change advances

[bart]

My humble opinion on the matter ? the following:
The advances are to be change in some circumstances. Should be done with the policy, knowing how, knowing why? and knowing what you can? go into the meeting.

I assume that if I want to get powers not monstrous, then reliability, the quantity? of diesel fuel to give and the amount? air to give (therefore pressure) ? modest.
Perhaps a practical example the speech is pi? simple for everyone.
A tdi 160 with 70mg of diesel delivers in theory 190cv to 4000 rpm. Because of the obvious loss of performance as you increase the power, these horses become almost 185 to 4000 rpm with pressure 1.49bar (original pressure detected with the diagnosis).
Power data (rolled) reflect what is obtained with the calculations before you map the drive, there? ? the index that the accounts have been properly made and that everything on the car is working.

You note a p? smoke in certain regimes (predictable in the mapping phase). The problem arises from the fact that for injection 70mg, is injected, typically 8? ATDC, with peaks of 11?.
Despite an AFR of about 15.5 the car smokes why? the diesel fuel ? injected too over the top dead point 8 - 10? the limit for the smoke; hence on many engines on the tdi about 10?.
The smoke does not ? of those exaggerated, you could keep everything cos?, but if you want to fix that?

Or you increase the pressure, or by the advance.
If the pressure does not want to change, is anticipated.
How much? The advance the you can? calculate starting from the original maps. From these, you must extract the required value of the quantity? injection that you are interested in.
To do this, just a p? ingenuity and an EXCEL spreadsheet.
In my case the calculated value ? the state of about 1.25 degrees to 4000g/min. little stuff, but enough to reduce the smoke. now ****lli pi? that acceptable

Change the advance of the injection ? risky. The increase of pressure in the inside of the cylinder ? distributed, but localized in a short time, during ascent of the piston. If the increases are slight, there are no problems, picked with pressure turbo original or low.
In other conditions, you may have an overheating of the engine, cracks in the cylinder head and the piston head, the stress important for the flywheel and the crankshaft.
For quantity? injected very high (a lot) if the values of advance required from the calculations are high, it means that you should change your strategy. You go to the injectors with nozzles increased. In that case, them you can? leave the original, postpone or very, very cautiously anticipate, depending on the size of the holes of the nozzles.
In the case of pressure the turbo is very high with intercooler series, the matter is complicated because of the high temperature of the charge placed in the cylinder and the pressures pi? high.

As I see it, do the logs of the car with the original map and after the map changed ? fundamental.

Ovviemante I don't want to convince anyone of what I say, all of this ? one of my most modest opinion, born from a p? of study, and a p? experience

dr. chem ? your second message that I read today and this time I totally agree with you: exactly the same conclusions which I had arrived myself, but I have yet been able to test, and then verify...
We are totally in tune: I know that we have done studies and professional experiences similar...

[munro]

*dr. chem:hello doc could you kindly explain why you say that is the limit to inject 10? after the pms??theoretically,for what it s? I could continue to inject,and the increase pme in the cylinder,until you open the exhaust valve....for example, in the jtd 115 with the axis cams are colombo &bariani opens to 56? the first of the smes in practice 180? from smes to less than 56? to advance openness in comparison to this we have 124? after the tdc before the valve is open causing you to lose the pressure of the working cycle.....

[cicciogsr]

it means that up to 8-10? after the pms you can inject without anticipating and working with the air flow you can not have excessive smoke with those 8-9? falls within the tolerance of the propagation of the flame front in a cylinder volume that this time will be? greater than when the beginning of the injection, and with an appropriate pressure of air to burn almost all of the mixture...

