DC Sports K-swap exhaust manifold 4-2-1 2.5'' stainless steel (Honda Civic/CRX/Del sol/Integra)
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Introducing the DC Sports K-Swap 4-2-1 Header – a meticulously engineered solution for Honda enthusiasts seeking to maximize the potential of their K20 or K24 engine swaps. This header is designed not only to address common K-swap installation challenges but also to deliver usable power gains. With its one-piece 304 stainless design, CNC-machined flanges, and equal-length Tri-Y layout, it ensures optimal exhaust flow and performance.
VEHICLE FITMENT AND COMPATIBILITY
Engineered to fit 1992-2000 Honda Civics, 1993-1997 Honda Del Sol, and 1994-2001 Acura Integras, this header is compatible with both K20 and K24 engine swaps using Hasport or Innovative mount kits. Hasport mounts accommodate two height positions, while the header works perfectly in both. For Innovative mounts with forward and back positions, the header optimizes performance in the most forward configuration. See the fitment section below for exact fitments.Â
HEADER DESIGN AND PULSE TIMING
The equal-length 4-2-1 layout mirrors Honda's original engine design, pairing cylinders 1-4 and 2-3 to match the 1-3-4-2 firing order. This configuration maintains consistent 360-degree spacing across the 720-degree cycle, allowing the low-pressure wave from one cylinder to reach the next during overlap. The result is enhanced scavenging, reduced exhaust reversion, and a more consistent torque curve.
At the head, we precisely opened the flange ports to match the PRC Type R oval profile. The 304 stainless steel head flange starts as a 1/2-inch plate and is CNC-machined down to 3/8 inches in low-stress areas to reduce weight while maintaining flatness and rigidity. Strategically reinforced zones remain at 1/2 inch to prevent warping and ensure a tight seal.
RUNNERS, WELDS, AND COLLECTOR GEOMETRY
Each primary runner is precision mandrel-bent from 304 stainless steel, featuring a 1.5-millimeter wall thickness. The runners are flared to match the PRC oval port shape and seated approximately one-quarter inch into the CNC-machined flange. We've implemented full internal and external flange welds to maximize penetration, ensure optimal sealing, and minimize potential cracking during repeated heat cycles.
The runner sizing follows a carefully calculated stepped design to balance velocity and flow:
- Primaries start at 48mm
- Step to 50.8mm
- Merge at roughly 15 degrees into 54mm secondaries
- Finish with a 7-degree transition into a 63.5mm 2.5-inch collector
