I already commented on this on another thread and agree its not possible. Drag racers acheive it by packing their Intercoolers in dry ice before making a run but other than that it should be physically impossible. Can only be duff readings/ calibration issues as stated above.
The wait is over
- Thread starter DivineE
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I already commented on this on another thread and agree its not possible. Drag racers acheive it by packing their Intercoolers in dry ice before making a run but other than that it should be physically impossible. Can only be duff readings/ calibration issues as stated above.
Hi Nick, I have had a lot of technical discussions with Ben to help him in his quest to improve his background engineering and technical knowledge and I admire his boundless enthusiasm which sometimes lets him get a bit carried away without thinking it all through first. Yes well we both knew the figures he stated were impossible but I was trying to be less agressive than usual and prompt an explanation out of Ben - so he would think it through a bit - and work out the physics and science as I know them - for himself and realise why the figures or explanations are just not physically possible. I found this the best way to learn myself (well I usually had to learn this way as so many other people used explanations that didn't work when I tested them and when I found what did work they had no explanation as to why - so I had to work most things out for myself - and I am sure from the background you have had that you understand exactly where I am coming from and why my comment was so laid back!). I guess also - being on holiday when I responded - brought out - that Sangria fuelled attitude - rather than my usual "havn't time to be too considerate" way of firing back at people when they make basic mistakes.
But if I had been here in the UK and at work - I probably would simply have respnded as you have.
Come on Ben - lets see what you make of it and why!
Baz
But if I had been here in the UK and at work - I probably would simply have respnded as you have.
Come on Ben - lets see what you make of it and why!
Baz
DivineE
New member
Now your asking, I don't have enough experience to compare what readings you'd normally expect inside the intake so not sure if my readings are typical of sensors in those locations?
There are three different sensors in the intake system on WUF one on the way from the turbo to the intercooler, one on the exit of the intercooler and one in the intake manifold. The one on the exit of the intercooler feeds a gauge, the one in the intake manifold feeds directly into the ECU. The gauge and the readout on the ECU were agreeing to within 1-2 degrees making a mechanical failure unlikely.
My guess was a wind chill factor from the air rushing into the engine was giving a slightly lower reading but that it was close enough to ambient that the intercooler was doing its job and so the car didn't need anything bigger?
If its not normal to see these kinds of readings i will have to give it more thought as to why I'm getting them?
Note, the temp coming out of the turbo was way higher than ambient. Usually between 60-120 deg, I wasn't suggesting I had a magic turbo that gave compressed air at less than ambient temp!
There are three different sensors in the intake system on WUF one on the way from the turbo to the intercooler, one on the exit of the intercooler and one in the intake manifold. The one on the exit of the intercooler feeds a gauge, the one in the intake manifold feeds directly into the ECU. The gauge and the readout on the ECU were agreeing to within 1-2 degrees making a mechanical failure unlikely.
My guess was a wind chill factor from the air rushing into the engine was giving a slightly lower reading but that it was close enough to ambient that the intercooler was doing its job and so the car didn't need anything bigger?
If its not normal to see these kinds of readings i will have to give it more thought as to why I'm getting them?
Note, the temp coming out of the turbo was way higher than ambient. Usually between 60-120 deg, I wasn't suggesting I had a magic turbo that gave compressed air at less than ambient temp!
I was wondering where the ambient temp is being measured, anywhere on the car is likely to be warmer than incoming air so an 'ambient' temp taken on the car would be hotter than air coming through the front grills and through the ic front to back (as opposed to left to right intake air)
Tony
Tony
I think the important point is Ben that you wrote "that you have learned a lot about the myths of intercooler temperatures" and then went on to reinforce that position by stating that the air came out of the intercooler 5 to 10 degress lower than ambient (even up to 14 degrees lower - 24 compared to 38) etc.
I thought this wrong and possibly misleading to other readers. Heat transfer can only take place when there is a hotter and a lower temperature in contact and the one influences the other.
Boyles law states that pressure * volume = temperature * a constant - in other words they are linked - and if the value of one side of the equation increases then so must the corresponding result on the other side lower.
