The st170’s bottom end is not forged. It does have rods with bigger little end bearings and bigger big end cap bolts making them stronger than a Blacktop. The Rs has bigger still gudgeon pins.

Pistons are Mahle, as are an Rs or a vanilla Blacktop but the crown looks a little thicker due to valve cutouts.

Rebuilding a Zetec isn’t cheap or usually needed if it’s had plenty of good oil changes in its life.

I bugger about with these for a hobby and run them all on the ford ecu. The ecu has limitations with tuning but it’s cheap.

For example an st170 ecu can be had for a few quid literally cheaper than chips just make sure you get at least one key or more accurately the rdif chip from the key.

A plain 2.0 is good for around 150bhp max Oem or 165 aftermarket.

A plain 2.0 st will do 170 Oem but most are less. They will do 200 with aftermarket induction and management.

A turbo Zetec can be cheap if you keep the power modest and can be upgraded as and when and can be run on a focus Rs ecu.


St


Rs managed Blacktop.