GSC Power-Division's CNC cylinder head for the Mitsubishi Evolution 8 & 9 is nothing less than perfection. GSC goes threw a 12 step process on each cylinder head to guarantee performance. GSC starts with a brand new OEM Mitsubishi cylinder head that is checked for port wall thickness and for casting flaws. After a good casting is approved, the steel valve guides are removed and the cylinder head is locked in to our Okuma 5 axis mill and the port work begins.
Using the latest in computer aided software GSC has designed new intake and exhaust ports for the 4g63 head along with a reshaped combustion chamber to maximize port velocity and flow. Once the Okuma is finished milling away the unneeded aluminum from the cylinder head the head is removed and cleaned to remove any loose aluminum from the milling process. GSC installs a set of Bronze valve guides into the head and it's off to have a precision valve job to allow for the +1mm over intake and exhaust valves.
For the valve job GSC relies on a CNC based Newen Contour-BB to perform precision accurate valve seats specially designed to allow for maximum velocity where it counts most, right at the valve! After all machining is finished the cylinder head is hot tanked and pressure cleaned before it is ready for final assembly. When installing each of the black nitrated stainless steel intake and Inconel exhaust valves proper stem height is checked on each and every valve stem. Every valve stem is ground to its OEM height to maintain exact valvetrain geometry. A matched set of GSC's Beehive valve spring and titanium retainers are installed using Viton valve seals and the exhaust and intakes are shimmed to provide seat pressures with in 3% of each other. Finally, a spec card is generated and the GSC CNC Cylinder head is ready for a life of extreme performance.
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