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Late Model Hemi - Gen III GiveawayGenn III 5.7L Hemi stroked, and you can win it! From the September, 2012 issue of Mopar Muscle By Dale Amy Photography by Dale Amy
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The annual Carlisle All- Chrysler Nationals event is rapidly approaching (July 6-8, 2012), meaning it's once again time for us to head off to Muscle Motors up in Lansing, Michigan, to document the assembly and dyno testing of a potent engine combo that some lucky Mopar maven will win at Carlisle. How potent? This year's giveaway engine is a Gen III 5.7L Hemi stroked to something over 392 cubic inches, yet topped with a Quick Fuel Technology carburetor and standalone MSD Hemi 6 electronic ignition controller for straightforward plug-and-play installation in someone's deserving project. Maybe yours. Mike Ware, head honcho at Muscle Motors, sees lots of cost-effective potential in the readily available Gen III Hemi architecture. As supplies of venerable old LA and RB cores dwindle, the reverse is true of the 5.7L Hemi, which continues to increase in both availability and affordability on the used market. And, as we'll see, thanks to Muscle Motors and the ever-expanding aftermarket, these modern Hemis can make a great foundation for a project engine.  1 This project's foundation...  1 This project's foundation is a seasoned Gen III Hemi block that has been squared, decked, and align-honed, etc. at Muscle Motors. These iron 5.7 blocks use the same 4.46-inch bore spacing as the old LA-series of small-blocks. Muscle Motors bored the block to 0.030-inch over (3.947 inches), and you can see there's still plenty of meat left between the cylinders. The sturdy, deep-skirt construction of these Gen III blocks puts their weight somewhere between that of the LA small-block and RB big-block. By the way, if contemplating your own Gen III Hemi buildup, Muscle Motors recommends starting with a 2008-or-older block, as newer blocks had some changes (required for variable cam timing, etc.) that would complicate the use of aftermarket parts.  2 Bottom-end rigidity won't...  2 Bottom-end rigidity won't be a problem area, as the 5.7's factory main bulkheads and caps are clearly beefy, and Muscle Motors has upped the main fasteners to ARP studs. The large holes on the pan rail are the block's internal oil return passages.  3 Each of the five main caps...  3 Each of the five main caps is also secured by a pair of cross bolts (arrow), so they're going nowhere. Again, stronger ARP bolts have been substituted on this build for the OEM fasteners.  4 To assure the proper clearance...  4 To assure the proper clearance of rod fasteners with our stroker crankshaft, we had to machine a very small clearance notch (arrow) at the base of each cylinder.  5 Orientation of the caps...  5 Orientation of the caps is critical, as the factory main-bearing design features opposing tangs as seen here. Our Gen III buildup uses Clevite H-Series (high performance) bearings with 180-degree oil grooves, and enlarged side chamfers for increased crank-fillet clearance.  6 Muscle Motors' Scott Marrison...  6 Muscle Motors' Scott Marrison nestles Manley's forged 4340 steel crankshaft in place. Its 4.050-inch stroke will result in a nice, historic 392 cubic inches with a stock bore. Our slight over bore job means this go-fast giveaway will really be packing just over 396 cubes (but, to simplify, let's just call it a 392). Crankshaft journal diameter is 2 inches, and the counterweights are profiled for 6.125-inch connecting rods. Visible near Scott's left hand is the 32-tooth reluctor (crank trigger) wheel, chosen to work with Chrysler's most cost-effective 2006 to 2008 crankshaft position sensor that will be harnessed to the MSD ignition controller (2009-and-up Hemi crankshafts have a 58-tooth reluctor.)  7 All Gen III Hemi engines...  7 All Gen III Hemi engines are internally balanced, and Muscle Motors neutralized the Manley stroker crank in-house, using slugs of dense mallory metal as needed. If you like, your Manley crankshaft can be sent to you already balanced.  8 After being dimensionally...  8 After being dimensionally checked, the Manley H-beam rods get a wash. These are of 6.125 inches in length (the factory powder-metal rods measure 6.246 inches) and, as previously noted, measure 2 inches in diameter at the big end. Manley, in fact, catalogs them as small-block Chevy rods, but we won't tell anyone.  9 Next to seasoned factory...  9 Next to seasoned factory hypereutectic 5.7 pistons is one of our project's Mahle forged pistons, with coated skirts. Though not visible in this shot, it's dome profile is about the same as the factory slug, giving our 392 a static compression of around 10.5:1 (with its reworked cylinder head chambers). You can see that the 1.5/1.5/3.0mm ring grooves are moved farther down from the piston top than in the factory configuration, providing room for valve relief cutouts that will allow a decently aggressive cam. Piston weight is about 439 grams.  10 After bolting the rod...  10 After bolting the rod and piston combo in place, Scott checks the rod side clearance at 0.013 inch. This meticulous--and no doubt sometimes monotonous--hecking of dimensions, clearances, and trueness is among the most important aspects of engine building.  11 With the bottom end buttoned...  11 With the bottom end buttoned up, Scott inserts the custom-ground Comp Cams hydraulic-roller bumpstick into its rather high tunnel in the block. Muscle Motors spec'd this cam with an eye towards a broad torque curve, a street-worthy idle, and horsepower that peaks at reasonable rpm. Gross lift is .577/.577 (factory is .472/.460), duration at .050 inch is 238/240 (versus 192/196), with a lobe separation of 112 degrees.  