World Products' Motown LS Engine- Something Old And Something New

For the people who understood what they were looking at in World Products' booth last fall at the annual SEMA convention in Las Vegas, their reactions were twofold: First was a quizzical, "what the $@#* is that?" reaction, followed by a, "oh, yeah, that's a great idea" wave of understanding.

What those convention attendees were reacting to was World's new, hybrid Motown LS engine, an engine that combines the architecture of a traditional small-block bottom end and the cylinder heads/intake system of a modern LS engine. (Motown is the name of World's line of Chevy small-block cylinder blocks, parts, and engines.)

Let that sink in for a moment: A small-block with LS heads. Hit your local cruise night in a hoodless Deuce with such an engine combo and you'll have to cover your kids' ears, because the locals will be spitting out their own quizzical expletives.

Beyond the comprehension that such a beast exists, the mind reels with questions of how and why. The "why" answer is the simple one: There are performance advantages of the small-block bottom-end that are exploited to their fullest when used with higher-flow heads. And to put it simply, conventional small-block heads don't hold a candle to the airflow capability of the LS lungs.

Now comes the "how" part. If you're familiar with the basic specs of both the small-block cylinder block and LS block, you know the small-block water jackets don't remotely match the water passages in LS heads, and let's not forget the incompatible head bolt arrangement. Also, the deck height of the small-block is much lower than the LS, making intake manifold installation problematic.

For just about any other engine builder, such details would be insurmountable obstacles, but World Products isn't just another engine builder. They manufacture their own cylinder blocks, heads, and more, so they're in the enviable position of being able to direct the design of their products, and that's just what they did. World Products redesigned the small-block casting to accommodate LS heads.

Like so many other game-changing products, the idea for the Motown LS was born out of "what if" questions that were thrown out on World's shop floor; mainly, what if they could build a small-block that breathed as well as an LS engine?

"Our Warhawk LS crate engine makes about 50 more horsepower than a comparable Motown small-block with the same displacement and induction system," says World's founder Bill Mitchell. "The basic design of the LS head is really that much better than the small-block design."

But while an LS-headed small-block seemed far-fetched, Mitchell and his engineering team figured there were more advantages than greater horsepower with such a combination, including:

* Easy, bolt-in installation on any vehicle already set-up for a small-block

* Significantly greater performance for racing classes that require a distributor-triggered ignition (LS engines are crank-triggered)

* Reduced overall engine cost, compared with a comparable LS engine, due to inexpensive, off-the-shelf small-block components, such as the oil pan, front cover, etc.

Bolstering the viability of the idea was the fact that GM designed the LS with the same 4.40-inch bore centers as the original small-block, which would perfectly align the LS combustion chambers over the small-block cylinders.

"As much as the small-block and LS are different, there are some key similarities that make it work," he says. "It's clear when you examine the LS engine that there is a direct path back to GM's SB2 racing engine-an extension of the small-block design."

Also, an LS-style camshaft fits inside the small-block cam holes; the journals align almost perfectly. All that's needed is a distributor drive gear on the back of it and fuel pump lobe on the front. (World got Comp Cams to build one for the engine seen in this story.)