NGK Laser Iridium Spark Plug Box of 4 (ILZKR8C8G) - 90909

The NGK Laser Iridium Spark Plug ILZKR8C8G (Part #90909) is a premium iridium ignition upgrade engineered specifically for performance-minded drivers. Sold here as a convenient box of 4, this plug fits a wide range of modern Kia and Hyundai engines — including the Forte, Seltos, Soul, Kona, and Veloster — making it a go-to service item for both routine maintenance and ignition performance upgrades. If your vehicle calls for a 12mm, gasket-seat spark plug with an extended projection fine-wire iridium center electrode, this is a plug worth serious consideration.

Key Features & Benefits

• Iridium Fine-Wire Center Electrode (0.6mm): The laser-welded iridium tip is harder and more durable than platinum, resisting wear over long service intervals and delivering a consistently stable spark for smooth combustion.
• Extended Projection Design: The center electrode projects further into the combustion chamber for improved flame kernel development, supporting better throttle response and more complete combustion.
• Platinum Ground Electrode: Standard-type platinum ground electrode complements the iridium center for a balanced, long-lasting ignition pairing.
• Copper Core for Heat Management: NGK's 98% pure copper core aids in heat removal from the firing tip, helping keep operating temperatures in the ideal range and reducing the risk of pre-ignition.
• Pure Alumina Silicate Ceramic Insulator: Provides superior mechanical strength and efficient heat transfer — critical for modern high-compression, high-tech engines.
• Trivalent Metal Plating: The shell's trivalent metal plating delivers superior anti-corrosion and anti-seizing properties, making removal far easier at the next service interval — particularly valuable in aluminum cylinder heads.
• Corrugated Ribs: Corrugated ribs on the insulator prevent flashover, protecting ignition system components even under high-voltage conditions.
• Triple Seals: Three internal seals prevent combustion gas leakage, maintaining compression integrity over the plug's long service life.
• 5kΩ Resistor: Built-in 5k Ohm resistor suppresses electromagnetic interference, protecting sensitive OBD and infotainment electronics common on modern vehicles.
• Up to 100,000-Mile Longevity: NGK rates this plug for up to 100k miles of service life, reducing the frequency of ignition service compared to standard copper plugs.

Specifications

• Part Number / MPN: 90909 / ILZKR8C8G
• Plug Type: Laser Iridium
• Quantity in Box: 4
• Shell Thread Diameter: 12mm
• Thread Pitch: 1.25mm
• Seat Type: Gasket
• Reach: 26.5mm (1.04")
• Hex Size: 5/8" (16mm)
• Terminal Type: Solid
• Gap: 0.031" (0.8mm)
• Center Electrode Material: Iridium — Fine Wire, 0.6mm
• Center Electrode Projection: Extended
• Ground Electrode Material: Platinum — Standard Type
• Resistor: Yes — 5k Ohm
• Heat Range: 8
• Insulator: Pure Alumina Silicate Ceramic
• Core: Copper
• Torque — Cast Iron Head: 10.8–18 lb. ft.
• Torque — Aluminum Head: 10.8–14.5 lb. ft.
• Rated Longevity: Up to 100,000 miles

Fitment

The NGK ILZKR8C8G (90909) is confirmed to fit a broad range of Kia and Hyundai models across multiple model years. Verified applications from manufacturer fitment data include:

• Kia Forte — 2022–2024 (FE, GT, GT-Line, LX, LXS trims)
• Kia Seltos — 2022–2025 (EX, LX, S, SX, X-Line, Nightfall Edition trims)
• Kia Soul — 2022–2025 (EX, GT-Line, LX, S, Turbo, X-Line trims)
• Hyundai Kona — 2021 (Limited, Night, SE, SEL, SEL Plus, Ultimate trims)
• Hyundai Veloster — 2021 (Base, Premium, Turbo, Turbo R-Spec, Turbo Ultimate trims)

This list represents a portion of confirmed fitment. Always use a vehicle-specific fitment check before ordering to confirm compatibility with your exact year, make, model, trim, and engine configuration. If you have questions about fitment, contact ThreePiece.us before placing your order.

What's in the Box

• 4x NGK Laser Iridium Spark Plugs, Part# ILZKR8C8G (90909)

Why Buy from ThreePiece.us

ThreePiece.us carries the NGK ILZKR8C8G box of 4 with free shipping on every order — no minimum required. Need to spread out the cost of a full ignition service? We offer financing through Affirm, so you can pay over time. Our team is available to help confirm fitment for your specific vehicle before you buy — just reach out and we'll make sure you're ordering the right plug for your application.

Frequently Asked Questions

Q: What is the correct spark plug gap for the NGK ILZKR8C8G (90909)?
A: The factory pre-set gap is 0.031" (0.8mm). NGK Laser Iridium plugs are pre-gapped at the factory and generally should not be adjusted, as the fine iridium tip can be damaged by gapping tools.

Q: How many spark plugs come in this listing?
A: This listing is for a box of 4 NGK Laser Iridium spark plugs (ILZKR8C8G / 90909). This is ideal for 4-cylinder engines common across the Kia Forte, Seltos, Soul, Hyundai Kona, and Veloster applications this plug fits.

Q: What torque should I use when installing these spark plugs?
A: NGK specifies 10.8–18 lb. ft. for cast iron cylinder heads and 10.8–14.5 lb. ft. for aluminum cylinder heads. Always consult your vehicle's service manual for the OEM-specified torque value as well.

Q: How long should these iridium spark plugs last?
A: NGK rates the ILZKR8C8G for up to 100,000 miles of service life. Actual longevity will depend on your specific engine, driving conditions, and maintenance habits. Following your vehicle manufacturer's recommended spark plug replacement interval is always advised.