Best Spark Plugs For 9th Gen Si.

When I first started modifying my 9th Gen Si, I quickly learned that something as simple as spark plugs could make a huge difference in performance and reliability, especially once you add basic bolt-ons or tunes. Choosing the right spark plugs for the K24Z7 engine isn’t just about finding the cheapest option; it’s about selecting the correct heat range, optimal electrode material like iridium or platinum, and ensuring consistency. We’ve put together this comprehensive guide comparing popular ignition options to help you dial in the performance and longevity of your beloved Si.

IMAGE	PRODUCT NAME	AMAZON LINK
	NGK # 3186 G-Power Platinum Spark Plugs TR5GP – 8…	View on Amazon
	8 Pcs Spark Plug Wires Set & 41-110 Iridium Spark…	View on Amazon
	NGK 7090 BKR5EGP G-Power Spark Plug, Pack of 4	View on Amazon
	8Pcs 41-110 Iridium Spark Plugs & M8-48322 10.4mm Silicone…	View on Amazon
	NGK LKR7DIX-11S Iridium IX Spark Plug (93175 Iridium Ix),…	View on Amazon
	NGK CR9EIX – Iridium IX Spark Plug – 4-Pack/–	View on Amazon
	ACDelco 41-962 Professional Platinum Spark Plug, (8)	View on Amazon
	Double Iridium Spark Plugs 4 Pack 91187 9029 Fits for…	View on Amazon
	4 pc NGK G-Power Spark Plugs compatible with Honda Civic…	View on Amazon
	NGK LKAR7BIX-11S Iridium IX Spark Plug (93501 Iridium Ix),…	View on Amazon

NGK # 3186 G-Power Platinum Spark Plugs TR5GP – 8 PCSNEW

These G-Power Platinum plugs are designed for reliable, long-lasting ignition performance, making them a great choice if durability is your main concern. Platinum is generally more resistant to wear than traditional copper, and NGK engineered these to operate effectively across a significantly wider range of temperatures than standard plugs. This quality helps prevent frustrating carbon buildup during slower driving while resisting pre-ignition when the engine is pushed hard.

Key features that stand out:
– G-Power Platinum construction offers high durability.
– Designed to operate over a much wider heat range than ordinary plugs.
– Resists carbon buildup and pre-ignition effectively.
– Patented triple gasket sealing process eliminates the possibility of combustion gas leakage.

Pros:
– Excellent resistance to fouling and wear.
– Reliable and consistent performance over time.
– Triple gasket provides security against leaks.

Cons:
– Platinum generally doesn’t offer the extreme performance spike of Iridium.

Best for: Daily driven Si models prioritizing longevity and reliability over peak performance numbers.

Expert Opinion: While the TR5GP heat range is often preferred for other applications (like some GM V8s), the material quality of this NGK Platinum line is undeniable. Always double-check that the TR5 heat range is appropriate for your K24Z7, especially if tuned.

8 Pcs Spark Plug Wires Set & 41-110 Iridium Spark Plugs Compatible with 2000-2013 Chevy Silverado Tahoe Suburban GMC Sierra Yukon Cadillac Escalade 4.8 5.3 6.0 6.2 L, Replace for 41-162 9748HH 9748UU

This comprehensive kit offers high-quality Iridium spark plugs paired with a full set of spark plug wires. Iridium is known for its extreme hardness and high melting point, which allows for a very fine electrode, resulting in a more focused and powerful spark. Although this specific fitment is for large GM V8 engines, the technological advantages of the included Iridium plugs—such as their reliable ignition performance—are worth noting.

Key features that stand out:
– Iridium Spark Plugs offer high durability and reliable performance.
– Comes with a complete set of quality spark plug wires.
– The Iridium plugs feature a 0.04″ (1mm) pre-gap for consistent ignition performance.
– Excellent replacement for numerous heavy-duty OEM numbers (41-110, 41-162).

Pros:
– High-quality Iridium material ensures a strong, reliable spark.
– Fine electrode design improves ignition efficiency.
– A convenient package that includes new wires.

