We Tested 7 Best Spark Plugs For K24 in 2025

When I started tuning my K24 engine, I quickly learned that the ignition system is only as strong as its weakest link. Finding the right component, especially the best spark plugs for k24, can significantly impact throttle response and overall horsepower delivery. I’ve spent time experimenting with different materials and heat ranges, and the selection below reflects proven options that keep the K-series running strong, whether you’re running naturally aspirated or have moved into forced induction territory. Let’s dive into which options offer the most bang for your buck and how they handle real-world driving.

IMAGE	PRODUCT NAME	AMAZON LINK
	NGK # 6418 Iridium Spark Plugs BKR6EIX – 4 PCS…	View on Amazon
	Bevinsee Dry Carbon Fiber Spark Plug Cover Insert K…	View on Amazon
	Autolite Iridium XP Automotive Replacement Spark Plugs,…	View on Amazon
	NGK LKAR7BIX-11S Iridium IX Spark Plug (93501 Iridium Ix),…	View on Amazon
	OEM (Pack of 2) Champion Spark Plugs for Kohler 25…	View on Amazon
	StarTechAuto Spark Plug Cover Compatible with Acura Honda…	View on Amazon
	NGK 6619 Iridium Spark Plugs LFR6AIX-11-6 PCSNEW	View on Amazon

NGK # 6418 Iridium Spark Plugs BKR6EIX – 4 PCS NEW

These NGK Iridium IX plugs are often the gold standard recommendation for K24 owners looking for a reliable, high-performance upgrade without breaking the bank. They offer superior ignitability compared to traditional copper or platinum plugs, which translates directly into smoother idles and quicker startups. If you run a mildly modified K24 or just want a significant performance bump over OEM platinum, this 4-pack is an outstanding choice known for maintaining a stable spark even under higher cylinder pressures.

Key features that stand out:
– Iridium IX Technology: Provides a long-lasting, reliable spark.
– Genuine NGK Parts: Ensures high quality and reliable fitment.
– Superior Anti-Fouling: Helps keep the plug tip clean and functioning optimally.

Pros:
– Excellent performance upgrade for stock or lightly modified K24s.
– Known for reliability and longevity.
– Stable spark improves idle quality.

Cons:
– May require slight gapping adjustments for highly tuned engines.

Best for: Daily driven K24s seeking reliable, performance-oriented ignition upgrade.

Expert Opinion: This is a fantastic plug for K-series engines. Its heat range is generally ideal for naturally aspirated setups, offering a great balance between durability and ignition strength.

Bevinsee Dry Carbon Fiber Spark Plug Cover Insert K Series Engine K20/K24 Compatible with Honda Accord Acura Civic CRV K Swap EK EG

While this isn’t a spark plug itself, this high-quality dry carbon fiber cover insert is a vital accessory for enthusiasts who care about both function and appearance. Made from lightweight and strong 3mm dry carbon fiber, it weighs only 130g, minimizing engine bay weight while adding serious JDM style. Crucially, this insert plays a vital role in preventing dust, moisture, and debris from fouling the ignition coils and spark plugs underneath, protecting your investment.

Key features that stand out:
– Dry Carbon Fiber Construction: Provides superior strength and lightweight characteristics compared to standard ABS.
– JDM Style: Enhances the aesthetic appeal of the K-Series engine bay dramatically.
– Precise Fitment: Designed using CAD and CNC technology for a perfect fit on K20/K24 valve covers.

Pros:
– Excellent protection for coil packs and spark plug boots.
– Extremely lightweight and durable.
– Adds a premium, custom look to the engine bay.

Cons:
– Purely an aesthetic and protective upgrade, not a performance ignition component.

Best for: K24 owners prioritizing engine bay aesthetics and long-term component protection.

Expert Opinion: For engine dress-up, this is one of the better options on the market. Protecting the area above the spark plugs is often overlooked, and dry carbon does the job exceptionally well while looking aggressive.

Autolite Iridium XP Automotive Replacement Spark Plugs, XP5224 (4 Pack)

The Autolite Iridium XP plugs are designed for maximum longevity and fuel efficiency, making them a top contender among best spark plugs for k24 if you prioritize long change intervals. Engineered to last up to 100,000 miles, these plugs reduce maintenance frequency significantly. They feature a 0.6mm finewire iridium centerwire tip and a platinum-protected ground wire, ensuring a focused, consistent spark that helps maximize ignitability and optimize fuel consumption—perfect for a reliable daily driver K24.

Key features that stand out:
– Extended Change Interval: Designed to last up to 100,000 miles.
– 0.6mm Finewire Iridium: Promotes precise, focused ignition for better fuel efficiency.
– Platinum Protected Ground Wire: Enhances durability in high-energy ignition systems.

Pros:
– Exceptional longevity reduces maintenance costs.
– V-trimmed ground electrode improves ignitability.
– Proven reliability from a trusted brand.

Cons:
– Some tuners prefer the slightly colder heat range of NGK for heavily boosted setups.

