Ryan.G Posted March 1, 2009 Share Posted March 1, 2009 Thought i would start a new thread with the below info as think its quite a rare picture Quoted for my Track car thread: As Ryan is getting his cylinder head built by a local company, they were asking about how much clearance there was from the valve ports to the water jackets etc. As it happens, I've got an old scrap cylinder head kicking about, so offered to stick it through the band saw at work to find out exactly how much material it was possible to remove. Turns out it's quite a lot! The thinnest section I could measure was 4.8mm thick, so I would say that you could potentially remove up to 3.5mm without any problems. This is a cut through the forward most valve centres of the no.6 cylinder, note the steel valve guides. (The ally band saw didn't like them! Or the steel valve seats ) Quote Link to comment Share on other sites More sharing options...
Ryan.G Posted March 1, 2009 Author Share Posted March 1, 2009 Mr Wilson has also kindly compared the head to an RB26 http://www.mkivsupra.net/vbb/attachment.php?attachmentid=88712&d=1235860113 Quote Link to comment Share on other sites More sharing options...
Wez Posted March 1, 2009 Share Posted March 1, 2009 Quote Link to comment Share on other sites More sharing options...
dani_r Posted March 1, 2009 Share Posted March 1, 2009 Cool! It's always smart to see inside things like this, it gives you a real feel for how these work, especially for someone like me who has virtually no experience with this kinda stuff! Quote Link to comment Share on other sites More sharing options...
Scooter Posted March 1, 2009 Share Posted March 1, 2009 As it happens, I've got an old scrap cylinder head kicking about, so offered to stick it through the band saw at work to find out exactly how much material it was possible to remove. Turns out it's quite a lot! The thinnest section I could measure was 4.8mm thick, so I would say that you could potentially remove up to 3.5mm without any problems. maybe........what impresses me is how the effective the ali/water heat transfer must be.........say in a 'single' you have a glowing red steel manifold egt's of maybe 900 degrees celcius and yet the flow of water allows the aluminium to remain stable when its melting point is approx 600 degree celcius! Not sure how crucial the volume of Alloy is to act as a heat sink before the water transfers the heat away............there are probably some very complicated thermodynamic equations involved, but i'd expect the volume/thickness general dimensions of the object (the heads internal walls) the heat is moving through plays a part............ Quote Link to comment Share on other sites More sharing options...
AlanM Posted March 1, 2009 Share Posted March 1, 2009 It is aluminium alloy, not pure aluminium, the melting point, or any of the temperatures where stability is threatened will be vastly different to the pure metal Quote Link to comment Share on other sites More sharing options...
Scooter Posted March 2, 2009 Share Posted March 2, 2009 so what Aluminium alloy has a higher melting point than pure Aluminium? Quote Link to comment Share on other sites More sharing options...
AlanM Posted March 2, 2009 Share Posted March 2, 2009 Depends on the alloy composition but generally yes. all the characteristics are different, thermal expansion, ductility, tensile strength .............................. Quote Link to comment Share on other sites More sharing options...
Scooter Posted March 2, 2009 Share Posted March 2, 2009 I agree that the alloys composition effects the things you mention and by adding small quantities of copper magnesium silicon etc to pure Aluminium you can tailor the end materials properties to suit your application but it will have a lower melting point...........is my point. Quote Link to comment Share on other sites More sharing options...
Scott Posted March 2, 2009 Share Posted March 2, 2009 I agree that the alloys composition effects the things you mention and by adding small quantities of copper magnesium silicon etc to pure Aluminium you can tailor the end materials properties to suit your application but it will have a lower melting point...........is my point. Nah it can be higher depending on the alloy made. Take a titanium alloy, its melting point is MUCH higher than pure aluminium. Quote Link to comment Share on other sites More sharing options...
Alex Posted March 2, 2009 Share Posted March 2, 2009 Great shots - Do you have some hi res images you can zip up or post somewhere? Quote Link to comment Share on other sites More sharing options...
Scooter Posted March 2, 2009 Share Posted March 2, 2009 Nah it can be higher depending on the alloy made. Take a titanium alloy, its melting point is MUCH higher than pure aluminium. err yes, but i was talking about alloys of aluminium!!?? Steel is a an Iron alloy and i know that has a higher melting point than any aluminium alloy.....but thats not the point.......the point is that Iron displays similar characteristics in that it has a higher melting point when pure than when its steel (Iron + carbon). As an example for Aluminium, if you combine it (660 celcius melting point) with say Copper (1080 celcius melting point ) at a certain ratio you can get an alloy with a melting point as low as 550 celcius. It can all get a bit complicated and not all combinations of elements or compunds are like these but "Eutectic" ones are if you are interested........its the same sort of thing that means our coolant ie ethylene glycol (when pure melting/freezing point -13 celcius) and water mix stays liquid well into -30 celcius. Quote Link to comment Share on other sites More sharing options...
TLicense Posted March 2, 2009 Share Posted March 2, 2009 Great shots - Do you have some hi res images you can zip up or post somewhere? Yes I've got a high res image I'll post up if I get home at anything like a sensible hour tomorrow evening. Quote Link to comment Share on other sites More sharing options...
