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Discussion Starter #1
Is there a reason Vitara piston face is rough, and would there be any benefit to a smooth/polished face? Reducing carbon build up and hot spots?

 

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They are rough because that is how they come out of a sand mould as they are sand cast.

It is better to debur, remove all sharp edges and smooth then polish as they then run cooler as they absorb less heat. They then also leave more heat in the charge which then makes more power. They are also less prone to promote detonation as they don't hot spot so easily and they release carbon easier.
 

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I wanna see the end product of the polished face
I have posted pics of them being polished. They aren't completely finished but close.
 

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They are rough because that is how they come out of a sand mould as they are sand cast.

It is better to debur, remove all sharp edges and smooth then polish as they then run cooler as they absorb less heat. They then also leave more heat in the charge which then makes more power. They are also less prone to promote detonation as they don't hot spot so easily and they release carbon easier.
Sound like it would be very beneficial to smooth them out . Thanks Pat rep for you.
 

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I just got mine coated by swain coatings. It's called a TBC coating on the dome and it also has PC-9 on the skirts. The domes are really nice looking on these.
Swaintech.com has all the info on them.
 

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IIRC I read somewhere either from Acid Beaver or Endyn or Pat that you don't want them to be mirrors. But you definitely don't want them to stay as cast.
Smooth but don't mirror polish because you want some surface for carbon crystals to build up on evenly. Mirror finish won't allow this, just a little rough so there is a surface for crystals to form on.

Coatings are cool too. :bigok:
 

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IIRC I read somewhere either from Acid Beaver or Endyn or Pat that you don't want them to be mirrors. But you definitely don't want them to stay as cast.
Smooth but don't mirror polish because you want some surface for carbon crystals to build up on evenly. Mirror finish won't allow this, just a little rough so there is a surface for crystals to form on.

Coatings are cool too. :bigok:
I've also posted pics of the pistons after a race season. They do get some coating on them even if they look like a mirror. Even with a 2000 grit wet sand there are some imperfections in the metal.
 

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It was not me who said do not mirror finish. I believe the better the finish the less heat is transferred to the piston. Of course if you are going to ceramic coat, finish to satin smooth as it has to be grit blasted anyway so the coating sticks.
 

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Graphite does but diamond does not
 

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