Lingenfelter LTCC - Manual (Page 3)

The OptiSpark Story
A Brief History
In 1991, General Motors Chevrolet Division introduced the 1992 Corvette with the
Second Generation Small Block, designated by RPO code LT1. The LT1 was used
exclusively in the Corvette until the 1993 model year, when it branched out into the
new forth generation Camaro and Firebird, commonly referred to as F-Body cars, and in
1994, the GM B-Body, full sized rear drive sedans (the Chevrolet Impala SS and
Caprice, Buick Roadmaster and Cadillac Fleetwood).
Based on the venerable Chevy Small Block that was originally introduced in the 1955
model year, this version was the most heavily reworked yet. The bottom end is
essentially the same as in the outgoing L98, but the heads, cooling, intake, ignition,
and output were much different. The last L98 produced 250 hp, the LT1, 300 hp.
Also unique to the LT1 is the reverse flow cooling system. The coolant goes through the
heads then to the block, returning to the radiator. The idea is simple – cool the heads
first will cut down on detonation. A unique facet of this system is the direct camshaft
drive water pump, hence the ability to operate without a belt.
In 1996, in the last year of Corvette production, the LT1 was augmented by the LT4.
The LT4 was a special, high output version of the LT1. It had unique heads, with roller
rockers, unique intake manifold and camshaft. It all added up 330 hp. The LT4 was
available in the Corvette, with the mandatory ZF 6-speed manual transmission. The LT1
was available only with the automatic.
In 1997, the LT4 was used in a limited number of special edition Camaro Z28 SS’.
At the end of the 1997 model year, the LT1/4 was retired, and with it, the last
connection to the original Small Block Chevy engine. All that the LS1 shares with the
LT1 and predecessors is bore center. Nothing else mechanical is compatible.
A word of caution, there are several versions of the LT1 engine. To a novice, they all look
like an LT1, because of the OptiSpark and water pump placement. This cannot be
further from the truth! The table below outlines the differences.
Cubic
Inches
Horsepower
SAE Net
Heads Mains Years Usage
265 165 Iron 2 bolt 1994-1996 Base Caprice
350 185 Iron 2 bolt 1994-1996 Caprice, standard on the
other GM sedans
350 265 Iron 2 bolt 1994-1996 Impala SS
350 275 * Aluminum 2 bolt 1993-1997 F-Body
350 320 Aluminum 2 bolt 1996-1997 F-Body specials
350 300 Aluminum 4 bolt 1992-1996 Corvette
350 330 Aluminum 4 bolt 1996 Corvette and some F-
Bodies in 1997.
* In 1995, there was a minor change in the exhaust that upped power to 285.