Terry Components has just come out with its Terminal Velocity fuel management system, which will help increase performance and economy for Harleys equipped with Delphi systems.
The new closed-loop system operates using the stock ECU and closes the system with an oxygen sensor installed in one of your exhaust pipes.
As with any closed-loop fuel management system, the Terminal Velocity module is always monitoring the amount of oxygen in your exhaust; therefore, your bike is always getting the most out of every drop of fuel, as well as the most horsepower and torque possible.
The system requires no dyno tuning or mapping, and it manages fuel delivery as you ride. It is easy to install and will continue to adapt to any changes to the bike, if you decide to make more upgrades after it is in place.
If you increase the displacement of your engine, you will have to flash the stock ECU at your local H-D shop for the appropriate timing adjustments.
After a short ride over to the Terry Components facilities in Newbury Park, California, we watched as Dave and Gary installed the Terminal Velocity module on a stock 88-incher and a hopped-up 103.
The only reason we used a Dyno for this article was to prove the gains that can be made from installing the system -- we didn't actually use it for any kind of tuning.
The Terminal Velocity system...
The Terminal Velocity system comes with everything you see here: module, O2 sensor, and quick-clips that tap into your ECU's existing wires.
We followed the installation...
We followed the installation of the module on a TC-88. After removing the saddlebag, Dave removed the side cover to expose the ECU and wiring.
Before we removed the slip-on,...
Before we removed the slip-on, the O2 sensor position was verified. Due to the shape of the sensor, it stuck out a good 3 inches from the pipe, so it had to clear parts of the frame without being obvious. We used a piece of 3-inch-long 1-inch OD pipe to simulate the size of the sensor, and thought it would fit just right at the base of the muffler.
Dave marked the area on the...
Dave marked the area on the slip-on, then pulled it off the bike.
Here, you can see where we...
Here, you can see where we marked the area to mount the sensor and the threaded weld-in bung.
An outline of the bung was...
An outline of the bung was marked in preparation for drilling.
We used a drill press, but...
We used a drill press, but a hand-held hole saw will also work to drill the hole in the pipe.
The chrome finish around the...
The chrome finish around the hole was ground off for better weld adhesion.
When the bung was welded into...
When the bung was welded into place, we slid an old O2 sensor into it to make sure the heat didn't warp its fit. If you don't have an old O2 sensor lying around, a proper size metric bolt will also work.
The slip-on was fastened back...
The slip-on was fastened back into place and the actual O2 sensor was tightened to the bung. To prevent tangled wires later, remember to wind the cable for the sensor counterclockwise approximately four or five turns before inserting it.
On to the wiring, in a few...
On to the wiring, in a few easy steps. To start, about 3 inches of insulation for the wire sheathing had to be removed, so we could find the correct wires. Then, we followed the instructions on connecting the new module to the existing wires.
Next, we connected the Terminal...
Next, we connected the Terminal Velocity unit to the ECU's wires.
The module can then be fastened...
The module can then be fastened to the bike somewhere near the ECU, in this case under the cover, fastened with a couple of zip-ties.
Once the bike was back together,...
Once the bike was back together, the last real step was riding the bike to allow the module to tune itself to the bike.
Gary put the 103ci on the...
Gary put the 103ci on the Dyno first, but the resulting numbers were great for both bikes.
The 103 is a complete package...
The 103 is a complete package Screamin' Eagle with stage III flash from H-D. It produced higher peak numbers, 12.2 hp more and 17.8 more lb-ft of torque, and it increased the numbers across the board as well. Plus, it evened out its fuel curve.
The 88ci also produced better...
The 88ci also produced better numbers in the form of 8.7 more hp and 8.2 more lb-ft of torque.