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Heart Of A Rat

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  • Externally identical to the Chevy small-block, World Products’ MoTown block has thicker front and rear bulkheads as well as more material cast in the cylinder banks in order to support large displacement with unrestricted cooling. Like Chevy’s block, the MoTown has a 9.025-inch deck height. The bores for our 454 measure 4.250 inches in diameter. - 1
  • The engine buildup begins with the installation of the camshaft. For our 454 it’s a solid roller-type that is designed for high-rpm power and low-rpm streetability. That means it idles well and fosters an easy-going manner when driving in stop-and-go traffic. - 2
  • Before the crankshaft is dropped onto the mains, their dimensions are checked for accuracy with a dial bore gauge. All of the conventional blueprinting procedures are performed during the crate engine’s assembly. The 454 uses 400-style main bearings. - 3
  • The crankshaft is a 4340-forged piece that is internally balanced. It delivers a 4.000-inch stroke. - 4
  • The crank is secured with splayed, billet steel main bearing caps. The inner fasteners are studs and nuts, with the outer fasteners half-inch bolts. - 5
  • Forged, H-beam-type connecting rods from Eagle are attached to Mahle friction-coated forged aluminum pistons with full-floating wrist pins. In addition to valve reliefs, the pistons have a dished section that helps ensure the streetable 10.5:1 compression ratio. - 6
  • Here, the 454’s builder checks the end gap on a piston ring prior to its installation on the piston. With 600 horses and nearly that much torque, a tight, leak-proof seal in the cylinders is a must. - 7
  • With the rings checked and filed to a precise fit, the piston is installed in the cylinder bore. World uses Total Seal rings on the Limited Edition 454. - 8
  • After all of the piston/rod assemblies are installed, a double-row, true roller timing set is attached to the camshaft and crankshaft. - 9
  • Camshaft degreeing is another blueprinting measure that ensures more accurate ignition timing at start-up. It is performed on all of World Products’ crate engines. - 10
  • Next on the installation list is a high-volume Melling oil pump. - 11
  • The oil pump is designed to work with a deep-sump, high-capacity oil pan, like this one from Moroso. - 12
  • Finishing off the bottom-end assembly is an SFI-spec ATI Super Damper. - 13
  • The engine is rolled over to start the top-end of the engine. First on the list is installing the MoTown aluminum cylinder heads. They’ve got large, 215cc intake runners and the valves are held at a 23-degree angle. - 14
  • A look at one of the heads’ combustion chambers reveals the fast burn-style chamber design (72cc volume) and large, 2.080/1.600-inch valves. - 15
  • Scorpion aluminum, 1.6-ratio roller rockers complement the solid-roller camshaft valvetrain. - 16
  • Rocker arm stud girdles are used on the Limited Edition 454 to spread out the load of the arms’ stud deflection, delivering more stable operation for the high-revving, big-cube small-block. - 17
  • With the valvetrain components secured, the intake manifold is installed. Like the cylinder block and heads, its anther World Products-designed and manufactured part. It has a “turtle” floor design that effectively makes it a dual-use (street and strip) intake. It’s also got cast-in bosses that can be tapped for nitrous nozzles or EFI. - 18
  • Feeding the intake manifold is a modified Dominator carburetor that flows 1050 cfm. That may seem excessive for a street engine, but it is commensurate with the airflow capability of the engine. - 19
  • An MSD Pro Billet high-energy distributor is on the 454 engine. - 20
  • The completeness of the crate engine package includes not only the distributor, but the plugs and wires, too. - 21
  • A set of polished valve covers finishes off the engine, each engraved with the Limited Edition 454 logo.  It’s a great detail that reinforces the high-end, exclusive nature of this combination. - 22
  • Here’s the completed engine assembly, ready for dyno testing. Each World Products crate engine is tested to ensure it makes at least the advertised power levels. The procedure also serves to break in the engine and set up ignition timing. In other words, the engine is ready to rock when it is un-crated by the customer. - 23
  • The aluminum version of the MoTown cylinder block saves more than 100 pounds and gives the engine an undeniably exotic appearance. This 427-cube example is rated at 550 horsepower. - 24
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by Barry Kluczyk  More from Author

Big-Block Performance In A Small-Block Package

With 454 cubic inches, 600 horsepower and 575 lb-ft. of torque, there’s no reason to believe anything else than the engine in question is Mark IV-type big-block. The displacement. The torque. It all adds up, right?

Not quite.

We’re not talking about a hopped-up vintage Rat motor. We’re talking about one of World Products’ overachieving MoTown-based small-blocks – an engine based on the Chevy small-block, but with World’s own cylinder case casting. (The New York-based manufacturer also casts its own big block case that goes by the name “Merlin.”)

Consider that for a moment: In a mid-year Corvette or C3, this engine offers the same road-wrinkling torque as a big-block, but without the front-end weight penalty. Fewer pounds on the nose means better weight transfer to the rear axle, for better launches and better overall handling. And for C4 owners, this combination is a great alternative to the factory small-block, particularly the lower-powered pre-1990 examples. It is compatible with fuel injection, too – just pop off the intake manifold and carb and replace them with your favorite injection system. Sure, you’ll have to source a controller, too, but that’s easy.

As is often the case, raw dyno numbers don’t tell the whole story. There’s a lot more to the Limited Edition 454 than cubes and a cam. For starters, it’s a small-block that didn’t originate in one of the General’s foundries. It’s one of World Products’ MoTown castings and also wears the company’s MoTown aluminum heads. The engine is also part of a six-step crate engine roster developed by World Products. Each level is signified by features such as a hydraulic or solid-lifter camshaft, increased compression, greater power and, of course, increased prices.