Whenever there is a material between two temperature sources - the transfer is never able to equal the temperatures both sides (there is always a slight loss) and so it would never be possible to reduce the temperature inside the intercoler as low as the ambient air flowing through it and certainly not make it lower. It is however theoretically possible to alter the temperature once it comes out - if volumes and pressures and the resulting temperatures were messed about with.
However Boyles law (like many others) relies on a fixed cylinder with trapped volume under controlled volume/pressure/temperature changes and not mass flow and this introduces other factors that need considering.
If for example the turbo was so powerful and the combined core area inside the intercooler was so small that the internal pressure of the air passing through the intercooler was raised significantly - its temperature would rise - and if it then reduced the pressure just afterwards at the sensor point - then theoretically it could read a lower than ambient temperature by virtue of the lower pressure effect (rather like a fridge or air conditioning system without the added benefit of condensation).
Similarly as air passes through a venturi it increases in speed but lowers in pressure - so again the temperature at a venturi could be read lower.
However - without trying to do any calculations - with inlet temperatures of around 120 degC and ambient of 38 degC - I think that both potential scenarios are well outside the capability to create the temperatures you have quoted and that it is far more likely that there is some error in the figures you are reading (i.e. is one celcius and one farneheight?). If this is so - then suggesting that all previous examples created a myth that you have exposed - would be the wrong conclusion.
It is interesting from a theoretical point of view and it is not a question of what figures to expect but how your figures can fault the whole basis of thermodynamics for centuries!
I only had occasional access to the Internet while on holiday and didn't manage to read through it all - so was concerned that I had misread something - but now I am back - I am sure that you have something that needs explaining somewhere in those figures and think it is important to try and get to the bottom of it.
With your desire to learn more I thought it would be an ideal issue for you to explore in more depth and await yours (and others) responses with great interest.
Baz
I thought this wrong and possibly misleading to other readers. Heat transfer can only take place when there is a hotter and a lower temperature in contact and the one influences the other.
Boyles law states that pressure * volume = temperature * a constant - in other words they are linked - and if the value of one side of the equation increases then so must the corresponding result on the other side lower.
Whenever there is a material between two temperature sources - the transfer is never able to equal the temperatures both sides (there is always a slight loss) and so it would never be possible to reduce the temperature inside the intercoler as low as the ambient air flowing through it and certainly not make it lower. It is however theoretically possible to alter the temperature once it comes out - if volumes and pressures and the resulting temperatures were messed about with.
However Boyles law (like many others) relies on a fixed cylinder with trapped volume under controlled volume/pressure/temperature changes and not mass flow and this introduces other factors that need considering.
If for example the turbo was so powerful and the combined core area inside the intercooler was so small that the internal pressure of the air passing through the intercooler was raised significantly - its temperature would rise - and if it then reduced the pressure just afterwards at the sensor point - then theoretically it could read a lower than ambient temperature by virtue of the lower pressure effect (rather like a fridge or air conditioning system without the added benefit of condensation).
Similarly as air passes through a venturi it increases in speed but lowers in pressure - so again the temperature at a venturi could be read lower.
However - without trying to do any calculations - with inlet temperatures of around 120 degC and ambient of 38 degC - I think that both potential scenarios are well outside the capability to create the temperatures you have quoted and that it is far more likely that there is some error in the figures you are reading (i.e. is one celcius and one farneheight?). If this is so - then suggesting that all previous examples created a myth that you have exposed - would be the wrong conclusion.
It is interesting from a theoretical point of view and it is not a question of what figures to expect but how your figures can fault the whole basis of thermodynamics for centuries!
I only had occasional access to the Internet while on holiday and didn't manage to read through it all - so was concerned that I had misread something - but now I am back - I am sure that you have something that needs explaining somewhere in those figures and think it is important to try and get to the bottom of it.
With your desire to learn more I thought it would be an ideal issue for you to explore in more depth and await yours (and others) responses with great interest.
