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LT1 Feature that would not interchange with the traditional small block. The crankshaft, connecting rods, pistons, and valvetrain assembly remained the same. The purpose of the reverse cooling was to keep the cylinder heads cool so the compression ratio along with the timing advance could be increased. The water pump and distributor was both cam driven from the front cover of the engine. The LT1 also featured a unique harmonic damper design, which also incorporated a drive belt pulley.
In 2015 will be the first ever Corvette with Active Fuel Management (AFM). The two stage hydraulic lifters deactivate cylinders in light load applications offering 26 mpg.
Under Other GM Hoods
at the rear cam bearing journal that drives the high pressure pump. Because of the “tri-lobe” design being at the rear of the camshaft, the high pressure pump is mounted in the rear of the engine valley between the cylinder heads and underneath the intake manifold. Pressure by the direct injection pump can reach as high as 150 bar (2175 psi). With the direct injection pump mounted in the rear of the valley of the engine between the cylinder heads below the intake manifold. The intake manifold is a “runners in a box” design where individual runners inside the manifold feed a plenum box which offers efficient high velocity airflow.
it from the LS family. The new LT1 features an aluminum block with a 4.060” bore and a 3.62” stroke to yield 376 cubic inches. The LT1 now features direct injection, AFM (Active Fuel Management), Continuous Variable Valve Timing, and a new combustion system that incorporates 11.5:1 compression ratio. The new LT1 has underwent many hours of research and development (over 6 million) and incorporates features from major advances in state of the art technology such as 3-D fluid dynamics, flame propagation analysis, and multiThe direct injection pump is linked cylinder comto the injectors by a common rail, bustion testing. which has the capability of injecting The LT1 comfuel into the cylinders at 2,175 psi. Out of the Shadows bustion system The LT1 would go into hiding again is the most infor another 18 years. Now, for the tensely analyzed, developed, and opAcoustic foam is then wrapped 2015 Corvette, the LT1 returns withtimized system in GM history. around the outside of the intake out a hyphen to bring about change In simple terms, direct injection is manifold which helps suppress noise and to raise the bar in performance where highly pressurized gasoline is from the direct injection pump. again and be known as the GEN 5 injected into the combustion chamBolted to the intake manifold is an small block. Even though the engine ber of each cylinder instead of conelectronically controlled 87 mm design is derived from the LS platventional muti-port injection that throttle body with “contactless” form, there are several variables of takes place in the intake tract. The throttle position sensor for more acthe new engine design that separate advantages of direct injection are incurate throttle control. creased fuel efficiency and power Following the Trends output along with lower emisAFM (Active Fuel Management) will sions. The direct injection system be the first ever offered for the for the LT1 utilizes a high-presCorvette. sure fuel pump that is feed by the AFM saves fuel by shutting down in-tank fuel pump and driven by half the engines cylinders. Two stage the camshaft. The camshaft of the hydraulic lifters deactivate cylinders LT1 is in the The LT1 camshaft has a cam during light engine load operation same position phaser driven by the timing and will reactivate when driving as the GEN chain at the front and a “tri-lobe” conditions demand full power. Firing 4(LS3) small design at the rear bearing order of the engine is 1-8-7-2-6-5-4-3. block and feajournal used to actuate the direct The deactivating lifters are placed on tures a “triinjection pump. cylinders 1-4-6-7. So at light load lobe” design The LT1 was produced from 1992 through 1997 and was also an RPO option for the Camaro and Firebird starting in 1993. The engine still remained 5.7 liters with 4.00” bore, 3.48” stroke, 5.7” connecting rods with 10.4:1 compression. The engine block was cast iron and also came with four bolt mains. The LT1 package produced 300 hp at 5000 rpm. Later in 1996, a high performance version of the LT1 was introduced for the Corvette known as the RPO code LT4. The LT4 featured a more aggressive camshaft, 1.6:1 rocker ratio, and higher flowing cylinder heads which produced 330 horsepower and 340 ft.lbs of torque.
22 March 2014 | High Performance Buyers Guide