At the entry level is the “Daily Driver” series, followed by the “Cruiser,” “World Class,” and “Hardcore” crate packages. After that comes the “Limited Edition,” and, finally, the competition-only “Drag Race” engines. As a Limited Edition engine, our 454 project engine comes with solid roller lifters, 10.5:1 compression, high-flow aluminum cylinder heads, and a Dominator-type carburetor. It is suitable for the street or strip.

There are numerous options, power levels and displacements within some of the categories. Suffice it to say there are more choices than we have space to outline on these pages.


Inside look


Like the other small-block engines in the World Product’s roster of crate engines, the company manufactures the block, heads and intake. World’s MoTown block and heads are cast to beefier specs than standard GM parts. The four-bolt MoTown block has one-inch-thicker front and rear bulkheads for added strength. There’s more iron around the cylinders, too, than a stock block. This allows for expanded coolant passages and head bolts that go in blind, meaning they don’t go into water – important considerations when you’re overboring to 4.000 inches and beyond.

Nodular iron main caps are used on some MoTown engines, but others – like our 454 – used splayed, billet steel four-bolt caps. They are cinched down with half-inch bolts on the outside and studs on the inside.

The crankshaft itself is internally balanced. Externally balanced cranks typically wear weights attached to the front and/or rear of the crankshaft, while an internally balanced crank has material added to the individual counterweights. An internally balanced crank is likely to last longer and make the engine run more smoothly.

Like the engine block, the MoTown heads are based on the production small-block castings, but they’ve got bigger water passages and some extra material to compensate for them. They bolt on like stock heads, though, and utilize all stock-type hardware and valvetrain components.

With its big-block-style output, the 454 obviously makes efficient use of the passages in new, 23-degree heads from World; each with 215cc intake runners, which are about 25 percent larger than a stock small-block’s (170cc) runners – necessary to feed the big displacement.

“The cubic inches won’t do it [make horsepower] alone,” Bill Mitchell says. “You’ve got to follow through with cylinder head flow. Remember: Horsepower is the product of torque divided by 5,250 times rpm. A high-flow cylinder head is going to give you more rpm and, consequently, more power.”

Complementing the volume of the intake runners are 72cc fast-burn combustion chambers. The bean-shaped chambers promote quicker light-off of the air/fuel mixture and more complete combustion.

Like everything else, the valves are big. Measuring 2.080 inches on the intake side and 1.600 inches on the exhaust, they’re actuated by a solid lifter cam specific to this engine combination (Mitchell keeps his cam specs close to his chest). It’s a quick-acting, deep-breathing cylinder head/valvetrain combination that allows the 454 to rev to more than 6,000 rpm.

“On the face of it, it seems like a simple concept: the bigger the air pump, the more power you get,” Mitchell says. “That’s true, but ensuring the power is usable, dependable and consistent is the trick. We’ve spent countless hours developing engines that not only deliver big power, but do it reliably.”


Induction details


Air enters the engine through a World Products-modified “Hardcore” Dominator rated at 1,050 cfm. It flows into a single-plane manifold that has passages designed to support good street-driving characteristics. Yes, it too, is a World Products-designed part. The “turtle”-shaped floor of the manifold is what makes it usable on the street or racetrack. Our experience with World’s big-inch, big-power engines bears out their claim for the manifold.

The 454 engine’s remaining components are a collection of the performance industry’s best: Manley, ARP, Melling, Moroso, Mahle, Speed-Pro, and so on – your basic who’s who of the high-performance aftermarket. The completed assembly includes plugs, wires, an MSD Pro Billet distributor, and a harmonic balancer – everything but a water pump, flywheel, and oil in the pan.

“Shipping regulations dictate we can’t send engines with oil in them,” Mitchell says. “But we dyno test and tune every engine with fresh oil, then drain it before crating up the motor.”

All of World’s crate engines come with a two-year warranty, which definitely provides peace of mind that generally doesn’t accompany other manufacturers’ engines – nor that home-built special you attempted a few years ago.

We love the fact that the Limited Edition 454 is everything a big-block could offer packaged in a small-block envelope. And with 600 horses on tap, it delivers much more than any Rat delivered by Chevrolet.



World Products

Ronkonkoma, N.Y.





The Aluminum Alternative


If there’s one thing we’ve learned after repeated trips to World Products’ build center on Long Island, New York, it’s like visiting a roadside fireworks store. There’s lots of great looking noise makers on the shelves, but you can’t help but ask the guy behind the counter, “Where’s the good stuff?”  He beckons you to the backroom, where an arsenal only a few dynamite sticks short of World War II is stacked to the ceiling.

At World Products, asking for the good stuff directs you to things like an aluminum casting of the MoTown cylinder block. That’s right; an alloy small-block. It carries all of the same strength-enhancing features of the iron version, plus more – like cross-valley ribs that not only strengthen the block, but also serve as cross-feed oilers for the lifters.

The promise, of course, of aluminum is lower mass and the alloy version of the MoTown weighs only 100 pounds in bare form. That’s more than 100 pounds less than the cast iron version. That’s a significant savings, no matter how you run the numbers – and it’s a saving that comes right off a car’s nose.

World Products doesn’t offer a 454-inch crate engine with the aluminum block, but you can order a 427-inch version. Think of it as a latter-day ZL1, with an advertised horsepower rating of 550 horsepower and 525 lb.-ft. of torque.


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