Strange Modder Question - Generac GP5500

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Originally Posted By: PandT
I am concerned with fuel dilution over time. Just what oil temp/duration is required for the fuel to evaporate out? Anyone have facts?


What fuel do you expect to dilute with the oil? Natural Gas??
If you're going to use it for outages exclusively, and you're running it on natural gas-- ??? What percentage of the run hours do you expect to be on gasoline?

Also, soot loading is a moot point with the Natural Gas, you will never need to change the oil because of soot loading or fuel dilution. Exclusively CNG fleet engines routinely double and triple their OCI for that reason. TBN depletion becomes the main the reason to drain.

For short sporadic runs, you may have to worry about condensation. If you're going to run 80+% on the natural gas, try high Ca, lower ash oil with a high TBN capacity. The idea is to keep the sulfuric constituents of the oil down which may behave badly in the presence of water and may erode the aluminum/brass in the engine, while providing enough buffer to deal with the acidic condensation. Condensing furnaces even have an acid neutralizer to treat the condensation before it hits the drain because sulfuric acid is no joke.
 
Originally Posted By: Cujet
Originally Posted By: PandT
Originally Posted By: Cujet

I have a lister CS, diesel generator. It's oil sump is modest in size. I also use a 0.5 micron Motorguard bypass filter as the only oil filter.
Interestingly, the tank settles out contaminates, instead of them remaining in the engine sump.


Sorry for the hack job on your post but -- Lister...

The low speed (~750 RPM) single or dual cylinder diesels?
[censored], I wanted one, spent a great deal of time/energy into research and then the EPA made them illegal in the US - I am still bitter over that. - Any pics??? or Vids???


finished_resized.jpg


No pics of the sump attachment underneath. But they are simple AN fittings, with surplus aircraft plumbing and a small tank. Circulation works through natural oil movement. The oil does circulate through the tank without problems and the tank warms up at the same rate the engine does.

I used a Grundfos water pump, which is located just under the radiator. The engine is currently a "stand alone" package, but will eventually be in a generator shed with the radiator on the wall of the shed.


That's a pretty slick machine, man!
 
Originally Posted By: jrustles
What percentage of the run hours do you expect to be on gasoline?


After I run out what I have - About 28 Gallons, I don't plan on using gasoline again but I will have the ability to do so if the need arises.

Originally Posted By: jrustles
Also, soot loading is a moot point with the Natural Gas, you will never need to change the oil because of soot loading or fuel dilution. Exclusively CNG fleet engines routinely double and triple their OCI for that reason. TBN depletion becomes the main the reason to drain.


I admit, I do need to change my thinking about oil contamination, I knew I was talking about NG but gasoline was on my mind and it just came out, just getting old I guess.

Originally Posted By: jrustles
For short sporadic runs, you may have to worry about condensation. If you're going to run 80+% on the natural gas, try high Ca, lower ash oil with a high TBN capacity. The idea is to keep the sulfuric constituents of the oil down which may behave badly in the presence of water and may erode the aluminum/brass in the engine, while providing enough buffer to deal with the acidic condensation. Condensing furnaces even have an acid neutralizer to treat the condensation before it hits the drain because sulfuric acid is no joke.


I have a condensing furnace and there is a reason they supply them with condensate pumps which brings me to a concern I had. My oil will be relatively cool (when it leaves the crankcase anyway) and ring blow by may be an issue - I will look up some water seperators.

OK, high Ca (Calcium, right?), Low ash, I never really looked at that, what am I looking for, a spec. for ash content? How low is low? I have read the Oil 101 post so I know that TBN is Total Base Number and has to do with the components of the oil to hold total PH so that acids do not form and that they are depleted as they get used (they have test kits for that).

What about shear? I keep hearing that air cooled, splash lubed engines have a lot of shear, why they would have more than any other piston engine I don't really understand, are they referring to the valve train?
 
Originally Posted By: PandT
What about shear? I keep hearing that air cooled, splash lubed engines have a lot of shear, why they would have more than any other piston engine I don't really understand, are they referring to the valve train?


My understanding is that the primary difference in shear is the temperature that air cooled engines run at causing more breakdown of the oil. Air cooled = oil cooled.

I don't think the valve train itself places any unusual demands on the oil, the spring tensions are much lower than in an automobile.
 
Originally Posted By: HerrStig
Lots of air mixing with the oil in a "slinger" system.


There's a lot of air mixing with oil in a "pumped" system too.
 
