sti pstons "help"
#1
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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
look different from my sti v4 pistons.
all help welcome
#3
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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
![](http://i20.photobucket.com/albums/b243/impreza300bhp/25012009198.jpg)
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
![](http://i20.photobucket.com/albums/b243/impreza300bhp/25012009198.jpg)
![](http://i20.photobucket.com/albums/b243/impreza300bhp/25012009197.jpg)
Last edited by ADAM TYPE R; 25 January 2009 at 05:50 PM.
#6
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#8
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iTrader: (1)
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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).
![](http://img.photobucket.com/albums/v499/mick24/24012008441.jpg)
Mick
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