It's a great time to be part of the performance world. With a decent budget, a good long-block, and the right bolt-on parts, you can easily raise your engine's power level into the stratosphere. We wanted to see how much extra power we could uncover from our pal John Barkley's 391small-block. A few years back, he assembled a long 3.82-inch-stroked Eagle crank and a 0.030-inch-over 350 block to power his street-driven '71 Camaro. This existing combo included a seasoned set of AFR 190 cylinder heads atop a good dual-plane intake manifold, and a 670-cfm vacuum-secondary carburetor. To actuate the 2.02/1.60-inch valves, Barkley had stuffed in a hydraulic roller camshaft with 217/225 degrees duration at 0.050 inch lift with 485/505 inch valve lift.
The engine provided reasonable performance, but Barkley wanted hordes of steam because he'd recently acquired an '80 Camaro that he wanted to race as a bracket car. Since the Camaro was equipped with 4.88:1 rearend gears, he wasn't really concerned with low-speed drivability but rather with midrange to top-end power. This meant his camshaft, intake manifold, and carburetor would need to provide increased breathing at higher engine speeds.
So with a pencil and pad, he mapped out a big power combo to transform his mild 391 into a heavy-breathing powerhouse. At the heart of his plan was a very stout solid roller camshaft from Lunati with lots of lift and duration. Since he wanted to move the powerband up, he decided to put the proven dual-plane manifold on the shelf and chose a Holley Strip Dominator intake manifold featuring a large open-plenum and big runners for strong power above 4,500 rpm. To provide fuel, Barkley thought either a Holley 830 HP or 950 HP carburetor would do the trick. Now all he needed was some dyno numbers.
Once the performance goodies were in hand, we followed along as Bob and George Vrbancic of Vrbancic Bros. Racing in Ontario, California, bolted on the parts, fired up the dyno, and recorded where the power needles stopped. After a day and a half of testing and tuning the 391, the dyno recorded an impressive gain, from 411 up to 537 horses. What's more, this was all done for about $2,700. Lots of power for a reasonable amount of dough. That's a pretty solid plan.