NGK SPARK PLUG CR9EIX 3521 NG3521
4.1 Trustpilot 99.9% positive on eBay
Delivery to United States 5–8 business days
Spread the cost with
NGK SPARK PLUG CR9EIX 3521 NG3521. Features an iridium alloy electrode 25% smaller than platinum and 1/4 the size of a conventional nickel electrode for superior ignition performance and efficiency. Fine wire center electrode reduces voltage requirements for ignition, extending the lifespan of your ignition system and providing a more reliable spark. High melting point iridium is ideal for high-performance engines. Corrosion-resistant trivalent metal plating enhances durability. Corrugated ribs prevent flashover and improve spark stability. Superior ceramic insulator made from pure alumina silicate ensures high strength and better heat transfer. Specifications include Heat Range: 9, Thread Size: 10 mm, Type: Resistor, Units: Sold individually, Weight: 0.12 lbs, Alternate/OEM Part Numbers: 3521, CR9EIX, Electrode Material: Iridium (fine wire center electrode), Hex Size: 5/8" (16mm), Reach: 19mm (3/4"), Seat Type: Gasket Seat, Gap: 0.031" (0.8mm), Terminal Type: Stud Terminal Threads, Plating: Trivalent metal plating, Seal Type: Triple Seals. Benefits include improved engine performance, enhanced durability, better fuel efficiency, and heat management.
- SKU
- 37-CR9EIX
- Brand
- NGK
- Availability
- In Stock (165)
Fitments (120)
| Make | Model | Year |
|---|---|---|
| BMW | G X 450 | 2008 |
| BMW | G X 450 | 2009 |
| BMW | G X 450 | 2010 |
| BMW | G X 450 | 2011 |
| BMW | G X 450 | 2012 |
| BMW | G X 450 | 2013 |
| BMW | G X 450 | 2014 |
| BMW | G X 450 | 2015 |
| BMW | G X 450 | 2016 |
| BMW | G X 450 | 2017 |
| BMW | G X 450 | 2018 |
| BMW | G X 450 | 2019 |
| BMW | G X 450 | 2020 |
| BMW | G X 450 | 2021 |
| GAS-GAS | EC F 300 | 2013 |
| GAS-GAS | EC F 300 | 2014 |
| GAS-GAS | EC F 300 | 2015 |
| GAS-GAS | EC F 300 | 2016 |
| GAS-GAS | EC F 300 | 2017 |
| GAS-GAS | EC F 300 | 2018 |
| GAS-GAS | EC F 300 | 2019 |
| GAS-GAS | EC F 300 | 2020 |
| GAS-GAS | EC F 300 | 2021 |
| HUSABERG | FE 250 | 2013 |
| HUSQVARNA | SM RR 450 | 2008 |
| HUSQVARNA | SM RR 450 | 2009 |
| HUSQVARNA | SM RR 450 | 2010 |
| HUSQVARNA | SM RR 450 | 2011 |
| HUSQVARNA | SM RR 450 | 2012 |
| HUSQVARNA | SM RR 450 | 2013 |
| HUSQVARNA | SM RR 450 | 2014 |
| HUSQVARNA | SM RR 450 | 2015 |
| HUSQVARNA | SM RR 450 | 2016 |
| HUSQVARNA | SM RR 450 | 2017 |
| HUSQVARNA | SM RR 450 | 2018 |
| HUSQVARNA | SM RR 450 | 2019 |
| HUSQVARNA | SM RR 450 | 2020 |
| HUSQVARNA | SM RR 450 | 2021 |
| HUSQVARNA | TC 449 | 2011 |
| HUSQVARNA | TC 449 | 2012 |
| HUSQVARNA | TE 250 | 2010 |
| HUSQVARNA | TE 250 | 2011 |
| HUSQVARNA | TE 250 | 2012 |
| HUSQVARNA | TE 449 | 2011 |
| HUSQVARNA | TE 449 | 2012 |
| HUSQVARNA | TE 511 | 2011 |
| HUSQVARNA | TE 511 | 2012 |
| HUSQVARNA | TE 511 | 2013 |
| HUSQVARNA | TE 511 | 2014 |
| HUSQVARNA | TE 511 | 2015 |
| HUSQVARNA | TE 511 | 2016 |
| HUSQVARNA | TE 511 | 2017 |
| HUSQVARNA | TE 511 | 2018 |
| HUSQVARNA | TE 511 | 2019 |
| HUSQVARNA | TE 511 | 2020 |
| HUSQVARNA | TE 511 | 2021 |
| HUSQVARNA | TXC 250 | 2010 |
| HUSQVARNA | TXC 250 | 2011 |
| HUSQVARNA | TXC 250 | 2012 |
| HUSQVARNA | TXC 250 | 2013 |
| HUSQVARNA | TXC 250 | 2014 |
| HUSQVARNA | TXC 250 | 2015 |
| HUSQVARNA | TXC 250 | 2016 |
| HUSQVARNA | TXC 250 | 2017 |
| HUSQVARNA | TXC 250 | 2018 |
| HUSQVARNA | TXC 250 | 2019 |
| HUSQVARNA | TXC 250 | 2020 |
| HUSQVARNA | TXC 250 | 2021 |
| KTM | 250 SX-F | 2006 |
| KTM | 250 SX-F | 2007 |
| KTM | 250 SX-F | 2008 |
| KTM | 250 SX-F | 2009 |
| KTM | 250 SX-F | 2010 |
| KTM | 250 SX-F | 2011 |
| KTM | 250 SX-F | 2012 |
| KTM | 250 XC-F | 2011 |
| KTM | 250 XCF-W | 2013 |
| KTM | 450 Rally Factory Replica | 2014 |
| KTM | 450 SX-F | 2007 |
| KTM | 450 SX-F | 2008 |
| KTM | 450 SX-F | 2009 |
| KTM | 450 SX-F | 2010 |
| KTM | 450 SX-F | 2011 |
| KTM | 450 SX-F | 2012 |
| KTM | 505 SX-F | 2007 |
| KTM | 505 SX-F | 2008 |
| KTM | 505 XC-F | 2009 |
| SUZUKI | DR SE 350 | 1994 |
| SUZUKI | DR SE 350 | 1995 |
| SUZUKI | DR SE 350 | 1996 |
| SUZUKI | DR SE 350 | 1997 |
| SUZUKI | DR SE 350 | 1998 |
| SUZUKI | DR SE 350 | 1999 |
| YAMAHA | TT 250R | 2003 |
| YAMAHA | TT 250R | 2004 |
| YAMAHA | TT 250R | 2005 |
| YAMAHA | WR 250F | 2007 |
| YAMAHA | WR 250F | 2008 |
| YAMAHA | WR 250F | 2009 |
