K20C Spark Plug Guide

The Honda K20C engine can be found in a wide range of vehicles from the new Civic Type R using the K20c1 to the Accord using the K20c3. This Turbo K series engine has replaced the NA K20/K24a port injection engines. The new K20c family or engines uses a single exhaust port (common for modern turbo engines to keep production cost down) and direct injection (key to ensure the lowest possible emissions). The K20c engines have only been on the market since 2015 but have already proven to pack huge power potential supporting over 500HP on the stock engine with upgraded turbo and fuel system.

K20c Spark Plugs

Whether you are running a bone stock K20c or a fully built big turbo K20c1 Civic Type R ensuring you have the correct spark plugs for your engine is key to reliable performance. Luckily the NGK spark plug linked above is the only k20c spark plug you will need. From stock power commuter cars to full blown race cars the NGK ILZKAR8H8S plugs are perfect for any k20c engine up to 800WHP. With the high boost pressures used in the K20c engines it is very common to experience spark blow out. This is when the spark plugs are un able to create an ark/spark and results in misfires. A misfiring engine will not only be WAY down on power it will also consume more fuel and potentially damage other engine parts. Luckily you are able to avoid all of these problems simply by staying on top of your spark plug maintenance, AKA change your plugs! While Honda suggests the K20C spark plugs only need to be changed every 90K miles we have found any K20C that is driven hard (stock or modified) will need the plugs changed every 10-20K miles in order to avoid the dreaded spark blow out problems.

K20c Spark Plug Installation Torque Specs & Plug Gap

-K20C1 & K20C4 Plug gap (factory setting) 0.7－0.8 mm (0.028－0.031″)
-Torque Specs for Aluminum cylinder head: 10.8-14.5 lb. ft.
-For high boost applications you may gap your spark plugs down as tight as 0.5mm If you are still experiencing spark blow out at this tight of a gap you will need to upgrade your ignition coils.

Those working with the older K20a or K24a engines can check out our K20/24a specific spark plug guide for the full breakdown of the correct NGK spark plugs to use in your K series build from 200HP to 1500WHP we have the sparkplugs your K series needs: K24 Spark Plug Guide

K20a/K24a VS K20c

Below you can see a picture of the exhaust ports on the K24a and K20C engines. As you will notice the K24a uses 4 exhaust ports (1 port per cylinder) while the K20C uses a single exhaust port for all 4 cylinders. While both designs work well the single port K20C offers a super simple and cost effective way to add a turbo to the engine. The K24a can also be turbo’d but requires a turbo manifold to merge the 4 ports into 1 at the turbo inlet.
The only downside to the K20c single exhaust port design becomes apparent as you start to push power past the 450hp mark. While the engine will support 800+HP anything above ~450 starts to add a TON of back pressure and heat to the exhaust side of the engine. This puts extra stress on everything and must accounted for when tuning any K20c making over 400whp. If you are looking to make BIG power (over 500whp) on a turbo K series with the best reliability possible we suggest using the K24a RBB1-4 as your base, (the 3 lobe cam K24). If you are looking for a super clean and simple Turbo K series option the K20C is absolutely perfect!

Most Popular K20C Modifications for reliable POWER