One of the concerns would be keeping the oil level in the engines crank-case at a proper level. Assuming that you are only going to use proper filling of the (original engine and add on section(s))so the level of oil in the crank-case is at the normal proper oil level, and you are not going to have any system that would keep the oil at the proper level even if a significant amount of oil was lost to burn-off within the engine. Because you will be increasing the run time between oil changes, and or oil level check. When the oil gets low you will be relying on the low oil shut down switch to protect your engine. And low oil shutdown switches can go bad and not shut down the engine. If that happened it would cause severe engine damage.

So, in order to not have this combination end up with low oil and shut down early in a use, or damage the engine if the low oil switch did not protect the engine. If it were mine, I would use GC, because GC is know for low loss.
 
Originally Posted By: HerrStig
Lots of air mixing with the oil in a "slinger" system.

That would be air entrainment, not shear. I believe that having a sump will take care of the entrainment issue. Also, just so that you are aware, I plan on having what is in essence TWO sumps, one on the bottom for the overflow and one on the top feeding the crankcase. I hope to explain further when the appropriate post comes along. I am still learning here at BITOG (Thanks Guys!)
 
Originally Posted By: JimPghPA
One of the concerns would be keeping the oil level in the engines crank-case at a proper level. Assuming that you are only going to use proper filling of the (original engine and add on section(s))so the level of oil in the crank-case is at the normal proper oil level, and you are not going to have any system that would keep the oil at the proper level even if a significant amount of oil was lost to burn-off within the engine. Because you will be increasing the run time between oil changes, and or oil level check. When the oil gets low you will be relying on the low oil shut down switch to protect your engine. And low oil shutdown switches can go bad and not shut down the engine. If that happened it would cause severe engine damage.
And what do you know, the appropriate post has just arrived.

Let me explain my current thinking as of now (BITOG has changed several of my first thoughts). The purpose of the system is to increase OCI without harming the generator in any way, to that end I must plan for the system to fail since all systems fail given enough time. I suppose that it would help if I just explained what I was thinking of and then giving as short a description of the theory as possible.

There is an oil fill port that sets the fill level of the crankcase by the drip method (when it drips from here you are full assuming you are on a level surface, stressed in the manual)

There is an oil drain port (To drain the oil from the bottom of the crankcase)

Now, to ensure that there is always a full, to the proper level, crankcase; we have to keep the fill port open while delivering oil to the drain or some other port that I would have to make/install. This reverses the normal thought on oil flow and has one distinct problem, namely, that deposits would accumulate in the bottom of the crankcase since they can't drain normally as during a regular oil change.

The very distinct advantages are that even if my system failed to deliver ANY oil, the crankcase would have the recommended level at the the time of failure and would continue to have it except for normal usage, just as if it had just been filled so that would be my safety factor - About 100 hours since I will be using good oil and burning Natural Gas.

I am still thinking about the plumbing. There are splashing concerns, the afore mentioned build up of [censored] on the bottom of the crankcase, breathing and much else.

I am eyeing an Internal Gear Pump as my pump of choice: I have not chosen yet.

http://vikingpump.com/pumps_internal_gear.asp

Please consider this just at the level of my current thinking, nothing is set in stone until I buy it. I would really like some advise on sealed oil tanks with ports appropriate to my use (1.5 Gallons, Approx.), cost appropriate tubing, fittings and other associated things like valves. I am soliciting any and all advise in this and any other matters or concerns.
 
hmm. auxiliary tank sitting at the side of the engine. air gap above it. plumb the drains together so both have equal level. bottom of aux tank can be lower than the engine sump. gear pump pulls from bottom of aux tank and dumps to top of valve cover. pump failure? system still has original sump + the volume of oil contained in the equal cross-section of the aux tank off to the side, gravity-leveling occuring from the line attached at the sump drain.

fittings? copper would be nice. oil-appropriate rubber/nylon could also be used, depending on routing, abrasion.

I was going to ask earlier for primary and secondary design goals. there is a lot of back-and-forth with this sort of guessing game. it is mentioned: "he purpose of the system is to increase OCI without harming the generator in any way, to that end I must plan for the system to fail since all systems fail given enough time". also seems to be an unwritten requirement for reliability.

Define OCI. based on runtime or does calendar come into affect. most of us service our OPE annually if the hours are low. With the expected use stated as minimal (stated as testing may even put more hours than actual use) then I might point out that the runtime OCI will accumulate far slower than than calendar-based OCI in this use scenario. That unfortunately negates some of the success of this design--- oil exposed to fuel/elements will be exposed to daily and season fluctuations in humidity, temperature... in other words, you might achieve a 200hr runtime OCI, but will you really want to leave the oil in there for 5 years to achieve it?
 
