Melting pistons.

[Accelerator]

Could you explain exactly what you mean here?

Sure,

every injection cycle starts as follows

timing-duration-fuel pressure

timing is when the event starts.

duration is how long the event last's

Pressure is how much pressure is is behind the fuel stream at the end of the event.

this is why i say that they can all affect each other, well im not the only one, but this i learned from bosch.

too high of a rail PSI and you will get much more advanced timing, and a longer duration, which could lead to lower RP than what started the cycle.

too much duration will lower RP and the atomization of the fuel.

Did that help any?

 

[sweetdiesel]

Sure,


Pressure is how much pressure is is behind the fuel stream at the end of the event. Dont you mean the start?

but this i learned from bosch.

too much duration will lower RP and the atomization of the fuel.

You had to go to school at a Boch learning centre? Heck ,I leaned most of that one night at the track

 

[Accelerator]

You had to go to school at a Boch learning centre? Heck ,I leaned most of that one night at the track

you quoted, do i mean at the start of the event, well no not really, because if you have the desired RP at the end it's inevitable that you have it in the beginning, and this is why RP and timing are important to consider together, beside's the engine calculates RP at the rail so it really does not really see what's going on at the injector tip (RP wise)

And most of my training is from hands on , schooling was just a bonus

 

[sweetdiesel]

you quoted, do i mean at the start of the event, well no not really, because if you have the desired RP at the end it's inevitable that you have it in the beginning, and this is why RP and timing are important to consider together, beside's the engine calculates RP at the rail so it really does not really see what's going on at the injector tip (RP wise)

And most of my training is from hands on , schooling was just a bonus

If/when you adjust pressure tables they are the start of the event NOT the end. Just ask bosch if you dont believe me If your not sustaing rail look at your duration

 

[JoshH]

Sure,

every injection cycle starts as follows

timing-duration-fuel pressure

timing is when the event starts.

duration is how long the event last's

Pressure is how much pressure is is behind the fuel stream at the end of the event.

this is why i say that they can all affect each other, well im not the only one, but this i learned from bosch.

too high of a rail PSI and you will get much more advanced timing, and a longer duration, which could lead to lower RP than what started the cycle.

too much duration will lower RP and the atomization of the fuel.

Did that help any?

How does rail pressure make the start of the injection cycle start any sooner?

 

[Accelerator]

How does rail pressure make the start of the injection cycle start any sooner?

X *timing will exit and hit piston @ Y* crank angle with 23kPSI

With more PSI and the same calculated *timing the fuel stream will hit the piston sooner, as in a more advanced timing calculation...

 

[JoshH]

What does hitting the piston have to do with injection timing?

 

[paint94979]

What does hitting the piston have to do with injection timing?

x2?

 

[Accelerator]

What does hitting the piston have to do with injection timing?

if it hit's the piston sooner it's the same as adding more timing advance! hence adding RP add's timing.

accually every RP box manufacture will tell you the same, higher RP add's timing...

 

[JoshH]

How is it the same as more timing advance? Everything I've ever seen times the injection cycle by when the injector opens and sprays fuel, not when the fuel hits the piston.

 

[Accelerator]

How is it the same as more timing advance? Everything I've ever seen times the injection cycle by when the injector opens and sprays fuel, not when the fuel hits the piston.

i understand what your saying, but what im saying is that there is more mechanicle advantage that the ECM has no controll over.

the ECM times the injection event by crank angle, right? ( that's appox when the fuel "should" hit the piston, or in that close visinity) well if your timing is 25* and your RP is at 29kpsi (ECM See's 26oooPSI) there is no way for it to adjust, right? so in reality your accually running about 29-30* of timing advance.

im sorry if i cant be any more clear on this , i just cant communicate as well as i want to over the net. i hope this helps.

 

[JoshH]

No, I understand what you're saying, but I disagree with you. There are no factors for fuel pressure in altering the injection timing. I have seen IAT, ECT, AAT, Baro, fuel quantity, and RPM. Nothing else will change it. Oh, and an LBZ ECM will log rail pressure over 26k.

 

[Accelerator]

No, I understand what you're saying, but I disagree with you. There are no factors for fuel pressure in altering the injection timing. I have seen IAT, ECT, AAT, Baro, fuel quantity, and RPM. Nothing else will change it. Oh, and an LBZ ECM will log rail pressure over 26k.

OK thats fine, i just have been taught this and have seen it my self, so im just passing on what i feel is a true and mostly unkown issue.


26000 was just an example..LOL

 

[TrentNell]

OK thats fine, i just have been taught this and have seen it my self, so im just passing on what i feel is a true and mostly unkown issue.


26000 was just an example..LOL

1 question that will honestly help decide whether i think your theroy is plausible ........ how far away ( aproximate measurement) from the TDC is the piston when the injection cycle starts @ say 30* timing ? which is not a far fetched #

 

[Accelerator]

1 question that will honestly help decide whether i think your theroy is plausible ........ how far away ( aproximate measurement) from the TDC is the piston when the injection cycle starts @ say 30* timing ? which is not a far fetched #

i dont know for sure,but i would venture to say that 30* before TDC is your mark.....:rofl:

i would have to look at a engine next time i degree one in, but i would say about 1.5-2 " before TDC........sound right?

 

[JoshH]

Here's how I do believe rail pressure can have an impact on timing. If you increase rail pressure significantly, it will shorten your pulse time for a given fuel quantity. Depending on how much you increase the rail pressure, you can shorten the pulse time so much that the entire injection cycle occurs before TDC. That said, I don't think you could ever get it to be a factor in WOT conditions.

 

[JoshH]

1 question that will honestly help decide whether i think your theroy is plausible ........ how far away ( aproximate measurement) from the TDC is the piston when the injection cycle starts @ say 30* timing ? which is not a far fetched #

I was wondering the same thing, Trent. If anyone knows the center to center measurement of a Duramax connecting rod, it wouldn't be difficult to calculate it.

 

[Accelerator]

Here's how I do believe rail pressure can have an impact on timing. If you increase rail pressure significantly, it will shorten your pulse time for a given fuel quantity. Depending on how much you increase the rail pressure, you can shorten the pulse time so much that the entire injection cycle occurs before TDC. That said, I don't think you could ever get it to be a factor in WOT conditions.

i can buy that, but IMO if your not spraying most if not ALL your fuel in BTDC your wasting HP.

 

[Accelerator]

I was wondering the same thing, Trent. If anyone knows the center to center measurement of a Duramax connecting rod, it wouldn't be difficult to calculate it.

6.640 i think is stock rod

 

[JoshH]

i can buy that, but IMO if your not spraying most if not ALL your fuel in BTDC your wasting HP.

Fingers might have some interesting data on that theory. He has done a lot of testing on cylinder pressures and injection timing.