What you are looking at above is Harley-Davidson’s ninth iteration of its “Big Twin” engines. It’s called the Milwaukee-Eight, named after Harley-Davidson’s home town and the fact that the engine head design employs a very modern eight valves in total (four per cylinder head).
Time will tell if the Milwaukee-Eight becomes as iconic as Harley-Davidson’s other designs, like the Flathead, Knucklehead, Panhead, etc. But, we do know that the Milwaukee-Eight marks a more modern approach to engine design from the Bar & Shield brand.
To this end, Harley-Davidson says that the new power plant offers a quicker throttle response, more passing power, purer sound (whatever that means), and a smoother ride (read: less vibrations).
The Milwaukee-Eight will first be used on Harley-Davidson’s touring and trike lines, though we can expect the engine design to permeate through Harley-Davidson’s lineup.
“The Milwaukee-Eight engine carries the legacy of Harley-Davidson Big Twins into the future,” said Chief Powertrain Engineer Alex Bozmoski.
“While respecting the essential Big Twin character, we’ve created an all-new motor. Every aspect of performance, durability and styling has been improved as a direct response to the voice of Harley-Davidson customers around the world.”
For now, the Milwaukee-Eight 45° v-twin engines will be offered in two displacements and three variations:
- Milwaukee-Eight 107 (107ci, 1750cc) – precision oil-cooled cylinder heads for the Street Glide/Street Glide Special, Road Glide/Road Glide Special, Electra Glide, Ultra Classic, Road King, and Freewheeler models.
- Twin-Cooled Milwaukee-Eight 107 (107ci, 1750cc) – liquid-cooled cylinder heads for the Ultra Limited/Ultra Limited Low, Road Glide, Ultra, and Tri Glide Ultra models.
- Twin-Cooled Milwaukee-Eight 114 (114ci,1870cc) – liquid-cooled cylinder heads for the CVO Limited and CVO Street Glide models.
As one would expect, the Milwaukee-Eight engine produces more power than its predecessor, 10% to be precise. The power increase comes in part from the added increase in displacement, but Harley-Davidson has also upped the compression ratio.
Additionally, the eight-valve head design has an increased 50% intake and exhaust flow capacity, while dual-spark plugs ignite the combustion.
Harley-Davidson also touts the Milwaukee-Eight engine’s ability to increase acceleration (11% quicker on the 107ci engine, and 8% on the 114ci engine), due mostly to the fact that the Milwaukee-Eight engine weighs the same as the Twin Cam motors it replaces, while obviously having a power advantage.
Heat management has been improved as well (due to refined precision cooling techniques), while engine vibrations have also been reduced by a single internal counter balancer that cancels 75 percent of primary vibration at idle.
We will see the Milwaukee-Eight engine on the 2017 Harley-Davidson touring and trike models, though we can expect the Milwaukee-Eight architecture to be used on other forth-coming models in Harley-Davidson’s arsenal. We expect that process to be gradual, and over the next few years.