| YAMAHA | WR 250F | 2010 |
| YAMAHA | WR 250F | 2011 |
| YAMAHA | WR 250F | 2012 |
| YAMAHA | WR 250F | 2013 |
| YAMAHA | WR R 250 | 2008 |
| YAMAHA | WR R 250 | 2009 |
| YAMAHA | WR R 250 | 2010 |
| YAMAHA | WR R 250 | 2011 |
| YAMAHA | WR R 250 | 2012 |
| YAMAHA | WR R 250 | 2013 |
| YAMAHA | WR R 250 | 2014 |
| YAMAHA | WR R 250 | 2015 |
| YAMAHA | WR R 250 | 2016 |
| YAMAHA | WR R 250 | 2017 |
| YAMAHA | WR R 250 | 2018 |
| YAMAHA | WR R 250 | 2019 |
| YAMAHA | WR R 250 | 2020 |
| YAMAHA | WR X 250 | 2008 |
| YAMAHA | WR X 250 | 2009 |
| YAMAHA | WR X 250 | 2010 |
| YAMAHA | WR X 250 | 2011 |
- General Product Group
- Ignition & Electrical Parts
- General Product Type
- Spark Plug
- Variant Id
- 235562
FULL DESCRIPTION
NGK Iridium IX Spark Plug - CR9EIX
Key Features:
- Iridium Alloy Electrode: Features a highly advanced iridium electrode that is 25% smaller than platinum and 1/4 the size of a conventional nickel electrode, enabling superior ignition performance and efficiency.
- Fine Wire Center Electrode: Reduces voltage requirements for ignition, extending the lifespan of your ignition system and providing a more reliable spark.
- High Melting Point: Iridium has a very high melting point, ideal for today's high-performance engines, ensuring durability under extreme conditions.
- Corrosion-Resistant Plating: The metal shell plating has enhanced anti-corrosion properties, ensuring the spark plug lasts longer and remains reliable.
- Corrugated Ribs: Prevents flashover and improves the stability of the spark.
- Superior Ceramic Insulator: Made from pure alumina silicate, ensuring high strength and better heat transfer for long-lasting performance.
Specifications:
- Heat Range: 9
- Thread Size: 10 mm
- Type: Resistor
- Units: Sold individually
- Weight: 0.12 lbs
- Electrode Material: Iridium (fine wire center electrode)
- Hex Size: 5/8" (16mm)
- Reach: 19mm (3/4")
- Seat Type: Gasket Seat
- Gap: 0.031" (0.8mm)
- Terminal Type: Stud Terminal Threads
- Plating: Trivalent metal plating for corrosion resistance
- Seal Type: Triple Seals
Benefits:
- Improved Engine Performance: The fine wire center electrode and iridium material ensure a more efficient spark, leading to better acceleration, throttle response, and overall performance.
- Enhanced Durability: The high-quality iridium electrode and anti-corrosion features ensure a longer lifespan, reducing the frequency of spark plug replacements.
- Better Fuel Efficiency: The improved ignition system reduces misfires and optimizes combustion, improving fuel efficiency and reducing emissions.
- Heat Management: The superior heat transfer properties of the ceramic insulator and copper core ensure that the spark plug performs well under high-temperature conditions, preventing overheating and ensuring consistent performance.
Overview:
TheNGK Iridium IX Spark Plug - CR9EIX is designed for performance enthusiasts who demand the best from their engine's ignition system. This spark plug provides the reliability, durability, and performance needed for top-level engine efficiency. The iridium center electrode, combined with advanced materials and design, makes it a top choice for anyone seeking enhanced engine performance and fuel efficiency.
QUESTIONS? JUST ASK
Talk to John or Phil. Real people, Monday to Friday, 10:00 to 17:00 (UK time).
Check the fitment table on this page against your make, model and year. Not sure? Call or email us and we will check it for you before you order.
Yes. We ship from the UK. Orders ship within 3 working days, then delivery to the United States takes 5–8 business days. The delivery price is shown at checkout before you pay. Delivery details
Yes. You have 14 days from delivery to return it, unused and in its original packaging. Contact us first and we will send you the return instructions. Returns policy
By card, PayPal, Apple Pay or Google Pay, or spread the cost with Klarna. Payment is taken securely by Stripe, and the options for your order are shown at checkout.
Any customs duties or import taxes charged in the United States are paid by you when the parcel arrives. Any tax we collect ourselves is shown at checkout before you pay.
More answers in our FAQ.
Trade pricing available
Buying parts for your business? Apply for a 2BrosParts trade account.