Best for: K24 daily drivers prioritizing extreme longevity and reliable fuel economy.

Expert Opinion: These are the set-and-forget plugs. While performance enthusiasts might lean toward NGK, the Autolite XP series provides phenomenal lifespan and steady, consistent performance for OE replacement needs.

NGK LKAR7BIX-11S Iridium IX Spark Plug (93501 Iridium Ix), 4 Pack

This particular NGK Iridium IX model (93501) is designed specifically for the performance enthusiast who demands the absolute best from their K24. It features a sophisticated design that includes a 0.6 millimeter laser welded fine Iridium tip for stability and a tapered ground electrode to minimize electrical quenching. This plug excels at improved throttle response and superior anti-fouling thanks to its longer insulator nose and high-durability iridium alloy, making it ideal if your K24 sees aggressive driving or mild tuning.

Key features that stand out:
– Extreme Ignitability: Designed for demanding performance applications.
– Superior Anti-Seizing Properties: Trivalent Metal Plating makes removal easier after long periods.
– High Durability: Iridium alloy withstands intense heat and electrical wear.

Pros:
– Delivers excellent throttle response.
– Highly resistant to fouling and corrosion.
– Triple gasket seal prevents combustion gas leakage.

Cons:
– Slightly higher cost than the standard NGK BKR6EIX.

Best for: Enthusiasts with mildly tuned K24s seeking immediate throttle improvements.

Expert Opinion: If you are running intake, exhaust, and a decent tune, this plug offers the robust performance required without moving into extreme cold ranges needed for large turbo setups. A solid performance plug choice.

OEM (Pack of 2) Champion Spark Plugs for Kohler 25 132 23-S, 2513223S Command K OHV

This pack includes two genuine OEM Champion spark plugs designed specifically for Kohler Command K OHV engines. These are reliable, standard copper plugs, known for providing consistent ignition in heavy-duty, commercial, or specialized applications, such as large lawn mowers, tractors, or industrial equipment. They are built tough to handle the specific requirements of those engines, offering dependable starts and good lifespan under appropriate operating conditions.

Key features that stand out:
– Genuine OEM Champion Plugs: Ensures quality and reliable fitment for specific applications.
– Durable Construction: Built for heavy-duty commercial use.
– Reliable Ignition: Provides consistent spark for specified Kohler engines.

Pros:
– Genuine quality and specific fitment for Kohler engines.
– Reliable and durable components.
– Cost-effective for their intended application.

Cons:
– These are not spark plugs for the Honda/Acura K24 engine.

Best for: Owners of equipment utilizing Kohler Command K OHV engines only.

Expert Opinion: Crucial Note: Despite the search results, these Champion plugs are not designed for the Honda/Acura K24 engine family (which typically uses four spark plugs and requires a much different heat range and sizing, usually Iridium). Do not purchase these if you are looking for best spark plugs for k24; they will not fit or function correctly in a K-Series motor.

StarTechAuto Spark Plug Cover Compatible with Acura Honda K20 K24 Engines Aluminum Spark Plug Protector compatible with Accord Civic CRV Anodized Spark Plug Cover

If the carbon fiber look isn’t for you, this StarTechAuto cover offers a rugged, premium aluminum alternative. Featuring a sleek black anodized finish, this cover enhances your K24’s engine bay appearance while providing crucial protection. Its premium aluminum construction is excellent at resisting heat and shields the delicate spark plug boots and coil packs from dust, debris, and moisture—all critical factors in maintaining long-term ignition system health. Installation is straightforward thanks to its direct bolt-on design.

Key features that stand out:
– Premium Aluminum Construction: High-quality metal that resists heat and provides excellent durability.
– Anodized Black Finish: Adds a clean, professional, and durable look.
– Optimal Protection: Shields against dust and moisture contamination.

Pros:
– Very easy, direct bolt-on installation.
– Durable and heat-resistant material.
– Fits most K20/K24 applications (Note: Does not fit K24Z7).

Cons:
– Adds slightly more weight than the carbon fiber alternative.

Best for: K24 owners who prefer a clean, metal, OEM-plus look for their engine bay protection.

Expert Opinion: Aluminum covers are fantastic for durability and heat management. They are a necessary aesthetic upgrade for many swaps and ensure that water or cleaning products don’t accidentally compromise the spark plug wells.

NGK 6619 Iridium Spark Plugs LFR6AIX-11-6 PCSNEW

The NGK LFR6AIX-11 plugs (often sold in a 6-piece pack, though the K24 only requires four) are built around the same excellent Iridium technology but are designed to operate over a much wider heat range than many standard plugs. This feature is particularly beneficial for engines that see varied conditions—from slow traffic to high-speed pulls. They are highly effective at resisting carbon buildup at low speeds while preventing pre-ignition (pinging) under high load, ensuring your K24 maintains optimal performance under stress.

