I was wondering what is the benefit of polishing the combustion chambers?
This PR3 head i am buying has P&P, 3 angle valve job, polished combustion chambers, new valve seals, shaved .030", ITR intake valves, crane stage 2 cams, dual valve springs, Ti retainers, adj cam gears.

 

polishing combustion chambers is really not all that good.

 

ok so, its not anything special then, eh. Thanks.

 

If the work was professionaly done then it good to have polished chambers.When done correctly the valve job is blended in and unshrouded,and the sharp edges of the casting are taken away,getting rid of a possible detonation hot spot.Also the polished surface refects more heat back into the cyl for the combustion process to take advantage of.Remember crankshaft hp is just a fraction of what's being produced,we only see about 30% of the real power generated by our engines the rest is taken up by the exhaust and the water jackets.Anything that keeps the lost heat in the cyl helps.

 

So would it be optimal in all engines to have the chambers polished to a mirror finish or is there more to it than that?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Ed’s Racing Heads &raquo;</TD></TR><TR><TD CLASS="quote">If the work was professionaly done then it good to have polished chambers.When done correctly the valve job is blended in and unshrouded,and the sharp edges of the casting are taken away,getting rid of a possible detonation hot spot.Also the polished surface refects more heat back into the cyl for the combustion process to take advantage of.Remember crankshaft hp is just a fraction of what's being produced,we only see about 30% of the real power generated by our engines the rest is taken up by the exhaust and the water jackets.Anything that keeps the lost heat in the cyl helps.</TD></TR></TABLE>

dont polished chambers aid in fuel separation from the mixture, thus hurting performance?
also dont a polished chambers inhibit the formation of carbon crystals?at first at least?
please correct me if im wrong

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mmuller &raquo;</TD></TR><TR><TD CLASS="quote">dont polished chambers aid in fuel separation from the mixture, thus hurting performance?
also dont a polished chambers inhibit the formation of carbon crystals?at first at least?
please correct me if im wrong</TD></TR></TABLE>
First if the fuel is suspended properly,to begin with,then no it won't hurt performance,and if it isn't the chambers not going to fix it.
Nobody polishs to a mirror finish so carbon will stick to it.
Are you saying that a stock chamber is better,just because of the sandy texture,then a properly reshaped and polished chamber?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Ed’s Racing Heads &raquo;</TD></TR><TR><TD CLASS="quote">
First if the fuel is suspended properly,to begin with,then no it won't hurt performance,and if it isn't the chambers not going to fix it.
Nobody polishs to a mirror finish so carbon will stick to it.
Are you saying that a stock chamber is better,just because of the sandy texture,then a properly reshaped and polished chamber?</TD></TR></TABLE>


what im saying is that if the chamber is mirror polish, then its harder for carbon to stick to it.
hehe im not implying that a stock chamber is better than a worked up one..., im just saying that is better(or at least think) for the chamber to be a little rough instead of mirror polish; for the reasons above.

 

the fuel is already atomized from the rough casting on the intake runners and intake ports on the head. Polishing the CC wouldn't effect the atomization to a notable degree after the initial startup.

Fuel atomization can be improved upon by dimpling the injector slotting on the intake tract.

EDIT- I was incorrect, the reduced detonation is a factor of less casting flaws in the CC, not the finish of the metal. The finish of a piston can aid in reducing detonation (polish, smoothed ETC)

I misspoke.


Modified by notstock93 at 11:54 PM 11/14/2004


Modified by notstock93 at 11:57 PM 11/14/2004

 

huh ??? thats some interesting ****

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mmuller &raquo;</TD></TR><TR><TD CLASS="quote">what im saying is that if the chamber is mirror polish, then its harder for carbon to stick to it.
hehe im not implying that a stock chamber is better than a worked up one..., im just saying that is better(or at least think) for the chamber to be a little rough instead of mirror polish; for the reasons above.</TD></TR></TABLE>

Whoah, I thought carbon buildup would be a bad thing. You are saying it is a desirable thing. What is the benefit it gives you?

-PHiZ

 

Someone will probably say they like the extra compression it gives, like thats a good way to get it. I don't like the way a lot of carbon acts like a glow plug and can cause preignition.

 

good stuff keep it coming.

 

no, it has othing to do with more compression and such.
Base carbon cristals are necessary for a more complete combustion

 

mmuller is correct according to my readings. carbon crystals have been shown to be necessary. flaky carbon is bad, shiny chambers are bad.

larger fuel droplets want to seperate toward the long turn radius while lighter mixture follows the short turn radius. somewhat rougher intake ports aid breakup of the larger droplets making it easier to remain in susupension. homogenous mixture reduces duration required for flame propogation.

as for polish reflecting heat, i think it may be that rougher chamber offers more surface area to absorb heat, so shiny is simply absorbing less, rather than reflecting it so to speak.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mike_belben@yahoo.com &raquo;</TD></TR><TR><TD CLASS="quote">somewhat rougher intake ports aid breakup of the larger droplets making it easier to remain in susupension. homogenous mixture reduces duration required for flame propogation.</TD></TR></TABLE>

Yes yes, but we are talking about the combustion chamber, not the ports. Can someone provide more information on the carbon crystals? I'm curious.

 

the man that i get my advise from claims that is his findings, i have no inclination to doubt him. since you guys do, i will look for a scientific explanation to this phenomenon.

 

so then, polished combustion chambers are bad?

 

it cannot be denied that shiny polished chambers take much longer for carbon to adhere to. to decide if polishing is bad, you must decide whether or not you believe a carbon base layer is beneficial. i personally do, but im still looking for an adequate explanation.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mike_belben@yahoo.com &raquo;</TD></TR><TR><TD CLASS="quote">it cannot be denied that shiny polished chambers take much longer for carbon to adhere to. to decide if polishing is bad, you must decide whether or not you believe a carbon base layer is beneficial. i personally do, but im still looking for an adequate explanation. </TD></TR></TABLE>

could of not sayd i better myself, its all about what theory you believe