Dare Posted November 17, 2004 Author Report Share Posted November 17, 2004 Answer is it wouldnt, it obviuosly would have to be where he put the air intake. Quote Link to comment Share on other sites More sharing options...
tdwindustries Posted November 17, 2004 Report Share Posted November 17, 2004 yes - thats what i was getting at. so it wouldnt matter if he had a BMC, a Pipercross or a small bean car stuffed with hay. Quote Link to comment Share on other sites More sharing options...
DanGTI Posted November 17, 2004 Report Share Posted November 17, 2004 surely the air intake should point down (so any water that might get in will run straight out)? Quote Link to comment Share on other sites More sharing options...
Jabo Posted November 18, 2004 Report Share Posted November 18, 2004 Right, let’s get back to some physics here. I’ll start from explaining myself a bit here.This stuff is my hobby, I am not a professional physicist or mechanical engineer. I do engineering in a different field.I do not have any ego problems and don’t find it difficult to admit I was wrong or partially right since it only makes me learn new things and gets rid of misconceptions I believed in as true.I designed and built liquid cooling systems where compressibility was not an issue.The main mistake I was making was confusing pressure as such and action of compressing a gas.Also, there is a fundamental difference in fluid behaviour in sealed system and open one (internal combustion engine). I was right in saying that pressure and temp have nothing to do with each other since any dynamic system will level energy to the lowest possible value. It basically means that in case of a hermetic cylinder with gas inside and moving piston inside, when piston is moved and gas compressed the temp will raise instantly only to come down and equal ambient in time dependant on cylinders heat dissipation characteristics (that’s the working principle of Diesel engine style="vertical-align:middle" emoid=":D" border="0" alt="biggrin.gif" />)=> so after a while we have highly pressurised system at ambient temp what I understood as pressure and temp being independent – or to put it otherwise I was talking out of my ass from a certain point of view Why I took my view on the problem? The system we were talking about is open and the laws of fluid mechanics apply there.I must admit that liquid mechanics are simpler than gases since in almost all cases liquids are treated as incompressible medium…Normally, in an induction kit assy. with changing geometry, mass preservation law as applied to liquids would make the whole thing quite easy to calculate.It is slightly more complicated with gases though since density varies depending on flow path geometry, temperature and pressure….Now I am trying to get through Eulers equations…. Pretty hairy stuff.To summarize:- I eat my hat and admit that when given gas molar amount is compressed in certain conditions systems temp will raise to comply with energy conservation law and conversely when a compressed gas in closed system and at ambient temp is decompressed it’s temp will get lower to obey Newtonian physics- Induction kit case => I am not sure for now since it is much more complicated than I thought referencing my experiences from liquid systems but in any case mass and energy preservation laws will have to obeyed which means that all these parameters are fluctuating and are cross dependant (gas density, pressure, temperature, velocity). From practical point of view… I simply do not know since I am not a Mech Eng., maybe TDi Si would be able to help here since he’s got his degree in the subject?Bossjohn=> my cubes tried to illustrate thermal inertia or thermal capacity of a system. Take two the same size and `make-up` cylinders (same therma properties) containing the different molar amount of gas. C1 is compressed and C2 is not. Both are at ambient temp. If you wanted to heat up both to the same temp the compressed one would require more energy to reach the same temp = it feels colder to touch.For my purposes I’ll need a boost pressure gauge and a temp sensor and pumping power of Garrett VNT15 turbine which would give me total kinetic energy of the charge to cool (2nd stage intercooler)TDi Si => Doeas Reynolds Number apply to gasses in the same way as it does to liquids? Where does the pressure come in? Quote Link to comment Share on other sites More sharing options...
bossjohnc Posted November 18, 2004 Report Share Posted November 18, 2004 :shock: :? style="vertical-align:middle" emoid=":lol:" border="0" alt="laugh.gif" /> style="vertical-align:middle" emoid=":D" border="0" alt="biggrin.gif" /> It really doesn't matter that much - the fact that the air might decompress slightly when it gets sucked in is probably completely irrelevant in the big scheme of things...Interesting read anyway - explains more about your cubes on the table and I can see where compression/density (rather than pressure) came in to it. Quote Link to comment Share on other sites More sharing options...
Jabo Posted November 18, 2004 Report Share Posted November 18, 2004 Hi hi hi, it's just me then, I always have to get to bottom of things.I remember once I went as far as to look up quantum mechanics to understand electron tunneling effect in some development cooling device researched by some former russian lab in Ukraine or was it Georgia ? style="vertical-align:middle" emoid=":P" border="0" alt="tongue.gif" /> Quote Link to comment Share on other sites More sharing options...
Dare Posted November 18, 2004 Author Report Share Posted November 18, 2004 All i read was Blah Blah Blah Blah. Only kiddin bud, you seem to know your crap! Quote Link to comment Share on other sites More sharing options...
