As you can see, a head swap does a lot for horsepower. Horsepower is up 17.8, and torque is up 6.3 lb-ft. We're convinced that this engine would create even more horsepower if pushed beyond 5,000 rpm. Because the engine's structural integrity is unknown, we've kept it conservative. We're more interested in the overall gains throughout our test. Since our baseline test, we've gained 37.1 lb-ft of torque and 47.9 hp. Call this an easy 50hp gain at the drive wheels-with aftermarket heads, an intake manifold, a 600-cfm carburetor, Hedman headers, National Parts Depot's Turbo 2-1/4-inch dual exhaust system, and super-tuning by Mike Morgan Motorsports.
So what does this tell us about aftermarket parts? It tells us that we should think of our modifications as a package for best results, then enjoy the benefits of power when the job is finished. Next month, we will round out this package with a more aggressive hydraulic camshaft from Edelbrock, along with one last trip to the dyno for good measure.