Genset fuel tank size?

[grantgoold]

I know that some of you have linked your main fuel tank to your genset. Others have independent tanks. I am looking to see what the average sized independent tank is amongst the group.

Please let me know your size!

Grant
Sacramento

[Hartley]

If it's for a Gasoline generator usually about 50 gallons. (aka 50 hours run )

If it's for a diesel then its usually about 30 gallons. Diesels use 1/4 the fuel that gas generators burn.

[tekebird]

our 04 had a seperate tank, was for the A/C pony motor.

gas genset, 1gph at max output 26 gallons.

we never did boondocking

generally the generator use was in ratio to driving time and Engine Fuel use.

so both were always filled at stops.

[WEC4104]

Are there really a bunch of you guys running around out there with 50 gallon gas tanks dedicated to a generator?  Geeez.   Mine is about half that (the original A/C engine tank on the 4104) and I seem to run forever on it.   (running 5500W gasoline unit and one roof A/C)  I can run about 2.5 days non-stop, or easily about 8 days the way we vacation.

I guess if you have an all electric coach, multiple roof units, and do a lot of boondocking, you need the big tanks.

Also, from what I have seen in published specs, the diesels use about 50-65% as much fuel as a comparable sized gas unit.

[Dreamscape]

I have a 12kw....Before I get flamed.....It was in the coach when I bought it...I know it's big, but anyway....I have a 30 gallon seperate diesel tank for the genset. Don't really know the usage as I have not run it much to check it out....Been working on the conversion way too long I guess...It does handle the coach elec. though..

Happy Trails,

Paul

Dreamscape

[Barn Owl]

Everything I have is from the PO. Onan 6.5 and a 40 gal tank. The aluminum tank on the right is the gen tank, the large black tank was an 165gal diesel auxiliary tank that I have since removed.

[Kwajdiver]

Why don't you want to tap off the main tank?  You save room.  I run off the main, only have one tank to fill and not worried about the gen running out of fuel. 


Bill

[grantgoold]

Keep your responses coming. As far as tapping into the OEM tank, I thought of a few ideas. First, seems like folks are getting bad fuel on occassion. If I fill up at two different places for both tanks, then if that was ever to happen I would have a back up. Second, it seems like alot of work to run two lines from front to drivers rear bay for the lines. Third, I want to make sure that I never run out of fuel by running the main tank dry.

Finally, I can purchase a fully self contained 60 gallon tank with all the works for $100.00 that will sit in the same bay as my water tanks. I know I lose a little bay space but that bay is already gone with black, fresh and grey water tanks.

Thanks for the input.

Grant

[Hartley]

My generator stops when the main tank is down to 55 gallons approximately.

That's a poor mans fuel gauge since I can't seem to get the generic gauges to
work right on the MC9 tank. I drilled two holes in the tank. one for the pickup tube
and the other for the return. Used 5/16 copper refrigeration line and epoxied them
into the tank with JB weld...

And before anybody starts with me about the fuel gauge... I am too cheap to buy
the $100 sensor that won't rust or corrode up. The open style resistance sensors
will rust up due to their position above the fuel fill line. The normal condensation
in the tank just eats them up.

My experience with 10kw Diesel Generators is that they generally burn less than
1/2 gallon an hour under 3/4 to full load. Light loads ( 1-a/c, water heater and such )
about a quart an hour.

I have measured this using a calibrated tank and load monitor. That's what I get...
at sea level. Those numbers are now off a little due to the low sulphur diesel
not working as good as the old stuff was. When I run 100% veggie the numbers get much
better for some reason which I haven't bothered to check exactly.

Many people really don't know how much fuel they really use and are guessing.

I am preparing to be off-grid for about a month and will be burning anything that will
pass through the kubota engines so will have a better idea of what works for a long run.
I figure 750 hours pretty much non-stop should be interesting...

[gus]

My 4104 came stock with a 24 gal (usable) gas tank for the original AC gas engine. I now have a Honda EV6010 6KW water cooled gas gen which uses about 0.5 gph at full load,  it never has been at full load.

I use so little gas from this tank, even though we run the gen for AC all the time while underway in hot weather, that I siphon gas from it at home all the time to use in my lawnmower and antique tractors. Helps keep the gas fresh.

