Can you guys explain and show using as much pictures and graphs and charts and whatnots as to exactly how a p7100 works? i have general knowledge about the cam plates and afc a tad about the governor springs, but beyond that i have no clue and want to learn as much as possible about them.
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Engine/Transmission (1994 - 1998) how a p7100 works??? (detail please)
- Thread starter Devan Manis
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Ttt
TTT I can't believe that no one on this whole board has info on this pump
TTT I can't believe that no one on this whole board has info on this pump
The P7100 is actually built like a small engine and you are asking for a lot! Many don't have the ability to send graphs, drawings and such, or the time. Do a search or go to the Bosh sites on the net, may find some usefull info there.
Kirwin
TDR MEMBER
I have the answer
I bought a book from Barnes & Noble that was put out by Bosch a few years ago that has several pumps from the 12 valve era. I know it has the VE and the P 7100 in it. If you are that interested PM me and I will get all the data from the book and fax it to you or you can buy the book from Amazon.com I'm sure. There was also a fairly detailed article in the old TDRs if you have access to those. I'd guess '95-'97 or so by Joe Donnelly. The book I have is a factory manual so it doesn't tell you how to get more power, but it does explain how the pump works. Ken Irwin
PS you might also try your local Cummins dealer. They might explain it to you, or let you look at their manual if your nice to them and bring their choice of cold beverage.
I bought a book from Barnes & Noble that was put out by Bosch a few years ago that has several pumps from the 12 valve era. I know it has the VE and the P 7100 in it. If you are that interested PM me and I will get all the data from the book and fax it to you or you can buy the book from Amazon.com I'm sure. There was also a fairly detailed article in the old TDRs if you have access to those. I'd guess '95-'97 or so by Joe Donnelly. The book I have is a factory manual so it doesn't tell you how to get more power, but it does explain how the pump works. Ken Irwin
PS you might also try your local Cummins dealer. They might explain it to you, or let you look at their manual if your nice to them and bring their choice of cold beverage.
how much are all these books?
CarlJensen is right. If explaining the P7100 was simple enough to post charts, pictures, explanations, calculations, dimensions, theory, etc. here then everyone would be an expert
The basics are easy enough, but tough to explain without some pictures. I bought some basic manuals from Bosch a few years ago that covered many of their pumps, including the P7100. That helped a lot. But you really can't get your arms around the details until you take one apart. I think the Bosch training class on just this pump is like a week long!
I'm not sure what your goal is, so I can only suggest. Get some of the books and learn what you can from those, but acknowledge that you're not likely to be rebuilding them without a huge investment in time and experience to get through the learning curve!
-Jay
The basics are easy enough, but tough to explain without some pictures. I bought some basic manuals from Bosch a few years ago that covered many of their pumps, including the P7100. That helped a lot. But you really can't get your arms around the details until you take one apart. I think the Bosch training class on just this pump is like a week long!
I'm not sure what your goal is, so I can only suggest. Get some of the books and learn what you can from those, but acknowledge that you're not likely to be rebuilding them without a huge investment in time and experience to get through the learning curve!
-Jay
i never thought it would be simple, I just wanted to learn as much as i could using the resource I already have access to (TDR) but if its gonna be to hard to explain in great detail could you explain it to me in simple terms but in better detail than the one thats on the cummins page... I think thats where i read it. the one about it being a miniature six cylinder. However pictures and stuff are always a plus to have for many reasons
Im only 17 and trying to learn as much about them (and all other aspects of the turbo diesels) as i can so i can do what you do... kind of
TMaas said:I'm rebuilding Bosch inlines as a full-time job, at the age of 20. Ain't I lucky!
Im only 17 and trying to learn as much about them (and all other aspects of the turbo diesels) as i can so i can do what you do... kind of
Hello! There was a quite detailed article in the TDR a while back which covered all the different fuel injection pumps prior to the third generation. If you could latch on to one of those, it would answer a lot of questions. I have done fuel injection since the '70's. Suffice a short answer to say that a lift pump provides a fuel supply to an injection pump gallery. The plunger/barrels (one for each cylinder) are timed to the pump camshaft to deliver fuel at the correct time to each cylinder. The pump camshaft is connected to the engine gear train and rotates at one-half engine speed. The plunger/barrel combinations receive gallery fuel and pressurize it and push it through the delivery valves (a calibrated check valve inside the top fittings that your lines connect to on top of the P7100) and on to the injectors through the high pressure injection pipes. The plungers are connected to each other by a "rack" in the pump housing. The amount of fuel sent to the injectors is determined by the governor which is connected to back of the pump housing. Inside the governor are springs and weights and levers. When the throttle lever is moved forward, it moves a linkage which in turn causes a "rack" in the fuel pump to turn the plungers for more fuel. This style governor is what they call a min/max governor, which controls idle speed, and maximum engine speed rpm. This type of governor gives the accelerator a better "feel" for road-style operation instead of like a farm tractor which typically has a "variable speed governor". Let me know if you have any more questions. Hope this helps. Thanks.
JGK said:TMass,
Well, you sound like the authority here! We vote you to be teacher and give BManis and the rest of us the lesson today!
