Motown LS Crate Engine - A Hybrid That Makes Horsepower

Here, a standard LS cam (right)... 

   

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Here, a standard LS cam (right) is shown with the custom stick from Comp Cams. Note the redesigned rear end, where the distributor drive gear is grafted. At the front is a fuel pump lobe. The cam used in our test engine had a standard small-block diameter, not the larger, 55mm size of the production LS cam--but the Motown II/Motown II LS blocks can accommodate a 55mm cam. Lift and duration specs are 0.650/0.660-inch and 250/255 degrees, respectively.

Spark plug wires are not conventional, however. Because of the differences in spark plug locations between LS and small-block heads, standard small-block wires don't quite fit. And, of course, the distributorless LS ignition system uses only the shortest of leads between the coil pack and plug, so cut-to-fit universal wires are required.

The Motown LS uses the LS-style firing order of 1-8-7-2-6-5-4-3.

Dyno Test
We didn't only document the first Motown LS engine during its assembly, we followed it into one of World Products' dyno cells and witnessed its very first test session.

After a brief warm-up/break-in period, the engine produced an eye-opening 629 hp/579-lb-ft result. That's about 70 hp more than one of World's regular Motown small-block 427 engines and about 15 horses more than their typical Warhawk LS combos.

Everyone on hand for the test was understandably impressed with the results, but surprised even by its performance over their Warhawk LS combinations with similar specs.

"I have to give credit to Jim Kuntz for working on the heads," said Bill Mitchell. "They flow great, but he has a lot of experience with the design, because it's so close to the Ford design."

As for the performance above and beyond a conventional small-block setup, it was pretty much what Mitchell expected.

"We've seen the difference between 427-inch Motown and 427-inch Warhawk engines, so the results are in line with what we predicted," he said. "It just proves that the LS design is head and shoulders above the small-block head design when it comes to airflow."

Here are the LS lifters being... 

   

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Here are the LS lifters being lowered into the block small-block-style, rather than the pocketed design of an LS engine. The block was designed for the LS lifters--this wouldn't work on a standard small-block.

The implications for the Motown LS are far-reaching, particularly for racers who are required to run a distributor. As for street enthusiasts, it is performance that was virtually unattainable in a naturally aspirated small-block combination. In fact, the only small-block crate engine in World's arsenal that makes more power than this pump-gas, streetable engine is their 13.5:1, race-gas-sipping Drag Race 427 that is rated at 650 hp.

Considering the Motown LS made about 630 on its first pull, it's not out of the question that with tuning it would equal the Drag Race 427 with 10.7:1 compression and premium pump gas.

By the way, the Motown LS isn't merely a concept. World Products is ready to go with crate engines, engine kits and the like.

It's the ultimate hybrid.