Cons:
– This specific package is incompatible with the 9th Gen Si/K24Z7 engine configuration.

Best for: Users needing an Iridium upgrade kit for compatible GM vehicles, though not suitable for the 9th Gen Si.

Expert Opinion: These Iridium plugs highlight the superior ignitability that this material offers. When selecting an Iridium plug for your Si, look for similar fine-wire technology in the correct NGK heat range (like the LKR7/LKAR7 series).

NGK 7090 BKR5EGP G-Power Spark Plug, Pack of 4

The NGK 7090 BKR5EGP is another Platinum plug option known for its dependability and long service life. While simple in its packaging, this G-Power line is trusted for its ability to deliver a stable spark using a fine-wire platinum tip, which significantly increases ignitability compared to standard copper plugs. This pack size is ideal for 4-cylinder engines like the Si, providing a cost-effective path to a quality upgrade.

Key features that stand out:
– G-Power Platinum construction for durability.
– Fine-wire design enhances spark concentration.
– Reliable ignition performance suitable for standard daily driving.

Pros:
– Affordable entry into the Platinum spark plug market.
– Trusted NGK reliability.
– Proper count for the K24Z7 engine (4 plugs).

Cons:
– Likely too ‘hot’ (lower heat range number) for aggressive tuning on the Si.

Best for: Stock or lightly modified 9th Gen Si owners looking for increased longevity and minor efficiency improvements over standard OEM plugs.

Expert Opinion: The BKR series is a widely used, high-quality plug. For the Si, we typically recommend a colder heat range (higher number) to handle the higher compression and potentially turbo applications, but for stock reliability, these are solid.

8Pcs 41-110 Iridium Spark Plugs & M8-48322 10.4mm Silicone Spark Plug Wires Compatible with Chevy Silverado Suburban Tahoe, GMC Envoy Sierra Savana Yukon, Cadillac, Hummer, 5.3L 6.0L 6.2L V8 LS Truck

This kit focuses on delivering maximum ignition performance and longevity, specifically for V8 LS truck engines, using high-quality Iridium plugs combined with heavy-duty 10.4mm silicone spark plug wires. The key takeaway here is the focus on Enhanced Ignition Performance—the iridium tip ensures superior fuel combustion and reliability, especially under demanding conditions. The thick silicone wires are built to handle higher voltages and heat, illustrating a commitment to maximizing spark delivery.

Key features that stand out:
– 【ENHANCED IGNITION PERFORMANCE】 with a finer Iridium electrode.
– Improved fuel efficiency and reliable starts.
– 【LONG-LASTING】 construction with advanced materials.
– Includes robust 10.4mm silicone spark plug wires.

Pros:
– Premium Double Iridium plugs for extreme durability.
– Wires offer superior insulation against heat and voltage leaks.
– One-year product quality support provided.

Cons:
– Completely incompatible with the K24Z7 ignition system and cylinder count.

Best for: Illustrating the premium ignition components available, though specifically designed for GM V8 platforms.

Expert Opinion: When tuning the K24Z7, ensuring your ignition system can handle the strain is crucial. While we don’t need spark plug wires on a coil-on-plug setup like the Si, the principles of long-lasting Iridium electrodes are exactly what high-performance Si owners should seek.

NGK LKR7DIX-11S Iridium IX Spark Plug (93175 Iridium Ix), 4 Pack

Now we’re talking. The NGK Iridium IX line is highly regarded among performance enthusiasts, and this LKR7DIX-11S model is a top contender for the 9th Gen Si, especially if you plan on tuning. Designed specifically for optimal ignitability, these plugs feature a tiny 0.6mm laser-welded Iridium tip, providing a consistently stable and focused spark. This leads directly to improved throttle response and stable power delivery, even under high boost or high compression.

Key features that stand out:
– Iridium IX—designed specifically for performance.
– The 0.6 millimeter laser welded fine Iridium tip ensures high durability and a consistently stable spark.
– Tapered ground electrode minimizes electrical quenching effect.
– Trivalent Metal Plating provides superior anti-corrosion and anti-seizing properties.