-Jay
Amen to that
Gtobey, thank you that helps alot. Another question though. When the rack turns the plungers does it twist them down or something so that the barrel is acctually bigger, or how does it push more fuel i guess is the question im trying to ask? Also what issue number is it do you know? I only joined not even a year ago so i only have 3 issues maybe i will buy whichever number it is.
BManis,
I think the rack actually turns the barrels, not the plungers, since they are moving up and down like pistons. But I'm not by any means an expert, so someone correct me please. But assuming that's correct, I'll continue...
The plungers have a groove cut in the side that spirals down. It's call a helix. The barrels have a hole in the side called the spill port. The fuel is pressurized by the plunger as it moves up in the barrel. Depending on where the rack has rotated the barrel, at some point the helix (groove) and the spill port line up and excess fuel is dumped out back into the system. But up until that point, the plunger is forcing fuel out the injector. So at high fueling, the spill port and helix don't line up until nearly at the top of the plunger's travel (if at all). But down low (low fueling) they line up earlier and much of the fuel just spills out rather than going to the injector.
Can you visualize that? If so, you got the fundamentals. A bit more...
As said, the governor will move the rack and thus rotate the barrels as needed to provide the necessary fuel (more or less) based on the load on the engine and the throttle setting. For example, suppose your foot is at mid-throttle and you're cruising down the hiway. Then you start up a hill. The load on the engine will cause it to begin to slow down. But the weights in the governor begin to move in (they are rotating around a central axle) due to the governor springs. As that happens, assuming you keep your foot in the same spot, the governor causes the rack to move and rotate the barrels to add a bit more fuel (spill port lines up with the helix higher in the plunger's travel, thus more fuel squirted out the injectors). As you start down the other side of the hill, just the opposite happens. Load eases off, engine speeds up, governor weights fly out moving the rack, fuel is reduced, truck slows down (a little!).
Hope I got that right and it helps. Otherwise, I just confused us all
-Jay
I think the rack actually turns the barrels, not the plungers, since they are moving up and down like pistons. But I'm not by any means an expert, so someone correct me please. But assuming that's correct, I'll continue...
The plungers have a groove cut in the side that spirals down. It's call a helix. The barrels have a hole in the side called the spill port. The fuel is pressurized by the plunger as it moves up in the barrel. Depending on where the rack has rotated the barrel, at some point the helix (groove) and the spill port line up and excess fuel is dumped out back into the system. But up until that point, the plunger is forcing fuel out the injector. So at high fueling, the spill port and helix don't line up until nearly at the top of the plunger's travel (if at all). But down low (low fueling) they line up earlier and much of the fuel just spills out rather than going to the injector.
Can you visualize that? If so, you got the fundamentals. A bit more...
As said, the governor will move the rack and thus rotate the barrels as needed to provide the necessary fuel (more or less) based on the load on the engine and the throttle setting. For example, suppose your foot is at mid-throttle and you're cruising down the hiway. Then you start up a hill. The load on the engine will cause it to begin to slow down. But the weights in the governor begin to move in (they are rotating around a central axle) due to the governor springs. As that happens, assuming you keep your foot in the same spot, the governor causes the rack to move and rotate the barrels to add a bit more fuel (spill port lines up with the helix higher in the plunger's travel, thus more fuel squirted out the injectors). As you start down the other side of the hill, just the opposite happens. Load eases off, engine speeds up, governor weights fly out moving the rack, fuel is reduced, truck slows down (a little!).
Hope I got that right and it helps. Otherwise, I just confused us all
-Jay
Thank you JGK it helps quite a bit. Just to make sure i follow you correctly so if i understand right the pump always starts injecting fuel at the same time (i do know its static timing) but when it ends the injection is what makes the power changes even as simple as reving the engine? So in a way its like a vp44 in that it injects fuel at a certain time but to meter it it stops it a certain time thereafter it begins, and thats where the governor springs come in?. By the way i tried getting some pictures of the pump more specifically the part your talking about... . and apparently there is a TON of printers also called a p7100.
Yes, the timing (start of injection) is fixed.
I think I follow your question. The length of the injection period and therefore the amount of fuel squirted out the injectors (and so the amount of power produced) is determined on where the spill port lines up with the helix. If you just rev the engine sitting in your driveway, the governor will limit the fuel injected since there is no load on the engine - it revs without using much fuel (the length of injection, and so the quantity of fuel injected, is short). But if you let out the clutch, the engine slows, though your foot is still pressing the throttle. So as the engine loads up the governor reacts by adding more fuel to the fire and here comes the smoke!
Not sure how this compares to the VP44 since I haven't studied it at all.
Hello again. Another bit of info about the P7100 pump: the plungers are rotated by the rack from the governor, the same plungers that are pushed up and pulled down following the lobes on the pump camshaft. The barrels are indexed into the flange assembly which is held down to the pump housing by the two nuts on the top of the pump on either side of the delivery valve holder (the splined piece in the center of the flange that the injection line connects to). You will notice that there are shims under that flange between the flange and the pump housing. These shims are there to allow the pump technician to adjust the startof injection of fuel to that cylinder while the pump is on the test stand. Under no circumstances do you want to loosen the nuts holding the flanges as the fuel delivery to that cylinder will change and you can over/underfuel a particular cylinder or you could lose the shims and get the timing out of spec! Engine damage will result!
