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An Honest Engine

Want to know how to design, develop, and build a low-volume engine without breaking the bank? Motorcycle builder Indian may have found the answer.
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Its looks are based on engine designs lost in the mists of history, yet those who helped in its design, development, and assembly represent an international cast of characters with strong credentials. They have created a handsome engine that is modern but retro with air-cooling, a carburetor, and pushrods activating two valves per cylinder. One that makes do without a balance shaft, and is the largest V-twin motorcycle engine from an American OEM. The design is based on the best V-twin technology, but purposely falls far short when compared to current sport bike practice, where cutting edge technology is king. And this engine–this 100-in.3 monster of an air-cooled V-twin–wears the name of a motorcycle company that died in 1953 and was resurrected in 1999: Indian.

"There were about 15 Indian employees involved in designing, developing, and bringing the Powerplus 100 to production over the past 24 months," says Fran O'Hagan, senior vice president, Product Management and Marketing for the Indian Motorcycle Corporation (Gilroy, CA). This group's capabilities were enhanced by Indian's reliance on outside consultants, including Thunder Heart Performance Corp. (White House, TN); VePro Ltd. (Leicestershire, England); the Ann Arbor and Southfield, MI, offices of England's Lotus Engineering; and Performance Assembly Solutions (Livonia, MI). The latter, in its role as a Tier 1 supplier to Indian, builds the engine, which is destined for the 2002 Indian Chief. (See "Building the Powerplus 100.")

Thunder Heart was involved from the very beginning, helped with engineering, and built the first prototype engine. VePro, fresh from its involvement in the design, engineering, and development of the ill-fated Excelsior-Henderson motorcycle (the parent company went bust), helped Indian set the design parameters, source the parts, and bring the engine into production. Once it was ready for testing, Lotus Engineering climbed on board, handling much of the durability, drive-by noise, and refinement testing and development.

Going to outside consultants made sense, says O'Hagan. "If you need someone who can design a combustion chamber, but only need them once every 10 years, it's hard to justify having them on staff." Yet using such a diverse group of advisors also had its drawbacks, including teleconferences that mixed British and American forms of a supposedly common language. "We had companies from the Midwest, the U.K., Tennessee, and California on line at the same time," says O'Hagan. "It took some getting used to, but they have complemented each other very well."

The result of all this talk and negotiation is the Powerplus 100, a dead-simple V-twin motorcycle engine. Made of aluminum, the long-stroke motor has billet rocker covers with a serrated edge that evoke memories of the vertical fins found on past Indian twins. Once production reaches high enough numbers–Indian plans to sell 6,000 motorcycles in 2002–cast pieces will replace the costly billet units.

"We did a lot of research to see what customers expected from an Indian engine," says O'Hagan. "The three things that stood out were: 1) It had to perform and have plentiful torque, 2) It had to have historic Indian design cues–as in carburetor on the left, round cylinders, vertical fins on top–and 3) Take the best of proven technology and create an engine that's both reliable and durable." And though O'Hagan refuses to give power figures prior to the engine's official introduction, an educated guess based on figures from Harley's competing 88-in.3 pushrod V-twin suggests the Powerplus 100 has at least 95 lb.-ft. of torque. Unfortunately, like Indian, Harley Davidson doesn't quote official horsepower figures for its engines, making a similar comparison impossible. Apparently torque is more important than horsepower in the Cruiser market.

The dry-sump Indian motor has a separate gearbox, a compact and efficient gerotor oil pump, a 26-lb. flywheel, hydraulic lifters, and places the pushrods in polished tubes that run outside the cylinder jugs. Intake valves are 1.94-in., exhaust valves 1.615-in., and the bore and stroke are 3-7/8-in. and 4-1/4-in., respectively. "The long stroke gives the engine lots of torque," says O'Hagan, "and we've used H-beam connecting rods for extra strength."

Strength was an important consideration because owners are not shy about modifying their engines. O'Hagan likens it to those who see a "Do Not Remove This Tag" label on a mattress, and pull it off the first chance they get. "It's awfully hard to dictate to somebody that they can't change the pipes, airbox, or carburetor jets," he says. "So we tested configurations that gave us 15 to 20 more horsepower, and 15 to 20 more lb.-ft. of torque than stock, just to make sure there would be no reliability problems if reasonable modifications are made by the owner."

And while modifications may have caused a ripple of concern, near-term emission and noise regulations haven't. "We've passed the current emission and sound standards," says O'Hagan, "and know we'll have to shift from carburetion to fuel injection in the future. We're already 80% down that path." So, for at least the next 3-4 years, the Powerplus 100 will be able to meet any of the regulations currently on the horizon, and the engine could have a 10-year lifespan should there not be any drastic legislative changes. This will be more than enough time for derivations of the engine to make their way across the Indian lineup, and more powerful versions of the Powerplus 100 to power future Indian Chiefs as well as other models currently under consideration.

All that, however, is in the future. For now, O'Hagan is content to busy himself with getting the 2002 Chief into production, and not lose out on the growth in the Cruiser market. "Harley sales grew a healthy 14% last year in a market that was up by 19%," says O'Hagan, "so there's a lot of growth in there for us." And though Indian doesn't have to sell 20,000 to 40,000 units each year to be successful, they now have a home grown engine–an important image factor for potential customers–that should help them get closer to that level than ever before. 



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