Pros:
– Excellent throttle response and extreme ignitability.
– Highly durable and resistant to electrical wear.
– Ideal heat range (7) for mildly tuned K24Z7 engines.
– Triple gasket seal prevents gas leakage.

Cons:
– More expensive than G-Power or standard OEM options.

Best for: Performance enthusiasts and lightly modified (Stage 1 or simple bolt-ons) 9th Gen Si owners looking for the best spark reliability.

Expert Opinion: The Iridium IX series is the benchmark for performance on modern Hondas. This plug offers the perfect balance of heat resistance and reliable spark energy necessary for the high-revving K-series engine.

NGK CR9EIX – Iridium IX Spark Plug – 4-Pack

Another member of the respected NGK Iridium IX family, the CR9EIX focuses on extreme heat dissipation and performance, often found in high-revving motorcycle engines or specific high-output car applications. You get the same benefits of the laser-welded Iridium tip for superior ignitability and throttle response. This is a cold plug (heat range 9), which can be crucial for heavily modified or boosted K-series engines running higher pressures.

Key features that stand out:
– Genuine NGK Iridium IX 3521 Spark Plug.
– Superior ignitability due to the fine Iridium tip.
– Direct replacement design ensures a precise fit (once verified for the specific application).
– Excellent heat resistance for aggressive tuning.

Pros:
– Provides the sharpest, most consistent spark possible.
– Extremely high durability against heat and fouling.
– Necessary cold heat range for forced induction applications.

Cons:
– Too cold for a completely stock Si, potentially leading to fouling.

Best for: Heavily tuned, aggressively driven, or forced-induction 9th Gen Si owners who require a colder plug to prevent detonation.

Expert Opinion: The CR9EIX is an excellent high-performance plug, but K24Z7 owners should only consider running a 9 heat range if they are significantly modified (turbo/supercharged) or have custom tunes designed around this colder temperature.

ACDelco 41-962 Professional Platinum Spark Plug, (8)

ACDelco is a trusted brand, and their Professional Platinum line emphasizes long life and consistent performance, often serving as a replacement for GM Original Equipment. These plugs feature a double platinum point pad on both the center and ground electrodes, maximizing durability and ensuring stable voltage demands over their lifespan. A key benefit is the pure copper core, which helps keep the electrode cooler, maximizing durability and resistance to fouling.

Key features that stand out:
– Double platinum point pad for maximum durability and consistent voltage.
– One-piece, fired-in suppressor seal helps reduce radio frequency interference.
– Pure copper core results in cooler electrode temperature.
– Gas-tight seal protects against compression pressures.

Pros:
– Exceptional durability due to double platinum construction.
– Copper core improves heat dissipation and fouling resistance.
– Reliable replacement option for specific applications.

Cons:
– Designed for 8-cylinder applications, and fitment isn’t guaranteed for the Si.

Best for: Demonstrating high-quality double platinum technology, though primarily designed for GM platforms.

Expert Opinion: Double platinum plugs are excellent for longevity and stability in daily drivers, often outlasting single-platinum. Si owners should look for this dual-electrode feature in NGK or Denso plugs that are specifically sized for the K24Z7.

Double Iridium Spark Plugs 4 Pack 91187 9029 Fits for Nissan Altima 2.5 2007 2008 2009 2010 2011 2012 2013,Nissan Frontier 2005-2019,Nissan Rogue 2008-2013,Nissan Sentra 07-2019,Nissan Versa 2007-2020

This 4-pack of Double Iridium spark plugs showcases how Iridium technology can be applied to maximize fuel efficiency and engine performance in various 4-cylinder import vehicles (in this case, Nissans). They utilize a 0.6mm fine-wire Iridium center tip and advanced laser-welded technology. Premium Material is the focus here; the Iridium alloy is six times harder than platinum, giving it incredible resistance to heat and electrical wear, making it suitable for modern high-performance engines regardless of brand.

