Peened pistons - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

gpvecchi · 02-26-2021, 05:29 PM

Facelift MT models have (except Europe) peened pistons.
What are they for? More resistance? Less friction?

NoHaveMSG · 02-26-2021, 05:42 PM

Quote:

Originally Posted by gpvecchi

Facelift MT models have (except Europe) peened pistons.
What are they for? More resistance? Less friction?

Shot peening improves fatigue strength.

This explains it pretty well. It has pikturs too.

http://www.superstreetonline.com/how...-wpc-treatment

Lantanafrs2 · 02-26-2021, 06:00 PM

Shot peen, cryo, micropolish. Parts still break lol.

Purist · 02-27-2021, 01:36 AM

I've not heard of pistons being peened before. Only rods. You learn new stuff every day.

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DarkPira7e · 02-27-2021, 11:13 AM

Perhaps we're misunderstanding and someone in manufacturing gave them all a nice mushroom stamp for QC

ls1ac · 02-27-2021, 11:38 AM

In the speed shop i work with they have tried it all. They still use cryo and dicronite as the main treatments for specialty engines. Shot peening had inconsistences that made it unreliable. Good suppliers of parts for high performance engines seems to be the most reliable way to build an engine.
I am sure that many of these prosses help, i can only talk about our shop experience.

NoHaveMSG · 02-27-2021, 12:21 PM

Quote:

Originally Posted by Purist

I've not heard of pistons being peened before. Only rods. You learn new stuff every day.

Sent from my SM-G973F using Tapatalk

Me either. Especially a part that needs high quality finish machining like a piston.

Lantanafrs2 · 02-27-2021, 01:35 PM

Quote:

Originally Posted by ls1ac

In the speed shop i work with they have tried it all. They still use cryo and dicronite as the main treatments for specialty engines. Shot peening had inconsistences that made it unreliable. Good suppliers of parts for high performance engines seems to be the most reliable way to build an engine.
I am sure that many of these prosses help, i can only talk about our shop experience.

There are no guarantees lol.

Purist · 02-27-2021, 04:36 PM

Quote:

Originally Posted by NoHaveMSG

Me either. Especially a part that needs high quality finish machining like a piston.

Yeah, you'd never peen the skirt or the ring lands right? Surely it'd be too rough. And are broken pistons that muchbof a problem?

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ls1ac · 02-27-2021, 04:49 PM

We tried putting a light knurl on the piston skirt and applying millennium disulfide. Very labor intensive and theory was good but we could never prove its worth.
Racers will try anything twice if you think it might give you an advantage.

Ultramaroon · 02-27-2021, 05:46 PM

Quote:

Originally Posted by ls1ac

millennium disulfide.

haha... molybdenum not in dictionary, or only available once every thousand years? Anyone interested in my executive summary of what shot peening does on a molecular level?

NoHaveMSG · 02-27-2021, 06:46 PM

Quote:

Originally Posted by Ultramaroon

haha... molybdenum not in dictionary, or only available once every thousand years? Anyone interested in my executive summary of what shot peening does on a molecular level?

Yes

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Ultramaroon · 02-27-2021, 09:09 PM

Ball bearing races last as long as they do because they are shot peened before they are ground to final shape.

It's another form of work hardening. All metals solidify as disorganized seeds of highly organized crystalline structures. Those grains grow into each other and remain attracted to each other less tightly than the crystals themselves. they can be displaced from each other only a certain amount until they slip and don't return to their original positions before the force was applied.

The further these grains are displaced from each other permanently, the more force it takes to reach the point where they slip again. This only goes so far before the bonds break down, but up to that point, the material is harder than it was before it was "bent."

Shot peening bends all the grains near the surface but leaves the layers underneath at rest. This increases the hardness of the surface layer relative to the desired hardness of the base material.

Lantanafrs2 · 02-27-2021, 10:13 PM

I heard the 13 valve springs were made from a material developed from ufo wreckage. Unfortunately there was a reason it wrecked.

02-26-2021, 05:29 PM	#1
gpvecchi Senior Member Join Date: Mar 2018 Drives: Toyota 86 GT Limited PP (Model G) Location: Italy Posts: 1,018 Thanks: 406 Thanked 335 Times in 187 Posts Mentioned: 14 Post(s) Tagged: 0 Thread(s)	Peened pistons Facelift MT models have (except Europe) peened pistons. What are they for? More resistance? Less friction?

02-27-2021, 01:36 AM	#4
Purist Senior Member Join Date: May 2017 Drives: Subaru BRZ Location: Australia Posts: 349 Thanks: 125 Thanked 261 Times in 145 Posts Mentioned: 5 Post(s) Tagged: 0 Thread(s)	I've not heard of pistons being peened before. Only rods. You learn new stuff every day. Sent from my SM-G973F using Tapatalk __________________ Less More

02-27-2021, 11:13 AM	#5
DarkPira7e Rust bucket enthusiast Join Date: Feb 2017 Drives: 2013 Turbo Firestorm FRS Location: Vermont Posts: 3,932 Thanks: 3,199 Thanked 4,095 Times in 2,045 Posts Mentioned: 31 Post(s) Tagged: 0 Thread(s)	Perhaps we're misunderstanding and someone in manufacturing gave them all a nice mushroom stamp for QC __________________ Turbo FR-S Build - Build Thread JDL EL Recirc manifold, Boostlab BL58x Turbo w/ T51R, 17x9 ARC-8, IAG block

02-27-2021, 09:09 PM	#13
Ultramaroon 義理チョコ Join Date: Sep 2014 Drives: a 13 e8h frs Location: vantucky, wa Posts: 31,865 Thanks: 52,120 Thanked 36,513 Times in 18,917 Posts Mentioned: 1106 Post(s) Tagged: 9 Thread(s)	Ball bearing races last as long as they do because they are shot peened before they are ground to final shape. It's another form of work hardening. All metals solidify as disorganized seeds of highly organized crystalline structures. Those grains grow into each other and remain attracted to each other less tightly than the crystals themselves. they can be displaced from each other only a certain amount until they slip and don't return to their original positions before the force was applied. The further these grains are displaced from each other permanently, the more force it takes to reach the point where they slip again. This only goes so far before the bonds break down, but up to that point, the material is harder than it was before it was "bent." Shot peening bends all the grains near the surface but leaves the layers underneath at rest. This increases the hardness of the surface layer relative to the desired hardness of the base material. __________________ service manuals Last edited by Ultramaroon; 02-27-2021 at 09:31 PM.

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02-26-2021, 06:00 PM	#3
Lantanafrs2 Senior Member Join Date: Jan 2018 Drives: 2013 frs red Location: South Florida Posts: 3,517 Thanks: 2,520 Thanked 3,088 Times in 1,654 Posts Mentioned: 6 Post(s) Tagged: 1 Thread(s)	Shot peen, cryo, micropolish. Parts still break lol.

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