The NGK Laser Iridium spark plug set for the Mazda RX-8 combines two RE7C-L Leading plugs and two RE9B-T Trailing plugs. Designed for the 13B-MSP Renesis rotary engine, this four-plug set retains the distinct ignition positions and specifications required by the Leading and Trailing circuits.
Key Features
- Original NGK products supplied as a four-plug vehicle-specific set.
- Includes 2 × RE7C-L Leading plugs and 2 × RE9B-T Trailing plugs.
- Laser Iridium technology with fine-wire iridium centre electrodes and platinum ground-electrode elements.
- Leading plugs initiate combustion; Trailing plugs help complete combustion in the rotary chamber.
- Trivalent metal plating provides corrosion and seizure resistance.
- Alumina silicate ceramic insulators provide thermal resistance and electrical insulation.
- Solid copper cores help dissipate heat during rotary-engine thermal cycles.
Technical Specifications
| Specification | RE7C-L — Leading | RE9B-T — Trailing |
|---|---|---|
| Quantity included | 2 | 2 |
| NGK stock number | 6700 | 6701 |
| Combustion position | Lower port — Leading | Upper port — Trailing |
| Thread diameter | 14 mm | 14 mm |
| Thread pitch | 1.25 mm | 1.25 mm |
| Thread reach | 21.0 mm | 19.0 mm |
| Hex size | 13/16 inch (21 mm) | 13/16 inch (21 mm) |
| NGK heat range | 7 | 9 |
| Centre electrode | Fine-wire iridium tip | Fine-wire iridium tip |
| Ground electrode | Platinum pad / chip | Fine-wire platinum tip |
| Preset gap | 1.1 mm (0.043 inch) | 1.2 mm (0.047 inch) |
| Internal resistor | 5 kΩ | 5 kΩ |
| Seat type | Flat, with gasket | Flat, with gasket |
Vehicle Application
- Mazda RX-8, 2004–2011.
- 1.3-litre 13B-MSP Renesis rotary engine.
- 192 HP and 231 HP versions.
Installation and Maintenance
Install each plug in its correct Leading or Trailing position; the two types have different heat ranges, thread reaches and preset gaps. The listed tightening torque for 14 mm dry threads in an aluminium head is 20–30 Nm (15–22 lb-ft). Follow the vehicle service manual and NGK installation instructions for the exact application. The plated threads are intended for installation without anti-seize compound.
The iridium electrode design helps resist carbon fouling during low-speed operation. The original technical information lists a service-life claim of up to 100,000 miles (160,000 km) under factory conditions and a specialist replacement recommendation of 8,000–10,000 miles for heavily driven cars. These are not interchangeable service intervals: use the vehicle maintenance schedule and an application-specific inspection to determine replacement timing.
Included in the Box
- 2 × NGK RE7C-L Leading spark plugs.
- 2 × NGK RE9B-T Trailing spark plugs.