How to change the advances of injection

[switing63]

I have to say that this is a purely theoretical event, only to better understand how to map an engine.
Let's assume that our client, mr. Red, has a car equipped with a motor that has x Hp, and the desire of improving them to y which coincide with the power of the same engine, but with one evolutionary step above and that this engine series has several mechanical changes, including a high-pressure pump that works with 200 bar compared to that of the model of our client.
In the map ORI of our customer to the maximum speed (4000 rpm) are injected 60mm3 of fuel pressure of 1400 bar. The injection part 939 µsec before TDC and lasts 851 µsec, and then ends when the piston is at 88 µsec from the PMS.
In the advanced model we have to 4000 rpm for an injection of 70mm3 of fuel injected at 1,600 bar. The injection begins 811 µsec before TDC and lasts for 790 µsec, and then ends when the piston is in 21 µsec from the PMS.
Now since we want to satisfy the power demand of our customer in our map MOD that we want to inject the 70mm3 in place of the 60, but we have a lower pressure then the time to inject the amount of diesel required is longer. In the map ORI, we see that for injecting 70mm3 to 1400 bar we want to 947 µsec.
So if we leave gold to the starting point in 939 µsec injection, this will -939+947= 8 µsec after the TDC.
And here the question arises, that is, what would you do?
(A) Early injection at 1035 µsec, so that terms always 88 µsec before TDC as the original, however, having injected the 70mm3
B) Seen that in the advanced model ends in 21 µsec before TDC, the spark advance always the beginning of the injection, but not at 1035 but to 968 µsec before the TDC in such a way that it ends in 21 µsec before TDC, as in the model evolved
C) I Leave the beginning of the injection to the original value, and leave that terms 8 µsec after the TDC.
D) .... The other solution to propose.

Thanks to all those who want to give me explanations

[valerio85]

hello, I introduce myself, I have never written on the forum, it's time to start. am writing for a bit, but I never had the opportunity.
personally, I think that the solution is the most suitable;
if you are not happy I would try the B;
NO, not the C ... if you don't want to jeopardize valves, turbine, etc
greetings

[switing63]

First of all, thanks for the reply.
I wanted to ask the technical reason that makes you believe the solution To the most suitable.

[valerio85]

hello switing, I think the solution is the most suitable with regard to the linearity of the delivery, respecting the timing of the eoi (end of injection) factory, for that mortore and, especially, the tolerances of the materials used, in order not to risk to verify the unpleasant phenomena of the injection time little appropriate (when the piston is too close to tdc).. by injecting later you could raise considerably the temperature in the combustion chamber.. you can ruin the valves, turbine, etc...
at least this is my thought
thanks

[valerio85]

for the sake of completeness, I would add that we need to know if the two models have pistons the same, materials the same, the turbine equal to, discharge the same, same ratio of compression fitting, the same system of lubrication and cooling... but I think no, since motors differ in these details. I give you an example:
we take two classic examples
vag 1.9 tdi 130 and the 1.9 tdi 150, or 160
or
vag 2.0 tdi 140 and 2.0 tdi 170
you have the engine less driven and more driven in comparison, and as you say, you would pump less stringent. well in this case, as in most of the cases, for the reasons which I have written before, I think that is appropriate to anticipate the injection, and to have it end at the same point.

[valerio85]

at least this is my opinion, according to what I have had the experience to try and learn. I'm not saying it as truth absolute, attention.
I'm expressing my thoughts.
if someone has something to add, and clarify, even if it were the contrary, it is well accepted, of course, a greeting

[switing63]

Thanks a lot for your contribution. So if I understand correctly, in case you don't know the mechanical differences between the two engines look similar, it's best to always finish the injection at the time established by the manufacturer in the original version, while if we are certain that the two engines have the same components as the solution "B" is practicable. So just to give one example, the 1.9 jtd 16v €3, 140 and 150 Hp are the same apart from the mapping, in this case, assuming that it's worth to try to earn only 10Cv is possible to apply the solution "B", assuming, of course, that the point end of injection is different (also because I have not checked the two maps).

[valerio85]

hello switing63,
I think it is always better to anticipate the injection to inject more, the rather that, however, delay it with respect to the eoi the original.
it is a good thing to do so, especially to avoid as I said before, the phenomena are unpleasant, smoke, etc
I have read many of your posts, and interesting speeches and content-rich,...