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LT1/LT4 Engine

Updated: 12/07/08

'92 - '93  GM's generation II engine, the LT1, was introduced in '92 in the corvette and was rated at 300hp. In 93 the new 4th gen F-body arrived with the LT1 rated at 275hp.  There are some significant differences between the new engine and earlier small blocks.  Among them are the opti-spark distributor located on the front of the engine behind the gear driven water pump and crank balancer.  The block, heads, timing cover, water pump, intake manifold and accessory brackets are not interchangeable with the earlier smallblocks.   Engine mounts and the bellhousing pattern remain the same.   There were early and later versions of the aluminum head.  The early head had a casting number of 10128374 and the later head had a casting number of 10128649. 
    The LT1 is reverse flow cooled meaning the water flows through the heads first then the block, instead of through the block and then the heads as is standard. Reverse flow cooling is a function of engine design and does not require a special radiator. An overflow tank is necessary to ensure there is no air in the system.
    There are some differences between LT1's.  The Corvette got 4 bolt mains and Aluminum heads.   The F-body cars got 2 bolt mains and aluminum heads.  The '94 - '96 Buick Roadmaster, Cadillac Fleetwood, Chevrolet Caprice, police cars and the Impala SS got the 5.7L with 2 bolt mains and cast iron heads and was rated at 265hp.  There was also a 4.3L LT1 available in the big cars which is indistinguishable from the 5.7L, except for the different casting number and 4.3 cast into the top of the block just ahead of the bellhousing flange.

'94  Sequential Port Injection introduced this year.  The new computer has a PROM that is not removable but can be reprogrammed.   A mass airflow sensor was added to work with the map sensor still in use. 

'95  A drain tube was added to the distributor to remove condensation buildup.  The distributor has a new electrical connector which is not compatible with the earlier      harnesses.  The distributor drive was enlarged and will not interchange with '92 - '94 LT1s. 

'96  The LT1 picked up 10 extra HP in the F-body cars with the addition of a second catalytic converter.  OBD II makes its debut this year.  A Crank Position Sensor is added.  The LT4 is introduced as an option in the Corvette only and was rated at 330hp.  A few of the supertuners offered special editions of the F-body cars with LT4's in them apart from the factory.

'97  The last year for the LT1 and available only in the F-body cars.  The new C5 or fifth generation Corvette came equipped with the new third generation smallblock; an all new, all aluminum 5.7L with no resemblance to the 1st or 2nd generation small blocks.


LS1 Engine

'97  The LS1, GM's generation III all aluminum engine makes it debut in the Corvette rated at 345hp.  The LS1 has a deep skirted all aluminum block with 6 bolt mains.  This block is 53 lbs. lighter than the LT1's block.  The aluminum heads have equally spaced tall, narrow ports which allows the injector spray to be aimed directly at the back of the intake valve.  The composite intake has a low mounted plenum with the 15" long runners curving smoothly over the top of it.   The LS1 uses a crank fire distributorless ignition system with one coil per cylinder.   Corvette uses an electronic throttle while the V8 F-body uses a conventional throttle cable setup. The new Corvette uses a rear mounted transaxle which is connected
to the engine by a torque tube, instead of using a conventional transmission.

'98  LS1 is introduced in the redesigned 4th gen F-body and is rated at 305hp.  The LS1 engines used in the Corvette and the F-body are essentially the same with only minor differences.  The Corvette has coil covers, different exhaust manifolds and the alternator mounted high on the left side requiring a remote power steering reservoir. The Corvette LS1 has a slightly different camshaft profile which allows the engine to meet emissions requirements without using an EGR valve.   The F-body has exposed coils and the alternator mounted on the left side below the power steering pump with integral reservoir.

'99  Minor changes in the head and valve cover.  Coils are now mounted on a bracket bolted to the valve cover as one unit instead of individually.  Valve covers have center hold down bolts instead of the '97-'98 perimeter bolts.

    The new Vortec V8s available this year are versions of the LS1 engine found in Camaros and Corvettes.  The truck engines have a cast iron block with aluminum heads and a different intake manifold with the plenum above the runners.  The truck LS1 variations are available in 4.8, 5.3 and 6.0 liters.  The exhaust manifolds are cast iron and the alternator is mounted high on the left side above the power steering pump with integral reservoir.  The A/C compressor is mounted low on the right side like the LS1. The Vortec V8 transmission will bolt up to the Camaro and Corvette engines.

'00  F-bodies receives cast exhaust manifolds. 

'01  F-bodies received a new cam profile which allowed removal of the EGR valve.
         2001 and 2002 F-body receive the ZO6 intake manifold.
         LS6 version of the LS1 available in the Z06 Corvette 385hp. 
         Corvette LS1 rated at 345 hp

'02  Corvette LS6 receives 405hp
         Last year for the F-bodies. 

'03  No notable changes for this year

'04  New Australian built GTO introduced.  Powered by a 350 hp LS1.
         Available with 4L65E or T56 Transmission and a independent rear with 3.46 rear gears
         GTO uses a front sump oil pan
          Cadillac CTS-V introduced with the LS6 engine and T56.

LS2 Engine

'05  6.0 Liter LS2 engine introduced, rated at 400 hp and 400 ft lbs of torque. 
         LS2 base engine for Corvette, Chevrolet SSR and Pontiac GTO.  C6 Corvette introduced.

 '06  LS2 introduced in Cadillac CTS-V and Trailblazer SS.  New Corvette ZO6 has a 7.0 Liter LS7 engine - 427 cu in
          Rated at 500 hp and 475 ft lbs of torque using a dry sump oil system

 '07  No significant changes

LS3 Engine

  '08  6.2 Liter LS3 engine introduced, rated at 430hp and 424 ft lbs of torque. 
            The new heads have shorter more square intake ports similar to the LS7.

'09  De-rated to 402hp version of the LS3 used in the Pontiac G8 GXP sedan.  New ZR1 engine introduced, a 6.2L Supercharged
         and intercooled engine with 620 hp and 600 ft lbs of torque.

  '10  The new Camaro will have two V8 engines available, the 1SS V8 will be the L99 which is a 400hp 6.2L
            with Variable Valve Timing, Active Fuel Management and only with an Automatic Transmission.
            The 2SS V8 will have the LS3.


LT1           Horsepower                Torque

F-body         93 – 95        275                       325

                   96 – 97        285                       325

Caprice         94 – 96        260                       330

Corvette       92 – 96        300                       340

LT4              96                345                      


LS1           Horsepower                Torque

F-body         98 – 99        305                       335

                   00                320                       345

                   01 – 02        325                       350

Corvette       97 – 00        345                       350

                   01 – 04        350                       375

LS6              01                385                       385

                   02 - 04         405                       400


LS2           Horsepower                Torque

                   05 - 06         400                       395

LS3           Horsepower                Torque

                   08 - 09         430                       424

LS7           Horsepower                Torque

                   06-09           505                       475