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Cosworth CNC Ported Big Valve Cylinder Heads


For over 40 years, Cosworth has been the leader in innovative multi-valve cylinder head design for both racing and high performance production cars. The Cosworth CNC Ported Big Valve Cylinder head range is the latest advancement. Modified from new OE cylinder head castings, substantial gas flow improvements and upgraded valve train components offer superior performance for your high performance engine. 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 valvetrain 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, both intake and exhaust ports are reshaped using a 5-axis CNC mill producing an accurate and consistent port shape every time. In addition to re-shaping and enlarging the intake and exhaust ports, most Big Valve Cylinder heads feature a re-shaped combustion chamber to unshroud the valves increasing air flow and performance. After machining, each cylinder head receives a multi-angle high performance valve job on Cosworth's precision CNC valve seat cutter. Then each cylinder head is ultrasonically cleaned, serialized and finally hand assembled with select high performance valve train components, ready to install on your engine.


Product Features:
  • All New OE Castings
  • Enlarged intake and exhaust ports
  • Machined port bore finish
  • Knife edge port divider
  • 4-angle Inlet Valve job
  • 3-angle & radius Exhaust Valve job
  • Valves are lapped
  • Back-Cut Inlet Valves
  • +1mm Stainless Steel Intake Valves (1800 degrees max.)
  • +1mm Inconel Exhaust Valves (2400 degrees max.)
  • Hi-rev, dual valve springs
  • Titanium Retainers
  • Hardened Steel Spring Platforms
  • Reshaped combustion chamber on most applications
  • Ultra Sonic cleaned prior to assembly
  • Flow bench proven design
  • Dynamometer tested
  • Serialized and sport a machined Cosworth logo
  • Pre-assembled, ready to install

Applications available for CNC Machined Big Valve Cylinder Heads
FORD
Part Number Engine Engine Type Years Applications Notes
20000691 Duratec 2.0L, 2.3L DOHC 07-09 Ecosport, Focus, Fiesta  
MAZDA
Part Number Engine Engine Type Years Applications  
20000704 MZR 2.0L, 2.3L DOHC 06-09 Miata, Mazda3, Mazdaspeed 3  
MITSUBISHI
Part Number Engine Engine Type Years Applications  
KK3672 4G63 2.0L DOHC 01-05 Evo VII, VIII  
KK3852 4G63 2.0L DOHC MIVEC 06-07 Evo IX  
20005685 4B11 2.0L DOHC MIVEC 08-09 Evo X  
NISSAN
Part Number Engine Engine Type Years Applications  
KK3918 VQ35DE 3.5L DOHC VVTi 03-06 350Z, G35  
SUBARU
Part Number Engine Engine Type Years Applications  
KK3670 EJ25 2.5L DOHC AVCS 04-06 Impreza WRX, STI  
SB8010 EJ25 2.5L DOHC AVCS 04-06 Impreza WRX, STI w/ KK3766 camshafts, USDM models
SB8012 EJ25 2.5L DOHC AVCS 04-06 Impreza WRX, STI w/ KK3920 camshafts, JDM/EUDM models
20001699 EJ25 2.5L DOHC AVCS 2007 Impreza WRX, STI w/ Air Injection Ports
20002024 EJ25 2.5L DOHC AVCS 2007 Impreza WRX, STI w/ Air Injection Ports. KK3766 camshafts; USDM models
20002026 EJ25 2.5L DOHC AVCS 2007 Impreza WRX, STI w/ Air Injection Ports, KK3920 camshafts; JDM/EUDM models
20004544 EJ257B 2.5L DOHC AVCS 08-09 Impreza STI w/ Dual AVCS
20010040 EJ257B 2.5L DOHC AVCS 08-09 Impreza STI w/ Dual AVCS, 20007395 camshafts