Issue link: https://read.dmtmag.com/i/738714
58 nNovember 2016n www.thunderpress.net THUNDER PRESS M-8 and beyond Elsewhere in this issue, you can see more details about the new Milwaukee-Eight Big Twin. Plenty of insight can be gained from some online searching and magazine reading as well, but the point of it all… the real difference… the big deal… about the new Big Twin is its breathing capa- bilities via four valves per cylinder. It's news—even if it isn't new! Fact is, Harley has a history with four-valve heads dating back almost exactly 100 years. The Motor Company built an all-conquering rac- ing engine with this notable feature, starting in 1916! The irony is, it wasn't so much about breathing then, and more about keeping things together for long races—small valves and springs being less likely to melt or explode, primitive metallurgy and lubrication being what it was. Thing is, it sure as hell worked then and it works now. Now, in addition to all the ben- efi ts four-valve heads have always offered, over a century of develop- ment and refi nement has added many more. All these upsides with virtually no downside have culminated in the Milwaukee-Eight engines, in both oil-cooled and liquid-cooled versions. Only in the future will we know what levels of further development the fac- tory has in mind for this powerplant, but that future is bright, rest assured. For now, however, let's look at cer- tain advantages and options we have before us as is. Take a deep breath H-D touts the fact that the new M-8 heads offer 50 percent more fl ow. Then they turn right around and say the engines offer 10 percent more power. What's up with that? Anywhere I've ever looked and anything I've read or experienced indicates 50 percent more fl ow meant 50 percent more power, all else equal. Not a mere 10 percent. Where'd all that extra poop go? Well, there are plenty of valid reasons why you won't see all the extra benefi ts of higher fl ow up front. For one thing, there's that pesky "compliance" the factory has to contend with—various government emissions and noise standards mostly, and nowadays worldwide. There's also the effort to cool things off, relative to the waffl e iron levels of heat the Twin Cam began to radiate as it grew. (More power does equal more heat as the laws of physics constantly remind us.) All the same, Harley-Davidson is also noted for never giving us the best they have all at once on the showroom fl oor. Meaning, in time-honored tradi- tion, you really don't need to go much further than the relevant pages of the Screamin' Eagle section in the new 2017 P&A catalog to see where plenty of that unrealized potential is hiding. If you want "all else equal," the equaliz- ers are there already—SE Stage II cam kits and Stage III engine kits that will get you much closer to that extra 50 percent! Not at all incidentally, all of it is smog legal and, once installed by your friendly local dealer, covered by the full factory warranty as well. It gets better. If a stroll through the showroom and a test ride make you feel like committing your hard-earned to the acquisition of a new Touring M-8 model, as you visit with the sales- person at point of sale, ask them this question: "What's the difference in my payments, if I have a cam kit or Stage III kit installed before I take delivery?" Then, prepare to be surprised! There's a concept known as "cost-benefi t analysis" which applies here for sure. Will all this added strength add to the bottom line? Sure, when hasn't it? The news is, if the tariff for turning poten- tial into results is stretched out over several years the bump in the monthly nut is negligible. Of course, you could always pay cash or install the goods within the fi rst 60 days, after the engine is broken in, and put it on the credit card. But what's point? The best deal is to buy the bike with the perfor- mance stuff taken care of, up front. Buck up for a big bang bumpstick So, what might you want (or get) for your fi nancial commitment to a 2017 M-8? Hereabouts, you'll fi nd some images of power gains to be had from simply adding an SE cam. There are three. Bear in mind, for baggers, torque is the best medicine. 130 120 110 100 90 80 70 60 50 40 30 20 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7 Milwaukee-Eight 107 Stock vs. 107 Stage II* Corrected Rear Wheel Torque (lb-ft) Corrected Rear Wheel Horsepower (hp) Engine Speed (rpm x 1000) *107 Stage II "POWER" with Ventilater A/C & Street Cannon Mufflers 107 Stage II "TORQUE" with Heavy Breather A/C & Street Cannon Mufflers 130 120 110 100 90 80 70 60 50 40 30 20 Stock 107 TQ 107 Stage II "POWER" TQ 107 Stage II "TORQUE" TQ STOCK 107 HP 107 Stage II "POWER" HP 107 Stage II "TORQUE" HP 130 120 110 100 90 80 70 60 50 40 30 20 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7 Milwaukee-Eight 114 Stock vs. 114 Stage II* Corrected Rear Wheel Torque (lb-ft) Corrected Rear Wheel Horsepower (hp) Engine Speed (rpm x 1000) *114 Stage II "POWER" with Ventilater A/C & Street Cannon Mufflers *114 Stage II "TORQUE" with Heavy Breather A/C & Street Cannon Mufflers 130 120 110 100 90 80 70 60 50 40 30 20 Stock 114 TQ 114 Stage II "POWER" TQ 114 Stage II "TORQUE" TQ STOCK 114 HP 114 Stage II "POWER" HP 114 Stage II "TORQUE" HP The additional muscle available from a 107" courtesy of a simple cam change is graphically demonstrated here. We've seen these kinds of charts before from The Motor Company, but what makes it compelling in this iteration is that it has to do with what a new Milwaukee-Eight is capable of, legally. It also hints at the potential in this new powerplant. Give the M-8's four-valve heads what they want… they will not disappoint! Pay attention to the aster- isks about exhaust choices and hardware kits and such, though. Because you'll need more than meets the eye to get this cam kit installed and yielding these kinds of results at this level. Same thing goes for this chart of the 114". Both the torque cam (SE 447) and power cam (SE 468) are represented and they are the same cams as for the 107". The difference in results is down to the difference in displacement as derived from two different bore and stroke specifi cations. The 107" measures 3.937" x 4.375" (99.999mm x 111.125mm) and the 114" 4.0" x 4.5" (101.6mm x 114.3mm). No matter your specifi c choice, big improvements in torque and horsepower can be had with a pipe, air cleaner and cam.