Crusoe Posted November 18, 2004 Report Share Posted November 18, 2004 i did a degree in that stuff but still don;t know what he was trying to say lol, what was the question adn i'll give you a straight answer. Quote Link to comment Share on other sites More sharing options...
johnyardley Posted November 18, 2004 Report Share Posted November 18, 2004 Hi, Does anyone know if bmc make a kit for a 1.4 tdi pd?CheersJohn Quote Link to comment Share on other sites More sharing options...
Jabo Posted November 18, 2004 Report Share Posted November 18, 2004 QUOTE(Crusoe)i did a degree in that stuff but still don;t know what he was trying to say lol, what was the question adn i'll give you a straight answer.The question is about properties of turbocharged air.What happens with it when it goes through different parts of induction system with different geometries, how's air density changing and where (filtration element section, intercooler, MAF sensor, tubing). If you took a crossection through any chosen part of combustion air delivery system you could describe parameters of air going through this chosen `cross-section` like velocity, density, temperature, pressure.The whole thing started from BMC induction kit thingie and its geometry and what happens with the charge air in there? If pressure fluctuates does it change temperature or is it compensated by incresed velocity to obey fluid mechanics laws? I need to know this stuff since it is essential for fine tuning design of my 2nd stage intercooler (at 20psi gauge pressure temp drop of 20C results in roughly 30% more oxygen in combustion air... - taken from Air Psychrometrics tables).Euler equations describing the whole thing are a tad complicated with its 6 variables (unknowns).... I was just wondering if there's a simplfied, practical way of establishing these variables given some measuarable parameters? Quote Link to comment Share on other sites More sharing options...
Jabo Posted November 18, 2004 Report Share Posted November 18, 2004 QUOTE(johnyardley)Hi, Does anyone know if bmc make a kit for a 1.4 tdi pd?CheersJohnAfter searching through their site didn't find an induction kit but I found the replacement filter element for our cars - btw, this thing is seriously BIG style="vertical-align:middle" emoid=":P" border="0" alt="tongue.gif" /> Quote Link to comment Share on other sites More sharing options...
bossjohnc Posted November 18, 2004 Report Share Posted November 18, 2004 Yeah Crusoe, explain for us, we're listening...*awaits a "straight answer"* Quote Link to comment Share on other sites More sharing options...
GTi Si Posted November 18, 2004 Report Share Posted November 18, 2004 I hated fluid dynamics style="vertical-align:middle" emoid=":(" border="0" alt="sad.gif" />Reynolds number is used in gases as far as I know.Euler, studied it but cannot remember it!I guess an induction kit is better as it has a larger surface area (more air going through it).As to laminar and turblent flow not sure. In theory turbulent air would mix better with the fuel, but it travels slower then laminar..............S Quote Link to comment Share on other sites More sharing options...
Crusoe Posted November 18, 2004 Report Share Posted November 18, 2004 QUOTE(bossjohnc)Yeah Crusoe, explain for us, we're listening...*awaits a "straight answer"*what was the question? style="vertical-align:middle" emoid=":lol:" border="0" alt="laugh.gif" /> Quote Link to comment Share on other sites More sharing options...
Crusoe Posted November 18, 2004 Report Share Posted November 18, 2004 temperature and pressure are mutually exclusive (you can have a diving bell at the bottom of the sea with water at the same temperature as that outside it but the pressure would be very different.) But, in the instance of air the effect of pressurisation moves the molecules together causing them to rub against each other more hence increasing the temperature, gasses by virtue of their lack molecular volume have a more pronounced thermal reaction to pressure though it would have to be assumed that it was under the same external conditions. Quote Link to comment Share on other sites More sharing options...
Jabo Posted November 18, 2004 Report Share Posted November 18, 2004 QUOTE(TDi Si)I hated fluid dynamics style="vertical-align:middle" emoid=":(" border="0" alt="sad.gif" />Reynolds number is used in gases as far as I know.Euler, studied it but cannot remember it!I guess an induction kit is better as it has a larger surface area (more air going through it).As to laminar and turblent flow not sure. In theory turbulent air would mix better with the fuel, but it travels slower then laminar..............SIn 'my book' he bigger the filter element area the lower the velocity of air coming through which in turn reduces frictional forces/air passage resistance (smaller pressure differential).I think it should be laminar all the way throughout delivery system and turbulent in combustion chamber so you get the best of both worlds style="vertical-align:middle" emoid=":)" border="0" alt="smile.gif" /> Quote Link to comment Share on other sites More sharing options...
bossjohnc Posted November 18, 2004 Report Share Posted November 18, 2004 QUOTE(Crusoe)What was the question?QUOTE(Jabo)QUOTE(Crusoe)i did a degree in that stuff but still don;t know what he was trying to say lol, what was the question adn i'll give you a straight answer.The question is about properties of turbocharged air.What happens with it when it goes through different parts of induction system with different geometries, how's air density changing and where (filtration element section, intercooler, MAF sensor, tubing). If you took a crossection through any chosen part of combustion air delivery system you could describe parameters of air going through this chosen `cross-section` like velocity, density, temperature, pressure.The whole thing started from BMC induction kit thingie and its geometry and what happens with the charge air in there? If pressure fluctuates does it change temperature or is it compensated by incresed velocity to obey fluid mechanics laws? I need to know this stuff since it is essential for fine tuning design of my 2nd stage intercooler (at 20psi gauge pressure temp drop of 20C results in roughly 30% more oxygen in combustion air... - taken from Air Psychrometrics tables).Euler equations describing the whole thing are a tad complicated with its 6 variables (unknowns).... I was just wondering if there's a simplfied, practical way of establishing these variables given some measuarable parameters? Quote Link to comment Share on other sites More sharing options...
