In 1992, GM created a new-generation small-block engine and again called it LT1 to recall the 1970 LT-1. It displaced 5.7 liters and was a 2-valve pushrod design, although a 4.3 liter variant known as the L99 was also offered beginning in 1994. The LT1 was unique with a reverse-flow cooling system which allowed for the engine to run at a higher compression. This was accomplished by cooling the heads first, thus reducing the risk for engine knock at the higher compression. The reverse-flow of the coolant enabled the vital engine components to run at a lower temperature than other small block V-8 engines. The LT1 could run at a substantially higher RPM than the previous F-body cars and corvettes without damaging the internal parts of the engine, thus increasing the peak torque and HP capability.
Other cars received detuned versions of the LT1 in the years following 1992. In the Camaro and Firebird, the LT1 engine was rated at 275 hp (202 kW) and 325 ft·lbf (439 Nm) for the years 93-95. The rated factory horsepower of the LT1 in the Camaro and Firebird was largely underated because of the rising popularity of its cousin, the Corvette (in reality, the LT1 produced the same horsepower and torque as the Corvette). The F-Body was up to a factory rated 285 hp (210 kW) and 335 ft·lbf (452 Nm) with this engine in the 1996-1997 model year with the addition of dual catalytic converters. In 1996-97 the SS/WS6 versions were rated at 305 hp. The base versions were rated lower in an effort to help customers feel like they were getting more for their money, when in reality the only difference was a different intake that became heat-soaked on the SS and provided marginally cooler air on the WS6. [citation needed]
In the 1994 to 1996 B-body (Impala SS, Caprice and Roadmaster) and D-body (Fleetwood) version, the LT1 engine produced 260 hp (191 kW) and 330 ft·lbf (446Nm).
There were a few different versions of the LT1. All feature a cast iron block, but only the Corvette and F-bodies got aluminum heads. 1994 saw new sequential port injection and a mass airflow sensor. A new vented version of the opti-spark distributor appeared in 1994 on the B-Bodies and Fleetwood and in 1995 on the Corvette and F-Bodies. 1996 saw major revisions for OBD-II - a second catalytic converter on the F-body cars (which was standard since 1995 in California), a crank position sensor, rear oxygen sensors, and a new computer. Some OBD-II features had been added to the Corvette starting in 1994 for testing purposes. The 1997 model year Camaro and Firebird were the last year for this engine in a GM production car. In 1993, the LT1 obtained the problematic optispark distributor, which can be found behind the water pump, just below the rubber intake boot. In 1996, the main problem GM had with the opti-spark was fixed when moisture vents were added to the outside of the distributor.
