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Although the Chrysler
HEMI was born in the 1950s and entered into legend in the 1960s and
'70s, today's version took much of its inspiration from the
original-particularly the namesake hemispherical combustion chambers
that provide power and efficiency.
When SRT powertrain engineers set out to develop a more powerful
HEMI for the Chrysler 300C SRT8, they were mindful of the engine's
heritage, which led to adopting traditional HEMI engine cues
including an orange-painted cylinder block and black valve covers.
SRT engineers who developed the Chrysler 300C SRT8's engine achieved
more horsepower by adding more cubic inches, increasing the
compression ratio, and redesigning the cylinder head, intake and
exhaust systems for better flow and increased engine speed.
For more displacement, SRT engineers bored out the diameter of the
cylinders in the HEMI by 3.5 millimeters each in order to increase
the total displacement to 6.1 liters from 5.7 liters.
Compression ratio was also increased to 10.3:1 from 9.6:1,
increasing engine efficiency and power.
Engine breathing was increased with new higher-flow cylinder heads,
a specially designed intake manifold, and exhaust headers with
individual tubes encased in a stainless steel shell, all unique to
the 6.1-liter HEMI engine. Larger-diameter valves and reshaped ports
in the heads allow for maximized air flow. The intake manifold was
designed with larger-diameter and shorter runners for higher-speed
tuning. Exhaust is routed through a large-diameter (2.75-inch vs.
2.5-inch) exhaust system with 3.5-inch chrome tips.
To further increase horsepower, performance-oriented camshaft
profiles were developed to allow more air in and out of the
cylinders, as well as manage a higher engine speed. SRT engineers
increased the HEMI's peak power output engine speed by nearly 20
percent to 6,000 revolutions per minute (rpm) from 5,000 rpm. Intake
and exhaust valve stems are hollow, and the exhaust valve stems are
filled with sodium to help dissipate heat more efficiently.
The high-performance SRT 6.1-liter HEMI is strengthened with
redesigned components, including a reinforced engine block, forged
steel crankshaft, high-strength powdered-metal connecting rods,
floating-pin pistons (cooled by oil squirters), and an oil pan
modified to manage oil return to the pan sump at high engine speeds.
Power for the SRT 6.1-liter HEMI is channeled through a five-speed
automatic transmission with specially calibrated driver-selectable
AutoStick®, which offers fully automatic or manual shifting
selection. A heavy-duty four-flange prop shaft sends the torque from
the transmission to an upgraded differential and axles. |
