Fuel Injection Specialties

Telephone: 210.654.0774
Fax: 210.654.1444

LT1 / LT4 / LS1 ENGINES

LT1 ENGINES

GM's Generation II LT1 engine was introduced in 1992 and first appeared in the 92 Corvette. This engine incorporates a number of innovations not previously seen with the quite popular small block V8. Among these are Optical Spark Control (OPTI-SPARK) and a gear driven water pump. The distributor has been relocated to the front of the engine and the watflow has been reversed as compared to the original small block V8 introduced in 1955.

The drivetrain for 92 included the familiar 700 R4 automatic. The ECM looked identicle to its predecessor, but actually was quite different. The LT1 engine uses an optical spark control system. The distributor incorporates a disc with 360 small holes through which a beam of light is passed, generating electronic pulses. These pulses are counted by the ECM which then fires the spark plugs with much greater accuracy. Base timing is preset when the distributor is installed. Spark advance is controlled by the ECM which monitors the distributor and other engine sensors to determine optimum timing parameters for all load conditions. The information exchanged between the ECM and distributor are not compatible with the earlier HEI magnetic style pickup distributors.

Some of the engine parts can be interchanged with the earlier small block. Among these are the camshaft (92-94 only), the 95 cam has a steel pin which drives the water pump instead of the 92-93 gear drive. The pistons, piston rods, oil pump, crankcase, valve covers, exhaust manifolds, rear oil seal, flywheel and valve train components are interchangeable. The block, heads, timing cover, water pump, timing gears and intake manifolds are not. Accessory mountings such as power steering pump, alternator, AC compressor and harmonic balancer cannot be interchanged. The A.I.R. compressor for emissions is now an electric air pump. The harmonic balancer is a two piece assembly and is the same on the Camaro, Pontiac, Caprice, but different on the Corvette.

There are also some differences between engines in the Corvette, F Body cars, and the Caprice. The Corvette has 4 bolt mains and cast pushrod guides in the aluminum heads. The F Body cars and Caprice have 2 bolt mains. The F Body cars have aluminum heads and the Caprice has cast iron heads.

As you can see the engines, while similar, are quite different than the original SB V8. If you are planning to install a LT1 engine in an earlier model Chevrolet you will find that it will bolt into place with the same engine mounting and that it will also bolt up to any transmission built for a small block V8. Be prepared to change all accessory mounts and accessories ie., AC compressor, alternator, power steering pump, related pulleys and belt tensioning components.

1994 LT1

In 1994 GM introduced sequential port injection for the small block V8. While the engine is essentially the same, GM replaced the "plug in" EPROM "CHIP" with Electrically Eraseable Programmable Read Only Memory (EEPROM). You can no longer install a performance chip in these computers which are now referred to as Powertrain Control Modules or (PCM). These PCM's also electronically control the transmission in addition to engine fuel management functions. The Mass Air Flow Sensor is back in 94. The LT1 also has a MAP sensor. This setup should enhance engine performance significantly. There are also a number of subtle changes which complicate engine swaps. With the new electronic transmissions, the Vehicle Speed Sensor (VSS) is now a Hall effect transfuse which has replaced the pulse generator used in the earlier models.

The new electronic automatic transmissions control shift points (RPM related), hydraulic pressures (firmness of shift). The 95 4L60E incorporates a pulse width modulated signal to control the lockup of the torque converter (seamless transitions).

1995 LT1

The 95 LT1 now has a vent on the distributor to minimize the possibility of condensation forming inside the distributor as a result of a cold water splash, due to its new location in front of the engine. The distributor is now driven by a dowel pin fitted to the front of the cam shaft. The distributor has a modified electrical connector and will not plug into an earlier harness.

1996 LT4

The 96 Corvette, last of the C4 body style, was introduced with a LT4 engine option, available only with the 6 speed transmission. The engine is rated at 330HP/340lb ft Torque. There are a number of performance modifications incorporated in this engine. Modifications include 2.00" Intk, 1.56 Exh Valves, a camshaft with enough overlap to eliminate the requirement for a EGR valve, Higher Compression heads (10.75:1), 1.6 aluminum rocker arms, and sodium filled valve stems. The Red Line is now 6200 RPM. We flowed the heads on the LT4 and found them to flow 240 CFM as compared to the LT1 heads at 195 CFM.

1997-XX GEN III LS1

The Corvette aluminum block LS1 345HP(5600RPM) / 350lbs-ft(4400RPM) of torque is the 3rd generation small block. The engine features cross bolted (6 bolt) main bearing caps, aluminum cylinder heads (10.1:1 CR), a hollow hydraulic roller cam, 3.9"bore x 3.62 stroke, tuned composite intake, individual ignition coils for each cylinder and a roller timimg chain. FIS has harnesses and calibrations available for these engines for any retrofit application.

