Using a test engine from the previous Speed Secrets: Single Pattern Camshaft Test, Richard Holdener and Comp Cams run the 420ci Stroker SBC with a Turbo to see how two of those single plane cams handle some boost. To recap, the team ran a complete mild to wild single pattern camshaft test on the Stroker Small Block Chevy featuring an aftermarket block with a 4.155 inch bore and 3.875 inch stroke. The SBC was topped with a set of Brodix aluminum 235 heads and a matching single plane intake, and because it was designed for boost, it had a low 8.5:1 compression ratio.
The team installed a mild Comp camshaft with a .526 lift, 210 duration, and 112 LSA. Equipped with the smallest of the camshafts, the engine made 467 HP @ 5,300 RPM and 495 Lb-Ft of torque @ 4,400 RPM. Removing the rockers and intake, Richard and the Comp team then remove the lifters, front cover, timing chain, and cam button and installed a medium Comp camshaft with a .551 lift, 232 duration, and 113 LSA. With a total peak power output gain of 41 HP, the SBC made 508 HP and 505 Lb-Ft of torque. However, there was a trade off. A loss in some torque below 4,000 RPM.
To be thorough, Richard then installed a twin 76mm turbo setup with a blow through carburetor and hat, and repeated the test. Equipped with the first camshaft and twin turbos, the SBC Stroker made 658 HP and 677 Ft-Lb of torque with a peak boost of only 5.7 PSI. With the wilder of the two cams the engine produced 714 HP and 691 Lb-Ft of torque, for a total of 56 HP gains over the same setup with the milder of the two cams. Remember, from the original test the medium camshaft already gave the SBC Stroker a gain of over 40 HP, meaning the original gains were more than multiplied with the presence of boost.
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