In my tenure at GMHTP, I've logged many a mile on I-95 and the good ol' Massachusetts Parkway, but never have I been so eager to make the 4.5-hour trek and brave the New England winter as when Golen Engine Service broke the news that it was releasing several Gen III/IV engine packages. Among them was the 402ci stroked LS2, topped off with Golen-prepped L92 heads. Owner Chad Golen put it together in the hopes of achieving at least 600 hp, unparalleled durability, and one of its most stout packages to date. Not even the lack of heat in my car and the subzero wind chill could dampen my willingness to strap this new package to the dyno and see what it could do.
The Hudson, New Hampshire-based shop was in the process of putting together the first of many LS2-based 402 strokers when I caught up with them last March, with plenty of Gen IIIs already under its belt. Unfortunately, at that time, parts were still being released for the L92 heads, so a few components will vary from the initial build (where noted) to the engines Golen will be shipping out to its customers. In this build, a Callies Dragonslayer 4-inch stroke crankshaft formed the backbone of the stroker motor. The American-made Dragonslayer is constructed with the highest quality 4340-steel available, and provides approximately 3 pounds of weight savings (according to Callies), over the more economical Compstar crank in Golen's base package. The Compstar H-beam rods are more than adequate, though, with high-quality 4340 forging and tuned weight distribution specific to LS1/LS2s. These rods have been used reliably in 1,600-horse motors, and are inspected and finished in-house. While awaiting the arrival of the new L92-specific pistons, Golen is using 4.005-inch versions of the same Mahle coated forged pistons it has used on many LS1 builds. Its durable 4032 low-expansion aluminum alloy carries a topside phosphate coating and Grafal on the skirts, for decreased friction and detonation.
As you'd expect from any Golen engine, each fresh GM LS2 block is put through thorough balancing and machining for maximum efficiency and reliability. The short-block is assembled using ARP main studs, with new GM parts filling in the blanks. A set of GM L92 heads are affixed to the block by ARP head bolts once they are prepped and assembled by Paul Rinaldi, Golen's new crack technician. Rinaldi does a slick five-angle valve job before bowl-blending and light polishing, to get rid of the factory casting imperfections. The heads are further machined for proper clearance and a combustion chamber conducive to an 11.0:1 compression ratio, then assembled with Manley NexTek beehive valvesprings, stainless steel valves, titanium retainers, spring seats, and locks. Golen chose these Manley components, since they have proved reliable pieces; however, the stock 2.16 intake and 1.59 exhaust valves will be swapped for additional performance gains in the coming months, when larger versions become available. When paired with the L76 intake and a streetable COMP Cams hydraulic roller selected by Golen (measuring 236/242 duration at .050, .602/.610-inch lift, 112LSA), this long-block is sure to far exceed the capabilities of any stock LS7-and for several thousand dollars less.
Since the LS2 block is brand...
Since the LS2 block is brand new, it can go right into the Sunnen machine to hone the cylinders to a 4.005-inch bore diameter. The cylinders are honed with a deck plate and the very same head gaskets that will be used during final assembly, to best simulate actual block distortion. Technician Paul Rinaldi says there isn't much distortion,...
...due to the wider spacing...
...due to the wider spacing on the Gen III/IV head bolt pattern. No chances are taken, though, as even the same ARP head bolts are used and step-torqued 35 then 70 lb-ft. The honing starts with a 70-grit for the first .003 inch,...
...and progressively finer...
...and progressively finer grit stones are used up to 400-grit, in order to remove the plateaus created by coarser stones. This cleans up the bores for better sealing and proper ring break-in. Witness the awesomeness of the crosshatch.
In accordance with the Clevite...
In accordance with the Clevite bearings of choice, the LS2 main caps must be honed to a minimum of 2.7509 inches on the Sunnen CH-100. If this turns out to be too tight for the crank, they can always be opened up. The caps must be torqued just like in final assembly, as this greatly affects clearances. The inner studs are cranked with 60 lb-ft, the outers with 50 lb-ft, and the side bolts with 19 lb-ft of torque. Great care is taken to preserve the integrity of the aluminum block's deck surface, as the boring bar is spun through the mains until the desired clearance is finally dialed-in, according to the tell-tale bore gauge. Rinaldi deburrs the edges of the block and the main caps before sending them to the jet wash.
The rod journals on the Compstar...
The rod journals on the Compstar rods must be sized to spec, in this case 2.1250 inches. For proper bolt stretch, the ARP 2000 rod bolts are torqued to 75 lb-ft. Rod-to-pin clearance is only .0006 inch, so Rinaldi opens them up .0001 inch (as he would on a racing engine), to keep the pins from hanging up on the rods and thus spin more freely....