T2 MSW Posted February 17, 2011 Share Posted February 17, 2011 but i have a foo foo valve that he doesn't. lmao Quote Link to comment Share on other sites More sharing options...
TLicense Posted February 17, 2011 Share Posted February 17, 2011 Radiation transfer of heat is not really applicable here , it is conduction and convection , heat moves hot to cold and given enough time and conductive materials reaches equilibrium the heat /energy source is the combustion chamber gasses , these being real hot and full of energy and a large mass of them come into contact with the manifold pipe this transfers heat easily as the pipe is metal ,given enough time the pipe reaches the equilibrium with the gas temp , but as the pipe is conductive(metal) it heats easily , the pipe convects heat to the surrounding air , solid to gas heat transfer, the air is not as good a conductor as the metal its rate of heat exchange is far slower - a large mass of air and small mass of hot metal difference in temperatures also affect the rate at which heat is transferred If the outer of the turbo manifold is coated then you reduce the rate at which heat is convected to the surrounding air and the pipe gets hotter , closer to the exhaust gas temp - the manifold gets to cherry red without any coating under high loads trying reverse this by using the hot pipe to heat the exhaust gas - the mass of exhaust gas is still quite large and it has some temperature already even at lower power and load (less differential) and the mass of the pipe is not that large ,also a short pipe (not like an exhaust for example) and heating a less conductive medium this affects the time required to transfer heat from metal pipe back to ex gas - any gain from exterior coating would only be the rise in pipe temp versus uncoated and how much would this be ? interior coating of the pipe reduces the rate of heat from ex gas to the conductive pipe putting a barrier to the highly conductive metal -less heat transfer to the pipe must mean more heat remains in the gas stream , the pipe temp would be reduced relative to uncoated . if then it is further externally coated then even less convected heat to the surrounding air must result We need a vote -lol internal , external or both or neither That doesn't really explain why having, what is effectively a thermal barrier on the outside of the pipe, rather than the inside will have a signifcantly lesser effect on the temperature of the exhaust gas. The difference in putting the coating on the inside, rather than the outside is that some of the exhaust energy is lost in heating, and holding at temperature the exhaust pipe. As you say, the pipe itself will heat up pretty quickly, so the only energy loss is from maintaining the pipework at the temperature. (It will be trying to lose its energy by convection and conduction). By coating the pipework you're reducing the rate at which heat can be lost by conduction to the air. If the only thing that the pipe can conduct heat to has a very low rate of thermal conductivity, then the heat is retained within the pipework. It can't just make the jump between the pipe and the air, there is a thermal barrier there. So to re-iterate, the only difference between coating the inner and the outer is the energy loss in heating the pipe in the first place. Quote Link to comment Share on other sites More sharing options...
Nic Posted February 17, 2011 Share Posted February 17, 2011 Would the coating have any effect on the life of a welded tubular manifold, would it be more/less prone to cracking? Quote Link to comment Share on other sites More sharing options...
jagman Posted February 17, 2011 Share Posted February 17, 2011 (edited) That doesn't really explain why having, what is effectively a thermal barrier on the outside of the pipe, rather than the inside will have a signifcantly lesser effect on the temperature of the exhaust gas. The difference in putting the coating on the inside, rather than the outside is that some of the exhaust energy is lost in heating, and holding at temperature the exhaust pipe. As you say, the pipe itself will heat up pretty quickly, so the only energy loss is from maintaining the pipework at the temperature. (It will be trying to lose its energy by convection and conduction). By coating the pipework you're reducing the rate at which heat can be lost by conduction to the air. If the only thing that the pipe can conduct heat to has a very low rate of thermal conductivity, then the heat is retained within the pipework. It can't just make the jump between the pipe and the air, there is a thermal barrier there. So to re-iterate, the only difference between coating the inner and the outer is the energy loss in heating the pipe in the first place. Take the senario into perfects ; the ceramic thermal insulator is perfect -total heat absorbtion is zero ,not one molecule is vibrated , it is a perfect barrier thermally , the hot gas in the pipe cannot exchage any heat, you can grab the manifold with your hand = all heat is kept in the ex gas coating again is perfect but on the outside of the pipe now = again you can hold the pipe with your hand But the pipe being conductive metal you have heated it to cherry red hot under the coating , to heat the manifold metal took energy ,vibrating the metals molecules where did this energy come from = the ex gas enough energy to heat metal to red hot temp ,thats lots!! coating the inner reduces losses to metal ,coating the outer reduces the losses to air from the metal - how much depends on the efficiency of the coating its K value whatever the coating would probably be better than metal as metal is one of the best heat conductors you can get The manifold is bolted to both head and turbo so also conducts heat to and from these too Of course anything that raises the temp of the pipe will be more crack prone an exhaust pipe is a different scenario as you have a much longer pipe and more heat is lost along its path so the air within gets cooler and denser but its still about conserving the heat rather than adding to it by higher pipe temp The cool down relative times coated uncoated needs more thought as it could be that the heat is transfered to the turbo/head rather than air Edited February 17, 2011 by jagman spelling -doh (see edit history) Quote Link to comment Share on other sites More sharing options...