[dott.chem]

It is a problem of kinetic type.
The diesel ? slow to burn. By injecting up to 10 degrees (approximately, varies from motor to motor) does not have the time to burn during the phase of the useful and ends to get to the exhaust manifold and the snail of the turbine during the combustion phase. There? causes an increase of EGT and particulate matter.
The phenomenon is reduced by using large excesses of air, of course. With low-pressure turbo-high, often this limit is a little less.
The camshafts increase the volumetric efficiency, as a result ? as if you're using pressure turbo more? high (not ? just cos? but you get the idea)

[cicciogsr]

changing the camshaft changes the volumetric efficiency why? change the timing of opening of the valves with a result of better and more filling the room... for the best I mean the speed? with which it fills the second what if ? well done best the intersection of valve you can empty the room first, and then fills the first and the fresh mixture, that you will have to? turn on is a room completely devoid of gas, with a few residues of unburnt and well as ir? the cool thing not to be underestimated

[munro]

It is a problem of kinetic type.
The diesel ? slow to burn. By injecting up to 10 degrees (approximately, varies from motor to motor) does not have the time to burn during the phase of the useful and ends to get to the exhaust manifold and the snail of the turbine during the combustion phase. There? causes an increase of EGT and particulate matter.
The phenomenon is reduced by using large excesses of air, of course. With low-pressure turbo-high, often this limit is a little less.
The camshafts increase the volumetric efficiency, as a result ? as if you're using pressure turbo more? high (not ? just cos? but you get the idea)

ok...putting a moment by the volumetric efficiency data from a certain type of cam, or pressure turbo etc and taking into consideration only the thermal cycle of a given engine and thus the pme that derives from it...my question ?:from when is the beginning of the injection of the diesel fuel, the intake valves have been closed already, such a beautiful piece,as well as the exhaust,and that air under pressure ? managed to enter in the cylinder ? the entrance to stop...then in the cylinder c'? a certain amount of pressure at the end of the compression phase of sara has also been increased in the heat ok?.. then in this condition ? match the combustion and we say "while" the piston passes the tdc..... what I did not go back ?=why? in the cylinder can not continue to inject diesel fuel into the mass which already is burning with a temperature and pressure much higher stage of compression to verebbe "interotta" only until the exhaust valve decides to open up??cinematicamente talking about the doc,why? by injecting 10?after the pms you should have more egt and smoke when it seems clear that the exhaust valve ? still closed, and all the heat and the pressure ? still trapped in the cylinder and pressed with a force unheard of on the piston??

[cicciogsr]

if you re-read everything from scratch I have also explained how the combustion of the diesel... looking for info on the combustion of the diesel, especially on the spread and maybe you put a lot of doubt

[cicciogsr]

in mjet the injections are multiple, in fact, you inject diesel in different times even when the combustion ? started

[munro]

if you allow me I would like to hear those who waste 2 words to try to understand us poor ingnoranti difficult concepts....and I am referring to dr. chem that as from his previous posts, evidently "waste" a few words to make it understandable concepts...translated and no offense...ciccio you're a great guy and an engineer titrated but to explain things you are a kiavika!!!forgive me!!
I believe that the combustion of the diesel the including and my questions are specifichea which I would like specific answers if you also don't want to give in this case I would like to ask you to avoid beating around the bush with useless wordplays....do not return to say and do the same things....come on!! a p? in a practical sense we want to!! the Doc sort of said what she thought without getting many saws mental!! why don't you adapt you or if that's just do you find it difficult from there? why do not you abstain to continue to "fight the can to the air??"

[dott.chem]

The process of combustion of any fuel with the oxidizer (in this case fuel and air) ? a chemical reaction.
The chemical reactions, all of which have a speed? typical that depends on several things.
Furthermore, the temperature and the pressure govern, in part, the thermodynamics of the combustion process.
In the specific case, an increase in pressure does not play in favour of the combustion process, at least from the thermodynamic point of view
In addition, from the point of view of kinetic phenomenon, chemical, "combustion" ? accompanied by physical phenomenon.
The drops of diesel micrometer, tend to burn from the outside, where they are in contact with oxygen, towards the inside.
Pi? ? large drop (formed from the atomization of diesel fuel) pi? time ? necessary for the flame front to reach the nucleus.
The time required ? such that, for durations of injection is very large and for high engine speeds (when the motor shaft runs through many corners in a short time) the relief valve is ? gi? open, by passing the droplets still in the process of combustion in the manifold.