i have a 2.5 semi closed block from a '04 - '06 USDM Sti and has done around 30,000
the thing is i will be getting a new crank with acl bearings and will also be getting forged pistons and rods ect.. but should i get over size pistons or drop in ones ?? as the bores look fine and still have cross hatching down them and have very little wear any help or advice would be great

 

Aftermarket Forged pistons generally run a larger piston/bore clearance than the standard subaru cast/forged HF pistons,so will need honing to get the correct clearance anyway.
You need to measure the bores for wear/taper/ovality and base your piston choice on the results.

Mick

 

thanks fella so what ever happens they still need to be horned again?

 

In a nutshell - Yes.

 

As above, you need to go for hone to fit pistons.

If it were a brand new short motor, you could have gone for drop ins...

 

As above go for the safe option and use hone to fit pistons.

Banny

 

thanks fellas