This LS-Based V4 Could Rid the World of Boring Four-Cylinder Engines

While Motus, America’s most interesting motorcycle company, is dead, their LS-based V4 lives on.

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Motus

What’s the difference between the Motus MSTR and the Loch Ness Monster? Simple: the Loch Ness Monster sounds like it might exist. The Motus, on the other hand, sounds like the wishful-thinking product of an afternoon bull session between engineering students. Take the Chevrolet LS V8. Scale it down by about twenty-five percent. Cut it in half to make a V-4. Then put it in a trellis-frame sport-touring bike with an optional full-carbon-fiber body. Sell the whole thing for the same price as a pair of Yamaha FJR1300s. What could go wrong?

The simple answer is that virtually nothing went wrong–with the bike itself, or its engine. Motus was founded by two men who were interested in rethinking the sport-touring motorcycle from first principles. Most importantly, they were interested in making a product that was both uniquely American and uniquely high-tech. Thus the space-age frame and the CF body and the aerospace materials found throughout.

You can’t find a Motus owner with anything bad to say about their bike–but it can be awfully tough to find a Motus owner besides, say, Jay Leno. It’s a little ironic, but today’s motorcycle buyers can be remarkably risk-averse in their purchase choices. They like to ride the same thing as everybody else in their club or touring group. The fact that even the base-model Motus could ring the cash register for $30,000 or more didn’t help matters much.

Which makes the decision by the founders of Motus to stop building bikes just two years after production began a tragic, but relatively predictable, occurrence. The good news is that the Motus engine, branded as “The American V4,” is going to stay in production for a variety of aftermarket and alternative applications. Some of those applications are obvious: the “Baby Block” V4 is already finding a home in upscale, one-off custom bikes in place of more expensive, but less powerful, bespoke V-Twin options. Others are yet to be realized–but before we go there, let’s talk about the engine itself.

When the American V4 was released, it was often described by the media as “half an LS V-8.” Strictly speaking, that’s not true. The design was entrusted by Motus to Katech, the veteran LS experts with countless competition wins and dyno-busting builds under their belts. Katech, in turn, re-sized the V4 to meet specific targets for both power and size. The bore and stroke of the 1650cc variant are 3.4 inches by 2.75 inches, compared to the current Corvette LT1 at 4.0 inches by 3.6 inches. The complete engine weighs about 150 pounds, approximately one-third of what the V-8 does.

Installed in a Motus motorcycle, the V4 made either 160 or 180 horsepower and over 120 pound-feet or torque. This compares very well with BMW’s six-cylinder 1.6-liter as found in the K1600LT. We’ve argued in the past that Munich could build an outstanding small car around their touring six, and the same would be true for the American V4. Virtually any Miata-sized roadster would be more than adequately powered by the engine in 180-horse trim, with a considerable weight and packaging advantage over a run-of-the-mill inline-four.

But wait, there’s more. The V4 was designed to accept a larger bore and stroke, although the limits of said resizing have not been published. Let’s say it could go to an even two liters, with a corresponding power increase to 220 horses or so. That makes it a viable alternative to the bland turbo two-liters that are currently seen in everything from hot hatches to middling-sized crossovers, in a significantly smaller and lighter engine.

Let’s take it one step further. It’s well-known that the LS family of engines obtains outstanding results with both supercharging and turbocharging. With the appropriately-sized supercharger, this is easily a 320-horse engine… or more. With turbos, the sky is the limit, but given how much effort GM has put into making supercharged pushrod V-8s pass emissions and longevity tests maybe the blower is the path of least resistance.

At this point, faithful readers have no doubt figured where I’m going with this. Yes, it’s my old pet project, the four-cylinder Corvette. Some of you laughed before, but you won’t be laughing after we look at what a supercharged V4 could do in this application. Weight? With appropriately-scaled running gear, perhaps a 500-pound savings from the current base Corvette’s 3,350 pounds. Handling? Even better than its already-impressive sibling. Not only is the V4 lighter and lower, it’s also significantly shorter, placing the center of gravity farther back and reducing the polar moment of inertia.

(A brief digression: Polar moment of inertia is one of the great unsung determining characteristics of vehicle handling. It works like so: The more weight you have at the center of a car, the quicker it turns. The more weight you have out at the ends, or “poles”, the harder it is to turn. You can test this for yourself at home: get a 45 pound barbell and a 45 pound Olympic weight bar, and put one in each hand. Now try to twist your wrists. The barbell will turn 90 degrees long before the equal-weight Olympic bar gets any momentum whatsoever. This is why mid-engined cars are dominant in any race series where all other factors are allowed to stay equal, and it is why mid-engined cars are so severely penalized in racing series where they compete against front- and rear-engine cars.)

What about price? This is where it gets tricky. In the past, Motus has quoted a price of $10,220 for the crate version of its V4. This is almost exactly what you’d pay for a crate LT1 V-8 from GM Performance. It also helps explain why the Motus bikes were premium-priced affairs, even without the carbon fiber and the fancy frame. Keep in mind, however, that the V4 crate engine price reflects remarkably low production volumes. It would be fairer to compare that number to the pricetag on a hand-built V8 from a builder like Katech, which can reach into the $20,000 range and beyond. A mass-produced V4 made in the same quantities as the LT1 should cost less than a short-run crate build.

Twenty years ago, when even traditionally conservative Toyota and Mercedes-Benz were able to justify the production of small-volume sports cars, this would have been a slam-dunk case for somebody. Engineer a mid-mounted two-seater, put V4 in, apply 220 horsepower to 2,300 pounds, watch the SCCA’s Solo Events Board tie itself in knots trying to classify an Elise-eater at an MR2 price. In the Crossover Era, there’s no chance of a major automaker trying something similar. But that mention of the Elise does give me an idea. The nice people at Hethel are currently trying to figure out which engines they will use as they design their first generation of products under Chinese ownership. Could the Motus engine power a new Elise or Exige? The packaging, power, and price are all right for job. It’s just a matter of someone at Geely picking up a phone. Using the American V4 to power a British sports car with Chinese money? It’s a great idea, but it also makes the Loch Ness Monster look downright plausible, doesn’t it?

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