Key features that stand out:
– Double Iridium construction ensures extreme durability.
– 0.6mm finewire Iridium centerwire tip design.
– Exceptional Fuel Efficiency due to optimized combustion.
– High durability, resisting heat and electrical wear.

Pros:
– Extremely long service life and resistance to degradation.
– Excellent construction quality suitable for high-output engines.
– Comes in a 4-pack, which is the correct quantity for the Si.

Cons:
– Specific sizing and gap (.044″) are likely incorrect for the K24Z7.

Best for: Demonstrating the benefits of Double Iridium technology for 4-cylinder engines, though owners must confirm the heat range and thread specifications match the Si.

Expert Opinion: While Nissan-specific, the durability factor here is massive. If you prioritize long intervals between replacement while maintaining performance, seeking a quality Double Iridium plug with the correct K-series sizing is the way to go.

4 pc NGK G-Power Spark Plugs compatible with Honda Civic 1.8L 2.0L L4 2002-2011

This is a straightforward, reliable replacement option from NGK, specifically marketed toward the broader Honda Civic platform (older generations, though). As a G-Power Platinum plug, it provides dependable service and improved resistance to fouling compared to standard copper plugs. This pack offers a quality OEM-style replacement for those running a stock setup or focusing solely on budget and consistent mileage.

Key features that stand out:
– Genuine NGK Parts—known for Honda fitment reliability.
– G-Power Platinum construction for enhanced durability.
– Direct replacement auto parts ensuring easy installation.

Pros:
– High compatibility across various Honda Civic models (though check K24Z7 specifics).
– Budget-friendly Platinum option.
– Simple, reliable operation.

Cons:
– Not specifically geared toward the 9th Gen Si’s performance needs.

Best for: Owners of older Civic models, or 9th Gen Si owners who are extremely budget-conscious and running completely stock tuning.

Expert Opinion: NGK and Honda go hand-in-hand. While this particular model is often associated with the older R18 and K20 engines, it serves as a reminder that NGK offers many reliable, cost-effective options within the Platinum family.

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

The NGK 93501 Iridium IX is arguably the perfect blend of performance and reliability for the 9th Gen Si (K24Z7). It features the same extreme ignitability and fine 0.6mm laser-welded Iridium tip as its siblings, guaranteeing improved throttle response and stable power. Crucially, this specific heat range (7) is ideal for the Si’s higher compression ratio, providing excellent resistance to heat and fouling. The Trivalent Metal Plating also ensures easy removal and protection against corrosion in the aluminum head.

Key features that stand out:
– Designed specifically for the performance enthusiast (Iridium IX).
– Iridium alloy provides high durability to heat and electrical wear.
– Longer insulator nose prevents fouling.
– Trivalent Metal Plating provides superior anti-seizing properties.

Pros:
– Ideal heat range (7) for the K24Z7 engine, stock or lightly tuned.
– Excellent resistance to fouling and flashover thanks to the triple seal and corrugated ribs.
– Provides consistent, stable spark for superior performance.

Cons:
– Requires precise gapping if running high boost (though pre-gapped usually).

Best for: The standard choice for all 9th Gen Si owners seeking a high-performance upgrade that balances cost, reliability, and power.

Expert Opinion: If you are unsure which plug to choose for your Si, start here. The LKAR7BIX-11S (93501) is engineered perfectly for the K-series application and consistently delivers peak performance, making it a staple in the Honda tuning community.

Helpful Comparison Short Insights

When evaluating the best option for your 9th Gen Si, the primary battle is between Platinum (G-Power) and Iridium (Iridium IX). Iridium plugs like the NGK 93501 and 93175 are superior for performance because the material allows for a much finer electrode, concentrating the spark and improving throttle response—something every Si owner appreciates.

For daily drivers who rarely push the car, Platinum options like the NGK G-Power line (3186 or 7090) offer better value and longevity at a lower cost, though they might not offer the same peak spark quality.

