Another DV Mod
Another DV Mod
Some later model IPs have relief bores along the main axis of the delivery valve and then transverse to this axis. The transverse cut is right above the quick return collar that everyone was grinding off in that other stupid mod.
These bores allow fuel to spill through them without raising the collar to greater and greater heights during high fuel delivery. The fueling curve is then leveled off until RPM max instead of tapering off like the stock pumps do.
The tapering off on the M and MW pump are due to the increasing distances that the DV must traverse until closing the high pressure line from the barrel.
in summary: Drill a a hole through the DV between the collar and the seat. Then another from the bottom of the DV at the plunger side, and along the central axis, all the way up to the region above the collar so it intersects with the previous cut.
These cuts will maximize fueling throughout a higher range of load and RPM... but most likely not increase max fuel by anything perceptible.
A cutaway view would look like a crucifix in the center of your DV. suhhweeet.
totaldisaster
03-02-2011, 12:37 AM #1I have not seen it mentioned, so here it goes. Correct me if it is a repost.
Some later model IPs have relief bores along the main axis of the delivery valve and then transverse to this axis. The transverse cut is right above the quick return collar that everyone was grinding off in that other stupid mod.
These bores allow fuel to spill through them without raising the collar to greater and greater heights during high fuel delivery. The fueling curve is then leveled off until RPM max instead of tapering off like the stock pumps do.
The tapering off on the M and MW pump are due to the increasing distances that the DV must traverse until closing the high pressure line from the barrel.
in summary: Drill a a hole through the DV between the collar and the seat. Then another from the bottom of the DV at the plunger side, and along the central axis, all the way up to the region above the collar so it intersects with the previous cut.
These cuts will maximize fueling throughout a higher range of load and RPM... but most likely not increase max fuel by anything perceptible.
A cutaway view would look like a crucifix in the center of your DV. suhhweeet.
I understand the machining limitations, and I certainly would not be able to do this with any tools I have.
I was just putting the idea out there for others to mull over and consider. I did not know the cut collars came to a conclusion such as you mentioned, but it still seems inaccurate and sloppy unless done on CNC.
Removing sections of the collar still nullifies the purpose of it and expose the pressurized line to the fuel gallery during the wrong events (at the wrong time).
I was reading a modern diesel book that mentioned some of the common DV types. The cylindrical DV has a more elaborate bypass system cut into it than what I suggested.
types:
fluted w/ by-pass chamfer
fluted w/ unloading collar
cylindrical w/ bypass
cylindrical w/ unloading action
totaldisaster
03-02-2011, 02:18 AM #3Tomnik,
I understand the machining limitations, and I certainly would not be able to do this with any tools I have.
I was just putting the idea out there for others to mull over and consider. I did not know the cut collars came to a conclusion such as you mentioned, but it still seems inaccurate and sloppy unless done on CNC.
Removing sections of the collar still nullifies the purpose of it and expose the pressurized line to the fuel gallery during the wrong events (at the wrong time).
I was reading a modern diesel book that mentioned some of the common DV types. The cylindrical DV has a more elaborate bypass system cut into it than what I suggested.
types:
fluted w/ by-pass chamfer
fluted w/ unloading collar
cylindrical w/ bypass
cylindrical w/ unloading action
I think the easiest thing would be buy some different dv's from china to mess with, some industrial mw pumps must have different ones...
1990 Power Ram 50 V6 SOHC 24V 6g72
I can be wrong, don't take everything I say as verbatim, please fact-check first.
My posts are my personal opinions and thoughts, unless otherwise noted.
EDM time, burn a hole!
I think the easiest thing would be buy some different dv's from china to mess with, some industrial mw pumps must have different ones...
1990 Power Ram 50 V6 SOHC 24V 6g72
I can be wrong, don't take everything I say as verbatim, please fact-check first.
My posts are my personal opinions and thoughts, unless otherwise noted.
in diesel books the grind collar is described but only informative not in detail as a possibility to shape the delivery curve.
Shouldn't we first discuss what we expect from modified DVs?
I had to use different DVs with increased release volume to get idle and partial load smoke free with larger elements.
I have not (yet) the need of more fuel neither an idea how I want to modify my delivery curve so what else could a DV do for me?