[WEC4104]

DrDave:

Burning less than .5 gal/hr at 75-100% load with a 10KW diesel unit sounds like you are doing really, really well.  I am not questioning what you say you are seeing, but I think you are doing exceptionally well, and not getting the results that most people will see.

I spent some time poking around the web and came across these two ditties:

1) First from a generator site that was comparing diesel/gasoline/LP pros and cons:

Diesel engines are less expensive to operate. The general rule of thumb for fuel consumption is 7% of the rated generator output (Example: 20kw x 7% = 1.4 gallon per hour at full load).

2) Also found the website referenced below that did a pretty extensive comparison of generator models.  Note the table that has the 15 different models listed.  Not a single unit had a consumption rate under .5 gal/hr at 75% load.  At 100% load, the median consumption rate was about 1 gal/hr.

source:  http://bizpost.com/Smythe/Full-Timing/Power/gensets.html

So Dave, I think you are doing super, and I'd actually like to know more about the model and set-up you have. But for the average Joe looking to size his tank, I think he needs to estimate based on .75 gal/hour for most diesel units.

[Hartley]

Tuned exhaust... I just find the sweet spot for the engine displacement and rpm.
I like quiet exhaust systems. Takes some fiddling around with resonant systems.

It just happens, I used to mess with go-karts and the exhaust system pressures
greatly affect the efficiency of the engines.

I choke them down until they won't take more. Then open them up until I get better
efficiency but not too much noise. So far this has worked only on Kubota 3 & 4 cylinder
engines, I haven't tried on anything else. I tune them for the typical loading that they
would see for a long run. It can cause problems and I have been lucky so far.

Other than that, No I don't have the science behind it and couldn't explain it any other way.
Just a gift I guess... Some people call it tuning, Others just call me crazy... All I hear from the pipe
is a whooshing sound, No droning impulses. The engines make more rattle noise than the exhaust.

I have done the same thing with the L-60 Kohler flat heat 4 cylinder engines on gensets although
they do tend to drink a lot of gasoline under load. At least they are quiet... You can't really do these things to air cooled engines, they will burn valves and warp heads due to hot spots and create a whole
array of problems. Onan did a pretty good engineering job on their mufflers and I have used the mufflers for the 2-cyl Onan 6.5kw Gas engine on Kubota's with the Onan resonator tip. Not too bad...

Now I use Kubota diesel tractor mufflers and play with pipe sizes.

What irks me is that if the exhaust manifold has an internal diameter of around 1 inch, why do people hook 1 1/2 to 2 inch pipes and mufflers to them? There is not enough backpressure to smooth out the power impulses in the hot gases. They just make everything downstream start to sound like a lawn mower with a throaty racket. I can't stand people's noisy generators that you can hear 100 feet away.
They just don't get it I guess....NO NOISE... Then add a stack to make more racket.... Shheeeesh!

More Noise = More Fuel wasted ....

[Jerry Liebler]

Drdave,
    I have the sound you are talking about at the exhaust of my genset, Onan with 3 cyl Kubota.  I increased the pipe size to 2" , run it through 2 JC Whitney  offset glasspacks then reduce it to 1 1/2" and run a 25 foot long tail pipe.  Just a smooth whoosh out of the tailpipe, no audible pulses. 
Regards
Jerry 4107 1120

[Hartley]

Drdave,
    I have the sound you are talking about at the exhaust of my genset, Onan with 3 cyl Kubota.  I increased the pipe size to 2" , run it through 2 JC Whitney  offset glasspacks then reduce it to 1 1/2" and run a 25 foot long tail pipe.  Just a smooth whoosh out of the tailpipe, no audible pulses. 
Regards
Jerry 4107 1120

That's the trick, compress, expand, restrict re-expand and compress. Then find the resonant sweet spot
of the pipe. The magic is in the theory of wave cancellation. The only problem that I have run into sometimes is the amount of space all the extra stuff takes up.

[Jerry Liebler]

I happen to have a Radioshack sound level meter & I checked the website that WEC4104 gave a link too so I had to find out how quiet my genset is, the best on the chart is 75 DB but that's fully loaded no doubt.   I couldn't really load it up, but at about 1/3 capacity (both AC's running off of it).  The highest readings on the 'a' scale that I got 3 feet from the bay it's in was 73 DB and around the exhaust outlet again 3 feet from the side of the bus the highest was 67 DB.  So, as I thought it's pretty quiet.
Regards
Jerry 4107 1120