Issue link: https://read.dmtmag.com/i/738714
59 www.thunderpress.net THUNDER PRESS nNovember 2016n When the Dyna/FXR/Softail/Whatever bikes hit the streets, then a so-called "power" cam could come in handy. Mostly because those other Big Twin "platforms" are substantially lighter and would respond better to high-rpm shenanigans without losing any nota- ble giddy-up from low speeds. Not so with a 900-pound dresser! That means, the SE8-447 (included in Stage II kit #92500047) promises the best results for anyone wanting massive midrange torque. Over 100 ft/lbs from 3000–5000 rpm means never having to worry about passing power, or pull- ing a trailer or sidecar. More impor- tantly (and true of any new M-8 cam) the torque does not drop off early (see the chart), as is the case with the stock cam. As delivered, I believe this char- acteristic is the reason the high-fl ow, deep-breathing nature of the M-8 is "restrained" to only a couple of bike lengths' advantage over the 103 Twin Cam. The original equipment cam has timing specs that strangle the engine as revs build, just as it should be demonstrating that superior increase in fl ow of 4-valve technology. Aside from the bulge in torque, installation of the "torque" cam offers a bonus of about 15 extra horses at peak and a notable stable of extra ponies all across the rev range. A usable, won- drous increase… period! I'm going out on a limb here, to say that this torque cam installation (including all the peripherals required: exhaust, air cleaner, install hardware, etc.) adds about all the power and torque to a Milwaukee-Eight that the vast majority of us can really use or ever will. I'm going further out to add that I doubt anyone gives a rodent's rectum about that reality. They want more… the whole Magilla… the inches… the maximum punch… the bragging rights. OK! Three-stage rocket Those who've faithfully followed my meanderings in this rag for going on a quarter century know I don't like to sound (or feel) like a salesman, especially for The Motor Company. I prefer to call it when I see it. Well, surprise! This time, I see it as Harley- Davidson executing a near-perfect "end run" on the aftermarket. Sure, given a year or two, the aftermarket is capable of building a better monu- ment from the foundations of the M-8 engine. They always have. It's just that this time Harley has kneecapped those efforts, not just by offering complete, competent performance "packages" that can be installed, warranted and fi nanced, but by setting up a whole new learning curve for the aftermarket competition. A learning curve the com- pany has already mastered. Witness the Stage III kits! If, as alluded to a couple para- graphs ago, folks want (and can afford) their M-8 to "be all it can be," Harley has provided—avail- able today! The factory has cov- ered these contingencies (as well as future new Big Twin models) complete with extra inches. Look closely at the charts for these kits. The 114" kit for 107" engines picks up a solid 30 horsepower and the torque curve takes off where the stock curve collapses to the "tune" of 110-plus ft/lbs from 3500–5000 rpm! That, gentle reader, is an ape of an engine… an 800-pound gorilla to be precise. (Cynics might note you get even more of this good stuff from a Twin Cam 120 crate engine, but not for 100,000 miles or more, you won't!) That's the magic in this new engine—it's not even breaking a sweat at this "stage." Then there's the 117" Stage III kit for the 114", which somewhat surprisingly doesn't make any more peak horsepower than the 114/107, but does make it at more accessible engine speeds. It also gives more power "under the curve," which is techno-slang for "feels a hell of a lot stronger all the time" to the rider. Not least because the 117/114 engine makes over 110 ft/lbs of torque from 3000–5000 rpm and damn near 120 ft/lbs from 3500–4500, right where you need it! From a good cam (SE 498) and three more inches! What's left to say—for now— except maybe, "What are you waiting for?" Stock 107 TQ Stock 107 HP 107 TO 114 Stage III TQ 107 TO 114 Stage III 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 107 Stock vs. 114 Stage III* Corrected Rear Wheel Torque (lb-ft) Corrected Rear Wheel Horsepower (hp) Engine Speed (rpm x 1000) *107 to 114 Stage III with High Flow A/C & Street Cannon Mufflers 130 120 110 100 90 80 70 60 50 40 30 20 Stock 114 TQ Stock 114 HP 114 TO 117 Stage III TQ 114 TO 117 Stage III 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. 117 Stage III* Corrected Rear Wheel Torque (lb-ft) Corrected Rear Wheel Horsepower (hp) Engine Speed (rpm x 1000) *114 to 117 Stage III with Ventilater A/C & Street Cannon Mufflers 130 120 110 100 90 80 70 60 50 40 30 20 This represents expectations for the 107" once made into a 114". The SE Stage III kits are pretty much the same for both 107" and 114" engines… a big bore kit. Where things go their own way relative to the Stage II cam kits is the cam! All Stage III kits use the third cam in the Screamin' Eagle lineup for M-8 engines, namely the SE 498. Plain to see in this chart is the fact that the SE 498 cam is engineered to offer the broadest spread of both torque and horsepower complementing large-displacement applications. It does this extremely well! The nature of the "curve" when this cam (in the kit) as applied to the 117" is a factor of stroke-lim- ited rpm. In other words the cam quits before engine speed in a 4" stroke engine can do any damage. Because the breathing of the heads won't quit! A bit too soon to tell for sure, but I doubt the results would be quite this spectacular if one chose to use this cam in a standard 107" and there's a reason. It's part of the learning curve for four-valve Harley engines. Gotta go with fl ow, once you know. Well done, H-D! "Only in the future will we know what levels of further development the factory has in mind for this powerplant, but that future is bright, rest assured."