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I have tried to understand the cooling system in the cylinder block and head and figure out how to make it better. The coolant flows from the block to the head mainly from the water holes in the back end and the exhaust side of the block.

The holes in the head gasket get smaller on the exhaust side from cylinder nr 4 to cylinder nr 1.

In the rear end of the cylinder head there are two water plugs and in their place I could put in tubes for water feed. All the flow could go to the head or a smaller part could still go to the block. The electric water pump could alone handle the flow so the original water pump could be bypassed or removed. The flow could be transverse thru the water plugs on the long sides of the head but that would need at least separate water manifolds and mods to the exhaust manifold flange.

The water pipe from the old head is going in the place of the expansion plug.

To reach the plug I needed to make a good hole in the plate

Same from above...

Water pipe added to cylinder head.

...and a pipe like this will come in the radiator return line. The coolant enters from the alectrical water pump which is under the pipe (from the right side in picture) and goes to the mechanical water pump. The smaller pipes take the coolant to the cylinder head through the new water pipe (exhaust side) and the heater hose (intake side).

To change valve timing I must remove the ignition coils, the valve cover and the upper part of the timing cover, the coolant can remain in the cooling system.

A few runs on Boxer Speed Day and the best was 13,6 s / 101 mph (163 kmph) which was a little disappointing. The boost pressure was only about 11 psi (0,8 bar) and afterwards I have changed the wastegate spring and now max boost is about 16 psi (1,1 bar). The best thing was that the coolant heating problem was gone after the camshaft change and the change in coolant flow path.The water temp is from 165 to 175 *F (75 to 80 *C) even after a good run at the track.

In order to speed up gear shift I modified the front ends of the shifter rods. I also lengthened the shifter levers by 20% which should shorten the movement of the gear knob by 20%, too.

The next goal is to get more power with a new turbo, wastegate and exhaust system. The turbo is a copy of Garrett GT3582 (without ball bearings). The compressor wheel is 61.4/82 mm and the turbine wheel 68/62.3 mm with  A/R 0,82. The turbo should work ok blowing thru the Eaton M62 blower (twin charging). A second air/water intercooler is coming between the chargers to keep charge temperatures in order.The wastegate is  a so called 50 mm WG though the orifices are 44 mm in and 48 mm out. Here are a few pics of the turbo and the wastegate.The exhaust manifold needs modifications or renewal. The exhaust system will be a shorter 3" version (up from 2.5").