6 portable slurry pump pump

HOW DOES HPOP SYSTEM WORK?

hawssie asks:

I sort of understand the HPOP system but I still had a few questions I was hoping someone could clarify for me. This is what I understand so far: The LPOP keeps the top reservoir supplied with engine oil for the HPOP, which in turn creates the high pressure oil needed to fire the injectors. This pressure is regulated by the computer by manipulating IPR,(which is basically a solenoid valve that is either open or closed) and the computer reads this pressure through the ICP. My question is with the mechanical part. This HPOP pump is geared to the engine I assume, but what does the degrees I've seen stated have to do with the way it works?(15 degrees or 17 degrees depending on year I believe) is the HPOP producing pressure regardless of the position of the camshaft and/or crankshaft or does it pulse pressure based on camshaft/crankshaft position? If its the former, In theory could you run the engine by using a belt driven pump with the ability to produce the oil volume and pressure required, as long as you still had the IPR and ICP in the system for the computer to manipulate it?

ford_doctor responds:

The High Pressure Oil System is not timed nor does it create "pulses" used for injection. All the system really does is create and maintain oil pressure for the injectors similar to how a common rail fuel system would work. The IPR is not simply an open or closed valve during operation. The PCM controls oil pressure by pulse-width actuating the IPR. The percentage of pulse width is calculated by the PCM depending on several factors such as load, accelerator input, engine temp and so forth. The pulse-width is measured in a percentage as you mentioned, typically about 10-14% at idle for a 7.3L and variable while driving.

Pat Dolan responds:

When you ask "how does it work", I have to reply: "not very well". As FD said, it is an energy supply to drive the hydraulically actuated unit injectors. It is also a variable pressure system - with the IPR dumping oil to stop the HPOP output at a set point consistent with how "hard" the computer tables would like to see the fuel forced out of the injectors for the measured conditions (MAP, temps & demand). The big shortcoming is that the oil system (and the fuel system) must operate above and below the miscibility pressure point, and there is no way provided to compensate for the compressibility of the unknown quantity of un-dissovled air below miscibility pressure. Not sure why you would want to belt drive a pump, when the stock one is gear driven reliably and there are several aftermarket upgrade pumps available that will support far more HP than the block and heads will tolerate. If these things trouble you, instead of trying to put endless layers of lipstick on a pig, just buy a CR engine and not worry about it.

klhansen responds:

The 15 and 17 degrees you see referenced is the angle of the swash plate that drives the pistons within the HPOP. A 17 degree pump has a slightly longer stroke than a 15 degree pump. Picture a cylinder cut off at an angle with multiple connecting rods and pistons extending from the angled end in the same direction as the axis of the cylinder. As the cylinder rotates, the pistons move up and down inside a cylinder (like a revolver), compressing the oil. Don't recall how many pistons are in our HPOPs, but it's at least 6, so the flow is really not that "pulsed". You could look up "rexroth pump" on wikipedia for a better description. It takes a fair amount of HP to run the HPOP, so gear drive is more positive. I'd hate to be stopped by a broken HPOP belt.

ford_doctor responds again:

Thank you, I learned something today! The 7.3L HPOP was a seven piston pump... as was the 6.0L HPOP in 2003 which was changed to a V 4 style piston pump late in 2004 for the 2005 model year.

hawssie responds:

Thanks for the info, I didn't want to run a pump off of the engine I was just using that as an analogy. I just got fooled by the degrees reference and was thinking in line of a typical fuel injection pump (like cummins uses in their B motors for example) with its timing. Thanks for the swash plate description. I understand how a swash pump works but the ones I am used to in most hydraulic applications are variable. I thought the Rexroth pump used was of a gear pump design not a swash plate. I also simplified the IPR I understand its Pulse Width modulated. The whole reason I was asking this was because of the problem often encountered with not having enough oil pressure/flow to run modified injectors etc. Why not just adapt a large displacement pump. I work with hydraulics and the pressure and flow required for this application seems minimal.

woodnthings8 responds:

Here is an animation of a swash plate. And pictures of a hydraulic pump swash plate that is similar to the HPOP. HPOP Disassembled

hawssie responds again:

Yeah your animation is shown with a variable displacement swash plate design such as in a hydrostatic transmission. Also great breakdown pics, so it looks like the input shaft is splined with a threaded end for the retaining bolt. Can you tell me the spline count and diameter?

Unknown member asks:

Do have instructions on how to disassemble hpop?