CP Forged Pistons

[ashley]

ok i get the point. il keep my opinion to myself.

mr2rich. sorry to have caused any confusion to you. after all. peter and co are the specialists on here so anyone elses points are invalid

opinions are fine, but you have to be open to challenge when throwing around statistics like that mate...all meant in good humour, apologies if I offended

ok so in other words. whats the chances of going and buying a set of 86mm CP's and a standard blocks measurments being bang on for required clearances on the spec sheet down to the last ten thou?

Based on your data: 0%
Based on my data: 75%

Real answer....???? No way of knowing without more data!

Only real way to know is to strip the block in front of you and inspect and measure it

[Peter Gidden]

ok i get the point. il keep my opinion to myself.

mr2rich. sorry to have caused any confusion to you. after all. peter and co are the specialists on here so anyone elses points are invalid

opinions are fine, but you have to be open to challenge when throwing around statistics like that mate...all meant in good humour, apologies if I offended

ok so in other words. whats the chances of going and buying a set of 86mm CP's and a standard blocks measurments being bang on for required clearances on the spec sheet down to the last ten thou?

You're thinking is ar$e about face.

Have bores checked first, then buy pistons to match.

[ashley]

Have bores checked first, then buy pistons to match.

Exactly!

[Gullzter]

Have bores checked first, then buy pistons to match.

Exactly!

+2

[kev8611]

Have bores checked first, then buy pistons to match.

Exactly!

+2

im aware of this lol. but in my case mines were outside tolerances so i had to go 86.25 then get block bored to spec

[ashley]

Only real way to know is to strip the block in front of you and inspect and measure it

Have bores checked first, then buy pistons to match.

in my case mines were outside tolerances so i had to go 86.25 then get block bored to spec

Sounds like we're all saying the same thing then

[MR2 Rich]

So what everyone is saying is buy 85mm pistons, then measure the bores and rebore it to 87mm?!

[Peter Gidden]

So what everyone is saying is buy 85mm pistons, then measure the bores and rebore it to 87mm?!

Who said that?

[Gullzter]

So what everyone is saying is buy 85mm pistons, then measure the bores and rebore it to 87mm?!

I think they mean check bore clearance then buy piston to suit said clearance?

[craig]

So what everyone is saying is buy 85mm pistons, then measure the bores and rebore it to 87mm?!

[ashley]

So what everyone is saying is buy 85mm pistons, then measure the bores and rebore it to 87mm?!

[MR2 Rich]

Thanks Ash...

Measure bores.
Buy pistons.
If rebore needed give the reborer the pistons.
Happy days.

[Gullzter]

So what everyone is saying is buy 85mm pistons, then measure the bores and rebore it to 87mm?!

[MartinF]

The plural of anecdote is not data.

PMSL.....that is a great line!

Filed for future use

[kev8611]

im sure i have a copy of a spec sheet for 86mm CP's and i deffo have my spec sheet for 86.25's

i can give you the specs for 86mm's and what your bore size needs to be. if every set is the same. not sure if each spec sheet is different or theyre all "off the shelf"

[bobhatton]

im sure i have a copy of a spec sheet for 86mm CP's and i deffo have my spec sheet for 86.25's

i can give you the specs for 86mm's and what your bore size needs to be. if every set is the same. not sure if each spec sheet is different or theyre all "off the shelf"

If the pistons are made to fit a 86mm bore then that is the size the bore needs to be. The piston clearance is built into the pistons

[ashley]

im sure i have a copy of a spec sheet for 86mm CP's and i deffo have my spec sheet for 86.25's

i can give you the specs for 86mm's and what your bore size needs to be. if every set is the same. not sure if each spec sheet is different or theyre all "off the shelf"

If the pistons are made to fit a 86mm bore then that is the size the bore needs to be. The piston clearance is built into the pistons

But you would of course still measure the pistons and check you actually do have the desired clearance wouldn't you Bob

[bobhatton]

im sure i have a copy of a spec sheet for 86mm CP's and i deffo have my spec sheet for 86.25's

i can give you the specs for 86mm's and what your bore size needs to be. if every set is the same. not sure if each spec sheet is different or theyre all "off the shelf"

If the pistons are made to fit a 86mm bore then that is the size the bore needs to be. The piston clearance is built into the pistons

But you would of course still measure the pistons and check you actually do have the desired clearance wouldn't you Bob

Oh yes.

Just had an engine in where the pistons were made to fit a 89mm bore, 9.5:1 comp ratio with 2 bar + boost, not a Toyota.

It melted the 4 plugs within 5 miles of leaving the mappers.

We stripped it down and I could see lots of piston rings down the side of the pistons.

We measured the bore and yes it was 89mm but the pistons were under size.
The machine shop had had the pistons when they bored the block but had not measured them, just bored to 89mm. They paid for a new set of pistons at 7.5:1.

On the first dyno run it now has 300 hp at 10 psi and will get over 500hp with under 2 bar boost

[JD]

The machine shop had had the pistons when they bored the block but had not measured them, just bored to 89mm. They paid for a new set of pistons at 7.5:1.

[Odin_S]

I'm doing an engine rebuild this year on my car the pistons I bought are 86.50 from ats They said that's the standard rebuild size...

Don't really want to bore out more out of the cylinder block than I need to. So I'm assuming I would probably need to buy new ones?

PW is doing my build in summer