Scott Posted March 3, 2009 Share Posted March 3, 2009 err yes, but i was talking about alloys of aluminium!!?? Steel is a an Iron alloy and i know that has a higher melting point than any aluminium alloy.....but thats not the point.......the point is that Iron displays similar characteristics in that it has a higher melting point when pure than when its steel (Iron + carbon). As an example for Aluminium, if you combine it (660 celcius melting point) with say Copper (1080 celcius melting point ) at a certain ratio you can get an alloy with a melting point as low as 550 celcius. It can all get a bit complicated and not all combinations of elements or compunds are like these but "Eutectic" ones are if you are interested........its the same sort of thing that means our coolant ie ethylene glycol (when pure melting/freezing point -13 celcius) and water mix stays liquid well into -30 celcius. Ahhh i'm with you now. I'm not sure about the aluminium alloys, i can find out if you like though? Quote Link to comment Share on other sites More sharing options...
paul mac Posted March 3, 2009 Share Posted March 3, 2009 Yes I've got a high res image I'll post up if I get home at anything like a sensible hour tomorrow evening. might it be worth uploading the images to the site, i can imagine people using these pics as reference for years to come and unfortunately with it being photobucket the pic will probably be gone in 6 months Quote Link to comment Share on other sites More sharing options...
AlanM Posted March 3, 2009 Share Posted March 3, 2009 Scooter, tak ea look at the equilibrium diagram. Still depends on the alloying elements though http://www.calphad.com/graphs/Ti-Al%20Phase%20Diagram%20Mass%20Pct.gif Sorry Ryan, not meaning to hijack, will butt out now Quote Link to comment Share on other sites More sharing options...
MarkR Posted March 3, 2009 Share Posted March 3, 2009 Some interesting reading here on the MKIV head: http://www.t04r.com/techarticle.php?id=5 Quote Link to comment Share on other sites More sharing options...
Scooter Posted March 3, 2009 Share Posted March 3, 2009 Scooter, tak ea look at the equilibrium diagram. Still depends on the alloying elements though http://www.calphad.com/graphs/Ti-Al%20Phase%20Diagram%20Mass%20Pct.gif Sorry Ryan, not meaning to hijack, will butt out now I acknowledged that though here..... It can all get a bit complicated and not all combinations of elements or compounds are like these but "Eutectic" ones are . You implied that the aluminium alloy in the supra's head could be made to have a higher melting point than pure aluminiums of 660 degrees celcius...............and have posted a diagram of a Titanium alloy to 'prove' it? I'm not getting the hump i'm just saying that the supra head will not have a melting point higher than 660 degrees celcius............and now i too will butt out. Quote Link to comment Share on other sites More sharing options...
edge Posted March 3, 2009 Share Posted March 3, 2009 If you make anymore slices can i buy one? Would love to make a little ornament out of it. Im after a piston aswel to make an ashtray. Quote Link to comment Share on other sites More sharing options...
Ryan.G Posted March 4, 2009 Author Share Posted March 4, 2009 If you make anymore slices can i buy one? Would love to make a little ornament out of it. Im after a piston aswel to make an ashtray. Let us see how much head we have left as i think a few others want a piece also Quote Link to comment Share on other sites More sharing options...
Digsy Posted March 4, 2009 Share Posted March 4, 2009 Good thread! If there are any more slices in the offing, one through the head bolt towers and one through the spark plug centreline would interest me. As for wall thickness, 4.5mm does seem a bit excessive if that is truly the thinnest part. I'd expect 4mm to be more the norm. 3.5mm is achievable with fettling but getting pretty trick for mass production. I'd suggest not going below that. Regarding heat transfer, the idea is to get the walls as thin as possible without compomising their structural integrity and while still making sure they are adequately cooled. The trickiest place is around the spark plug, where the spark plug boss and back up material for the valve seat inserts all tends to blend toegther, creating a thick section right where you want to keep things cool. Melting points aside, realistic temperature limit for Al is about 250degC. Beyond that it starts to get too weak to be of much use. Quote Link to comment Share on other sites More sharing options...
JustGav Posted March 4, 2009 Share Posted March 4, 2009 Slice it into .5 inch thick pieces, put it in a frame, give each a number and sell them as RyanG Art Quote Link to comment Share on other sites More sharing options...
jevansio Posted March 4, 2009 Share Posted March 4, 2009 Being a complete newb at this could someone illustrate what material is meant when you are describing "valve ports to the water jackets"? Quote Link to comment Share on other sites More sharing options...
TLicense Posted March 4, 2009 Share Posted March 4, 2009 Slice it into .5 inch thick pieces, put it in a frame, give each a number and sell them as RyanG Art *ahem* Quote Link to comment Share on other sites More sharing options...
TLicense Posted March 4, 2009 Share Posted March 4, 2009 Good thread! If there are any more slices in the offing, one through the head bolt towers and one through the spark plug centreline would interest me. As for wall thickness, 4.5mm does seem a bit excessive if that is truly the thinnest part. I'd expect 4mm to be more the norm. 3.5mm is achievable with fettling but getting pretty trick for mass production. I'd suggest not going below that. I'm letting Ryan have the head in return for some bits and bobs he's sorted for me, but I'm cutting it up into slices for him. I would cut it up into all the bits everyone has asked for if Ryan was happy to do that, but by god cutting it up is a right pain in the arus, so I'm keen not to go overboard with it. I've only done the 1 cut, but the thinnest I could measure was something like 4.7mm, so quite thick! Most of it was closer to 6mm IIRC. Quote Link to comment Share on other sites More sharing options...
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