Here's the basic long-block...
Here's the basic long-block assembly, prior to the installation of the intake manifold and carburetor.
But what about the power increase over World's own LS engine? It wasn't all due to a simple port job on the heads. Mitchell reminded us of the differences between the SBC and LS cylinder-block designs. The LS block has a deep-skirt design (also known as a "Y" block"), while the small-block casting extends only to the crankshaft centerline.
The LS block design enhances overall rigidity, which is particularly helpful with OEM aluminum castings, but it creates considerably more crankcase windage than the small-block. The Motown II block is plenty stiff to begin with, with thicker-than-stock key features (bulheads, "China" walls, and more) and four-bolt mains.
The other unique parts created...
The other unique parts created for the Motown LS include adapter plates for the front of the heads, to mount a water pump and other accessories. A crossover tube is used to connect the small-block's standard water-pump inlet and outlet ports, so the water flow will correspond with the LS circuit.
"Windage makes a huge difference," Mitchell says. "With this combination, you've really got this best of both worlds-an affordable, performance-oriented bottom end and the great breathing of LS heads."
The implications for the Motown LS are far-reaching for street and racing enthusiasts-and exciting. Just imagine this monster in a C3 or C4 Vette.
World Products deserves an achievement award for the Motown LS, and enthusiasts everywhere are the beneficiaries of the company's progressive attitude toward building big power.
The Motown II LS deck height...
The Motown II LS deck height is raised to the LS production spec of 9.240 inches, so any LS intake will bolt right up. In this case, it's an Edelbrock capped with a velocity-enhancing spacer and an AED-built 1050 Dominator carb.
| DYNO RESULTS |
| RPM | HORSEPOWER* | TORQUE* |
| 3,500 | 333 | 500 |
| 3,600 | 347 | 507 |
| 3,700 | 357 | 507 |
| 3,800 | 366 | 507 |
| 3,900 | 375 | 506 |
| 4,000 | 386 | 507 |
| 4,100 | 397 | 509 |
| 4,200 | 410 | 513 |
| 4,300 | 425 | 520 |
| 4,400 | 443 | 529 |
| 4,500 | 463 | 540 |
| 4,600 | 481 | 550 |
| 4,700 | 500 | 559 |
| 4,800 | 517 | 566 |
| 4,900 | 534 | 572 |
| 5,000 | 549 | 577 |
| 5,100 | 562 | 579 |
| 5,200 | 571 | 576 |
| 5,300 | 575 | 570 |
| 5,400 | 575 | 559 |
| 5,500 | 577 | 551 |
| 5,600 | 584 | 548 |
| 5,700 | 595 | 548 |
| 5,800 | 605 | 548 |
| 5,900 | 614 | 546 |
| 6,000 | 620 | 543 |
| 6,100 | 625 | 538 |
| 6,200 | 629 | 533 |
| *PEAK NUMBERS IN BOLD |
Just like a regular small-block,...
Just like a regular small-block, the distributor slips in at the rear. The only problem is the plug wires. Standard small-block wires don't fit quite right, so a cut-to-fit kit is necessary. On this engine, an electronic MSD distributor provides the spark.
On the left is one of World's...
On the left is one of World's Warhawk LS engine assemblies, and on the right is the Motown LS. The greater deck height makes the Motown LS taller and, at the top, wider than a conventional small block, but the front-to-rear length is essentially unchanged.
With minimal tuning and 36...
With minimal tuning and 36 degrees of total timing, the Motown LS engine cranked out 629 hp and 579 lb-ft on the first try. That's about 70 horses more than a comparable World Products small-block and about 15 more than one of the company's LS crate engines.