NGK SILKGR9A7EG Laser Iridium Spark Plug
This NGK Laser Iridium plug is built for high heat and high RPM use. It offers strong spark, stable combustion, and reliable ignition under load. The iridium centre electrode needs less voltage to fire, which helps cold starts and keeps performance consistent as temperatures rise. A platinum-tipped ground electrode improves durability, so gap growth is slower over time.
Use this plug when tuning for sustained track use or when the OE specification calls for a colder heat range. It is a resistor type to reduce electrical noise that can affect sensors and the ECU.
Only buy spark plugs that match your engine’s exact specification. Use the site’s vehicle lookup or check the Vehicle Fitment tab to confirm.
| Part number | SILKGR9A7EG |
| NGK stock number | 91731 |
| GTIN | 87295917312 |
| Category | 686 – Spark Plug |
| Technology | Laser Iridium (iridium centre, platinum ground) |
| Heat range | 9 (cold – suited to high temperature operation) |
| Resistor | Yes |
| Electrode design | Fine-wire centre, tapered cut ground |
| Pre-gapped | Yes – set to OE specification (do not adjust) |
| Fuel type | Petrol |
| Service life | Follow vehicle manufacturer interval |
- Ideal where a colder plug is required to manage combustion heat during spirited driving or track days.
- Helps maintain a clean burn and reduce misfire risk at high boost or high RPM.
Important: Always torque to the vehicle manufacturer’s spec and install on a cool engine with a clean, dry seat.
The price displayed is for a single plug, please add the desired amount to your basket.


