Originally Posted by
big_wasa
Are you planning on keeping the St head ? The St head will offer no advantage with a budget turbo but there are disadvantages. Sure it has bigger valves and flows more but a Zetec head will flow more than the pistons and rods can take so it’s not the limiting factor.
With the St head The inlet ports are higher so most manifolds need work.
If your going the thicker head gasket route then you want the thickest you can lay your hands on.
So from what your research, what are the upper limits of the blacktop head and when is a good time to swap over to the ST170 head?
Interesting point about the inlet ports though...will need to check my inlet up against a ST170 head!
Did I also read somewhere that ST170 were more prone to warping than conventional black top heads? Is there any hard evidence on this?