In my tenure at GMHTP we seem to have covered a wide variety of LS engine builds, even some tall deck stuff. However, one increasingly popular (and sometimes considered controversial) configuration that we had yet to touch on was the 440+ cube LSX-based motors. This configuration usually has the cylinder walls near its limits and relies on a lengthy 4.100 or 4.125-inch stroke. For very high horsepower applications the top builders will recommend staying conservative on the bore and stroke-say 408 to 427 cubic inches. But on a pump gas street motor, even one that will get a healthy taste of giggly gas, there is no need to be so conservative. As the result, we began to wonder what would happen if we played it fast and loose with a GM Performance Parts LSX block and tried to squeeze as much power as we could out of it, but in a totally streetable configuration-meaning pump gas, hydraulic roller spinning no more than 7,200 rpm, and reasonable clearances that aren't going to have us going through two quarts of oil before its next scheduled change.
To make the dream work, it was going to take some teamwork. And who better to call in such a situation, but Late Model Engines in Houston? In addition to cranking out all of the 7-second LS motors for its neighbors at Late Model Racecraft, LME has been shipping top-of-the-line custom engines around the world since its inception by School of Automotive Machinists graduates Bryan Neelen and Pecos Loughlin. The two have assembled a dream team capable of any type of engine machine work, cylinder head porting, and assembly you can think of-specializing, though, in late-model GMs with a very heavy emphasis on the LS engine. Simply put, they make engines that will make any Gen III/IV enthusiast's pants tight. And having done this many times over, it didn't take long for the very enthusiastic Mr. Neelen to work out a plan and a parts list with me. Bryan goes through the same procedure with all of LME's customers, hopefully with the same exuberance. We had originally planned to pit this motor against a comparable Windsor build in a Mustang publication that will remain nameless, but they ran from the challenge in fear of greater humiliation than simply being a Mustang enthusiast. But I digress.
After consulting with Bryan, a Callies rotating assembly was the natural choice to complement our GM Performance Parts LSX block. A Callies Compstar 4.100-inch stroke crankshaft, made from 4340 forged steel, would be providing the thrust for Compstar 6.125-inch H-beam connecting rods with 2.1-inch journals and ARP 2000 7/16-inch bolts. Meanwhile, Wiseco 4.185-inch bore forged pistons with -7cc valve reliefs were ordered for a healthy 451 cubic inches of displacement and a street-friendly compression ratio. Though we had planned this to be more or less a naturally aspirated build, we also wanted a set of pistons that would accommodate a healthy shot of nitrous just in case, and Wiseco was happy to oblige. Much has been said on the debate over the stronger 2618 versus the more quiet 4032 alloy in street applications, but Wiseco seems to have done its homework in using a number of features to overcome these inherent problems to give its customers the strongest, most durable product with little comprimise. In this installment we'll be going over these elements as well as the machining and blueprinting of the block in preparation for assembly.