Performance Parts - Dyno Thrashin'

We Bust Out the Wrenches & Bust a Few Knuckles in Search of Bolt-On Horsepower

John Nelson Mar 28, 2008 0 Comment(s)
0804chp_05_z Bolt_on_manifold 1/15

Intake Manifold
The bolt-on
We followed up the rocker swap with an Edelbrock Performer dual-plane aluminum intake. $120

The mule
The '70 Chevelle now fitted with the Lunati rocker arms. Power measured at the rear wheels.

Our take
The Performer intake flows more air than the portly factory iron piece. Equally important is that its more modern design evens out the airflow between cylinders. Both factors lead to a nice increase in power.

0804chp_04_z Bolt_on_roller_rocker 2/15

Roller Rocker Arms
The bolt-on
Lunati Voodoo 1.6:1 roller rocker arms. $338

The mule
A bone-stock '70 Chevelle SS convertible powered by an RPO L65, 9.0:1-compression 350 small-block, which came factory rated at 250 gross horsepower and 345 lb-ft of torque, running through a Turbo 350 trans. The only modification was a 21/2-inch dual exhaust system with turbo mufflers. Power measured at the rear wheels.

Our take
Some of the increase undoubtedly came from the extra lift provided by the rocker arms, but Lunati's James Humphrey told us most of the gain likely came from the decrease in valvetrain friction achieved by installing full roller rockers in place of the factory stamped-steel pieces.

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