InlinePro Head Studs for the Civic Type R/Integra Type S

InlinePro Head Studs - K20C1/C4/C6/C8 2.0T (Civic Type R, Integra Type S & More)

The K20C is turbocharged from the factory, and the moment you start building boost and power beyond stock, the factory head bolts become the weak point that lets go. These InlinePro M11 head studs replace them with the clamping force to keep the head sealed under serious cylinder pressure. They're offered in two materials, a Premium American Alloy and a higher-strength Super Alloy, so you can match the studs to how far you're taking the build. Both are heat treated and tested, and both are the foundation that holds the top end of a boosted K20C together.

What Head Studs Do and Why You Need Them

The head studs clamp your cylinder head to the block and squeeze the head gasket to seal combustion, coolant, and oil. Every power stroke, cylinder pressure is trying to lift the head off the block, and the studs are what hold it down against that force. The factory uses torque-to-yield bolts sized for stock boost, and they do the job at stock power, but as you turn the boost up the cylinder pressure rises right along with it, and at some point those bolts can't hold the clamp anymore. When that happens the head lifts just enough for the gasket to lose its seal, and you get the classic failure: coolant or oil in a cylinder, boost leaking between cylinders, and an overheating engine. Studs apply far more clamping force, and they apply it more evenly and consistently, which is what keeps the gasket sealed when you're making real power.

Choose Your Material: Alloy or Super Alloy

Both versions share the same M11 design, the same true-beam construction, and the same resistance to hydrogen embrittlement. The difference is how much clamping headroom you want:

• Alloy (Extreme Duty), 230 kpsi minimum tensile: made from the highest-grade premium American alloy. This is the right choice for the large majority of boosted and built K20C setups, with plenty of strength for strong street and moderate power builds.
• Super Alloy (Xtreme Power), 260 kpsi minimum tensile: made from InlinePro's highest-grade super alloy for maximum clamping headroom. This is the one to step up to when you're chasing the highest cylinder pressures and biggest power, where you want every bit of clamp you can get.

The InlinePro Difference

Both materials are built to avoid the compromises other high-strength studs make. A lot of studs on the market use L19 or H11, which are strong but prone to hydrogen embrittlement, a failure mode where the metal can crack unexpectedly, and they have to be handled carefully to avoid it. InlinePro's alloys aren't susceptible to that, so you get the strength without the fragility, and you can handle and install them without worrying about it. On top of that, these use a true-beam design that holds full diameter down the entire length of the stud rather than being necked-down or undercut like a lot of competitors, which InlinePro builds for better, more consistent clamping force and torque values.

What's in the Kit

• Head studs
• Nuts
• Washers
• Assembly lube
• Instructions

Install and Honest Notes

Know what these are for. On a stock K20C you don't need them, but once you're adding real boost or building the engine for more power, they're the insurance that keeps the head sealed, and they're cheap next to the cost of fixing a lifted head gasket. Installing them means the head has to come off, so the natural time to do this is during a head gasket job or an engine build. Thread the studs into the block hand-tight, then torque the nuts to spec using the included lube and the correct sequence. One quiet benefit of studs over bolts is that you're not repeatedly torquing a fastener into the aluminum block threads, so you're easier on the block and you get a more accurate, repeatable clamp.

Fitment

Fits the K20C 2.0T engine (K20C1, K20C4, K20C6, K20C8):

• 2017-2021 Honda Civic Type R (FK8)
• 2023-2027 Honda Civic Type R (FL5)
• 2024-2027 Acura Integra Type S (DE5)
• 2019-2025 Acura RDX 2.0T
• 2018-2022 Honda Accord 2.0T
• 2021-2025 Acura TLX Type S