Milwaukee-Eight Build Makes Big Power
With the right parts (and the right builder), it isn’t hard to put up big dyno numbers with a Milwaukee-Eight.
Despite mixed reviews, it’s become pretty clear that Harley-Davidson’s new Milwaukee-Eight powerplant represents an overall improvement over the old V-Twin. Producing more power with a smoother delivery and returning better fuel economy sounds like a win-win-win. But when it comes to the folks at HD Forums, more is never enough. And that’s why there’s an aftermarket.
To demonstrate just what the Milwaukee-Eight is capable of, member Steve Cole recently threw up a dyno sheet for a customer’s 2017 Road Glide. With a little background information, of course. And it turns out that this is one well-ridden bike. But after a poor Stage III installation by a local dealer, the customer sought out Cole’s expertise.
“The bike has had a SE Stage III kit installed by a local dealership. The first one failed pretty quickly and when they went to replace it, they called and asked if I could look it over for them. Typical deal, cylinders out of round and too tight. So for the second kit we fixed the cylinders before it went together and replaced the oil pump and pan, along with cleaning things out. This is how I got to know the customer. After 100 miles, oil and filter were changed and checked/inspected for metal in the oil. Everything looked good, so he went another 1000 miles and called and asked what more could be done as he was done worrying about warranty.”
Ah, the never ending quest for more. It just never goes away, and that’s especially true in this case.
“So we upgraded to a TTS-200 camshaft as one of our Beta testers. He put about 2,500 miles on it and was happy but asked for more again. So we talked about going with bigger Injectors as we were at the limit of the stock injectors with just the cam added, stock exhaust, and slip-on mufflers. He really wanted a Thunderheader as he had them on his previous bike in the past and told me he had already ordered one. So we ended up adding the Thunderheader and a larger throttle body and injectors.
Tuned it up and down the road he went with the understanding that we needed to check it every 2,500 miles. So after 10K on the parts, we did the final inspection and asked how it had been. His answer was kind of funny – it runs fine but eats rear tires now! I told him that’s his fault and to take it easy on it and it would not do it. He said that’s no fun. So after going over everything and finding nothing wrong with the engine side of things, I put it back onto the dyno for its last check.”
Even with 10,000 miles on the clock, the Milwaukee-Eight is still purring away like nobody’s business. After providing a complete list of mods, we get a glimpse at the actual dyno sheet.
SE Stage III kit modified (114cu in)
TTS 200 Camshaft
64 mm Throttle Body
5.5 Injectors
Thunderheader
High Flow Air Cleaner
Mastertune II
Upgraded clutch
Pretty impressive, indeed. And as Cole reveals, installing the bigger injectors, throttle body, and Thunderheader added roughly 17 horsepower themselves.
“Here is the same bike prior to adding the 64 mm, 5.5 injectors and Thunderheader.
Parts list:
SE Stage III kit modified (114cu in)
TTS 200 Camshaft
High Flow Air Cleaner
OEM header with Cat
Street Cannon Slip-ons
Mastertune II
Upgraded clutch”
Aside from providing proof that the Milwaukee-Eight can make big power, Cole also delves into some fascinating insights only a guy who builds engines for a living can provide. If you’re contemplating upgrades for your M8, it’s well worth the read!
