not sure if these are sti forged pistons or not they have the cut outs for the valves like sandard wrx piston but underneath there is hf embossed are they forged or not was removed from a sti v1.
look different from my sti v4 pistons.
all help welcome

 

V1 and 2 pistons have been described as more crude than the v3 onward pistons, but they are forged, though i would try to replace same for same

Tony

 

The one on the left was removed from a sti version 1 (is it a forged piston) and the one on the right is a forged piston from a vesion 4 sti.
If they are both forged which is best for a closed deck block.
the version 1 piston has hf underneath and the version 4 has hf2 underneath

 

Not being an expert on sti forged pistons, i would hazzard a guess at the v4 ones being the better choice

Tony

 

This thread might help slightly.

https://www.scoobynet.com/general-te...d-pistons.html

 

thanks but no help as im not sure they are the original pistons and i need it confirming that they are forged and not standard wrx pistons

 

Wrx pistons have a cross hatch pattern underneath and forged pistons are smooth.

 

The piston on the left is a "dog-bone" forged piston as fitted to the STi Version 1+2 and marked HF/1/2.
Early dog-bone pistons had a slot type oil drain-back on the oil contol ring land of the piston and were prone to failure in this area. Later dog-bone pistons were modified to a hole type oil drain-back.

Piston on the right is STi Version 3 ~4 forged piston and marked HF/1/2/3.
Normally lighter than the dog-bone forged pistons due to the narrower skirt design and seem to take more "punishment" than the dog-bones.

Pic below is Version 3 ~ 4 Cast (left)and Forged(right).




Mick

 

nice one thanks mick