2018 Harley-Davidson Softail Street Bob Cam Upgrade

Stock Milwaukee-Eight 107 cam versus Screamin’ Eagle Stage II Torque Cam

With more performance parts becoming available for the new 2018 Softails, we decided to make yet another mod to our in-house 2018 Harley-Davidson Softail Street Bob. The thought was we’d stick one of Harley’s cams into the Milwaukee-Eight 107 motor, pairing it with a Stage I Kit (air cleaner and mufflers) to see how big of a jump in performance we could get over stock. Of course we needed to remap the ECU after the installs, and we used the base map the Screamin’ Eagle Pro Street Tuner offers for this exact setup.

When all was said and done, we ran the modified bike on our dyno and recorded the numbers. Bottom line? The Softail Street Bob showed an increase of 18.93 hp along with a jump of 1.45 pound-feet of torque. But more important than the peak numbers are the torque and horsepower curves; notice how the horsepower tracks a steady increase all the way through the rpm. The torque curve also has a smoother decrease rate than the stock numbers, with a drop-off at a much later rpm, which is also less severe than stock. With our Screamin’ Eagle Stage II Torque Cam installed, the Street Bob’s M-8 107 engine is now able to stay closer to peak power throughout more of the powerband.

 horsepower and torque

The red lines are the horsepower and torque with the stock cam, while the blue lines represent the new Screamin’ Eagle cam. Running fourth-gear pulls, the Street Bob produced 73.49 hp at 4,820 rpm, compared to 92.42 hp at 5,610 rpm with the Screamin’ Eagle Stage II Torque Cam Kit. In the torque department, the Milwaukee-Eight 107 offered up 104.89 pound-feet at 2,590 rpm compared to 106.34 pound-feet at 3,300 rpm with the upgraded cam.

Jon McDevitt


Year/Make/Model: 2018/Harley-Davidson/Softail Street Bob
Year/Manufacturer 2018/H-D
Type/Size Milwaukee-Eight/107
Cam Screamin’ Eagle Stage II Torque Kit
Air Cleaner Screamin’ Eagle Extreme-Flow
Exhaust Screamin’ Eagle Street Cannon Mufflers
Tuner Screamin’ Eagle Pro Street Tuner
Grips H-D Defiance Handgrips
Footpegs H-D Defiance Pegs
Turn Signals H-D LED Bullet Turn Signal Inserts
Trim H-D Gloss Black Oil Cooler Cover
Tank H-D Diamond Black Fuel Cap
Seat H-D Badlander Two-Up Seat