NGK BPR7EIX Iridium IX Spark Plug – Stock No. 4055
The NGK BPR7EIX is a high-quality iridium spark plug designed for reliable ignition under hard use. It uses a fine iridium centre electrode for a strong spark and better throttle response. The projected tip helps cold starts and smooth idle, while the resistor design controls electrical noise for ECU and audio systems.
It is a colder NGK heat range (7), suited to many tuned or high-load petrol engines that run hotter than standard. It can also help reduce fouling in stop-start or short-trip use.
- Finer 0.6 mm iridium tip for a stable spark and clean combustion
- Resistor plug to reduce interference with electronics
- Projected tip for easier starting and smoother running
- Durable under high temperature and pressure
Always confirm fitment and heat range against your engine’s specification. Check and set the spark plug gap to the vehicle manufacturer’s spec.
Technical specifications
| Part number | NGK BPR7EIX |
| NGK stock number | 4055 |
| GTIN | 087295140550 |
| Category | 686 – Spark Plug |
| Thread diameter | 14 mm |
| Thread reach | 19 mm |
| Hex size | 20.8 mm (13/16 in) |
| Seat type | Gasket (flat seat) |
| Heat range | 7 (NGK scale – colder than 6) |
| Centre electrode | Iridium, 0.6 mm fine tip |
| Ground electrode | Nickel alloy, tapered cut |
| Resistor | Yes (approx. 5 k?) |
| Terminal type | Removable terminal nut |
| Factory set gap | 0.8 mm (check and adjust to OE spec) |
| Electrode configuration | Single ground |
Fitment guidance:
– Suits petrol engines designed for a 14 mm thread, 19 mm reach, gasket seat, projected tip, and NGK heat range 7.
– Common in many performance and motorcycle applications, but specifications vary.
Use the site’s vehicle lookup to confirm, or check the Vehicle Fitment tab for full details.
The price displayed is for a single plug, please add the desired amount to your basket.


