Does Subaru make over sized pistons?

I'm looking into rebuilding my block. I can find lots of forged pistons but I just need a set of factory over sized. Anybody know if they exist and where to get them?

Call Ryan or the guy's at Fredbeans. I'm sure they have them.

 

How do you know you need oversized pistons ? Did the machine shop tell you ?

 

Oh, I see, your just planning ahead.

 

Do you have a machine shop that will be doing the work ?

My question is wwwhhhhhuhyyyyyyyyyy go with factory ?

 

Throw some forged goods in there.

It must be a money thing.

I think they're just called the A, B, and C sized pistons. Which corresponds to the 99.5, 99.75, and 100mm bores. But they probably have different part numbers obviously. I couldn't tell you what they are, however. Best to call a dealership and talk to the parts guy, and if he gets lost, talk to the engine builder who will know.

 

FWIW I wouldn't ever put OEM pistons back in a Subaru 2.5L turbo. Forged only.

I'm wrong, sort of

 

The STD sizes are

A = 99.505-99.515

B = 99.495-99.505

 

The Oversize bores are

0.25 OS = 99.745-99.765

0.50 OS = 99.995-100.015

 

Since the piston clearance spec (and taper, out-of-round etc) is the same regardless of bore size, obviously the thing that has to change is piston size.

That's why you see some numbers and AA or AB or whatever stamped on the block. It defines the bore. Google some images and you'll see, it's right at the mating part of the cases near the front.

I have been back and forth on what to do with this car all summer. I have a month before the seasonal plate runs out on my Miata and my truck will need to be put away for winter as well.

 

We just dumped our AWD Matrix this week and bought a new leftover 2013 CRV EX for the wifes commuter.

 

I have been all over the map on what to do with the LGT. I tore the motor down and found a scuffed cylinder when I was replacing head gaskets. I was going to put it back together and run it just to see what else could be wrong with the car before I spend a ton of money. I wasn't sure if I wanted to dump a bunch of money into the car and it's going to take a major investment to get it running how I expect it to plus it's a 5EAT. If it was a manual and a wagon the decision would have been much easier.....motor build and boost the snot out of it.

 

I have been floating between a complete EJ257 short block or a rebuilt bottom end. The trouble with the rebuild is there is nobody around that I trust to do the machine work.....until today. I drove 2 hrs to talk to a guy that seems like he knows what he's talking about. They have done a bunch of Subaru motors and he has all the jigs for machining the block halves.

 

I'm planning on stock power with maybe a BNR16G. Stock pistons would be fine for my needs but I may have to go with something like CP's. I'm just not really super sure on what is the best choice for my needs.

P.S. - I know I'm dealing with a good guy because he told me they would do a rough bore to see how far I will have to go to clean up the cylinders. After that, I can order the smallest pistons that will allow me to clean up the bores.

Yeah, boring with torque plates is required for a good machine job.

 

My 2 cents, is OEM pistons would never go back in a Subaru 2.5L turbo car. They could last 10k, 50k, 100k, or 150k but to me it's too much to risk rather than putting a $500-600 set of forged pistons in and forgetting all about ringland failure.

 

If your turbo is good, build the motor and wait on the turbo.

I just stripped the motor. The bottom end and heads will get dropped of this week so they can tell me what pistons I can get away with. After talking with everyone, I think after market is pretty much the only option. I'm leaning towards the CP's but does anyone have any experience?

I hear cp's are a bit louder than others. I have wesicos