Author Topic: Which would you choose????  (Read 30801 times)

apogee_man

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Which would you choose????
« on: January 25, 2009, 04:39:11 AM »
Greetings,

Here's my dilemma:

I've been a lurker here for many years.  I've also at one time been a mechanic and while not a "properly" trained machinist, I do have a garage with metal working tools and enough knowledge to be very dangerous.  I also have years of engine building experience...

So here's the thing, I've been wanting a Lister twin for about five years.  Until today, I thought they fired 180 degrees out and my thinking was that I wanted to minimize pulses with a genset..

Today, I find out that they don't fire that way...  (don't know how I missed that...)

So, the dilemma is this, I can either stay the course and find either a 20/2 or 25/2 and slow it down as planned (850 rpm or so) or I can go with a locally available 10/1.

For now this is a hobby genset.  However the long term plan is buy a piece of retirement property someplace far removed from the grid and use it as a prime mover.  As such, I want enough power for it to run my machine tools and whatever else I may want.  My compressor is likely my worst load with a 7.5 hp single phase motor...

I'm specifically curious to hear from the folks who have actually owned the larger twins (rocketboy) to see how they would approach the whole shebang if they were to do it again from the beginning.

The 10/1 that is available nearby can come with a ST12 head so that pair might be a possibility...  I know the genhead is a bit large but the price would be right...

While I'm not a Lister long-timer, I do have a fair amount of experience and am not afraid of the big twin.  For example, my initial reaction to the camshaft issue is simply to remove it during tear down of the new engine and have a pattern made for a "real" one at the local camshaft grinder and simply replace it.

Finally, I also have a real Lister SR2 6.5kw set that I recently acquired.  I haven't even had a chance to play with it to make sure it works.  The point is, I think I have the lower power demand stuff covered already by using this genset.  However, the slow speed larger units are just very appealing for some reason...

Thoughts / opinions?

Thanks in advance for the help!

Steve
« Last Edit: January 25, 2009, 04:55:07 AM by apogee_man »

diesel guy

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Re: Which would you choose????
« Reply #1 on: January 25, 2009, 06:01:14 AM »
Steve,

I don't have a twin and I never will. I don't have anything against the twins if they are used for standby use. But I like to have a generator that can run 24/7, need little work to keep operational and provide the highest fuel economy figures possiable.

That is why I will only run 14/1's and 16/1's. They allow me to have the power of a small twin, with reduced headaches and reliability problems. They have xyzer's offset bolts and hollow dippers, I also installed bronze idler gears.

They have less displacement than the twins but there is something to said about a longer stroke per engine displacement, 5.12 x 5.79 on the 14/1 and 5.12 x 6.3 on the 16/1. The longer stroke singles produce more torque per engine displacement than the shorter stroked twins.

They need to operate at a slightly higher rpm to produce the same given HP output of the twins, but this provides greater stored kinetic energy potential and the greater torque per displacement ratio enables the engine to maintain a more constant rpm level when heavy loads are engaged, with maximum fuel efficiency (the fuel savings alone is substantial when in 24/7 mode). There is also half the loading pressures on the idler gear from a single to a twin.

I know there are people here who would totally disagree with me and I fully understand. I think a offgrid/survival engine should be as simple of a device as it can be, to be the most reliable/durable it can be and produce the work needed to be done, with the least amount of fuel consumed.

Diesel Guy

diesel guy

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Re: Which would you choose????
« Reply #2 on: January 25, 2009, 06:36:12 AM »
One more thing, both singles have the extra heavy, large diameter 23.6" 1,000 rpm flywheels, the highest kinetic energy storage potential possible for a Lister type.

Not nearly as good as the legendary Start O Matic flywheels. But greater than the twins light 23.6" 650 - 850 rpm flywheels and heavy 20" 1,000 rpm flywheels.