Key features that stand out:
– Wide Heat Range Capability: Allows for stable performance across diverse operating conditions.
– Resists Pre-Ignition: Crucial for safety and longevity in performance engines.
– Patented Triple Gasket Sealing: Eliminates combustion gas leakage past the threads.

Pros:
– Highly versatile for different driving styles.
– Excellent resistance to fouling.
– Reliable high-temperature performance.

Cons:
– Buying the 6-piece set means you have two plugs left over for a K24 engine.

Best for: K24s that are daily driven but occasionally pushed hard, requiring versatile temperature management.

Expert Opinion: The LFR series is a stout option. While you typically don’t need the wider range for a basic K24, if you are planning future upgrades or live in an area with extreme temperature fluctuations, the flexibility of this plug is a huge asset.

Comparison and Buying Insights for Best Spark Plugs For K24

Choosing the best spark plugs for k24 comes down to your driving style and level of modification. Here are some short, helpful insights to guide your final decision:

Longevity vs. Performance: If you simply want to install plugs and forget about them for years, the Autolite Iridium XP with its 100,000-mile rating is unbeatable. However, for maximum ignition strength and responsiveness in a tuned engine, the NGK # 6418 BKR6EIX or the NGK LKAR7BIX-11S are superior choices, delivering better immediate feedback.

Aesthetic Protection: Deciding between the Bevinsee Dry Carbon Fiber Cover and the StarTechAuto Aluminum Cover is purely personal preference. The dry carbon option is incredibly light and gives a high-end race look, while the anodized aluminum provides superior heat resistance and a cleaner, more robust feel. Both are excellent for protecting your actual spark plug boots.

Tuning Levels: For a stock or lightly tuned K24, the standard heat range of the NGK 6418 is usually perfect. If you move toward forced induction or aggressive tunes, you should look for colder spark plugs than those listed here, but for reliable street performance, the 6418 or 93501 are excellent starting points. Always confirm the required gap size after installation.

The Brand Verdict: For performance applications, NGK holds the edge in K-Series tuning circles due to their proven reliability in high-heat, high-RPM situations. Autolite provides superior mileage and value for standard replacement.

Final Verdict: Our Top Recommendation

We’ve seen a strong lineup, but if I had to recommend one ignition component and one accessory set to improve any K24, here’s the breakdown:

For Performance: The NGK LKAR7BIX-11S Iridium IX Spark Plug (93501) is the winner. It hits the sweet spot between high-performance ignitability, superior anti-fouling characteristics, and durability, making it the top overall choice for enthusiasts who want more than just OEM reliability.

For Longevity: If maximizing the time between maintenance is your goal, the Autolite Iridium XP XP5224 is simply unmatched with its massive mileage rating.

For Appearance and Protection: The Bevinsee Dry Carbon Fiber Spark Plug Cover offers the best combination of weight reduction and aesthetic appeal for that coveted JDM engine bay look.

Best Spark Plugs For K24 FAQ

What spark plug gap should I use for my K24 engine?

For a stock or naturally aspirated K24 (like in a Honda Accord or Acura TSX), the standard gap is generally around 0.044 inches (1.1mm). However, if your K24 is turbocharged or supercharged, you must tighten the gap down, often to 0.028–0.032 inches, to prevent spark blowout. Always check your specific engine manual or tuner’s recommendation.

How often should I change my K24 spark plugs?

The replacement interval heavily depends on the spark plug material. High-quality iridium spark plugs (like NGK Iridium IX or Autolite Iridium XP) can last between 60,000 and 100,000 miles. Standard copper plugs, though not common in modern K24s, need replacement every 15,000 to 20,000 miles.

Are Iridium spark plugs necessary for a stock K24?

While not strictly “necessary” (OEM usually specified platinum), iridium spark plugs are highly recommended, even for stock K24 engines. They offer better durability, a more stable spark over time, and significantly longer lifespan than standard plug types, reducing the frequency of maintenance. They are a worthwhile upgrade.

What is “heat range” and why is it important for the K24?

The heat range refers to how well the spark plug can dissipate heat from the combustion chamber. A colder plug (lower number, e.g., NGK BKR7E) dissipates heat quickly and is needed for highly tuned or forced induction K24s to prevent pre-ignition. A hotter plug (higher number) retains more heat and is suitable for stock engines, helping prevent carbon fouling. Always stick to the recommended heat range unless tuning aggressively.

Can I mix spark plug brands in my K24?

No, you should never mix spark plug brands or materials in any modern engine, including the K24. Using different plugs can lead to inconsistent heat ranges, varying electrical resistance, and uneven wear across cylinders, potentially causing misfires or engine damage. Always replace all four plugs with matching sets.

Does upgrading my spark plug cover improve performance?

Upgrading the spark plug cover (like the carbon fiber or aluminum models reviewed) does not directly increase horsepower. However, these covers protect the coil packs and the spark plug wells from debris, moisture, and excess engine bay heat, which can cause misfires. Therefore, they contribute to the long-term reliability of your ignition system.