Dyno Test 4
The review of the dyno graphs showed a more linear power curve and also a substantial gain in upper rpm power with more grunt down low at the same rpm. Would it be possible to still get more power from the 496ci? Brulé had one more trick up his sleeve and re-installed the original Ultra-Gold rocker arms from our baseline configuration. Here's why; in a nutshell, we've changed the combination to a lightened valvetrain assembly and we could benefit from additional weight savings with the aluminum. Hydraulic vavletrain components benefit from lightweight pieces since it acts like an increase in the spring pressure without jeopardizing the lifter-it could collapse under too much pressure. To Brulé's credit, we were happy to find another increase in power and a smoother power curve throughout the rpm.
What's It All Worth
To recap, we began with an excellent turnkey motor for the street. 496 ci is plenty big for hauling groceries around town, but this motor will also be spending a lot of time at the strip. It's important that the motor rev high enough and take full advantage of its valvetrain and cubic inches. Taking advantage of Comp's tech line, it was explained to us that the valvetrain components that come assembled with the RHS 320cc cylinder head will satisfy your average daily driver and weekend warrior when matched with the original hydraulic roller lifters (PN 854-16) and cam (PN 11-602-8) to its rated 6,100 rpm. Comp continued to explain that it's when you start asking more (above 6,100 rpm) from the combination that it will not suffice. Hence, the reason behind swapping to stronger springs, titanium retainers, and "R" series lifters. While it's difficult to illustrate how quickly the motor will rpm on the dyno, we are confident the driver will certainly feel it in the car. With the newer lightweight components, the engine will pull harder, faster, and stronger to its shift point-ultimately landing the motor back into its sweet spot after the shift.
1. Big-blocks need fuel to burn. We planted a Holley 950 HP on top of the Weiand dual-plane manifold. We jetted the carb with 80/80 primary/secondary jets for the all of our dyno pulls.
2. Out of the box, these 24 degree RHS 320cc cylinder heads are a bargain at just $1,020 each. They come with a 112cc combustion chamber which keeps compression low for the street and also rectangular ports. Exhaust ports are raised 0.500 inches.
3. Our cam came with 243/257 degrees of duration at 0.050 and 0.570/0.554-inch lift (intake/exhaust). This cam is good for and rated to make power from 2,500-6,100 rpm.
4. Joining our valvetrain is a set of Ultra-Gold rockers. The set only costs $273 and keeps the factory 1.7:1 ratio. These come complete with poly-locks and install on a 7/16-inch stud.
5. The foundation is a factory GM four-bolt main with steel caps and bored 0.060 inches over. SRP 4.310-inch pistons swing on an Eagle 4.250-inch stroker crank with 6.385-inch H-beam rods.