Baz
DivineE
New member
Hmmm just re-read my post with those quotes and can see my doubt at the time saying it was close to atmospheric and 'showing' as low as 24 on the motorway when atmospheric was 38, but I obviously didn't give it enough thought. That does sound ridiculous so I've deleted the post until I can get some proper readings to report.
I've got two boost gauges at home so I'll fix them up either side of the intercooler and try to get some readings on pressure drop at the same time. That would be interesting to know, shouldn't be too bad with that thick core and those modified end tanks. I was more concerned that the lindsey unit had gone too far the other way and wouldn't be cooling effectively.
I'm on holiday too at the moment, just playing with my new phone, so will report properly with an update on my return.
I've got two boost gauges at home so I'll fix them up either side of the intercooler and try to get some readings on pressure drop at the same time. That would be interesting to know, shouldn't be too bad with that thick core and those modified end tanks. I was more concerned that the lindsey unit had gone too far the other way and wouldn't be cooling effectively.
I'm on holiday too at the moment, just playing with my new phone, so will report properly with an update on my return.
bertelli_1
New member
Just to add something else regarding wind chill. Imagine you are sitting in your house on a hot day feeling rather, well, hot. So you switch on your fan & it cools you down, hence windchill. But how is it possible as the air being blown over you is the same temperature as the air you've been sitting in all along & now it feels cooler. The reason is due to the air rushing past your skin & drawing out moisture (sweat) which then evaporates (the air draws the heat energy from the moisture). If you then replace your body with a metal item, an intercooler, for example it will not be affected by wind chilll as there is no 'sweat' involved & the surface temperature will remain constant.
sawood12
New member
The point about evaporation is true, however it is also the case that moving air feels cooler than static air because it is - Wind chill can also be measured by a thermometer. Moving air has less pressure than static air (and it is true in the case of a stationary object with air moving around it, like in a wind tunnel, or an object moving through stationary air), therefore it has a cooler temperature. I have no idea if it is possible for the charge air in an IC to be cooled to lower ambient air, I guess it is theoretically possible, but whether or not it is technically possible in all but very very cold ambient air conditions i'm not sure.
DivineE
New member
Last update before the finished pics (hopefully) the car is due back either Friday this week or early next week (I'm away again sat till wed 25th so wont be able t pick it up till the Thursday). For anyone considering going to fibreglass wings, and I imagine there will be a fair few over the next couple of years as all the galvanised parts finally begin to rot seriously, look at the photos on this thread carefully and really think about it. Greg who owns the bodyshop chain who are doing my car has personally been pulling his hair out over this car! It took them 4 days to remove and strip all of the panels and ancillaries on the car, a week to do all the necessary metal work and a couple of days to primer the car to spray. He personally along with two other guys have spent that time again and more cutting, moulding, sanding, grinding and re-cutting the three fibreglass panels to get them to look right. Even with all they have done he says in his opinion its going to crack the primer in the first year as it finishes expanding and settling (because of the thickness differences in the fiberglass) so I'll have to come back and have the wings re-done then once its had 12 months to sort any movement.
My car would have been ready two weeks ago if he had just cut out the rusted area and done it in metal like the rest of the sills. Whilst he was fully aware of the situation from the start I feel rather sorry for them about the trouble the car has caused them and I cannot imagine what I'm paying is now in any way going to cover the actual time they have spent on the car. He is only doing it because he refuses to let any job leave his workshop that he's not proud to put his name to.
I will put up finished pictures as soon as I get the car back but in the meantime if anyone needs work doing in the Northamptonshire area, I cannot recommend these guys enough.
My car would have been ready two weeks ago if he had just cut out the rusted area and done it in metal like the rest of the sills. Whilst he was fully aware of the situation from the start I feel rather sorry for them about the trouble the car has caused them and I cannot imagine what I'm paying is now in any way going to cover the actual time they have spent on the car. He is only doing it because he refuses to let any job leave his workshop that he's not proud to put his name to.
I will put up finished pictures as soon as I get the car back but in the meantime if anyone needs work doing in the Northamptonshire area, I cannot recommend these guys enough.
Hi Ben, just for interest - strange for me to be able to offer something on the subject of composites - but I can.