Don't be concerned too much about the end of injection, as it changes when the quantity of fuel being delivered changes. The start of injection (static pump to engine timing)is of primary concern. The time of burn of the fuel/air mix usually is a fixed amount of time. As the engine speed is at idle, if the pump to engine timing is optimized for this engine speed, if you run the engine at wide open (example: 3200 rpm), the injection timing could be late. That is, in order to utilize all the btu in the fuel to make power, the start of injection has to occur early enough so that the burn time of the fuel, from the start of the burning of the fuel to the end of the burn, occurs so that the expanding gases can use all their force in pushing down the piston to make power. As you increase engine speed, you have to advance the start of injection to optimize the burn for complete utilization of power. Of course emissions, etc. enters into the mix, but that's a whole new ball game.
With the P7100, the static pump to engine timing is a compromise for the most power while still allowing for easy starting even in cold weather as there is no timing advance mechanism incorporated into the drive of the pump.
The VP44 comes with a timing advance mechanism built into the pump (controlled electronically) much like that of a gas engine distributor, only this one is hydraulically operated instead of vacuum operated. This can allow for retarded timing for easier starting, and advanced timing during operation to reduce emissions and increased power.
If you need further info, feel free to PM me... .
Hope this doesn't muddy the issue for you...
Don't be concerned too much about the end of injection, as it changes when the quantity of fuel being delivered changes. The start of injection (static pump to engine timing)is of primary concern. The time of burn of the fuel/air mix usually is a fixed amount of time. As the engine speed is at idle, if the pump to engine timing is optimized for this engine speed, if you run the engine at wide open (example: 3200 rpm), the injection timing could be late. That is, in order to utilize all the btu in the fuel to make power, the start of injection has to occur early enough so that the burn time of the fuel, from the start of the burning of the fuel to the end of the burn, occurs so that the expanding gases can use all their force in pushing down the piston to make power. As you increase engine speed, you have to advance the start of injection to optimize the burn for complete utilization of power. Of course emissions, etc. enters into the mix, but that's a whole new ball game.
With the P7100, the static pump to engine timing is a compromise for the most power while still allowing for easy starting even in cold weather as there is no timing advance mechanism incorporated into the drive of the pump.
The VP44 comes with a timing advance mechanism built into the pump (controlled electronically) much like that of a gas engine distributor, only this one is hydraulically operated instead of vacuum operated. This can allow for retarded timing for easier starting, and advanced timing during operation to reduce emissions and increased power.
If you need further info, feel free to PM me... .
Hope this doesn't muddy the issue for you...
Do a search in this forum for the P7100 pump discusssions. There are some excellent discussions on pump operation, tuning, performance, etc, complete with pictures and diagrams. All the info you need is here in one form or another. You just gotta search.
The radial pumps (VE and VP) work a bit different as they have the ability to set dynamic injection advance. The VE pump uses pressure to mechanical advance the plunger plate where the VP uses an electriconic advance on the plunger plate and a solenoid to limit the amount of fuel on each injection event. The P-pump is static timed so no injection advance but by rotating the barrels the pressure is built faster and you get some pressure advance to the injection event. The P7100 pump's greatest asset is the ability to deliver large amounts of fuel at high pressures for a long period of time.
The radial pumps (VE and VP) work a bit different as they have the ability to set dynamic injection advance. The VE pump uses pressure to mechanical advance the plunger plate where the VP uses an electriconic advance on the plunger plate and a solenoid to limit the amount of fuel on each injection event. The P-pump is static timed so no injection advance but by rotating the barrels the pressure is built faster and you get some pressure advance to the injection event. The P7100 pump's greatest asset is the ability to deliver large amounts of fuel at high pressures for a long period of time.
gtobey,
Thanks for the correction. So just how are the plungers rotated by the rack while moving up and down in the barrels, if that can be easily explained? I can't remember that it was explained or diagrammed in what I read (2 or 3 years ago!).
I was aware of the shims under the nuts for each barrel on the top of the pump, and the fact that they (barrels) are rotated slightly to match them up with each other. I watched the tech bench tune my pump and he rotated them all so as to get near max fueling possible with that adjustment yet still keep them balanced. Man, those pumps sure clatter on the test stand!
Thanks again,
-Jay
Thanks for the correction. So just how are the plungers rotated by the rack while moving up and down in the barrels, if that can be easily explained? I can't remember that it was explained or diagrammed in what I read (2 or 3 years ago!).
I was aware of the shims under the nuts for each barrel on the top of the pump, and the fact that they (barrels) are rotated slightly to match them up with each other. I watched the tech bench tune my pump and he rotated them all so as to get near max fueling possible with that adjustment yet still keep them balanced. Man, those pumps sure clatter on the test stand!
Thanks again,
-Jay
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