What you see here is the much-anticipated, highly secretive, and oft-dreamt-about RHS LS Race Block. We won't go into the history of this block, but suffice it to say it is real, it is ready to ship, and it certainly delivers on all of its promises. The amount of time and thought RHS has poured into this block shows in every improvement, and believe us, there are many. This all starts with a massive amount of A357-T6 aluminum, which is eventually formed into one of two castings, a standard 9.240-inch block or, the much more interesting, 9.750-inch "tall deck" version. For the tall deck, you get a set of very long 6.38-inch sleeves, which are built specifically to minimize "piston rock" at the bottom of a long stroke, while still maintaining enough clearance for larger 4.600-inch stroker crankshafts. The press-in, spun cast-iron liners are surrounded by a full water jacket, which provides maximum cooling for the 4.125-4.165-inch bores. The tall deck also benefits from a very thick 0.750-inch deck, which can be configured to hold a set of standard head bolts or 0.5-inch ARP studs in a six-bolt configuration. With big cubes in mind (up to 502ci, as shown here) the engineers at RHS decided to move the camshaft up in the block (0.388-inch), which provides two major benefits. The first is the ability to run a large 4.600-inch crankshaft without clearance issues. The second, and more important, advantage is the ability to run a regular or (enlarged) 60mm camshaft, as opposed to the small base circle camshafts that a normal cam position block would require. Once you select a camshaft, the RHS block affords a number of lifter choices, including room to install oversized 1.060-inch bushings for keyed lifters. You will need to run a tie-bar style lifter, but enlarged lifter windows allow for an easy install and even the possibility of removing the lifters with the heads still installed.
Further inside the new block, you will find the improved and doweled main cap area, which has been built specifically to maximize the main cap surface area to prevent movement. Using billet mains and a smart design provides the additional benefit of improved bay-to-bay breathing and significantly improved windage control. For piston life, RHS has included the ability to run GM and RHS-specific piston oil coolers, a feature we find especially helpful. With a focus on longevity, the new block also features chilled main bearing bulkheads and an all-new, "no restriction" oil filter feed gallery. On the outside, RHS has spent a lot of time maximizing the block and its oiling. The most noticeable improvement is the outboard oil gallery, which ships ready to be used with either a dry- or wet-sump system. By moving the gallery outside of the block, RHS created a ton of room inside, further helping an engine builder maintain acceptable clearances when building these large strokers. Two -12 AN plugs are placed front and rear, which allow for an easy dry-sump installation. Owners of older-generation GMs will appreciate the multiple engine mounts, which allow them to use either traditional small-block Chevy mounts, or the newer Gen III/IV mounts. Of course, for the hard-core racer using a motor plate, RHS has included two boltholes on the front of the block, which allow for an extremely easy and convenient install.
While all these features are awesome, the biggest question remains; how does it all go together and how well does everything really fit? Follow along with us to find out, but we warn you, you may want to hide your checkbook before you go any further. You are going to want one of these.