🏁 The Legendary Inline-Six. Finally Breathing Right.
The 4.0L AMC inline-six in your TJ is one of the most beloved engines in American off-road history. Reliable, torquey, and nearly unkillable.
But that factory intake system — a flattened plastic box with a tiny paper filter sitting right in the hot engine bay — was designed for one thing: not breaking.
It was not designed for crawling over rocks, fording streams, or conquering sand dunes.
Flashark's 76mm cold air intake fixes all of that:
→ 76mm smooth-bore aluminum tubing — right-sized for the 4.0L I6
→ Dry high-flow filter — massive surface area vs. factory paper element
→ Heat shield pulls cooler air away from the engine bay
→ Stronger low-end and mid-range torque
→ Throttle response is instant
→ No tune — factory ECU adapts
→ Direct bolt-on in your garage
The 4.0L was built to be off-roaded. Flashark just gives it the air to prove it.
BEFORE YOU BUY — READ THIS
• Stock ECU / No tune: ✅ Fully compatible (4.0L, 2.4L, and 2.5L all supported)
• Off-road/hard use: ✅ Built for it (heat shield, sealed airbox, dry filter)
• With bolt-ons (exhaust, header): ✅ Gains stack with any performance combo
• With a supercharger: ✅ Works great (The 4.0L I6 handles forced induction well)
• CARB compliance:
⚠️ 1997-2006 TJ not CARB-exempt for all states. Check the product listing for the CARB EO# before ordering if in CA, NY, or other CARB states.
Technical Specifications
System Type: Cold Air Intake (CAI)
Tubing Material: 6061-T6 Aluminum
Tubing Finish: Polished / Black Powder Coat
Tube Diameter: 76mm (3.0") — large bore throughout (no reducer) matched to 4.0L throttle body
Air Filter: High-Flow Dry Cotton (washable & reusable) No oil required — zero mess
Heat Shield: Included — full enclosure seals filter from the engine bay heat routes to the coolest available air source
MAF Housing: CNC-machined 76mm aluminum precise bore = no CEL on 4.0L I6, 2.4L I4, and 2.5L I4
Couplers: Multi-ply silicone (black) high-temp rated, clamp-sealed
Clamps: Stainless steel T-bolt (all hardware)
Installation: 100% Bolt-On, No welding, no drilling
Hardware: All included
Why Flashark? 5 Reasons
1️⃣ THE RIGHT TUBE FOR THE 4.0L I6
The AMC 4.0L straight-six is a torque machine — it makes peak torque at low RPM and needs air volume throughout the power band.
Flashark's 76mm mandrel-bent tubing:
• Matches the 4.0L throttle body bore
• Smooth interior — no flow turbulence
• Aluminum dissipates heat faster than factory plastic
• No CEL on the AMC/Jeep ECU calibration
→ More torque where the 4.0L makes it: 2,000-4,000 RPM on the trail
2️⃣ DRY FILTER — BUILT FOR OFF-ROAD
Off-roading means dust, dirt, water, and everything in between.
Flashark's dry media filter:
• No oil to attract and hold fine dust
• Wash and reuse — no re-oiling
• Maintains airflow even when loaded with dirt
• Better fine-particle filtration than cotton-oiled alternatives
• Zero risk of oil coating your MAF sensor
For a TJ that actually goes off-road, dry is the right call.
3️⃣ SEALED AIRBOX — WATER & DEBRIS PROTECTED
This is critical for serious off-road use.
Flashark's enclosed airbox:
• Seals the filter from engine bay heat
• Protects filter from direct water splash (stream fordings, heavy rain)
• Blocked from large debris at the air intake
• Keeps the MAF sensor signal clean even in dusty conditions
The airbox enclosure is the difference between a CAI that survives off-road and one that hydrolocks your engine.
4️⃣ NO TUNE. JUST BOLT ON AND GO.
The AMC 4.0L ECU is simple and robust. Flashark's MAF housing gives the Jeep computer exactly what it expects:
→ No check engine light
→ No reflash or tune required
→ All factory systems remain functional
→ 4WD, ABS, OBD-II all unaffected
5️⃣ BOLT-ON IN YOUR DRIVEWAY
Designed for the TJ chassis — every mount point and clamp is an exact fit.
Tools needed: Basic hand tools (ratchet, 10mm/12mm sockets). Estimated time: 60-90 minutes
No cutting. No drilling. Jeep TJ owners have been bolting things on for decades — you know the drill.
✅ Fits — 4.0L I6 (Primary):
• 1997-2006 Jeep Wrangler TJ — 4.0L (AMC 150 / 242 engine code)
• All trims: Sport, Sahara, Rubicon, SE, X, Unlimited
✅ Fits — 2.4L I4:
• 2003-2006 Jeep Wrangler TJ SE — 2.4L (Chrysler G24GD / 2.4L DOHC)
✅ Fits — 2.5L I4:
• 1997-2002 Jeep Wrangler TJ / SE — 2.5L (Chrysler ETE / 2.5L OHV)
All configurations: 2-Door, 4-Door (Unlimited)
❌ Does NOT fit:
• 1987-1995 Jeep Wrangler YJ (different engine bay layout)
• 2007-2018 Jeep Wrangler JK (TJ to JK is a different generation)
• 2018+ Jeep Wrangler JL (completely new platform)
• Jeep Cherokee XJ (different chassis)