TLicense Posted February 17, 2011 Share Posted February 17, 2011 Take the senario into perfects ; the ceramic thermal insulator is perfect -total heat absorbtion is zero ,not one molecule is vibrated , it is a perfect barrier thermally , the hot gas in the pipe cannot exchage any heat, you can grab the manifold with your hand = all heat is kept in the ex gas coating again is perfect but on the outside of the pipe now = again you can hold the pipe with your hand But the pipe being conductive metal you have heated it to cherry red hot under the coating , to heat the manifold metal took energy ,vibrating the metals molecules where did this energy come from = the ex gas enough energy to heat metal to red hot temp ,thats lots!! coating the inner reduces losses to metal ,coating the outer reduces the losses to air from the metal - how much depends on the efficiency of the coating its K value whatever the coating would probably be better than metal as metal is one of the best heat conductors you can get The manifold is bolted to both head and turbo so also conducts heat to and from these too Of course anything that raises the temp of the pipe will be more crack prone an exhaust pipe is a different scenario as you have a much longer pipe and more heat is lost along its path so the air within gets cooler and denser but its still about conserving the heat rather than adding to it by higher pipe temp The cool down relative times coated uncoated needs more thought as it could be that the heat is transfered to the turbo/head rather than air So you're agreeing with me. The point is, anything that holds heat within the exhaust as a system, will go towards keeping the exhaust gas velocity high. Higher exhaust gas velocity = better turbo performance. I'm not saying that coating the inside of the pipe is worse than coating the outside, what I'm disputing is that only coating the inside will improve turbo performance. Quote Link to comment Share on other sites More sharing options...
Ryan.G Posted February 17, 2011 Share Posted February 17, 2011 Only thing i would worry about with the internal coating at camcoat is when the ceremic coating comes away which it will if it can only withstand 1000c then its going to go straight through a turbo spinning at a serious rpm. Quote Link to comment Share on other sites More sharing options...
Josh Posted February 17, 2011 Share Posted February 17, 2011 Only thing i would worry about with the internal coating at camcoat is when the ceremic coating comes away which it will if it can only withstand 1000c then its going to go straight through a turbo spinning at a serious rpm. The guy touched on this before saying it would turn to dust as soon as it hit the blades. Surely anything going through the turbo would be bad.. Quote Link to comment Share on other sites More sharing options...
jagman Posted February 17, 2011 Share Posted February 17, 2011 I prefer to look at it in terms of volume or specific volume ,related to pressure and temp rather than velocity , look at the problem in thermodynamic terms rather than usual airflow terms in automotive -heat loss to the manifold is to be minimised = internal coatings As an example; in jet engines the combustion chamber is ceramic coated in something called codep, this protects the chamber from melting and cracks , they also use cooling holes which have cooling air around 700 degrees passed in them , yep the cooling air is 700 degrees!! the coating is on the inside not the outside , they also want to preserve the heat as its promptly fed into the turbine to create the kinetic energy and save fuel with the highest possible temp in the turbine . the codep does come off and passes through the turbine without damage ,but leaves the chamber open to failure due heat -you really dont want that -lol Quote Link to comment Share on other sites More sharing options...
dude Posted February 17, 2011 Share Posted February 17, 2011 Only thing i would worry about with the internal coating at camcoat is when the ceremic coating comes away which it will if it can only withstand 1000c then its going to go straight through a turbo spinning at a serious rpm. Hello members -I am Peter Carter of Camcoat. I hope I am not breaking any forum rules but I would like to add some technical information regarding our coatings to this thread. Camcoating is the application of chemical polymer coatings which, when cured at temperatures up to 400 degrees C, change properties to provide thermal insulation, corrosion resistance and pleasing finishes. Because they are liquid chemicals we can coat exhaust manifolds and pipes internally as well as externally. The internal hard, smooth, insulating finish keeps more heat in the exhaust gas which adds to the energy available at the turbocharger turbine wheel. The combination of internal and external coatings provides the reduction in under bonnet temperature which means cooler air into the engine. Quote Link to comment Share on other sites More sharing options...
