Rywire Mil-Spec Hondata Coil Plug Retrofit Harness

If you're converting your B-series or H-series Honda to coil-on-plug ignition with Hondata, this is the harness that makes it clean. The Rywire Mil-Spec Hondata Coil Plug Retrofit Harness is purpose-built for the Hondata Coil Plug Retrofit (CPR) system running on Hondata S300 - no hacking OEM wiring, no compromises.

This harness is built to the same Mil-Spec standard as Rywire's engine harnesses. That means tefzel wire, new OEM-quality connectors, and RayChem DR25 heat shrink tubing throughout. The result is a harness that can handle the heat, vibration, and tight quarters of a Honda engine bay without degrading over time like a budget or DIY solution would.

It's designed to pair directly with RSX or S2000 coil plugs and ties in cleanly with the Rywire COP Plate for a fully integrated coil-on-plug setup. If you're already running - or planning to run - a Rywire Mil-Spec engine harness, this retrofit harness is matched to it in construction and routing.

Why Coil-On-Plug?

COP conversion eliminates the distributor and individual spark plug wires from your ignition system. The benefits for a performance B-series or H-series build are real: more reliable spark delivery at high RPM, reduced ignition system weight, cleaner engine bay routing, and better compatibility with aggressive tuning on Hondata S300. This harness makes the Hondata CPR retrofit the straightforward part of that conversion.

Mil-Spec Construction - What That Actually Means

Mil-Spec isn't a marketing term here - it refers to the wire spec, insulation rating, and build standards Rywire applies across their harness line. Tefzel (ETFE) wire insulation is rated for higher temperatures and chemical resistance than standard automotive PVC wire. RayChem DR25 heat shrink is dual-wall adhesive-lined tubing used in motorsport and aerospace applications. These aren't upgrades over OEM - they're upgrades over most aftermarket harnesses on the market.

Fitment and Compatibility

This harness is compatible with Honda and Acura B-series and H-series engines running the Hondata S300 ECU with the Hondata Coil Plug Retrofit (CPR) kit. It works with RSX (DC5) or S2000 (AP1/AP2) individual ignition coils. Common applications include EF, EG, EK, DA, and DC chassis builds with B16, B18, B20, or H22 swaps. The Hondata CPR kit and Hondata S300 are required separately - see the technical requirements section below.

What's Included

• 1x Rywire Mil-Spec Hondata Coil Plug Retrofit Harness (tefzel wire, RayChem DR25 heat shrink)
• Coil plug connectors compatible with RSX / S2000 coil packs
• Pre-terminated connector ends for direct integration with Hondata CPR and Rywire COP Plate

Note: The Hondata Coil Plug Retrofit (CPR) kit and Hondata S300 ECU are required to complete this conversion and are sold separately. If you're also running a Rywire Mil-Spec engine harness, this harness is built to match it.

Frequently Asked Questions

What Hondata systems is this harness compatible with?
This harness is designed specifically for Hondata S300 with the Hondata Coil Plug Retrofit (CPR) kit. It is not currently listed as compatible with KPro or FlashPro - verify with Rywire or our team if your application differs.

Do I need additional parts to complete the COP conversion?
Yes. You'll need the Hondata CPR kit, Hondata S300 ECU, RSX or S2000 coil packs, and the Rywire COP Plate (sold separately). This harness is one piece of the full conversion.

Is this harness plug-and-play or does it require splicing?
It is designed as a direct-fit harness for use with the Hondata CPR system and Rywire COP Plate - no splicing required when used with the intended components.

What wire gauge and spec is used?
The harness uses tefzel (ETFE) wire and RayChem DR25 dual-wall adhesive heat shrink, consistent with Rywire's Mil-Spec harness line. Exact gauge specs can be confirmed with Rywire directly.

Will this work on a K-series engine?
No - this harness is built for B-series and H-series engines. For K-series COP applications, a different harness is required.

Part Number: RYW-COP-CPR-HARNESS