WORLD Engine Castings-Complete Engines presents...

And while regular-production Hemi engines disappeared in the early 1970s, it was the racing community that kept it from dying out altogether. In fact, it flourished. Engine builders, racers and street enthusiasts created a healthy aftermarket for the second-generation 426-style Hemi, with countless aftermarket vendors and Chrysler’s own Mopar Performance arm offering parts and complete crate engines.

Recently, Mopar Performance released an updated version of the Street Hemi block that was co-developed with World Products. Known mostly for its Chevy-based Merlin big-block and MoTown small-block engine lines, the Ronkonkoma, N.Y.-based engine manufacturer applied its proven formula of strength-enhancing design to revamp the Hemi block. At a glance – and from all external measures – the revised block casting matches the original Street Hemi block. It’s on the inside, however, where the new block holds its enhancements.

In a nutshell, the new Hemi block has more iron cast in strategic areas to shore up strength and resist bending. The added material is packed around the cylinders, although the bore centers and deck height remain at the factory 4.800-inch and 10.725-inch specifications, so all factory-style cylinder heads and intake manifolds bolt on without a problem. The front and rear bulkheads are thicker than stock, for extra rigidity; and water and oil circulation is improved with this updated Hemi block design. The new block’s added girth allows for some truly epic displacements, on the order of 600 cubic inches or more. It is available with 4.250-, 4.500- and 4.600-inch bore diameters and can accept a crank with up to a 4.750-inch stroke (as along as an external oil pickup is used), giving a maximum displacement of an impressive 632 cubic inches.

A new feature of the block is a change in the design of the oil pick-up tube mount, which was repositioned and features a new, two-bolt flange that enables larger-stroke combinations. An adapter is provided for the original-style screw-in pick-up. Also, the oil circuit is improved. It feeds the rockers from both oil galleys, rather than the cam bearings.

While the block is available exclusively through Mopar Performance, World Products is almost ready with its own Hemi crate engines and short-block assemblies. We recently got a peek inside one of their prototype engines to see the ingredients they’re working with.

The engine is a 528-cube Hemi, using 4.500-inch bores and a 4.150-inch stroke. Of course, all of the internals are forged. They include Arias pistons – providing about 10.25:1 compression – connected to 6.86-inch-long Eagle rods, all swinging on an Eagle 4340-forged internally balanced crankshaft. The camshaft is a hydraulic roller with 0.524/0.543-inch lift specs.

Doing the breathing for the prototype engine is a set of Mopar Performance Hemi heads. No porting or any other enhancements were made for the test engine – just an out-of-the-box evaluation. A Mopar Performance dual-quad intake manifold straddles the heads and it is topped with a pair of Holley four barrels. All that’s missing is the iconic chrome Street Hemi air cleaner setup.

In order to make our deadline and get this story posted on the Web site, we weren’t able to take in any of the dyno test sessions, but a similar combination in the Mopar Performance catalog is rated at 610 horsepower and 650 lb.-ft. of torque. With the enhancements and tuning World Products clued us in on, we suspect their engine will top out in the 650-horsepower range and make around 675 lb.-ft.

The caveat to all this is that our glimpse at World Products’ Hemi was with a prototype engine. Some details are bound to change during testing. An enthusiast’s best bet is checking with them on their Website worldcastings.com, or giving them a call: 631-981-1918.

Perhaps the most encouraging aspect of this story isn’t the crate engine itself, but the possibilities the new Hemi block delivers. With an extra-strong block casting, huge displacement capabilities and a 45-year heritage of performance to back it all up, we’re looking at a new golden age of Hemi performance.

Oh, and did we forget to mention the block is also available in aluminum? Well, there’s that, too!