Ferrea 6000 Series Intake & Exhaust Valves for K Series

Ferrea 6000 Series Valves - K Series

You've done full bolt ons and are eyeing the next step in your project. Valvetrain should be it. The stock valves weren't designed for the spring pressures and RPM that aggressive cam profiles demand. Ferrea's 6000 Series valves are the upgrade for K20 and K24 builders who need valvetrain reliability at high RPM without spending Competition Plus money. These are one-piece forged stainless steel valves with hard chrome stems and radius groove profiles. They're stock size, 35mm intake and 30mm exhaust, so they drop straight into a stock K series head with no machine work required. If you're running aggressive cams, dual valve springs, or you're revving past 8,500 RPM regularly, upgrade your valves before they become the weak link.

Here's Why Factory Valves Fail

Stock K series valves are designed for factory spring pressures and stock RPM limits. When you install Stage 2 or Stage 3 cams with dual valve springs, you're multiplying the forces on the valves. The springs are pressing harder on the valve stem and the cam's hitting the valve faster. Stock valves aren't heat-treated to handle that abuse. The stems wear from the increased spring pressure. The tips mushroom from repeated lash adjustments. At high RPM, 8,500+ - the stock valves can't handle the stress and you're risking valve float or worse. Ferrea 6000 Series valves are forged and heat-treated specifically for high spring pressures and high RPM. The hard chrome stems resist wear and the tips are hardened to prevent mushrooming when you're checking valve lash.

One-Piece Forged Stainless Steel

Ferrea forges these valves from one piece of stainless steel. They're not welded or assembled from multiple parts. The one-piece forging means there's no weak point where different pieces meet. The valve's solid from the head to the tip. After forging, Ferrea runs them through a proprietary heat treatment process that increases strength and fatigue resistance. That matters when you're running the motor hard at 9,000 RPM or sitting on the limiter. The valves take the beating without cracking or failing. Both intake and exhaust valves use the same stainless steel construction and heat treatment process.

Hard Chrome Stems and Radius Groove Profiles

The valve stems are hard chrome plated. Hard chrome's way harder than the raw stainless so the stems resist wear from the valve guides and valve spring pressure. You're not getting stem wear that leads to oil consumption or valve guide damage. The intake valves use a 20 degree radius groove profile and the exhaust valves use a 22 degree radius groove profile. The radius groove design improves airflow compared to a sharp-edge valve seat. You're getting better flow into and out of the cylinder which means more power. The tips are hardened so they don't mushroom when you're adjusting valve lash. Stock valve tips get beat up after a few lash checks. These don't.

Stock Size Valves Drop Right In

These are stock diameter valves, 35mm intake and 30mm exhaust. They drop straight into a stock K series head. You're not cutting new valve seats or doing any machine work. Pull the old valves, drop the Ferrea valves in, done. If you're doing oversized valves - +1mm or bigger - that's a different part number and your machine shop needs to cut new valve seats. Don't try to run oversized valves in stock seats. You'll actually lose power because the valve seat won't seal properly. For most builds, stock size valves with a good port and polish job are plenty. Save the oversized valve headache for when you're chasing every last horsepower on a race motor.

What You Get

Intake Valves (Part Number F6073):

• Set of 8 intake valves (one complete side)
• 35mm head diameter (stock size)
• 5.47mm stem diameter
• 109.3mm overall length
• 2.5mm tip length
• 20 degree radius groove profile
• One-piece forged stainless steel
• Hard chrome stem
• Hardened tip
• Proprietary heat treatment
• Fully CNC machined

Exhaust Valves (Part Number F6071):

• Set of 8 exhaust valves (one complete side)
• 30mm head diameter (stock size)
• 5.45mm stem diameter
• 109.15mm overall length
• 2.5mm tip length
• 22 degree radius groove profile
• One-piece forged stainless steel
• Hard chrome stem
• Hardened tip
• Proprietary heat treatment
• Fully CNC machined

Fits These Engines

• K20A2, K20A3, K20Z1, K20Z3 (all K20 DOHC)
• K24A1, K24A2, K24A4, K24A8 (all K24 DOHC)
• JDM K20A (DC5/EP3 Type R)

Note: Intake and exhaust valves are sold separately. If you're doing a full valvetrain refresh, order both part numbers. Each part number gets you 8 valves (one complete side). You'll also need valve springs, retainers, locks, and seals. The 6000 Series works with any quality K series valve spring setup. If you're running aggressive cams, get dual valve springs rated for your RPM and spring pressure. Make sure your locks match your retainers - 7 degree or 10 degree - and don't reuse old valve seals on a fresh build. These are stock size valves so no machine work's required. If you want oversized valves (+1mm or bigger), that's a different part number and your machine shop needs to cut new valve seats before you install them.