NGK-R7438-8 (4905) Racing Spark Plug
The NGK R7438-8 is a high-performance racing spark plug designed for tuned engines that demand a stronger, more reliable ignition. As an authorised NGK retailer, we supply these plugs to enthusiasts and racers who need consistent spark performance when their engine is working harder than standard.
This plug is recommended for vehicles running Stage 1 software or beyond, particularly where an enthusiastic driving style is the norm. Increased boost pressure, higher cylinder temperatures and aggressive ignition timing all place greater demand on the spark plug. The R7438-8 helps prevent the misfires and ignition breakdown that often appear when factory plugs are pushed past their intended limits.
Why Fit a Racing Spark Plug?
When an engine is tuned, the spark has to jump across the electrode gap under far higher pressure than standard. A weaker spark can be “blown out” before it ignites the fuel mixture properly, causing a misfire. The R7438-8 uses a fine-wire iridium centre electrode and a colder heat range to deliver a strong, stable spark and quickly transfer heat away from the combustion chamber, reducing the risk of pre-ignition or detonation in highly tuned engines.
Key Features
- Fine wire iridium centre electrode for a consistent, focused spark and long service life
- Iridium alloy with an extremely high melting point, suited to high-output engines
- Trivalent metal plating for anti-corrosion and anti-seizing properties
- Corrugated insulator ribs to prevent flashover (electrical tracking down the plug body)
- Pure alumina silicate ceramic insulator for superior strength and heat transfer
- Solid copper core for efficient heat removal
- Triple seals to prevent combustion gas leakage
Gapping and Installation
These plugs are pre-set from the factory and must not be re-gapped. The fine-wire iridium electrode is extremely delicate and will be damaged if you attempt to adjust it. Fit them straight from the box.
Sold individually. Please remember to add the correct number of plugs to your cart to match your engine’s cylinder count (typically four for most 2.0 TSI/TFSI engines).
Technical Information
| Part Number | NGK R7438-8 (Stock No. 4905) |
| Type | Resistor, Racing |
| Electrode | Fine wire iridium |
| Gap | 0.8mm (0.03″) |
| Insulation Projection | 0.8mm (0.03″) |
| Heat Range | 8 (Racing/Cold) |
Fitment
The R7438-8 is a popular choice for tuned VW, Audi, SEAT and Skoda 2.0 TSI/TFSI engines, along with many other turbocharged performance applications. Please use the vehicle lookup on our site or check the Vehicle Fitment tab to confirm this plug is correct for your specific car before ordering.
About NGK Racing Spark Plugs
NGK is the world’s leading spark plug manufacturer and supplies original equipment to many major car makers. Their racing range can be found in F1, WRC and MotoGP, as well as countless club-level and trackday cars. Built to cope with the severe conditions inside a racing engine, NGK Racing plugs combine a zinc-dipped shell, triple gasket seal and specially designed insulator nose to deliver sharp throttle response and resist fouling, even under sustained high load.
For tuned road cars, the R7438-8 brings that same racing-grade build quality to your engine bay, giving you the spark reliability needed to make the most of your tune.
Applications
Please note, customers are wholly responsible for checking fitment for their vehicle.