Wez Posted February 17, 2011 Share Posted February 17, 2011 For those wishing to run antilag and launch control I wouldn't bother with the internal coating. Quote Link to comment Share on other sites More sharing options...
dude Posted February 17, 2011 Share Posted February 17, 2011 For those wishing to run antilag and launch control I wouldn't bother with the internal coating. Why dude Quote Link to comment Share on other sites More sharing options...
Wez Posted February 17, 2011 Share Posted February 17, 2011 Why dude Both push up the exhaust temps as you are creating combustion in the exhaust manifold. Quote Link to comment Share on other sites More sharing options...
dude Posted February 17, 2011 Share Posted February 17, 2011 Both push up the exhaust temps as you are creating combustion in the exhaust manifold. I would say the exhaust tem is FAR greater doing a long pull in 6th gear, the launch will be on for maybe 3 secs and the anti lag is between shifts if thats longer than a fraction of a sec you shouldnt be driving a car !!!!! Ive watched under bonnet when people are setting anti lag up and not seen the exhaust cherry up at all. I would imagine the Le Mans cars camcoat coatings are used on will all run anti lag. Quote Link to comment Share on other sites More sharing options...
Wez Posted February 17, 2011 Share Posted February 17, 2011 I would say the exhaust tem is FAR greater doing a long pull in 6th gear, the launch will be on for maybe 3 secs and the anti lag is between shifts if thats longer than a fraction of a sec you shouldnt be driving a car !!!!! Ive watched under bonnet when people are setting anti lag up and not seen the exhaust cherry up at all. I would imagine the Le Mans cars camcoat coatings are used on will all run anti lag. Can you ask camcoat if they recommend using the internal coating with AntiLag and Launch Control? Quote Link to comment Share on other sites More sharing options...
jagman Posted February 17, 2011 Share Posted February 17, 2011 Not trying to be a smart arse here , but its a thermodynamic reaction in turbines and most people think in the wrong way as its easy to visualise fast moving air spinning a windmill and not realise its a thermal thing at play in the turbine On another note coating the turbo turbine housing and or blankets ,will help with heat reduction around the area , BUT the important thing turbo wise is the temp at the turbine inlet- not the casing -holding heat in the casing with coatings and blankets could be worse performance wise for the turbo you alter the clearance between turbine and case and who knows the longevity implications ,holding heat in the turbo - it uses heat and not made to hold heat -- not one test have I ever seen on a proper calibration rig for turbos with/without blankets, blade creep,cyclic stress etc may look crap ,all rusty compared with the shiny clean coated or covered turbos but .... Quote Link to comment Share on other sites More sharing options...
dude Posted February 17, 2011 Share Posted February 17, 2011 Can you ask camcoat if they recommend using the internal coating with AntiLag and Launch Control? For you anything !!!!!!! Quote Link to comment Share on other sites More sharing options...
dude Posted February 17, 2011 Share Posted February 17, 2011 They have not had any problems and agree the ex temps will be lower than a flat out pull down say the Mulsanne straight, the coating will not get 'blown' off. My header will be off at some time so we can always see how that fairs. Quote Link to comment Share on other sites More sharing options...
JamieP Posted February 17, 2011 Author Share Posted February 17, 2011 Wow this has turned into some thread, i cant be arsed to read though it all so whats the outcome? camcoat or zirotec ftw? Quote Link to comment Share on other sites More sharing options...
dude Posted February 17, 2011 Share Posted February 17, 2011 Wow this has turned into some thread, i cant be arsed to read though it all so whats the outcome? camcoat or zirotec ftw? The hot ticket is smooth peanut butter slowly baked on the outside only !!!!!!! I would say reading the thread, camcoat internal and zircotec external and maybe wrap it as well, that way all angles are covered. Quote Link to comment Share on other sites More sharing options...
