Hi guys I've bought some forged pistons for my rebuild and noticed they are shorter in depth than my stock ones so I dropped one in and it doesn't quite reach the top of the block when it's at its highest there is 3mm difference will this cause me problems or is this normal for a forged piston

orged piston

 

i'm assuming standard does have you compared both , i know the skirt of the forged pistons are normally shorter which is why you get more noise , i'm sure some one with more knowledge than me will be along soon , sorry to sound silly i assume crank is definitely at it's highest point

 

Have you got the correct piston for the rod length ?

 

You may have 2.1 stroker pistons, youll possibly need the right rods

 

Did some digging on them and found out they are 92mm to use with a 79mm crank (newage) I believe ej205-ej207 and standard rods. No good for me as mine is a classic with a 75mm crank so I'll sell them on

 

You need a 2.5 crank then

 

Are all 2.5 cranks rear thrust because mine is a centre thrust crank. Is it possible to have my block converted to rear thrust?

 

there is an early EJ25 N/A that uses a centre thrust but generally better & stronger to convert your block

we undertake these conversions as well as most other machining required and parts

 

How much do you charge to convert the block?

 

are you forging an open deck block?

If I was you I'd start with at least a semi thats rear thrust.

Are you sure you know what you're doing?

 

If I use these pistons will it cause any problems

 

my knowledge is not good enough to answer that , won't compression be down a lot or maybe not ? i would call a couple of engine builders , personally i see no reason why it would not work it would need its mapped checked any way , at least if it works well you then know your pistons are strong

 

The c/r will be down, the squish will be wrong, also more prone to gasket failure as the ignition will be happening down the bore. Dont know specifics about subaru blocks yet as new to imprezas but maybe posible to machine the top of the block to correct the deck height. (Usual practice on a lot of other manufacturers blocks)

 

This, but I don't think the block could be decked that much without affecting the timing.
Best bet is just speak to ASperfomance, alyn will machine your block and supply the crank and bearings. Hes cheaper than anyone else and always genuine parts.