turbo900

Can these be fitted without any machining to standard block?

Cheers

**jay**

iTrader: (1)

Will need to be bored or honed to suit clearance, if you just throw them in they will be either too tight or end up with horrid piston slap and high oil consumption with a very noisy engine.
Jay

turbo900

Thats maybe why my car is detecting so much knock then? Lol

rob84

iTrader: (5)

as per the other thread ideally they need machined to suite, Unless the bores are generally spot on or a brand new block

turbo900

Think the garage is feeding me a lot of mince. They think i'm stupid and wont question what they say. Getting fed up now. Time for not being so understanding!!!

Primeiro

What pistons are you refering too?

If there 92mm then more than lickley you will have a large bore clearence depending on your state of liner, keep in mind a light hone is needed for the new rings.

If you are running .25/.5 oversize then you can set your piston manufacturer advised bore clearence or to what you wish.

All the best with it.

rob84

iTrader: (5)

Have it rebuilt elsewere and send them the bill

turbo900

I would if i knew they'd pay
Been patient but getting fed with limited answers. Car is back in for the e.ngine builder and dealer to look into and listen to car from cold and hot and decide how they plan to fix it!

turbo900

Notes:
SUBARU WRX 2.5L STI | 100.0mmbore | 79.0mmstroke | 130.4mmrod | 30.7mmc/h | 23mmpin | -22ccvol | 405g | 8.5c/r | 4032

Wrx209937122 could be what they fitted. Presume these need hone/bore

rob84

iTrader: (5)

Hell aye it will have needed bored for those.
std pistons are 99.5mm.
Those are half a mm bigger plus the correct running clearance

Shaks-STI

iTrader: (7)

I had 100mm fitted and needed machine work before it was done.

Baz82

Same as that . I think 3 thou of an inch is road spec clearance, mine is 4 thou and is rattly when cold

Shaks-STI

iTrader: (7)

Mine is rattly when cold but once warmed up its fine.

Baz82

Mines the same cold = diesel sounds , up to temp she is perfect but still noticeable noisier than a standard engine I have to say.
When on track thats the quietest I've heard it after a few hard laps

turbo900

You guys I take it all have remaps, and non standard other bits?
I think my issue is a forged piston engine with standard other bits and standard ECU. Mine is quiet once hot but by this point the car detects slap as knock and adjust ignition and fuel until its running like a dog!
Managed to get some info today and block was machined properly to accept these pistons so thats a bit better news so just need to find out how to sort the slap on cold running issue!!

MOTORS S GT

iTrader: (2)

These pistons are 4032 material forged piston, ideal for your std type road based engine, if there noisy they have been fitted in a incorrectly sized bore, ie to big, these should be 0.002" clearence.
If they were 2618 material for high power applications they would require extra clearence, & would be noisy when cold.

Baz82

That should not be happening may be an issue with the knock sensor. You should really have the car mapped.
I'm running an Autronic ecu which has no knock control but is mapped to suit the engine

turbo900

Andy F is going to work his magic