A signature characteristic of the Chrysler Hemi is the rocker arrangement featuring separa
Beck handled machining the factory ’56 Chrysler early Hemi block, installing a 3.825-inch stroke Bryant billet crankshaft, filling the 4.015-inch bores with custom Ross pistons for a displacement of 388 ci. The internals are linked by Pauter rods, and Federal-Mogul bearings were used throughout. Beck relates that the short-block assembly was relatively straightforward: “Assembling the bottom end was academic, really, once the deck height was set and the piston-to-head clearance was worked out.” The high-dome Ross pistons were drilled for gas ports to load a .043/.043/3mm Total Seal ring package, and were targeted at producing massive squeeze. The compression ratio of the completed engine assembly topped 15:1. Beck disclosed that this setup was not without its compromises: “The piston dome proved to be just too high, and it compromised flame travel. A shorter dome and less ratio would have likely resulted in better combustion efficiency and more power.”
The four-hole Hilborn injection and Hot Heads manifold comprise an induction system that w
The camshaft choice was on the large side of extreme, with a custom Engle solid-roller profile that measured 280/280 degrees duration, with a whopping .950-inch lift on the intake, and .750-inch on the exhaust. The very high intake valve lift was courtesy of the 1.9:1 ratio of the Rocker Arm Specialists rocker arms. The combination did present some problems, as Beck described: “We found the high lift was really hard on the valvesprings, and maintaining the lash adjustment proved problematic. We developed a routine for readjusting the lash after every few pulls.” There was little doubt that these guys were pushing the limits in regard to valve opening intensity, and as a result the entire valvetrain was being tortured to the bone.
With time being a critical factor in making the 2011 AMSOIL Engine Masters Challenge event, there was little time for ongoing cylinder head development. The team largely carried over the cylinder heads from Dan’s previous competition engine. The Hot Heads castings featured Ferrea 2.200/1.750-inch valves with peak flow in the mid 300-cfm range. Holmes relates, “Several different people worked on the heads over the previous few years, including Gene Adams and fellow Engine Masters competitor Brett Miller. The big focus was on the induction system, ram tubes, and EFI.”
Inside the induction tract the manifold and injector are divided to effectively create eig
The task of working out the elaborate induction system was put into the capable hands of Smithberg. Smithberg literally shut down his shop and focused entirely on the development of this one-of-a-kind induction. Starting with a Hot Heads manifold mated to a four-hole Hilborn injection unit converted to EFI, the components underwent intensive internal modifications. The result was to effectively create an individual-runner induction. Inside the Hot Heads manifold, the plenum area was epoxy-filled to transform what would normally comprise the plenum into eight runners right up to the injector base. From there, the four-pot Hilborn was bisected vertically along the axis of the throttle shafts, effectively creating eight separate induction paths once the throttles were fully opened. The throttle plates actually nest into the divider wall above and below the throttle plates at wide-open throttle, presenting one streamlined surface to incoming airflow.
Nick Smithberg of Smithberg Racing worked to size the manifold’s runner cross-section and
Topping the Hilborn unit are the air horn stacks, which beyond their airflow capabilities, qualify as works of art. These units were the creation of Smithberg, who explains, “I believed there was room for improvement in the design of the stacks, and decided that an elliptical shape would be optimal. There was also the consideration of injector placement and angle, two design aspects we experimented with. The steep injector angle required a thick stock to CNC-machine the finished pieces from. Luckily, I managed to find a very thick-walled aluminum tubing to have them machined from.” Smithberg tells us the divider wall configuration was critical to making the system function as an individual runner induction, “There was cross talk between the runners that made the tune very uneven in terms of cylinder-to-cylinder distribution. The final arrangement of the divider and injector placement isolated the runners and eliminated that problem.”