Crusoe Posted November 18, 2004 Report Share Posted November 18, 2004 internal cylinder gas flow is controlled by the intake valves which are designed to produce a turbulent flow which mixes the fuel better and produces a better burn. On the intake you ideally want a huge in take narrowing through a venturi to a fairly open filter (the sportier filters have a less dense construction) assuming the engine management could compensate for the additional air this would then provide a ram air effect at higher car speeds providing more power. Quote Link to comment Share on other sites More sharing options...
bossjohnc Posted November 18, 2004 Report Share Posted November 18, 2004 What about the variables? Quote Link to comment Share on other sites More sharing options...
DanGTI Posted November 18, 2004 Report Share Posted November 18, 2004 someone just stick a panel filter in go for a drive...take it out and stick the BMC in....go for another drive. whichever feels best wins. simple Quote Link to comment Share on other sites More sharing options...
Crusoe Posted November 18, 2004 Report Share Posted November 18, 2004 The question is about properties of turbocharged air.What happens with it when it goes through different parts of induction system with different geometries' date=' how's air density changing and where (filtration element section, intercooler, MAF sensor, tubing). If you took a crossection through any chosen part of combustion air delivery system you could describe parameters of air going through this chosen `cross-section` like velocity, density, temperature, pressure.The whole thing started from BMC induction kit thingie and its geometry and what happens with the charge air in there? If pressure fluctuates does it change temperature or is it compensated by incresed velocity to obey fluid mechanics laws? I need to know this stuff since it is essential for fine tuning design of my 2nd stage intercooler (at 20psi gauge pressure temp drop of 20C results in roughly 30% more oxygen in combustion air... - taken from Air Psychrometrics tables).Euler equations describing the whole thing are a tad complicated with its 6 variables (unknowns).... I was just wondering if there's a simplfied, practical way of establishing these variables given some measuarable parameters?[/quote']The simple answer is I really don't know if there is a good series of equations to give you the answers you are looking for. If you know the intake temperature pressure and sensity you can work out the changes accross the different components but there are too many variables including the heat from the engine which would vary form the worst situation with lots of heat soak if you were sitting in traffic after a fast drive to a cold winter morning. Variations in the piping, unknown densitys of filter elements and the dynamic compressioin of the turbo would also complicate things furthe. The last car i helped setup we just fitted several oxygen sensors in the intake tract and adjusted the fuel map and boost pressure accordingly. I can tap into sensors in mine using the aircon unit, the intake temperature tends to be around 8 degrees below the ambient at steady state running though it increases to as much as 10 degrees above ambient sat in traffic. After the intercooler it is usually a further `10-12` degrees above the intake temp. Quote Link to comment Share on other sites More sharing options...
bossjohnc Posted November 18, 2004 Report Share Posted November 18, 2004 Ahh right, ok - just wondered. Quote Link to comment Share on other sites More sharing options...
Jabo Posted November 18, 2004 Report Share Posted November 18, 2004 I think tha answers i Crusoe, ya da Man mate ! style="vertical-align:middle" emoid=":)" border="0" alt="smile.gif" /> Thank you Sir! style="vertical-align:middle" emoid=":P" border="0" alt="tongue.gif" /> Quote Link to comment Share on other sites More sharing options...
Jabo Posted November 18, 2004 Report Share Posted November 18, 2004 I can tap into sensors in mine using the aircon unit, the intake temperature tends to be around 8 degrees below the ambient at steady state running though it increases to as much as 10 degrees above ambient sat in traffic. After the intercooler it is usually a further `10-12` degrees below the intake temp.What do you mean by 'tapping into sensors using aircon unit'?8 degrees below ambient intake temp - is it turbocharger intake (post filtration, pre filtration)? or just before valves? If temp is below ambient it surely must have been cooled beforehand somewhere, right?I thought that you get ambient all the way to turbo, then quite a spike due to parasitic heat gains from exhaust gases and friction and then again it goes down after intercooler... ? Quote Link to comment Share on other sites More sharing options...
Crusoe Posted November 18, 2004 Report Share Posted November 18, 2004 http://www.audiworld.com/tech/int6.shtml gives you ambient and front air intake temperature, engine intake after the intercooler of 2 deg C was seen on the cars that were on the rolling road Quote Link to comment Share on other sites More sharing options...
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