Tuning from the driver's seat
Track conditions change, fuel changes and drivers change. Plugging in a laptop every time you want a little more or less boost is slow and, between rounds, often impossible. A rotary trim module lets you adjust chosen parts of the tune with a knob, while the ECU stays in charge of the limits you've set.
How the trim module works
The 12 Position Rotary Trim Module is simple hardware. It's a three-wire potentiometer with 12 detents: a 5V supply, a ground, and a signal wire that returns a different voltage for each click. That signal goes to an analog voltage input on the ECU, and the ECU turns it into a position from 1 to 12.
Once the ECU knows the knob position, it becomes just another axis you can use in the tune.
What can you map to it?
Almost anything with a table. Some of our favorite uses:
- Boost levels: 12 steps from wastegate spring pressure to full boost.
- Traction control: change how much wheel slip is allowed, front to rear.
- Launch RPM: the track got a bit better since your last pass, so click up and add a small amount of launch RPM per step.
- Driveshaft RPM target: adjust the curve when the surface is worse than you planned.
- Nitrous, ignition correction and torque management.
One knob, many tables
A single knob can drive several tables at once. We often build an "aggression" knob: position 1 is a soft street map and each click adds a bit of boost, a bit more throttle angle, a higher launch RPM and a higher rev limit. The driver has one control to think about and the tune moves together.
This works because ESP lets you set any table axis to any channel. Set one axis to the trim knob position and fill in the values for each step.
Worked example
Say you want three knobs on a drag car: boost, launch RPM and traction control slip. Wire each to its own analog input, then in ESP set the boost trim table, the launch RPM table and the slip target table to use the matching knob as an axis. Start with a conservative value at position 1 and small, even steps. That way a wrong click doesn't mean a big change, and you can see the effect of each step in the logs.
A trim knob only goes as far as you let it. Keep your safety limits, like overboost cut and rev limits, above the highest knob setting so a knob can never switch protection off.
Panel kits
| Kit | What's in the box | Panel size |
|---|---|---|
| Dual kit (HT-010509) | 2 trim modules with black knobs, 1 yellow knob, the dual panel (HT-010507), instructions | 4.666 x 2 in (118.5 x 50.8 mm), 0.080 in (2 mm) thick |
| Triple kit (HT-010510) | 3 trim modules with black knobs, 1 yellow and 1 red knob, the triple panel (HT-010508), instructions | 7 x 2 in (177.8 x 50.8 mm), 0.080 in (2 mm) thick |
Both kits are listed as compatible with the Elite 2500T, Elite 2500, Elite 1500 and Elite REM.
Try it before you buy
ESP is a free download, so you can open a base map, set up a trim knob as an axis and plan your tables before any hardware arrives.
FAQ
How many trim knobs can I run?
As many as you have spare analog inputs. Each knob needs its own input.
Can a knob control more than one thing?
Yes. Any number of tables can use the same knob as an axis.
Where do I find the setup steps?
See our rotary trim modules guide, and switching tunes with a dash switch for bigger changes. Want help planning the controls for your car? Book a free consultation.
