2018 Harley-Davidson Softail Street Bob Cam Upgrade
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.

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
Specifications
Year/Make/Model: | 2018/Harley-Davidson/Softail Street Bob |
Engine | |
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 |
Accessories | |
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 |