/* case study */
Seven-Tree Tuning
Reverse-engineered the encrypted .hcf tune format for a 1996 F-350 7.3L Power Stroke Hydra chip, then built a web tune editor to change shift points and idle speed and save a new, flashable tune.
// impact: A proprietary binary format turned into a browser-based editor
// Context
Our farm truck, a 1996 Ford F-350 7.3L Power Stroke with an E4OD transmission, runs a Power Hungry Performance Hydra chip. It also has 34" tires, 30% over-nozzle injectors, a billet converter and a shift kit, so the stock shift schedules are no longer right.
// Challenges
- ›Hydra .hcf tune files are an undocumented, encrypted binary format
- ›34" tires make road speed run ~7% above what the PCM computes, so speed-based shifts arrive late
- ›Editing tunes by hand risks bricking the transmission's shift behaviour
// Approach
- ›Used agentic, AI-assisted reverse engineering to build a decryptor/encryptor and document the format
- ›Wrote a tire-compensation tool that scales every upshift and downshift speed for 34" tires
- ›Generated a per-tune reference with the full up/down shift schedule of every tune
- ›Built a Next.js web editor: load a tune, edit shift points and idle speed, save a new .hcf
// Outcomes
- ›Nine base tunes plus five tire-compensated variants, ready to flash
- ›A browser-based tune editor deployed on Vercel
- ›Documented file-format notes others with the same chip can reuse