Originally Posted By: meep
hmm. auxiliary tank sitting at the side of the engine. air gap above it. plumb the drains together so both have equal level. bottom of aux tank can be lower than the engine sump. gear pump pulls from bottom of aux tank and dumps to top of valve cover. pump failure? system still has original sump + the volume of oil contained in the equal cross-section of the aux tank off to the side, gravity-leveling occurring from the line attached at the sump drain.


I was thinking - (Oil Flow as follows) Two tanks, one above the engine (Valve cover) with a very simple drip system regulated by a manual valve (I was visualizing a site glass to count the drips going into the valve cover). the oil would drain into the crankcase and from there (The oil fill hole that sets the fill level) drip out of a fitting I installed into a second tank, the sump as I see it.

Failure mode: Tank runs out of oil, all excess oil goes onto the sump and stays there.

From the sump: I want (so far) an external gear pump powered by the generator itself (still looking at them) going to a water separator then a filter and from there to the upper tank.

Failure Mode: Pump or switch fails, top tank not replenished.

I am still looking at this since it would require a float switch of some kind to operate the pump and they are the failure points in any system of this type. A side note, the pump control (right now a switch) could be a continuous duty system except I have not looked at the run dry capabilities of the pumps in question but it would eliminate the float switch which I would greatly like to avoid if possible.

Originally Posted By: meep
I was going to ask earlier for primary and secondary design goals. there is a lot of back-and-forth with this sort of guessing game. it is mentioned: "The purpose of the system is to increase OCI without harming the generator in any way, to that end I must plan for the system to fail since all systems fail given enough time". also seems to be an unwritten requirement for reliability.


Agreed, since the system was, and still is in flux, an exact description was a waste of time both yours and mine. I wish I knew how to make post-able diagrams, we could then work from the same beginning premise but I don't know where to begin on that except asking a coworker who seems to have done it before - I don't have any knowledge at all on how to do so.

Originally Posted By: meep
Define OCI. based on runtime or does calendar come into affect. most of us service our OPE annually if the hours are low. With the expected use stated as minimal (stated as testing may even put more hours than actual use) then I might point out that the runtime OCI will accumulate far slower than than calendar-based OCI in this use scenario. That unfortunately negates some of the success of this design--- oil exposed to fuel/elements will be exposed to daily and season fluctuations in humidity, temperature... in other words, you might achieve a 200hr runtime OCI, but will you really want to leave the oil in there for 5 years to achieve it?


I know this is stupid thing to do from my proposed usage scenario. I accept that and I still want to do it. I have my reasons, think end of the world and there is no more oil available except what you have on hand at the time. This is a project that I do intend to complete without any expectation that it will ever yield a payback of any sort, in fact, I don't ever expect to recover the cost of the parts never mind the oil, filter, pump expenditures.

I want to do it as a "case in point".

What are the reasons for all the time limits anyway, oxidation?

I could use oxygen absorbers in the breather system while in storage but my preferred idea is to fill it from sealed oil containers when the disaster arrives and then it would be a mote point, I would be running it long term which is what I am planning all this for.
 
I don't have anything to back this up, but my thoughts about the concern of particles accumulating in the bottom of the engines sump if the bottom (normally drain) were used as the oil input, are that this is not grandmas engine in a drive 10 MPH to church once a week vehicle that idles at something like 500 RPMs and is lucky to ever see 1500 RPMs. It is a gen-set, and it probably is a 3600 RPM all the time unit. That higher RPMs (also probably combined with a tang on the bottom of the connecting rod that dips into the oil) and the vibrations that these engines see, is all going to keep that oil pretty well stared up so that particles will find there way out of any oil exit, regardless of if it is high or low in the sump.
 
Originally Posted By: JimPghPA
I don't have anything to back this up, but my thoughts about the concern of particles accumulating in the bottom of the engines sump if the bottom (normally drain) were used as the oil input, are that this is not grandmas engine in a drive 10 MPH to church once a week vehicle that idles at something like 500 RPMs and is lucky to ever see 1500 RPMs. It is a gen-set, and it probably is a 3600 RPM all the time unit. That higher RPMs (also probably combined with a tang on the bottom of the connecting rod that dips into the oil) and the vibrations that these engines see, is all going to keep that oil pretty well stared up so that particles will find there way out of any oil exit, regardless of if it is high or low in the sump.


I would tend to agree (also without any actual facts). With a detergent oil and the constant stiring and agitation from the tang, I expect the crankcase bottom to remain mostly free of particles.

Does anyone know the actual reasons for the mandatory 1 year OCI's?
 
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