When I was involved in motor cycle racing we made the first carbon fibre framed racing motorcycle (Armstrong 250 and 350) which went on the win the British Championship for two years. When I wanted to leave Armstrong (nearly 30 years ago now) my contract prevented doing anything similar for 3 years and I joined a development business (that manufactured Carbon Fibre) in charge of "new applications and manufacture). Some years later I ran the Composite division of a subsidiary of Aerospace Engineering plc - making parts for commercial and fighter jets - so My experience is quite wide.
I had owned a Porsche from the age of about 22 (1st a 356C) so was still into them privately (924 turbo and 911 SC at that time) and so was the stress engineer at the 1st composite company who ownerd a 924. While there we manufactured tools to make a set of panels to convert a 924 to look like a 944 and learned all about the problems (still have the photos).
Basically the fit problem is often because the glass fibre is thicker than the steel it is replacing - so when a panel fits on to the original mounting area -the other side (the outside) of the panel is sticking up more and doesn't match the position of its adjacent metal panel.
Similarly when the rear wings were designed the window appature becomes smaller and thicker on which to fit the seals and glass - etc etc. By the same method - door gaps become less etc, etc and you have to stick it on top of the old panel (as the old steel part there is a stressed chassis member).
At the time another Porsche specialist was also making the same panels using the original steel ones as patterns - but by using the outside of the 944 steel panels to make the moulding for the inside of th enew ones and then laying inside that the extra thickness of the glass fibre wings - the inside shape obviously becomes too small to fit the car. To solve this he then hammered the old steel mounting points of the original car chassis until they were smaller (bashing the original steel chassis) to allow for this fit. We did it by making the patterns the right way and adding the right amount of sheet self adhesive pattern makers wax to the new 944 panels and also allowing for a much thinner area at the mounting point etc so our wings fitted straight on to the car - without problems.
Our plan was to upgrade 924's to 944's but my life then took a different direction to run an aerospace company and the patterns were sold to someone from "down South".
They do craze on the surface and shrink and release gasses over time etc - so your fitters/painters are quite right to point out that resprays will probably be required quite often. Also as panels set on the moulds there are stresses created and shrinkeage that can distort the new panel being made and quantities are usually too small to justify several different attempts to correct this.
Don't think I am not a fan - I am - but just confirming there are a lot of potential problems to overcome to make it as good as steel.
Of course steel replacement panels are not galvanised (since it is impossible to reproduce the sequence and conditions of new manufacture) so their life expectancy is reduced - hence often better to cut and fit a small panel from a crashed car (that was galvanised) by grinding off the zinc coating locally and preserving the majority of the orginal chassis or panel still galvanised and keep the integrity of the original construction and reduce the untreated area to that close to the welds.
Baz
When I was involved in motor cycle racing we made the first carbon fibre framed racing motorcycle (Armstrong 250 and 350) which went on the win the British Championship for two years. When I wanted to leave Armstrong (nearly 30 years ago now) my contract prevented doing anything similar for 3 years and I joined a development business (that manufactured Carbon Fibre) in charge of "new applications and manufacture). Some years later I ran the Composite division of a subsidiary of Aerospace Engineering plc - making parts for commercial and fighter jets - so My experience is quite wide.
I had owned a Porsche from the age of about 22 (1st a 356C) so was still into them privately (924 turbo and 911 SC at that time) and so was the stress engineer at the 1st composite company who ownerd a 924. While there we manufactured tools to make a set of panels to convert a 924 to look like a 944 and learned all about the problems (still have the photos).
Basically the fit problem is often because the glass fibre is thicker than the steel it is replacing - so when a panel fits on to the original mounting area -the other side (the outside) of the panel is sticking up more and doesn't match the position of its adjacent metal panel.
Similarly when the rear wings were designed the window appature becomes smaller and thicker on which to fit the seals and glass - etc etc. By the same method - door gaps become less etc, etc and you have to stick it on top of the old panel (as the old steel part there is a stressed chassis member).
