Mitsubishi Evo6 4G63 Cylinder Head

I would like to share a recent cylinder head I just finished. The cylinder head came out from a Mitsubishi Evolution VI with a 4G63 turbocharged 2.0L engine. The client came to our workshop complaining of severe oil burning and lack of power.

After we took out the head we found that the head had badly worn valve guides and digged seating’s and also we found out that the cylinder head was badly ported by a prior tuner compromising the durability hence the severe oil burning.

After cleaning, we made some testing on the in house Superflow flow bench and I went to the conclusion that the head needed some serious work to be able to make it better as the cylinder head was flowing less than an original standard head. What we did first was removing the standard cast iron valve guides, and had some special ones we use on the flow bench so we could test the flow after each porting modification. To solve the heavily digged seatings we decided to increase the valve sizes on both the inlet and exhaust valves by 1mm, to further try and make the port more efficient. After several hours the finished head was completely restored and flowing more than 30% more than when it came and i would like to point out that this was not a competition porting job but a street one and had to have full durability.

Below are some finished pictures and flow bench results.