Bourne HPP Intake & Exhaust Valves for Honda K Series

Bourne HPP K-Series Intake & Exhaust Valves - K20/K24

Valves are the parts that actually let your engine breathe. The intakes open to pull the air and fuel in, the exhausts open to push the spent gases out, and both have to seal the combustion chamber dead tight in between, slamming onto their seats thousands of times a minute under serious heat and pressure. On a stock engine the factory valves handle that fine. But once you're making real power with boost or high compression, the valves, and especially the exhaust valves, are living in a much harsher world, and that's where these Bourne HPP valves come in. They're a performance replacement for the K20 and K24, made from EN52 steel, Pulse Plasma Nitrided, and super-polished, built for turbocharged and high-compression naturally aspirated builds.

Why Upgrade Your Valves

It comes down to heat and stress. On a high-output K-series, cylinder pressures climb and exhaust gas temperatures go way up, and the exhaust valve in particular runs glowing hot every time the engine's working. Push a stock valve past what it was designed for and it can warp, burn, or lose its seal, and a burnt exhaust valve means lost compression and a down cylinder. At high RPM there's also the valve stem riding in its guide at huge speed, where friction and heat can cause scuffing or micro-welding between the stem and guide. Upgraded valves are built to survive all of that, which is why they belong in any serious head build.

EN52 Steel, Built for the Heat

These valves are forged from high-grade EN52 steel, a proven valve material chosen specifically for its thermal stability. That matters most on the exhaust side, where EN52 resists the warping and failure that extreme exhaust gas temperatures cause, so the valve stays straight and keeps sealing even when the engine is under sustained load. It's the kind of material you want when the head is going to see real heat, not just occasional spirited driving.

Pulse Plasma Nitrided for Wear Resistance

Every valve gets a Pulse Plasma Nitrided treatment, which hardens the surface and sharply reduces friction, especially on the stem. The payoff is wear resistance and protection against the micro-welding and scuffing that can happen between the stem and guide at high RPM and high heat. In plain terms, the valves slide freely and last, instead of galling and wearing the guides out early. On a championship-level engine where consistency is everything, that durability is the whole point.

Super-Polished for Flow

Both the intake and exhaust valves carry a super-polished finish. On the intake side that smooth surface helps air and fuel flow into the chamber with less restriction, so the head breathes more freely. On the exhaust side the same finish helps resist carbon buildup, keeping the valve cleaner and flowing over the long haul. It's a small detail that adds up when you're chasing every bit of flow and reliability.

Intake Set or Exhaust Set

These are offered as separate intake and exhaust sets, each a pack of eight, so you can buy the side you need or grab both to do the full head. A standard K-series head uses eight intake and eight exhaust valves, so a complete valve job takes one of each set. The intake valves carry a 0.29cc dish and the exhaust valves a 0.31cc dish. Pick your side from the variant options.

Installation

These are parts for a proper head build, not a driveway drop-in. Plan on professional installation and machining: your machine shop should cut and lap the valve seats for a correct seal, verify valve-to-guide clearances, and confirm everything seats properly before assembly. Done right, these give you a head that seals tight and breathes freely at the limit.

Fitment

Fits the K20 and K24 engines, including the K20A, K20A2, K20A3, K20Z1, K20Z3, K24A1, K24A2, K24A4, and K24A8, found in:

• 2002-2006 Acura RSX (Base and Type S)
• 2004-2008 Acura TSX
• 2003-2007 Honda Accord
• 2002-2011 Honda Civic Si
• 2002-2006 Honda CR-V
• 2003-2011 Honda Element