JamieP Posted February 17, 2011 Author Share Posted February 17, 2011 I would say reading the thread, camcoat internal and zircotec external and maybe wrap it as well, that way all angles are covered. Sounds like its going a bit ott to me, Internal coating is not happening on mine, i hear what he says about turning to dust if that is the case but i dont even like the idea of that, id worry about it killing my turbo no matter what they say. I was not to bothered about leaving mine un coated and with no heat wrap in the first place, zirotec ceramic coating just on the outside will do me, i went with the performance black, manifold/screamers/downpipe, looking forward to getting the bits back so Lee can crack on with getting it back together, will stick some pictures up of the heat coating when i get it back. Quote Link to comment Share on other sites More sharing options...
JamieP Posted February 17, 2011 Author Share Posted February 17, 2011 Email i got back from Zirotec, i sent them a link to this thread:) Hi Jamie Thanks for your e-mail and the link to the Supra forum thread………was it you that had a conversation with Peter Whyman this afternoon? I have read through the thread you gave us and it’s great to see the ongoing debate on exhaust coatings……… Have you had chance to read through our Frequent Questions (see http://www.zircotec.com/page/frequent_questions/5) since these answer many of the questions raised on the forum. You might also take a look at http://www.zircotec.com/page/comparing-zircotecs-ceramic-coating-with-ceramic-paint-products/127 and the comparison made with paint products. The performance of Zircotec’s coatings have been independently verified by MIRA and the results are published on our website (see http://www.zircotec.com/page/independent-testing-of-zircotecs-performance-white-coating/90). I understand that Peter explained to you that Zircotec’s ceramic coating is a near pure solid ceramic material that is melted within our process at ~10,000oC (18,000oF) and directly hot sprayed at twice the speed of sound onto the surface to be coated. When this molten ceramic hits the cold component surface it immediately solidifies and "welds" itself in place, producing a very firmly attached ceramic coating that can be made quite thick (we coat to 0.3mm thick). This is typically 10 times thicker than a paint product. See our video of the coating being applied (http://www.youtube.com/user/Zircotec?gl=GB#p/u/2/MDazh7f1Q_o). We are so confident over the quality of our performance coatings that we offer a 3yr guarantee even when we have coated a used exhaust. Zircotec is widely recognised within motorsport supplying all levels including more than 80% of the F1 grid. We supply coatings to many of the supercar manufacturers and are used as a standard feature on their production cars. Many car companies won’t let us use their name, though we are allowed to name just a few, i.e. we are on all of the current Lamborghini’s (and have been supplying Lamborghini cars for more than 4 years now); we are on all of the Koenigsegg cars; we supply Jaguar, Ariel Atom, Caparo and many others. Zircotec’s Performance Range coatings are generally more costly than Camcoat; whilst our Primary Range coatings are often comparable with Camcoat on price. We do of course offer a very different product to that offered by Camcoat. Feel free to use this material on the Supra forum if you feel it would help your members. Regards Terry Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted February 17, 2011 Share Posted February 17, 2011 (edited) How does Hammerite compare, can you ask them? Edited February 17, 2011 by Chris Wilson Smiley added in case anyone thinks I am actually being serious (see edit history) Quote Link to comment Share on other sites More sharing options...
JamieP Posted February 17, 2011 Author Share Posted February 17, 2011 How does Hammerite compare, can you ask them? Thought you would know better as this is in tech, i never asked them to compare anything. Quote Link to comment Share on other sites More sharing options...
jevansio Posted February 17, 2011 Share Posted February 17, 2011 Am I getting the wrong end of the stick when I think that from that report there are zero bhp gains to be had, and that "The performance of Zircotec’s coatings" relates purely to how well it protects things around the manifold? Quote Link to comment Share on other sites More sharing options...
jagman Posted February 17, 2011 Share Posted February 17, 2011 reading the mira report , outer coatings made less than 5 degree shift in gas temp (the accuracy of the temp probes being +- 5 degrees - on a normal exhaust manifold - with 2 thermocouples being suspect and ignored -ie short version, bugger all gain but the convection heat reduction was 30%+ good for your engine bay so where did the heat go ? conducted into the material of the manifold ? not exactly the test the turbo owners would want to see ,a simple measurement of turbine inlet temp is what we would need to know and probably not a great idea to repeat the 5 mins time used at full boost either -lol Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.