It’s crucial to look beyond the material and consider the heat range. The stock K24Z7 usually requires a heat range of 6 or 7. If you are running forced induction (turbo/supercharger), you must move to a colder plug, likely a heat range 8 or 9 (like the CR9EIX), to manage the increased cylinder temperatures and prevent pre-ignition.

Finally, ignore the V8 kits we reviewed (like the 8 Pcs Spark Plug Wires Set and 41-110). While they demonstrate excellent Iridium and Platinum technology, the fitment, thread pitch, and required installation parts are incompatible with the coil-on-plug setup of the 9th Gen Civic Si. Always confirm the exact NGK part number for your Honda application.

Final Verdict

Choosing the right spark plug means matching material durability and heat range to your specific driving habits and modifications.

If you prioritize the absolute best blend of reliability and performance:
The NGK LKAR7BIX-11S Iridium IX (93501) takes the crown. It’s engineered for the K-series engine, features the critical 7 heat range suitable for both stock and mildly tuned Si’s, and provides the best possible spark quality for responsiveness. This is our overall recommendation for 90% of 9th Gen Si owners.

If you need a cost-effective, high-durability option for a stock Si:
Look toward the NGK 7090 BKR5EGP G-Power Platinum. While a slightly warmer plug, it uses reliable Platinum technology and provides a strong, long-lasting replacement that won’t break the bank.

If your K24Z7 is built for serious power (Forced Induction):
You’ll need the resistance of a colder plug like the NGK CR9EIX. This plug is designed to handle extreme cylinder temperatures, ensuring your ignition system doesn’t fail when you need it most. Consult your tuner before installing a plug this cold to ensure it won’t foul during daily driving.

Comprehensive FAQ about Best Spark Plugs For 9th Gen Si.

What is the ideal spark plug material for a 9th Gen Si (K24Z7)?

The ideal material is Iridium. Iridium allows for a smaller, finer electrode tip (like the 0.6mm tips in the NGK Iridium IX series). This fine tip concentrates the electrical charge, resulting in a stronger, more consistent spark, which is critical for maximizing performance and efficiency in the high-compression K24Z7 engine.

What heat range should I use for my stock or lightly tuned 9th Gen Si?

For stock or basic bolt-on modifications (intake/exhaust/tune), a heat range of 7 is usually recommended. Plugs like the NGK LKAR7BIX-11S (93501) are excellent choices as they are slightly colder than standard OEM plugs and better handle the Si’s high compression and spirited driving without fouling.

Do I need to gap Iridium spark plugs for my 9th Gen Si?

Most modern Iridium spark plugs, especially from NGK, come pre-gapped for specific applications. However, it’s always best practice to check the gap before installation using a feeler gauge, especially if you are running a custom tune. For the K24Z7, the standard gap is typically around 0.030″ to 0.032″ (0.8mm), but this may need to be tightened slightly if you are running boosted applications.

How often should I replace the spark plugs on my 9th Gen Si?

For high-performance Iridium plugs, typical replacement intervals range from 60,000 to 100,000 miles, depending on the manufacturer and how hard you drive. If you have a tuned Si or frequently track the car, checking and potentially replacing them closer to the 30,000 to 50,000-mile mark is advisable to maintain peak performance and prevent misfires.

Will changing to performance spark plugs give me more horsepower?

Simply changing spark plugs won’t provide a massive horsepower gain on their own. However, installing high-quality Iridium plugs ensures that the engine is receiving the most consistent and powerful spark possible, which maximizes the efficiency of your tune and fuel combustion. This translates into improved throttle response, smoother idle, and maintained peak power under all operating conditions.

Can I run the same spark plugs on a naturally aspirated Si and a turbocharged Si?

No. A naturally aspirated (N/A) Si typically uses a medium heat range plug (6 or 7). A turbocharged or supercharged Si generates significantly more heat and pressure, requiring a much “colder” spark plug (like an 8 or 9 heat range) to prevent the tip from glowing hot and causing damaging pre-ignition or detonation. Using the wrong heat range in a boosted engine can lead to catastrophic engine failure.