For many GMHTP readers, the object of desire is none other than a high-power LS V-8 to shove under the hood of his or her GM muscle machine. But until now, many budgets have only allowed the likes of bolt-ons or perhaps the odd head/cam package to enhance their ride's otherwise-stock Gen III/IV engine. Fortunately for enthusiasts, advents like the release of dirt-cheap, high-flow GM heads mean the price point for putting together a hi-po LS has fallen to lows never thought possible a decade ago. Prompted by these developments, GMHTP has decided to test the envelope of what kind of all-out mill can be had for bottom dollars, while still using capable components. And while doing it on the cheap also means assembling it at home, such an undertaking is not beyond the abilities of the mechanically competent and detail-oriented DIYer.
While picking up a "junkyard" LS engine and building around a stock bottom end certainly has its merits, it can't hold a candle to the power unleashed by adding bunches of cubes with a stroker crank, so that's exactly what we'll be doing here. Keeping it naturally aspirated will forego the added money needed for the likes of superchargers or nitrous (even though the engine components we'll be selecting could easily handle them if called upon). Join us as we up the ante and show how little one can pay to reap the rewards of serious horsepower!
Parts, Parts, Parts
The foundation of any LS build is an engine block, and picking one that will hit a rock-bottom price point while still providing ample cubic-inch capability is a no-brainer. Look no further than GM's 6.0L iron block, as used in the LQ9 (and LQ4) truck engines. Featuring a 4-inch factory bore and strength to support hundreds of horsepower over stock, this Gen III block is a superb choice for not just N/A builds like our own, but power-adder applications as well. If you're lucky, you can find a used LQ9 block for just a few hundred bucks, or just opt for a new one under GM PN 12572808; major retailers like Summit or Scoggin-Dickey sell them for around $725. Sure, there's a bit of a weight penalty that comes along with iron, but we're saving hundreds of dollars versus going for the comparable LS2 aluminum block--and the L92/LS3 blocks, with their slightly larger bore, go for double the price of an LQ9 block or more!
Next on the list is choosing a rotating assembly to fill it with. You've probably already figured out from the title of our story that we're going with 408 cubic inches (6.7L), which is accomplished with a 4.030-inch bore and 4.00-inch stroke. Choices abound on the LS market, but one standout company for rotating assembly components that hit a fantastic price point is Wiseco. The company provided us with a set of its PN K464F3 pistons, which are a tough 2618 (as opposed to more-brittle 4032) alloy forging and go for $739 including rings. (These "F" series pistons have been recently updated to a new "X" series, which includes an even further improved ring set and adds about $42 to the price.) As we'll explain in the photo captions, Wiseco has done some serious homework when it comes to the design of these pistons.
Wiseco also provided its close partner K1 Technologies' PN CH6125ALLB-LSL8-A connecting rods, which are a great deal at $520 a set--especially considering they are 4340 forged and include features like a special low-friction bushing material, pin oiling, and a double-bridged cap secured with proprietary asymmetric-thread ARP 2000 bolts. Finally, Wiseco rounded out the package with one of K1's forged steel crankshafts (PN 346-4000RB6F-24, $780), which among other things is stress-relieved and features nitrided (rather than induction hardened) journals for long life. According to Wiseco's Brian Nutter, "the K1 crankshaft and connecting rods are priced extremely well and offer attention to detail not often seen in budget parts."
With all said and done, we end up with a super-strong block and all-forged rotating assembly for under $2,800--talk about a tough act to follow, especially considering all of these parts are brand new! While we've yet to add in the cost of other necessaries like main and rod bearings, things are still shaping up nicely for our short-block.
Machine Work And Short-Block AssemblyOf course, our parts weren't quite ready for their day in the sun--they still needed to be machined before we could make them a part of our budget LS. While the vast majority of the work to be done involved the block, the rotating assembly would need to be balanced as well. The School of Automotive Machinists (Houston, TX), one of the most respected names in motorsports education, was happy to help out. Started in 1985 to impart students with the "art of engine building," SAM offers courses ranging from engine block and cylinder head machining to use of CNC equipment. Not to mention, SAM fields a pair of winning LS-powered Camaros at races around the country--and founder Judson Massingill is one of the most knowledgeable individuals in the United States when it comes to V-8 race engine building.
Check out the photo captions for a rundown of the machine work done by SAM (where GMHTP contributor Stephen Kim lent a hand at photography), followed by assembly of our short-block back at this author's New Jersey shop. Then, grab our September issue for the remainder of the engine assembly, a full dollar rundown of how much (er, little) this 408 set us back, and of course, dyno results!