By the early 1990s, talk had begun to center around the potential release of the fifth-generation Corvette. By this time, the C4 Corvette had already weathered the 1980s, leaving many to wonder when the next generational divide might take place. However, those at the helm of GM ultimately decided to postpone the release of their fifth-generation Corvette, largely due to budgetary constraints of the day.
However, the development of a new powerplant for the aging C4 Corvette was greenlighted nonetheless. This engine would ultimately carry the LT1 designation, and prove quite capable beneath the Corvette’s hood. The 1992 LT1 would serve as a bridge between GM small-block development, past and present.
LT1 History
Throughout the years, the Corvette has been powered by its fair share of memorable small-blocks. Though initially equipped with a 150 horsepower inline-six, “Blue-Flame” engine, the Corvette began being offered with an optional 265 cubic-inch small-block V8 in 1955.
The introduction of this engine would drastically alter the trajectory of subsequent Corvette sales, even saving the fledgling sports car from a near-certain demise during its earliest days of production.
In the years following its release, the 265 cubic-inch V8 underwent a significant amount of revision, growing in displacement along the way. The storied small-block had reached 350 inches of displacement by the mid-1960s, at which time it had already reached near-iconic status.
However, the 1970s brought about winds of change, which most notably included the introduction of legislation aimed at curbing environmental pollution. In a bid to reach compliance, many manufacturers began detuning their already existing powerplants, with General Motors being no exception.
As a result, the 350 small-block’s output suffered. By 1975, the legendary small-block, in its base form, produced only 165 HP. Luckily, as anyone familiar with the performance figures of late-model Corvettes is well aware, this story does indeed have a happy ending. The 350ci small-block would eventually return to greatness, though this redemption was slow to come.
One such stepping stone along the 350ci V8’s return to performance superiority was the release of the LT1 in 1992. The 1992 dished out an impressive 300 horsepower, which served as a 50 horsepower increase over the L98 small-block before it. For the first time in the better part of two decades, those purchasing a base-model Corvette were provided with enough gusto beneath their car’s hood to make the average motorist weak at the knees.
1992 LT1 Specifications and Technical Configurations
The 1992 LT1 featured a cast-iron engine block (#10125327), which was of a four-bolt configuration, and housed a cast-iron crankshaft. Connected to this crankshaft, was a set of powdered-metal connecting rods, which featured eutectic aluminum/silicon alloy pistons at their opposing ends.
These pistons reciprocated within 4.00-inch cylinder bores, with a stroke of 3.48 inches. The culmination of these figures presented the LT1 with an effective compression ratio of 10.4:1, which served as a slight increase over that of the L98 before it.
Valve actuation was managed by a high-performance hydraulic lifter camshaft, which featured valve durations of 279 (intake) and 276 (exhaust), respectively. This specialty cam also carried valve lift values of .447” (intake), and .459” (exhaust).
The LT1 utilized a set of free-flowing cast aluminum cylinder heads, which were fitted with 1.94” (intake) and 1.50” (exhaust) diameter valves. These heads were fitted with a single-piece low-profile intake manifold.
Of special note, was the LT1’s use of a reverse-flow cooling system. This system first introduced coolant into the LT1’s heads, rather than into the engine’s block. In doing so, the LT1’s combustion chambers were able to reach higher temperatures, thereby minimizing piston ring to cylinder bore friction.
The LT1’s cylinders were supplied fuel, through a redesigned Multi-Port Fuel Injection system. The adaptation of this system also provided the LT1 with a noticeably improved throttle response.
1992 LT1 Specs Index
- Horsepower: 300 hp @ 5,000 rpm
- Torque: 330 lb.-ft @ 4,000 rpm
- Compression Ratio: 10.4:1
- Displacement: 350CI (5.7L)
- Cylinder Bore: 4.00” (101.6 mm)
- Stroke: 3.48” (88.39 mm)
LT1 Additional Uses
The LT1 was widely used by General Motors, within a number of applications. The specifications regarding the LT1 differed from one application to the next. The LT1 was offered with aluminum heads in all Y and F body applications, while cast iron heads came standard in all B and D body applications. Though the LT1 showcased four-bolt mains when used in the Corvette, nearly all other LT1 small-blocks featured two-bolt mains.
The following are several of the LT1’s most prominent uses, outside of its time spent beneath the Corvette’s hood.
- 1993-1997 Camaro Z/28
- 1993-1997 Pontiac Firebird, Trans-Am, and Firehawk
- 1994-1996 Buick Roadmaster/Wagon
- 1994-1996 Chevrolet Caprice/Police Package, and Impala SS
Power On-Demand
Today, the LT1 small-block is often fondly remembered, for its more pronounced performance capabilities, and responsive throttle. Those behind the wheel of a mid-1990s Corvette were keenly aware of the output that awaited each stab of the accelerator.
Perhaps more importantly, was the fact that the LT1 showcased an upward trend in GM small-block performance, following the largely restrictive period that befell the automotive industry during the 1970s and 80s. The Corvette, even in its base form, was once again a force to be reckoned with.
