance among GM’s line of powertrain offerings. The engine produced 345 HP at 5,600 RPM, and churned out an impressive 350 ft./lbs of torque at 4,400 RPM. In 2001, improvements to the LS1’s intake and exhaust manifolds brought the figures to 350 HP and 365 ft./lbs of torque respectively.
How Do They Stack Up?
Needless to say, little disappointment can be expected, no matter which of these two timeless small-block engines you find under your hood. Both the LT1 and LS1 engines carry a high level of merit and have held equally rich positions within the Corvette’s lengthy history toward ever-increasing performance. However, this is not to say that one of these two engines does not take a slight edge over the other in some regards.
When comparing both practical and technological advancements, the LS1 is hard to beat. Between the end of the C4’s reign, and the C5’s rise to prominence, GM engineers went back to the drawing board to design the small-block of the future, and that they did. Considering the LS1’s 12 percent reduction in weight and 45 horsepower gain in performance, it is quite clear to see the natural progression between the two engines.
Furthermore, by the time that the LS platform had made its way to market, electronic engine control technology had begun to hit its stride. Ignition timing had become increasingly advanced, rendering higher levels of efficiency, and cumbersome distributors became antiquated with the development of ECU driven coil to plug systems.
The LS1’s dominance over its predecessor is less of a slight toward the LT1, and more of a nod toward the GM design team’s continual drive toward growth in the areas of outright power and performance. Just as each successive generation of Corvettes become dated with time and warrant a complete redesign with the emergence of a new generational divide, so do the engines that lay at the heart of these iconic vehicles. The LS1’s emergence was just the next progression toward the Corvette’s bid for dominance.