RBC Intake Manifold Adapter for 2012-2015 Civic Si: Install Guide

Quick Answer

Yes, you can install an RBC or RRC intake manifold on your 2012-2015 Civic Si using the right adapter flange and a throttle body adapter. This guide walks you through the process and highlights the common mistakes to avoid.

Step-by-step install guide

1. Disconnect the battery and drain coolant: Start by disconnecting the negative battery terminal. Drain the coolant below the level of the intake manifold to avoid spills when you remove the coolant hoses. You'll need to disconnect the coolant hoses from the stock manifold. Check the coolant level and top up after the install.
2. Remove the stock intake manifold: Label and disconnect all vacuum lines, electrical connectors, and the throttle cable. Remove the intake manifold bolts in a crisscross pattern and lift the manifold off. Keep the stock gasket and bolts if they're in good condition. Inspect the intake ports for debris and clean them before reassembly.
3. Install the throttle body adapter: If you're using your stock throttle body, attach the throttle body adapter to the RBC manifold using the provided hardware. Apply a thin layer of gasket sealant if needed, but don't overdo it—you don't want excess sealant in the intake tract. Ensure the adapter sits flat and the gasket is aligned before tightening.
4. Mount the RBC manifold with the adapter flange: Place the adapter flange between the RBC manifold and the cylinder head. Use new gaskets on both sides. Hand-tighten the bolts, then torque them to spec in a crisscross pattern. The adapter flange's bolt pattern matches the K24Z head, so everything should line up. Torque to the manufacturer's spec—over-tightening can crack the flange.
5. Reconnect everything and check for leaks: Reconnect all vacuum lines, hoses, and electrical connectors. Refill coolant and reconnect the battery. Start the engine and let it idle. Listen for vacuum leaks and check for coolant leaks. Use a smoke test or carb cleaner spray around the adapter joints to verify no leaks. If the idle is rough, re-check the vacuum line routing and torque.

Products used in this guide

• 2012-2015 Honda Civic Si RBC/RRC Intake Manifold Adapter Flange w/Hardware: This adapter flange allows an RBC or RRC intake manifold to bolt onto K24Z engines found in the 2012-2015 Civic Si, 2013-2015 ILX, 2009-2014 TSX, and 2008-2012 Accord. It's the key part that makes the manifold swap possible without custom fabrication.

  

• RBC Intake Manifold to Stock 2012-2015 Honda Civic Si Throttle Body Adapter: This throttle body adapter lets you keep your stock K24Z throttle body when using an RBC or RRC manifold. It saves you the cost of a new throttle body while still letting you use the better-flowing manifold.