Time was, anyone with a 454 big-block was sitting pretty. But with aftermarket small-blocks upsizing to 450-plus cubes, big-block lovers have to raise the ante. Even a 502 is no longer sufficient; today's Chevrolet Rat motor of choice is rapidly becoming the 540. Everyone and his uncle is now building these megamotors, and they're beside themselves with just how much power and torque these babies are capable of making. HOT ROD decided to get on the bandwagon and build a stout 540 to evaluate a whole series of mild to wild power recipes. Even in its initial mild street form, this stout engine makes more than 650 lb-ft at 4,200 rpm with Brodix oval-port heads, an Edelbrock RPM Air-Gap intake, and a Lunati hydraulic roller cam with 230-ish (at 0.050) duration. And that's just Phase 1. Future plans for our multi-installment flog include progressively more radical Lunati solid roller cams and valvetrain components, bigger Holley Dominator carbs, a full range of Edelbrock intakes, ever-larger Brodix rectangular-port heads, and a variety of Hooker headers. Read on as we put the pedal to the metal.
The Short-Block
For this project, we chose to work with Speed-O-Motive, long known for its expertise in building stout stroker engines of all makes and flavors. With a complete, state-of-the art machine shop, assembly facilities, and a DTS engine dyno all under one roof, it was the perfect choice to handle an extensive and complicated engine-flog. Now all we needed were parts. That used to be a big deal requiring a bunch of hard-to-get special-order items, but these motors have become so routine that nowadays all the components are just about standard issue.
What makes these giant Rat motors viable is the ready availability of thick, siamesed-wall, aftermarket cylinder blocks like Dart Machinery's Big M Sportsman series that are re-engineered in critical areas to easily accommodate stroker rotating assemblies. Starting with a 4.5-inch-bore, 9.8-inch (nominal) deck height, Big M, Speed-O-Motive dropped in a Scat 4340-steel, 4.25-inch-stroke crank that swings Scat I-beam rods hooked to JE/Sportsman Racing Products (SRP) pistons. Depending on the final deck height, cylinder head selection, and head-gasket thickness, the result is a pump-gas-friendly 9.9 to 10.9:1 compression ratio.
Federal-Mogul's Speed-Pro division threw in a set of its premium Competition Series main, rod, and cam bearings, while its Fel-Pro division supplied all the gaskets. The high-volume oil pump is also a Speed-Pro item, but the rest of the lubrication system (as well as the distributor driveshaft and the valve covers) are all Milodon. Critical fasteners not included by Dart with the block were supplied by ARP.
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