Longer stroke per displacement and greater kinetic energy storage potential allows the 14/1 and 16/1 to compete with the small twins, with less fuel.

Diesel Guy

Wizard

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Re: Which would you choose????
« Reply #3 on: January 25, 2009, 07:26:02 AM »
How much these legendary SOM flywheels were?

Cheers, Wizard

Oilengines

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Re: Which would you choose????
« Reply #4 on: January 25, 2009, 08:42:30 AM »
Greetings,

Until today, I thought they fired 180 degrees out


Genuine Lister twins are all 180 degree crankshafts, that goes for the earlier water-cooled and the later air-cooled engines.

Thus you will have two firing pulses folowed by two 'dead' pulses. Sound lopsided when they start up.

360 Degree crankshafts are mostly common on British motorcycle vertical twins.
 
Pare


t19

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Re: Which would you choose????
« Reply #5 on: January 25, 2009, 01:45:43 PM »
I wanted a twin in the beginning... they look so kewl.

I settled for a 10/1

It has enough power to run my entire house, yes it runs faster than a 6/1 or 12/2, but at 1000 rpm it is still slow

I went with the KISS principal after talking to JohnF who sold twins an used them... they just added extra issues that I did not need with my generator...BTW Ontario hydro cancelled the outage last night

There is plenty of room for all of Gods creatures... right next to the mashed potatoes...

billswan

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Re: Which would you choose????
« Reply #6 on: January 25, 2009, 02:00:08 PM »
Hello diesel guy

 I have a question for you?
 
You said "They have less displacement than the twins but there is something to said about a longer stroke per engine displacement, 5.12 x 5.79 on the 14/1 and 5.12 x 6.3 on the 16/1." can I please find out from you what brand of engines the 14/1 and the 16/1 are that you refer to in your post that I borrowed the above line from?

Have you worked on these engines and would you know what the bump clearances are on each one?
I'm assuming both engines are direct injection or not?

Thanks for your time Billswan ;D
16/1 Metro  in the harness choking on WMO ash!!

10/1 OMEGA failed that nasty WMO ash ate it

By the way what is your cylinder index?

mobile_bob

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Re: Which would you choose????
« Reply #7 on: January 25, 2009, 02:25:08 PM »
that 7.5 hp compressor is going to dictate what you will end up needing

as i see it there are at least two possible compressor loads and variants of each

1. a commercial grade compressor with centrifugal unloader, these are the easiest to start because
they keep the valves open on the compressor head until the unit has fully started and come up to full speed.
this dramatically reduces startup current requirments

2. a consumer grade compressor, might have a pressure unloader (some do not) which help to reduce the loading
but not as well as a centrifugal unloader,, so the startup current is generally higher and for a longer period

worst case scenario are the "sears" rated home  owner type compressors, that have the compressor starting against head pressure
these demand the highest starting current.

single phase motors generally require much higher starting currents as well.

bottom line is i think a 10/1 driving a 5kwatt genhead (about as much as a 10hp engine can drive continuously) is going to be
marginal for your needs if you have a commercial aircomp with a centrifugal unloader, maybe barely adequate maybe not if you have a consumer grade compressor with a pressure unloader,, and no way is it going to start up against a tank of air a 7.5 hp single phase sears
"good enough" compressor.

flywheel surge is one thing, but worse case scenario might be 5 times the running current to start the compressor.

btw, compressor loads are some of the hardest loads to start, along with deep well pumps, refrigeration compressors and the like.

personally i think you might be disappointed in a 10/1 if you need the compressor to start without intervention and baby sitting it.

although you might be better off getting a compressor head and adding it to the 10/1 genset? that would be interesting and much more efficient in my opinion. why make AC power with a genhead to feed an AC motor to drive a compressor, when you can direct drive the compressor?

bob g
otherpower.com, microcogen.info, practicalmachinist.com
(useful forums), utterpower.com for all sorts of diy info

apogee_man

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Re: Which would you choose????
« Reply #8 on: January 25, 2009, 05:25:19 PM »
Thanks for the replies thus far!

