Jim Smart
January 1, 2001

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.

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Dyno Run No. 1
Baseline Test
rpm power torque
3,400 125.5 193.9
3,500 125.7 188.6
3,600 125.9 183.6
3,700 127.2 180.5
3,800 127.1 175.6
3,900 127.1 175.6
4,000 128.0 186.0
4,100 128.4 164.5
4,200 127.5 159.4
4,300 125.8 153.6
4,400 125.1 149.3
4,500 123.7 144.4
4,600 123.7 144.4
Dyno Run No. 2
Upgrade to Pertronix Ignitor
rpm power torque
3,400 126.3 195.0
3,500 127.6 191.4
3,600 129.3 188.6
3,700 130.0 184.5
3,800 131.0 181.0
3,900 131.1 176.6
4,000 130.7 171.6
4,100 130.6 167.3
4,200 129.6 162.1
4,300 128.7 157.2
4,400 128.7 152.8
4,500 128.0 147.9
4,600 123.6 141.2
Dyno Run No. 14
Edelbrock Performer RPM Heads
rpm power torque
2,600 102.1 206.3
2,700 117.6 228.7
2,800 122.5 229.7
2,900 127.2 230.3
3,000 132.0 231.0
3,100 135.8 230.1
3,200 139.7 229.3
3,300 143.4 228.2
3,400 147.0 227.1
3,500 150.4 225.6
3,600 153.3 223.6
3,700 156.7 222.0
3,800 159.3 220.0
3,900 161.4 217.4
4,000 163.5 214.7
4,100 166.8 213.7
4,200 168.5 210.5
4,300 170.1 207.8
4,400 172.1 205.4
4,500 173.5 202.5
4,600 174.4 199.2
4,700 175.4 196.0
4,800 176.1 192.7
4,900 176.3 189.0