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Cosworth Performance Racing Parts

Cosworth Performance Racing Cylinder Heads

Cosworth Head

Cosworth Racing Cylinder Head Features:
  • All New OE CaSTings
  • Enlarged Intake and Exhaust ports
  • Large diameter stainless steel intake valves
  • Large diameter Inconel exhaust valves
  • Hi Rev, Dual valve springs
  • Titanium Retainers
  • Hardened Steel spring platforms
  • Reshaped combuSTion chamber on most applications
  • Flow bench proven design
  • Dyno tested
  • Machined Cosworth Logo
  • Precision Multi angle valve job
  • Pre-assembled, ready to install
  • Machined port bore finish
  • Knife edge port divider

CNC Ported Big Valve Cylinder Heads
KK3670Subaru WRX STi EJ25 (2.5L) Pr. 2004-2006
20001699Subaru WRX STi EJ25 (2.5L) Pr. 2007 (w air injection ports)
20004544Subaru WRX STi EJ25 (2.5L) Pr. 2008-2009 (w dual AVCS)
KK3918Nissan VQ35 (3.5L) Pr. 2002-2006 (includes rev up version)
KK3672Mitsubishi Evo VII-VIII 4G63 (2.0L) 2000-2005
KK3852Mitsubishi Evo IX 4G63 (2.0L) -2006 MIVEC
20005685Mitsubishi Evo X 4B11T (2.0L) -2008 MIVEC
20000691Ford Duratec, 2.0L/2.3L
20000704Mazda MZR, 2.0L/2.3L
CNC Ported Big Valve Cylinder Heads w Camshafts
SB8010Subaru WRX STi EJ25 (2.5L) Pr 2004-2006 w KK3766 Camshafts (USA & MY06 Japan/Euro) Electronic Throttle
SB8012Subaru WRX STi EJ25 (2.5L) Pr 2004-2006 w KK3920 Camshafts (Japan/Euro) Cable Throttle
20002024Subaru WRX STi EJ25 (2.5L) Pr 2007 w KK3766 Camshafts (USA/Japan/Euro)
20002026Subaru WRX STi EJ25 (2.5L) Pr 2007 w KK3920 Camshafts (Special Applications Only)
20010140Subaru WRX STi EJ25 (2.5L) Pr 2008 w Camshafts

Each original cylinder head design is carefully evaluated and tested to establish the improvements required to meet the target performance level. Hours of teSTing and flow bench validation are used to determine the best advanced port design yielding maximum usable power and response. However, there is more to cylinder head design than just maximum flow. It is critical that port velocity is maintained to ensure drivability and valve train components are matched to guarantee reliable performance. Once all of these factors have been tested and validated, the final port contour is digitized. Using the digitized program, Cosworth Racing then reshape both intake and exhaust ports using a 5 axis CNC mill producing an accurate and consistent port shape every time. In addition to reshaping and enlarging the intake and exhaust ports, most Big Valve Cylinder heads feature a re-shaped combuSTion chamber to un-shroud the valves increasing air flow and performance. After machining, each cylinder head receives a multiangle high performance valve job on Cosworth's precision CNC valve seat cutter. Then each cylinder head is ultrasonically, cleaned, serialized and then hand assembled with select high performance valve train components, ready to install on your engine.

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