25
hood profile for the Z06. There is
another issue related to the overall
package size of the LT4: the engineers
had to take pedestrian protection
regulations in Europe, which specify
the distance between the top of the
engine and the hood.
The LT4 features a cast-aluminum
block. The crankshaft is 1528MV
forged steel; it features tungsten
balancing inserts. The damper is
forged 6061 aluminum with a T6
anodized hub and iron inertia ring. The
6.125-in. connecting rod is produced
with powder metal steel. The forged
aluminum pistons feature a flat-top
crown and internal ribs for strength.
The top piston ring is PVD-coated.
The floating piston wrist
pins have a diamond-like
coating.
"Our objective when
developing this
engine," Jordan Lee,
chief engineer and
program manager,
GM Small Block
Engines, "was
to create ultimate
horsepower and
torque, to help make
the most capable Corvette
ever."
*The 8L90 is also used in the 2015 GMC Sierra,
Yukon and Yukon XL and the Cadillac Escalade
and Escalade ESV.
t The LT4 V8 for the 2015 Corvette Z06. This supercharged
engine produces 650 hp @ 6,400 rpm and 650 lb-ft
of torque @ 3,600 rpm. It is one of the most powerful
production engines available in the U.S.
p The tops of the forged aluminum pistons are
comparatively flat. The compression ratio is 10:1.
The fuel injectors, which operate at 25 cc/second,
produce a unique spray cone that optimizes
combustion under boost.