Tom
Hi,
in diesel books the grind collar is described but only informative not in detail as a possibility to shape the delivery curve.
Shouldn't we first discuss what we expect from modified DVs?
I had to use different DVs with increased release volume to get idle and partial load smoke free with larger elements.
I have not (yet) the need of more fuel neither an idea how I want to modify my delivery curve so what else could a DV do for me?
Tom
For you, the purpose of modifying the DV is different than for me. I will probably never modify a pump, so any change to the DV will just be an optimization campaign on the existing fuel output (or maximum MW output with 5.5 elements). The bores I mentioned in the first post should also increase fuel unloading I just do not know enough to suggest how much the difference might be over cut collars. But one would think that keeping the entire collar helps end the injection cycle, so i n your case, with loads of extra fuel, perhaps the bored out DV is a reasonable option?
I cannot comment on the ground collar except that I did come across a collar that is fluted on the bottom but retains the entire circumference on top so that the unloading potential is not affected. (Imagine 4 cuts in the shape of a radius that only go 1/2 the way through the thickness of the collar and are concave down). This flattens the fueling curve also and keeps the fuel unloading in spec with the collar height.
totaldisaster
03-02-2011, 12:28 PM #6You are absolutely right, Tom. You probably have more fuel than you know what to do with.
For you, the purpose of modifying the DV is different than for me. I will probably never modify a pump, so any change to the DV will just be an optimization campaign on the existing fuel output (or maximum MW output with 5.5 elements). The bores I mentioned in the first post should also increase fuel unloading I just do not know enough to suggest how much the difference might be over cut collars. But one would think that keeping the entire collar helps end the injection cycle, so i n your case, with loads of extra fuel, perhaps the bored out DV is a reasonable option?
I cannot comment on the ground collar except that I did come across a collar that is fluted on the bottom but retains the entire circumference on top so that the unloading potential is not affected. (Imagine 4 cuts in the shape of a radius that only go 1/2 the way through the thickness of the collar and are concave down). This flattens the fueling curve also and keeps the fuel unloading in spec with the collar height.
But I don't think this will give healthy extra fuel.
I doubt that the delivery valve is a limitation of flow, take a closer look at the orifice of the delivery valve holder.
What a DV can do is to open earlier (spring tension and lift until the collar is off the bore) but only to pressurise the hard line until the injector opens.
During fuel flow (injection) the DV is open. Very important now is to end injection without dropping the residual pressure in the hard line too much (that would reduce the fuel coming out of the injector). The limit for this is to avoid post spray. I had post spray already with 6.5mm elements.
For more fuel I'd rather lower the pop pressure of the injectors than touching the DVs.
Tom
I think I understood the shape of your idea.
But I don't think this will give healthy extra fuel.
I doubt that the delivery valve is a limitation of flow, take a closer look at the orifice of the delivery valve holder.
What a DV can do is to open earlier (spring tension and lift until the collar is off the bore) but only to pressurise the hard line until the injector opens.
During fuel flow (injection) the DV is open. Very important now is to end injection without dropping the residual pressure in the hard line too much (that would reduce the fuel coming out of the injector). The limit for this is to avoid post spray. I had post spray already with 6.5mm elements.
For more fuel I'd rather lower the pop pressure of the injectors than touching the DVs.
Tom
This is the purpose.
The DV does not limit flow, more importantly, it reduces initial pressure in the line before the next cycle. By allowing fuel through bores in the DV, we will not have to raise the DV collar so much higher during high load / high RPM fueling situations.
The collar must raise higher to allow more fuel to pass in a short amount of time in these situations. Raising the collar means more time for pressure to leak out of the injector line before it reaches the carrier and initiates the metered fuel pressure unloading at the end of injection.
totaldisaster
03-03-2011, 01:24 AM #8A DV mod cannot add any perceptible amount of fuel, except to different regions of the fueling volume vs. rpm chart.
This is the purpose.
The DV does not limit flow, more importantly, it reduces initial pressure in the line before the next cycle. By allowing fuel through bores in the DV, we will not have to raise the DV collar so much higher during high load / high RPM fueling situations.
The collar must raise higher to allow more fuel to pass in a short amount of time in these situations. Raising the collar means more time for pressure to leak out of the injector line before it reaches the carrier and initiates the metered fuel pressure unloading at the end of injection.
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