OBD1 Honda 1720 VTEC Conversion Kit Installation Instructions
We sell the components required for this conversion as a complete kit here: OBD1 USDM VTEC conversion kit
This guide covers the installation of components needed to convert a non‑VTEC 1720 ECU to VTEC. After performing the hardware conversion, you must install an EEPROM chip or emulator with a calibration that enables VTEC functionality.
Required Components
- 1uF tantalum capacitor (C60)
- Jumper wire (use repurposed lead from another component)
- NPN transistor (Q26)
- 1N4002 clamping diode (D11)
- 5151 High‑side switch (IC14)
- 820k ohm resistor
If RM11 is not present:
- 10k ohm resistor
- 12k ohm resistor
- 51k ohm resistor
All components are included in our VTEC conversion kit.
Installation Steps
1. Install Capacitor at C60
- Solder the yellow tantalum capacitor to the C60 position.
- Ensure correct orientation as indicated on the board.
2. Install Jumper Wire at J10
- Use a trimmed lead from another component as a jumper.
- Solder it in place at J10.
3. Install NPN Transistor at Q26
- Place the NPN transistor at location Q26.
- Follow the shape and footprint markings on the board to orient correctly.
4. Install Diode at D11
- Solder the diode to D11.
- Align the stripe on the diode with the stripe indicated on the PCB silkscreen.
5. Install High‑Side Switch at IC14
- Solder the high‑side switch at IC14.
- Ensure correct orientation per the footprint.
6. Install 820k resistor
- Install 820k resistor at R67
7. Install VTEC resistors (if RM11 is not present)
- De-solder holes 1, 2, 3, and 8
- Install 10k resistor between hole 1 and 2
- Install 51k resistor between hole 2 and 3
- Install 12k resistor between hole 3 and 8
Final Notes
- Once these components are installed, the ECU hardware will support VTEC.
- A compatible calibration (EEPROM chip or emulator) must be installed to enable VTEC activation.
- Refer to the highlighted 1720 board image below for component locations.
