Indian has unveiled the all-new liquid-cooled PowerPlus 108, a 1,768cc (108ci) V-twin that makes a claimed 128 lb-ft of torque and 122 horsepower and will be the beating heart of a new fixed-fairing bagger called the Challenger.
Rider got a chance to see and experience the PowerPlus 108 during a multi-day, hush-hush ride on the Challenger, and we’ll post a full review when the embargo lifts on Tuesday, October 29. For now, we can only reveal details about the new engine.
With ever-tightening emissions regulations, the era of air-cooled engines is drawing to a close. Euro 5 standards, which go into effect on January 1, 2020, further reduce limits for carbon monoxide, hydrocarbons and nitrogen oxides, and adapting air-cooled engines to meet these standards will become increasingly difficult.
Indian’s air-cooled Thunder Stroke 111/116 V-twin has powered all of its heavyweight baggers and tourers since it debuted for 2014. Rather than implement partial liquid cooling like Harley-Davidson did with its Twin-Cooled Milwaukee-Eight V-twin and BMW did with its R-series boxer twin, Indian decided to go all-in with liquid cooling for the PowerPlus 108. And it didn’t have to go far for inspiration. Indian’s middleweight Scout lineup is powered by a liquid-cooled, 60-degree V-twin with DOHC and 4 valves per cylinder, and the PowerPlus has the same engine configuration and 4 valves per cylinder but uses a SOHC head.
Interestingly, PowerPlus revives the name given both to an 18-horsepower 1,000cc V-twin and the motorcycle it powered, which Indian produced from 1916 to 1924. The U.S. War Department ordered 20,000 PowerPlus motorcycles for service during World War I, and the PowerPlus helped Erwin “Cannonball” Baker set several endurance records. According to motorcycle historian Tod Rafferty, when the 600cc Scout was introduced in 1920, it “was basically a downsized Powerplus.” Today’s PowerPlus, on the other hand, is basically an upsized Scout.
Indian says the PowerPlus “was developed with a big-piston, big-torque mindset with an end game of maximum power delivery across the entire curve.” With an oversquare bore and stroke of 108.0 x 96.5mm, the PowerPlus 108’s 1,768cc displacement is 122cc smaller than that of the 1,890cc Thunder Stroke 116 found in most of Indian’s heavyweight lineup for 2020, but the PowerPlus makes more claimed torque: 128 lb-ft at 3,800 rpm versus 126 lb-ft at 2,900 rpm. The PowerPlus also revs higher, redlining at 6,500 rpm versus 5,300 rpm on the Thunder Stroke.
Dual-bore 52mm throttle bodies take big gulps of fuel and air, which is compressed at a ratio of 11.0:1. With throttle-by-wire actuation, the PowerPlus offers three riding modes with different throttle response settings. The unit crankcase has a semi-dry oil sump that holds five quarts. To reduce maintenance and improve reliability, the overhead camshafts have hydraulic chain tensioners and the valves have hydraulic lash adjusters. The 6-speed constant mesh transmission has an overdrive top gear and a cable-actuated wet assist clutch.
Indian says the “PowerPlus was tested, refined and proven by one of the industry’s most rigorous development and testing programs, accumulating over one million miles of simulated testing, including state-of-the-art dyno testing, and more than 300,000 on-road miles.” Designing and developing an entirely new engine is a major investment, and Indian clearly sees the PowerPlus as worth the effort.
Unfortunately, we are prohibited from providing any riding impressions about the PowerPlus or the Challenger or other information at this time. Check back on October 29 for the full story.