12 The cam works through...  12 The cam works through a fresh set of OEM Mopar roller lifters, inserted into their bores in groups of four. These rather long lifters combined with the cam's high position in the block permit reasonably short pushrods--6.550 inches on the intake side and 7.800 on the exhaust. The pushrods are drilled with oil passages. This shot also shows the valve relief pockets in the pistons, and that the pistons at TDC are flush with the deck.  13 Manley's adjustable double-roller...  13 Manley's adjustable double-roller timing chain is similar in design to the single-roller factory version, but makes it easy to advance or retard cam timing up to eight degrees during installation. Note that the rectangular holes in the ring attached to the cam gear are read by the engine's cam position sensor, which, along with the crankshaft sensor, will feed signals to the MSD Hemi 6 ignition controller.  14 With the short-block more...  14 With the short-block more or less complete, let's have a look at the heads. Mike Ware likes to stick with 5.7 castings on his Gen III Hemi long-block combos, and not just because they are the most available and affordable. More importantly, Mike feels that port volume and cross section on the rarer and pricier 6.1 or 6.4 heads are so large as to hinder low-lift flow velocity. That said, he did CNC port our factory 5.7 castings, but purposely kept volumes smaller than on 6.1 heads to promote velocity and, therefore, torque. He also enlarged the intake valve seat to 2.100-inch diameter, allowing use of 6.1-spec 2.08-inch Manley valves (the factory 5.7 intake valve is a smallish 2 inches). Exhaust valves are also upsized from the factory's 1.55 inches to 1.60 (which does not require seat mods).  15 In the foreground is a...  15 In the foreground is a factory 5.7 aluminum head casting. Compare its open-chamber contours (arrow) to our project's reworked head behind it, which has had material welded in and machined to increase quench, theoretically increasing chamber combustion efficiency and reducing chances of detonation, thereby permitting a higher compression ratio. This closed-chamber shape is very similar to what the factory is now using on the latest 6.4 Hemi.  16 Initial calculations notwithstanding,...  16 Initial calculations notwithstanding, we double checked valve-to-piston clearance by trial fitment of a head and rotating the crankshaft through a full intake/exhaust cycle with clay in one piston's valve relief pockets. This verified plenty of clearance (around 0.185 inch).  17 A pair of factory rocker...  17 A pair of factory rocker shafts (with their 1.6:1 ratio) are employed. Here, Scott is fitting the intake-side shaft (in between the two shafts are the chimney-like spark plug tunnels). Our lumpier cam demanded upgraded Comp Cams beehive valvesprings.  18 If you were air transitioning...  18 If you were air transitioning the intake manifold, this is the straight-shot view you'd have through the port to the back face of the intake valve. Such short, direct paths are an obvious advantage of the Gen III Hemi's cross-flow head design.  19 A factory gerotor-style...  19 A factory gerotor-style oil pump is well up to the task, as the same one is used on the SRT 6.1 and 6.4 variants. The arrows are pointing to spacers that are required by, and supplied with, Manley's double-roller timing chain.  20 Thanks to the increased...  20 Thanks to the increased stroke, strategically placed slots had to be cut into the otherwise-stock Hemi windage tray, in order to clear the rod fasteners. Though not as shown in our completed engine photo, a new Milodon 6-quart oil pan will be part of the giveaway engine, specifically designed to work in '59 through '74 A-, B-, C-, and E-Bodies.  21 Mike isn't impressed by...  21 Mike isn't impressed by the currently available low-rise carb-style manifolds for the power levels he wants this Gen III Hemi to achieve, and so he opted for Mopar's lofty, single-plane Challenger Drag Pak high-riser. Incidentally, Muscle Motors will soon be manufacturing a similar intake, but one that will be a bit shorter, a bit more affordable, and will accept a Dominator-style carb. Speaking of carbs, the giveaway 392 gets a very tunable Race-Q Series 750 from Quick Fuel Technology. This shot also shows the project engine's OEM valve covers and coil packs.  22 Quick Fuel's Race-Q has...  22 Quick Fuel's Race-Q has five-stage emulsion billet metering blocks for the ultimate in tunability, and wears these highly accessible quick-change jet plugs, for jet swaps without removing the fuel bowls. Whoever wins the Gen III 392 will have no trouble keeping it in tune.  23 Helping out in that regard...  23 Helping out in that regard is MSD's Hemi 6 ignition controller. It fires the coil packs with input from the Hemi's crank, cam, and MAP sensors, and comes with software for quick tuning adjustments on timing curves, two-step limits, nitrous retard, and boost/timing mapping.  24 Shown here prior to having...  24 Shown here prior to having its Quick Fuel Technology 750 carb and MSD Hemi 6 ignition controller fully plumbed, and sans front accessory dress, Muscle Motors' stroked Gen III Hemi will make a formidable project powerplant. Due to some dyno technical difficulties beyond our control, we were unfortunately unable to do any dyno tuning with the engine, but rest assured, when it gets to Carlisle, it will have been tested and tuned. In fact, you'll be able to hear it run throughout the weekend at the event. Finally, someone will win it--in fully finished form, of course--at the All-Chrysler Nationals in Carlisle.
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