for aftermarket pistons for example 85mm do the cylinders have to be bored to exactly 85mm or slightly more.

my problem is I have a scuffed cylinder 84mm sleeved block that I don't know if its gonna be 84.5 or 85mm after scuffing is removed
I wanted to bore it out before I order pistons so I know what size to get but not sure how the process works

 

Research PTW (piston to wall) clearance then take them, and the block, to the shop.

 

I agree, talk to your shop. They will help you make the right decisions.

 

Here we go again...

*Most* aftermarket forged pistons are designed to be bored to (in this case) 85mm for a factory preset clearance recommend by the manufacturer. Wiseco for instance specifies 0.0025" PTW built in at the specified bore size. If you need more then you over bore accordingly. Most "real" performance machine shops already know this. You really need to talk to people that know more than you.

PS - Don't even waste your time asking for proof. I am not giving any.

 

so much butthurt bro. Chill out.
Um just adking for my personal information
If u gonna bring your butthurt in every thread i post then please dont post and let others post

Thats what i was asking if the ptw clearance is machined into the piston or the cylinder wall because 85mm piston and 85mm wall as advertized would mean zero clearance
U tryin to be a smartass and throw in some sneaky sarcastic comments all the time trying to prove your supperior knowledge.

all you need is to read the damn questions more carefully and then u will have less problems because ur answer might be right but its not what the op is asking like ive seen in some of your replies

 

The machinist should always have the piston in hand to be certain the PTW is maintained correctly. The measurement is very critical and decides alot of motor characteristics like warm up noise and turbo/ nitrous use without scuffing etc.
PTW is very important and should not be guessed.

 

I didn't start this rift. You did, so deal with it. You are on the wrong side of this battle and are clueless. It is OK if you don't have a clue what you are doing as long as you actually make an effort to research. You do no such thing and make thousands of threads that could easily be taken care of by researching on your own. Like this thread, you could have called the manufacturer and had the correct answer in minutes. To top it all off your grammar is horrible for a self proclaimed OCD.

Since you need it spelt out: The pistons are typically undersized from factory. Meaning if you purchased an 85mm sized piston and had your cylinders bored over to exactly 85mm then you would have a built in PTW clearance for that exact manufacturers specifications. For instance, Wiseco is usually 0.0025" and CP pistons either 0.0035" or 0.003" built in PTW. How much PTW clearance you need will be determined by your horsepower goals and piston type be it 4032, 2618, hyperputic, etc...

If you want to continue the drama then PM me, if not then we can cut the crap at any time. I am nowhere near upset like you think I am.

 

I can see by the way you respond that you are butthurt but i do appreciate your answers when they are actually on topic.
And i do research as much as i can before i ask questiin here if i dont find what im looking for through search engines then i ask here.
And u assumed in ur first reply that im asking about ptw clearance whwn i was asking completely different question then you probably red it again and thats exactly what i was asking so thank you for thatminus the shitty remark at the end
And yes i did understand the first time although you jumped on the oppirtunity to reinforce your supperiority again which i set you up for in my last reply

And if you know about ocd u should know that ocd doesnt apply to everything only ceetain things... in my case cleaning engine bays which i do for almost every car i see because it bothers the sht out of me
So back at ya: ill stop when you stop

 

You cannot answer your question until you get the work performed.

 

How about this. Your pistons should come with a sheet specifying p2w clearance recommended.

Bring the sheet, your block, and pistons to you machinist and say "im cluless, do this for me"

He'll then bore it, and hone it to the correct p2w provided by the sheet, give you parts, you fork over cash.

Btw as long as your bores arent gouged and look like an engine exploded inside them, 84.5mm will be fine.

Just bring the block to a machinist amd ask him if the bores are ok for a 0.5mm overbore. If he says it is, buy 84.5mm. If he says itll need to go to 85mn, buy 85mm.

 

He wouldnt know until its bored out
It could be 84.5 or 85mm

So unless you want to buy the extra set of pistons for me u didnt read the first post


Turbocrv already answered it. Exactly what i was looking for