The 98 plus F-Body cars have a LS1 engine option, this engine is almost identical to the Corvette but is rated 305HP at 5200 RPM and 335 lbs ft Torque at 4400. The engines are identicle with the exception of Accessory mounting and emissions components. A forced air package on the F-Body cars increases this rating.

FIS offers electronic packages for both Full Emissions and Off Road (no emissions) applications.

FIS has LS1 engines in stock Complete Engine: All Accessories - Starter / Alternator / PS Pump / AC Comp / 4L60E / Computer Programmed for your application and Harness Modified for your application. These are "pullout" engines from wrecked cars. Prices and mileage may vary.
Price $6995.00

99-XX GM Truck Engines
GM intoduced 3 Engines in 99 engines the LR4-4.8L, LM7-5.3L, and LQ4-6.0L engines These engines are very similar to the LS1 in design and performance characteristics. FIS is building harnesses for these engines.
Be advised that 98 and up GM trucks use a different VATS system. It requires a resistor key and key rotation sequence signal. The vehicle has a module that receives these signal and generates a pulsed code which is sent to the PCM to enable the fuel system.

LT1 CONVERSIONS

The LT1 as earlier mentioned will bolt into any vehicle previously fitted with a SB V8. The only mechanical problems will be adapting accessories such as AC compressor, Alternator and PS Pump. None of the earlier accessory mounting brackets will fit. The LT1 / LT4 will fit most Chevy V8 vehicles using the Corvette accessory mounting. We have installed LT1 / LT4 engines with F-Body accessory mounting in late model GM pickups, suburbans and Monte Carlo's, however, it required notching the frame on the passenger side to accommodate the AC compressor.

The F Body AC compressor is not interchangeable with the Corvette unit. The Corvette accessory mount seems to work very nice on most conversions. The cost for the accessory mounting bracket, pulleys, PS pump, PS reservoir, PS hoses, alternator, AC compressor, belt tensioner and related items to make the conversion to Corvette mounts is about $1500.00 for all new equipment.

FIS can build harnesses and furnish a ECM or PCM for virtually any LT1 / LT4 / LS1 transmission combination. The Vehicle Anti-Theft System (VATS) module used with the pass-key system can be deleted from all systems thru 95. The module must be installed on all Sequential Port Injection Systems (96 +). It is good to note that the 94 + PCM's can be reprogramed. This allows use of a PCM that was previously installed in a vehicle with a electronic transmission to be reprogramed for use with a standard transmission or any of the earlier automatic transmissions. Similarly, a standard shift unit can be reprogramed for use with a 4L60E transmission or any of the earlier automatics. FIS can reprogram these PCM's.

PCM CONTROL FUNCTIONS

There are a number of program changes that can be made to a LT1/LS1 PCM on the 94 + vehicles which can improve performance on the stock vehicle and also allow custom configurations for retrofits. Vehicles manufactured without speed rated tires are speed limited to 110 MPH. This can be removed by reprograming the PCM.

Configuration options from FIS Include:

OTHER PERFORMANCE AND OFF ROAD OPTIONS

All FIS Performance Camshafts render great driveabilty with significant horsepower increase. Engine idle approx 800-850 RPM no stalling with AC and Auto Transmissions. These cams have a distinctive lope but it is not excessive. Competition Cams grind all FIS cams.
  • LT1 Power Pack 1 (Horsepower Gain=75)

    OR

  • LT1 Power Pack 1A (Horsepower Gain=75)
  • LT1 Power Pack 2 (Horsepower Gain=90)
  • LT1 Power Pack 3 (Horsepower Gain=130)
  • LT1 Power Pack 4 (Horsepower Gain=220)
  • 1998 LS1 345HP Engine (Call for price)

    (New In Crate)
    Includes the following:
  • LS1 Conversions

    The following items are presently available:

    1. LS1 Harnesses are available for installation in any vehicle.

    2. VATS bypass for LS1. 

    3. Harness Conversions ie.:
       LS1------>Camaro / Firebird / Pickup trucks / Suburban / Caprice
    4. Programming for LS1 with / without / 4L60E.

    5. Accessory Mounting / Accessories ie., Alternator, PS Pump, AC Comp, Starter.

    6. Fuel Pump / Fuel Filter.

    7. Throttle cable. 8. Full Emissions and Off Road applications.

    If you're in San Antonio please stop by and say hello, or email us at fuelinjection@fuelinjection.com.
    Copyright © 1996-2005 Fuel Injection Specialties, 11051 Wye Drive, San Antonio, TX 78217
    Phone: 210.654.0774, Fax: 210.654.1444