Upgrade the cooling system of your 2012-2015 Honda Civic Si with the Mishimoto MMRAD-CIV-12SI Performance Aluminum Radiator. Designed for the sustained thermal output of the high-revving K-series engine, this radiator provides increased cooling capacity for daily driving, spirited street use, canyon runs, and weekend track sessions. Its all-aluminum construction and precision TIG-welded end tanks replace the factory plastic-tanked design, helping resist cracking caused by heat cycling and repeated high-rpm operation. The enlarged core provides a 63% increase in volume over the OEM radiator, adding surface area and thermal capacity to help maintain stable coolant temperatures when your Civic Si is pushed hard.

Designed as a direct-fit replacement, this Mishimoto radiator installs without cutting, fabrication, or vehicle modifications. It is compatible with the original hoses and cooling system components, allowing for a straightforward upgrade using the factory mounting locations. An included high-pressure radiator cap helps maintain optimal system pressure from the first drive, while the Mishimoto Magnetic Drain Plug captures ferrous metallic debris before it circulates through the cooling system. Together, these features support reliable cooling performance and help protect K-series engine internals during demanding use.

Whether your Civic Si is a daily driver or part of a higher-output K-series build, the Mishimoto Performance Aluminum Radiator provides a durable cooling solution engineered for long-term service. Corrosion-resistant aluminum construction supports dependable performance across varied driving conditions, while the direct-fit design simplifies installation. Backed by Mishimoto's Lifetime Warranty, the MMRAD-CIV-12SI is a practical cooling upgrade for owners seeking greater thermal capacity and improved durability over the original radiator. Fits 2012, 2013, 2014, and 2015 Honda Civic Si models.

Features:

• High-revving K-series performance: The oversized aluminum core helps manage sustained thermal output during back-to-back pulls, spirited driving, and track sessions.
• 63% increased core volume: Provides greater heat-transfer surface area and thermal capacity than the factory radiator.
• All-aluminum construction: Precision TIG-welded end tanks eliminate the factory plastic-tanked design that can crack under repeated heat cycling.
• Direct-fit installation: Designed for 2012-2015 Honda Civic Si models and compatible with factory hoses and cooling system components without modification.
• Magnetic drain plug: Captures ferrous metallic debris before it circulates through the cooling system, helping protect engine internals.
• Included high-pressure radiator cap: Helps maintain optimal cooling system pressure without requiring additional components.
• Mishimoto Lifetime Warranty: Provides long-term coverage for added ownership confidence.