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I supported Toymods
Location:
Toodyay, WA
Registered:
July 2002
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: Head Annodising
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Sat, 17 July 2004 02:02
 
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please don't.
aluminium has good heat transfer to gas.
normally aluminium oxidses a little and this prevents further corrosion.
anodising is where you increase the thickness of the oxide layer to increase the surface protection against corrosion..
i am pretty sure that alumina (a ceramic) has a lower thermal conductivity than aluminium.
Cya, Stewart
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I supported Toymods
Location:
Toodyay, WA
Registered:
July 2002
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Re: Head Annodising
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Sat, 17 July 2004 02:09
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Hey Stew,
I'm not so sure that its to protect against only oxidisation.
Why do they annodise heat sinks ?
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Location:
Newcastle NSW
Registered:
June 2002
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Re: Head Annodising
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Sat, 17 July 2004 02:11
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i cant say i know much about the heat transfer properties and all the technical stuff but id say just anodise the outer surfaces of the head. dont stuff around with the innards cos you might have troubles there.
just think that if this were a good idea wouldnt every race motor with an alloy head be anodised? i havent seen any.
just do it for bling factor! 
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: Head Annodising
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Sat, 17 July 2004 02:35
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The thermal conductivity of pure aluminium = 2.165 W cm-1 K-1 at 20C
cast and wrought Al alloys can go down to around 1 W cm-1 K-1
for Alumina .276 W cm-1 K-1
so nearly ten times less transfer of heat through alumina.
aluminium is almost always anodised for corrosion protection and for appearance..
the other thing is, anodising is usually performed kinda like electroplating, ie the object is one electrode, and the solution causes accelerated oxidation of the surface.
it might be difficult to evenly anodise something like a head..
give it go if you want.. it would certainly look inteesting.
the colour from anodising is from dyes that go into the pores in the oxide that form during the anodising process... after dyeing, you chuck it into boiling water and this seals the pores with the dye inside.. or something like that 
i don't think much heat is lost from the surfae of a head anyway, compared to from the water jacket, as heat transfe to a liquid is higher than to a gas, if you finned the head, it might improve the heat transfer properties....
Cya, Stewart
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: Head Annodising
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Sat, 17 July 2004 04:26
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i agree it would look pretty spiffy if you were to get it dyed red or blue 
but if you are after heat loss, then it would be more efficient to get grooves in the outer surface of the head.
the rate limiting step for heat loss will be the surface-air interface. if you increase the surface area... you could get 2-3 times the surface area with the right shape/deep enough grooves... you will increase the rate of heat loss...
would also look interesting... anyone got a CNC machine handy?
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Location:
Sydney
Registered:
May 2002
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Re: Head Annodising
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Sat, 17 July 2004 05:58
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dam you guyz got technical already it a bit late for my "stick your head in a bucket of food colouring" joke now    
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Location:
Brisbane
Registered:
October 2002
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Re: Head Annodising
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Sat, 17 July 2004 07:50
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that'd look mad, and cost a bundle
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Location:
Sydney
Registered:
June 2004
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Re: Head Annodising
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Sat, 17 July 2004 07:54
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oldcorollas what do you do for a living? everytime i read a post of yours you got formulas coming left right and centre...
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Location:
Brisbane
Registered:
May 2002
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Re: Head Annodising
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Sat, 17 July 2004 11:42
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Did you miss oldcorolla's thread when he finished his thesis? The man knows a thing or two about metals!
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I supported Toymods
Location:
Toodyay, WA
Registered:
July 2002
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Re: Head Annodising
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Thu, 22 July 2004 14:01
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sorry, must have missed that one Norbie...
hmm, i thinks i'll talk to a place that does annodising and see how much this will hurt financially....
Stew, Do you have any idea how much the surface area is increased by annosiding ? if it is over 4x then its going to work better....
Cam
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Location:
tallahassee FL usOFa
Registered:
May 2002
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Re: Head Annodising
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Thu, 22 July 2004 19:50
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so you basically want to anodize for heat transfer - so that means in the water jacket only and masking off everything else that is a machined surface, like ALL the threads, cam journals & follower bores, etc.
i wouldn't use heat sinks as an example of anodizing, as most are done for corrosion resistance & eye candy for squirrels.
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: Head Annodising
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Fri, 23 July 2004 02:06
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anodising will notincrease the surface area
anodising increases the thickness of the naturally occurring aluminium oxide layer, to provide superior corrosion resistance and the colour is done for appearance only.
| allencr wrote on Fri, 23 July 2004 05:50 |
eye candy for squirrels.
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currently i'm looking at jet turbine blade coatings.
Cya, Stewart
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I supported Toymods
Location:
melbourne
Registered:
June 2002
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Re: Head Annodising
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Fri, 23 July 2004 02:15
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i can't be the first one to point this out, but if anodizing the head increases the thermal conductivity, why would you do it? people ceramic coat combustion chambers to REDUCE heat transfer dont they?
what you are getting at with the heat sinks is partially true, but think of it like this,
anodizing increases the surface area, which increases the emissivity (radiation heat transfer)
BUT it also reduces the thermal conductivity, so more of less of the heat is getting radiated, if you get my meaning.
excuse me if i missed the point, i skimmed most of this post.
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I supported Toymods
Location:
Toodyay, WA
Registered:
July 2002
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Re: Head Annodising
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Sat, 24 July 2004 12:25
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I think you summed it up pretty well...
but i get where your going, i think...
less heat transfer per area, but more area.
but not enough to make up the difference ??
but also on the point of minimizing heat transfer. like HPC coatings, maybe it's be a great idea on inlet manifolds and plenums and combustions chambers ??
ohh, and it'd look good...
Cam
i guess the other thing is i could do it and just see what happens, it's only going to happen to a crappy old ford head...
i'll get a few stickers and bling it up and it'll do easy 10's
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Location:
Adelaide
Registered:
July 2002
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Re: Head Annodising
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Sat, 24 July 2004 13:04
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lol one guy saying it will increase surface area one guy saying it wont
i'd like to know HOW it can increase surface area. ok for example take a cube, its surface area is lets say 2m^3. now anodise it. how has the surface area increased??
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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I supported Toymods
Location:
Toodyay, WA
Registered:
July 2002
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Re: Head Annodising
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Mon, 26 July 2004 10:53
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To increase surface area is rather easy.
Imagine that the surface was affected so that there were millions of tiny imprefections, lumps humps bumps and holes...
bingo, more surface area.
also you could mash your cube.
spread it out as far as possible, if it was 1 micro thick imagine how much area it would cover !
going to have a look at your link now Stew !
cam
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I supported Toymods
Location:
Toodyay, WA
Registered:
July 2002
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Re: Head Annodising
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Mon, 26 July 2004 11:16
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Hey Stew,
I've just read your links, it sounds good, but i was planning on having the head done professionally as its a pretty big thing !
but i appear to be correct...
From the site :
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The anodised layer is very much like honeycomb or a bunch of drinking straws standing on their ends, it has a cellular like formation. These cells or pores are what enables the aluminium to be dyed, it is where the dye goes when the aluminium is submerged in a dye bath. After dying, the oxide layer is sealed (by steaming), in effect plugging or closing off the pores and sealing the dye in.
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If the item is not dyed or sealed the surface area will increase due to the pores !
But i'm still yet to find more info on the thermal side of cast vs. anodised ally... (even tho i'm really after info about anodised cast ally, which might not even anodise !  )
Cam
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