Polishing Piston Tops?
#898052
01/06/11 05:35 PM
01/06/11 05:35 PM
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Joined: Jul 2006
Posts: 383
Essex, Ont., Canada
Fishmarket
OP
enthusiast
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OP
enthusiast
Joined: Jul 2006
Posts: 383
Essex, Ont., Canada
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Any benefits to this? Obviously it would be more difficult for carbon to stick... here is an excerpt from the kb-silvolite website,
"Tests have shown that polishing the combustion chamber, valves and piston top can increase Hp and fuel economy by 6%. So far it has proven difficult to keep a coating on a polished piston."
Anyone doing this on their engines or have tested the practice on a dyno?
1972 Plymouth Cuda 340 4 speed
1971 Plymouth Road Runner 383 Auto
1970 Plymouth Duster /6 Auto
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Re: Polishing Piston Tops?
[Re: Fishmarket]
#898053
01/06/11 06:32 PM
01/06/11 06:32 PM
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Joined: Nov 2004
Posts: 3,544
Syracuse,NY
CompWedgeEngines
master
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master
Joined: Nov 2004
Posts: 3,544
Syracuse,NY
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Its more a case where you are trying to control detonation by eliminating areas that can cause pre-ignition. any sharp edge sticking out will often be a place for a hot spot to develop. Polishing keeps this to a minimum. You'll see boosted motors often polished very smooth, as they are worse.
RIP Monte Smith
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Re: Polishing Piston Tops?
[Re: jcc]
#898055
01/06/11 08:16 PM
01/06/11 08:16 PM
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Joined: Jul 2006
Posts: 383
Essex, Ont., Canada
Fishmarket
OP
enthusiast
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OP
enthusiast
Joined: Jul 2006
Posts: 383
Essex, Ont., Canada
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Here's the link referring to the testing that united engine and machine (kb-silvolite) has done http://kb-silvolite.com/article.php?action=read&A_id=36The article states that the polished piston doesn't transfer heat to the intake charge as much as a non-polished one, thus the increase in performance. Here's another quote, " A smooth polished piston runs cooler than a non-polished piston even after combustion deposits have turned both pistons black. A cool, smooth piston will transmit a minimum of heat to the incoming fuel air mix."
1972 Plymouth Cuda 340 4 speed
1971 Plymouth Road Runner 383 Auto
1970 Plymouth Duster /6 Auto
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Re: Polishing Piston Tops?
[Re: jcc]
#898056
01/06/11 09:38 PM
01/06/11 09:38 PM
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Joined: Jul 2010
Posts: 2,091
Delray beach, Florida
Performance Only
top fuel
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top fuel
Joined: Jul 2010
Posts: 2,091
Delray beach, Florida
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Quote:
However you can have polished sharp edges, Seems to me polish is just more heat reflective, and that would likely be a small power boost, but only as long as it stayed reflective, wonder how long the dyno tests lasted that showed a boost.? What kinda of fuel, ie carbon/lead buildup? If coatings don't last why would polishing? 
the coatings do last. they are a ceramic heat barrier, unlike simple polishing.
machine shop owner and engine builder
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Re: Polishing Piston Tops?
[Re: Fishmarket]
#898057
01/06/11 09:44 PM
01/06/11 09:44 PM
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Joined: Oct 2004
Posts: 1,752
detroit area
moderncylinder
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top fuel
Joined: Oct 2004
Posts: 1,752
detroit area
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when you look at castings or forgings that are not machined on their surfaces,, they have more area due to all the little bumps, edges, ripples,, or whatever,, polishing that surface then reduces the total surface thus allowing more heat to be retained in the chamber, or less heat reflected into the intake charge,, thats probably what they mean...
also,, usually fluids do not like to flow over mirror polished surfaces,, there is no friction on the surface to create a boundary layer,, so the fluid flow is chaotic,, rather than uniform if a boundary layer is there,,, though with that said,, you want the thinnest layer possible
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Re: Polishing Piston Tops?
[Re: Performance Only]
#898058
01/06/11 11:12 PM
01/06/11 11:12 PM
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Joined: Dec 2003
Posts: 22,696
Bitopia
jcc
If you can't dazzle em with diamonds..
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If you can't dazzle em with diamonds..
Joined: Dec 2003
Posts: 22,696
Bitopia
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Quote:
Quote:
However you can have polished sharp edges, Seems to me polish is just more heat reflective, and that would likely be a small power boost, but only as long as it stayed reflective, wonder how long the dyno tests lasted that showed a boost.? What kinda of fuel, ie carbon/lead buildup? If coatings don't last why would polishing?
the coatings do last. they are a ceramic heat barrier, unlike simple polishing.
After rereading the OP, I misread the point of coatings not lasting is due to the polishing, so that means the issue to me is, does the alledged reduction in surface area thru polishing out weigh the benefits of a thermal heat barrier, or something like that?
Reality check, that half the population is smarter then 50% of the people and it's a constantly contested fact.
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