At the time another Porsche specialist was also making the same panels using the original steel ones as patterns - but by using the outside of the 944 steel panels to make the moulding for the inside of th enew ones and then laying inside that the extra thickness of the glass fibre wings - the inside shape obviously becomes too small to fit the car. To solve this he then hammered the old steel mounting points of the original car chassis until they were smaller (bashing the original steel chassis) to allow for this fit. We did it by making the patterns the right way and adding the right amount of sheet self adhesive pattern makers wax to the new 944 panels and also allowing for a much thinner area at the mounting point etc so our wings fitted straight on to the car - without problems.
Our plan was to upgrade 924's to 944's but my life then took a different direction to run an aerospace company and the patterns were sold to someone from "down South".
They do craze on the surface and shrink and release gasses over time etc - so your fitters/painters are quite right to point out that resprays will probably be required quite often. Also as panels set on the moulds there are stresses created and shrinkeage that can distort the new panel being made and quantities are usually too small to justify several different attempts to correct this.
Don't think I am not a fan - I am - but just confirming there are a lot of potential problems to overcome to make it as good as steel.
Of course steel replacement panels are not galvanised (since it is impossible to reproduce the sequence and conditions of new manufacture) so their life expectancy is reduced - hence often better to cut and fit a small panel from a crashed car (that was galvanised) by grinding off the zinc coating locally and preserving the majority of the orginal chassis or panel still galvanised and keep the integrity of the original construction and reduce the untreated area to that close to the welds.
Baz
You cannot weld galvanised sheet steel together except during new manufacture by a high current spot weld in which the temperature bubbles the galv away from the steel and allows a steel to steel weld and then it bubbles back to seal it.
Applying body shop welding techniques you cannot get behind the existing panel to spot weld the new one to it and anyway it has paint etc on it by now.
Galvanising an existing piece of steel applies stress to the surface and badly distorts it (even to a chassis) and especially to a panel.
The panels are made from very neatly zinc coated steel but a panel to retrofit is made from plain steel.
It could theoretically be made from galv steel and the galv ground off where you intend to grind it (as you do to the existing parts you are welding to) but it would become thinner then and any galv left in the grooves would spoil the weld.
Hence often better (although it unfortunately sounds like a bodge) to cut out the rust and weld in a piece - leaving all the original part that was OK as it was made new.
Often fitting a piece from a good panel on a scrap car will make a good job like this.
However we do not undertake body work so there might be someone along to alter that philosophy who does and if so please listen to them not me!
Baz
Applying body shop welding techniques you cannot get behind the existing panel to spot weld the new one to it and anyway it has paint etc on it by now.
Galvanising an existing piece of steel applies stress to the surface and badly distorts it (even to a chassis) and especially to a panel.
The panels are made from very neatly zinc coated steel but a panel to retrofit is made from plain steel.
It could theoretically be made from galv steel and the galv ground off where you intend to grind it (as you do to the existing parts you are welding to) but it would become thinner then and any galv left in the grooves would spoil the weld.
Hence often better (although it unfortunately sounds like a bodge) to cut out the rust and weld in a piece - leaving all the original part that was OK as it was made new.
Often fitting a piece from a good panel on a scrap car will make a good job like this.
However we do not undertake body work so there might be someone along to alter that philosophy who does and if so please listen to them not me!
Baz
ORIGINAL: DivineE
ORIGINAL: pauly
Seems like overkill to me as it's usually only the outriggers that rot, but then I don't understand going to all the trouble of fettling fibreglass wings to make them fit on a road car either [
[
A good selling point when it's for sale next year [
][].
DivineE
New member
ORIGINAL: pauly
ORIGINAL: DivineE
ORIGINAL: pauly
Seems like overkill to me as it's usually only the outriggers that rot, but then I don't understand going to all the trouble of fettling fibreglass wings to make them fit on a road car either [
[
A good selling point when it's for sale next year [
Not a chance.[
] I'm more and more in love every day and still discovering good things I didn't know it had when I bought it. Right down to the remote boot release button[] Pretty soon and with the help of Mark K's contact I will also have it looking like a new car with a fresh interior to go with its fresh Guards red exterior. 
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