179.If your engine cylinder pressure is 120 bar why you are tightening cylinder head at 1200 bar

As we know that Pressure = Force / Area
So Force = Pressure x Area
We know that Pressure = 120 bar, Lets take cylinder bore = 60 cm
So area of head = ㄫ r x r = 3.14 x 30 x 30 = 2826 cm2
There for Force acting on cylinder head = 120 x 2826 = 339120 Ncm

In order to keep cylinder head in place we need to apply a force that is greater than 330120 

Now cylinder head is tighten with 8 hydraulic nuts and assume  area of one nuts as 100 cm2

For safety we take the force needed to keep head in place as 800000 Ncm

Now There are 8 nuts so total area = 8 x 100 = 800 cm2

Pressure = 800000 / 800 = 1000 bar

So we need to tight nuts around 1200 bar