Tech: Indian’s power secrets
O How US firm built its most powerful motor yet O ‘Liquid-cooled, 60-degree twin produces 121bhp’
Indian’s new Challenger will be powered by this new-from-the-ground-up ‘PowerPlus’ motor when it hits dealers early next year.
A nod to the vintage Indian of the same name (made between 1916 and 1924), the 1769cc (108 cu in), liquid-cooled, 60-degree V-twin produces 121bhp @ 5500rpm and 131ftlb @ 3800rpm. That’s a big hike over the current air-cooled 1811cc ‘Thunderstroke’ engine used in their big capacity cruisers, which will continue to run alongside the Challenger.
‘Milwaukee-Eight’ rival
The American firm claims that the new ‘bagger’ style machine (think low-slung, feet-forward fully-faired tourer with hard panniers) has the performance to beat its closest rival: HarleyDavidson’s new Road Glide Special, which is powered by a slightly bigger 1868cc ‘Milwaukee-Eight 114’ V-twin, but produces ‘just’ 94bhp and 123ftlb of torque.
Indian’s engineers say they started work on the new PowerPlus motor late in 2016, under the code name ‘Raptor’ and by borrowing technology from Indian’s liquid-cooled, 1133cc Scout motor – including that bike’s four-valve, single overhead cam design.
Revving to 6500rpm – high for a big American V-twin, the new short-stroke motor has a semidry sump, an 11:1 compression ratio and its twin 52mm throttle bodies are oval-shaped, so they can be tucked in deeper towards the intake valves to maximise performance. The motor also features hydraulic cam chain tensioners and tappets for ease of maintenance, reliability and, because there’s no need for valve checks, major services will be cheaper, too. Service intervals are at 500 miles, 2500, 5000 and every 5000 after.
In order for the new Challenger to have ‘the best passing power’ in its class, as Indian boasts, the PowerPlus engine produces over 120ftlb of torque right through the rev range, from just under 3000rpm to over 5000rpm. Indian also says the Challenger pulls a five-bike lead over the Harley from zero to 60mph.
True overdrive
The new motor’s six-speed gearbox is heavily based on the tried-and-tested Thunderstroke unit and features what Indian call a ‘true overdrive’, which is basically an extra-tall sixth gear for lazy cruising. An ‘assist’ clutch has a lighter action at the lever and, to control the harshness of engine braking, the motor automatically revmatches and auto-blips off the throttle (not to be confused with a gearbox auto-blipper, which it doesn’t have).
Indian have always mixed traditional design with modern tech, so it’s no surprise electronics play a big part with the new Challenger featuring a new Bosch ECU, ride-by-wire and three riding modes.
O Look out for our first full test of the new Indian Challenger in next week’s MCN.