NGK IKR9J8 Iridium Spark Plug – Stock No. 93311
This NGK iridium spark plug is built for reliable ignition under high load and high temperature. The fine-wire iridium tip needs less voltage to spark, which helps cold starts and keeps the spark stable at high rpm and under boost. A colder NGK heat range 9 helps control combustion temperatures on tuned engines, reducing the risk of knock and misfire.
Use one heat range colder than stock only when needed. Too cold for your setup can lead to fouling in daily driving.
| Part number | IKR9J8 |
| NGK stock number | 93311 |
| Category | 686 – Spark Plug |
| GTIN | 87295933114 |
| Design | Iridium centre, resistor type |
| Centre electrode | Fine-wire iridium (approx. 0.6 mm) |
| Ground electrode | Nickel alloy with platinum pad |
| Heat range (NGK) | 9 (colder than standard) |
| Thread diameter | M12 |
| Thread pitch | 1.25 |
| Reach (thread length) | 26.5 mm |
| Hex size | 14 mm |
| Seat type | Flat seat with gasket |
| Projection | Projected insulator |
| Resistor | Yes |
| Pre-set gap | 0.8 mm |
| Terminal | Solid terminal nut |
- Strong, consistent spark at high boost and high rpm.
- Colder heat range supports tuned engines and track use.
- Long service life from iridium and platinum-tipped electrodes.
Fitment guidance
Often chosen for modern turbo petrol engines that use M12 long-reach iridium plugs and need a colder heat range for tuning. Please use our vehicle lookup to confirm fitment, or see the Vehicle Fitment tab for full details.
Important: Always check the required heat range and gap for your engine and tune. Adjust gap only if the manufacturer or tuner specifies it. Install on a cold engine and torque to the engine maker’s spec.
The price displayed is for a single plug, please add the desired amount to your basket.


