The Gen III Hemi was unveiled to the world in 2003 in Dodge's Ram pickup trucks, and we didn't yet know what to make of the clean-sheet-of-paper engine design. Well, we now know that this is one bad dude. It's mean enough that the stock heads are capable of making a true 700 hp on 91-octane pump gas, as Tony Bischoff's 417-cube engine recently did at the 2010 AMSOIL Engine Masters Challenge. It's tough enough that even the stock head and main bolts were used to capture the 621 lb-ft of torque the mill was twisting out.
Nothing says sexy like a set of dual-plug Hemi heads!
In a recent conversation with Bischoff, PHR learned a little history as to what lead the NMCA record holder to choose the late-model Hemi as his platform for the EMC: "Two things really. One, we do a lot of short-blocks and cylinder heads for HHP [High Horse Performance] and they've been pushing me to do it. Two, per the rules, with the hydraulic roller cam rule and .650 lift, and the powerband of 2,500-6,500, I honestly thought it was the best engine for the job. Small bores and big strokes work really good when you're talking about a low powerband and broad rpm range."
Bischoff started his small-bore/big-stroke combination with a stock cast-iron 5.7 block that was treated to a half-fill of Hard Block to stabilize any potential cylinder movement due to the engine making twice its original horsepower. "We've done a lot of the 426s that guys put superchargers and turbos and nitrous on, and at least from the mains' standpoint and even the cylinders, even though they're pretty thin, they actually hold up really well." Similar to the Hemis of yesteryear, the Gen III takes advantage of cross-bolted mains and a full-skirted block to house and stabilize the crankshaft.
The BES Hemi's dual plugs are fed by a set of dual high-output 10-amp coils. Bischoff said
The cylinders were bored and torque-plate honed to match a set of Ross pistons designed specifically for Bischoff. "They have a real neat inboard pin boss forging that they use that actually runs real well. The only problem with the motor combination that we had, and that we had to kind of compromise on, was that because we had such a large stroke and only a 6.125-inch rod, it ends up with a compression height of under 1 inch. To run a camshaft that is in at 102 degrees, because of the Hemi design, the valve ends up almost in the ring land. We had a ring land that was only 20-thousandths thick between the ring land and the valve pocket. The farthest we could advance the cam was 102 degrees to make it fit together, and we actually had to sink the valve into the head .070 inch to make that fit together. That was kind of a challenge." On the other end of the difficulty scale, the Bischoff Engine Service team used an off-the-shelf Sealed Power ring pack for the pistons. "It's designed to be put in your everyday
The crankshaft used was a K1 piece with a 4.25-inch stroke that is commonly used in "440" Gen III combinations. It was matched with a set of K1 H-beam rods and Mahle/Clevite bearings to finish off the rotating assembly.
A Chevy-style crank trigger bolts right up to the late-model Hemi, thanks to the fact that
Innovators West provided the harmonic balancer for the engine using a trick-looking CNC-machined aluminum housing and a unique inner structure. The damper houses spring-loaded inertia rings that work in conjunction with friction clutches. Fluid inside the damper acts as a lubricant for the clutches and does double duty dissipating heat.
On the rear end of the crank, an SFI-approved flywheel connects the shaft to the dyno; however, for enthusiasts interested in seeing an engine like this in an actual hot rod, Chrysler conveniently designed the bellhousing with the same bolt pattern and size as the old-school small-block LA engines. So with a crankshaft adapter and a kick-down cable like the ones available from Buchillon Performance, it is entirely feasible to hook one of these up to an early style tranny that might be residing in your "muscle generation" car.