Compressor is a commercial Ingersoll Rand 80 gallon upright and yes, it does have an unloader.  Don't know if it's centrifugal or not - T30 pump.

Agreed regarding driving the pump directly.  However, then there is the lathe, the milling machine, and the welders...  (you get the picture)

This is why I'd been planning on going the twin route...  Figured that I'd just turn it more slowly and would have the backup power when I needed it.

I've read on the board about guys wishing they'd bought two smaller units rather than one large but that just doesn't make sense to me.  Twice the space, maint, cost, etc...

Doesn't make sense to me about needing to load the twin when one is not drawing a bunch of current.  Is it due to poor regulation on the genhead or poor governor design on the engine?

The fuel use still doesn't seem to be a big issue to me.  Yes, it will use more, but "more" being defined as 3 gal a day vs 1.5 really doesn't seem too bad.  Especially when compared to a small gas unit that uses 9 gal for example.

Finally, do not understand the slobbering issue running one of these under light load.  I do understand that diesels prefer to be loaded, but my thinking is it ought to be fine with a light load some of the time as well... I would contend that the diesel vehicles on the road are at light load approximately 95% of the time and they seem to do just fine.  Anyone willing to enlighten?

I've been thinking that 2/3 of the slobbering issues that I've read about actually revolve around the crankcase breather being painted shut and guys not realizing it, however perhaps I'm completely off base here with the definition of slobbering???

Please keep the thoughts and opinions coming, they're much appreciated!

Thanks,

Steve

mobile_bob

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Re: Which would you choose????
« Reply #9 on: January 25, 2009, 05:47:40 PM »
well ya brought some interesting questions and observations
maybe i can answer a few of them

1. these engine's don't like to run partly loaded, or running at low loads...

basically it comes down to making heat, alot of folks run with hopper cooling and in order to have enough capacity to cool properly
at full loading there is simply too much cooling capacity at part/low load operation.  the engines turn slowly which allows more time for the
heat to be sucked away to the relatively cold coolant, less heat until the engine is not combusting properly and it starts to slobber.

the injection systems play a part in the game as well, the are relatively low pressure injection compared to todays engines. this in itself is not
a problem when operated up to temp and running under load

2. economy plays a significant roll as well, you mention 3 gallon per day vs 1.5 gallon per day...

i guess this comes down to the available fuel to be used, if it is 5 dollar diesel as opposed to "free" waste veggie, it makes a difference
and who knows what the fuel price will be next week much less next year or decade. even the "free" waste oils might very well be legislated out of existance to the diy'er,, who can say for sure. so it would seem prudent to at least recognize economy as being important if not now
certainly down the road.

this also plays in a decision to part load an engine,

the baseline fuel consumption of an engine can be as much as a 1/4 gallon per hour just to turn itself over, add belts and a generator
and it goes up from there, larger engine's can consume even more.

so what happens is the first kwatt generated it the most expensive kwatt, the second splits the baseline with the first, the third splits the baseline with the first and second and so on.

the result being any engine will consume less fuel per kwatt/hr generated if it is working at or near its max capability.

there are tons of other factors that play into this question

while in practice you could use a radiator, electric fan, and t stat to keep the coolant temps up to normal temps to a point
very large engines will still have problems making enough heat to burn as cleanly and efficiently at low loading.

you already have a smaller diesel set, in my opinion that should be the one that carries the load most of the time, and then use
the big guy to carry the heavy loads as needed

hope this helps

bob g

otherpower.com, microcogen.info, practicalmachinist.com
(useful forums), utterpower.com for all sorts of diy info

needenginerunnin

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Re: Which would you choose????
« Reply #10 on: January 25, 2009, 06:43:39 PM »
evening all

living off grid means a change to your life style in most areas, includeing the size of machines you can use.
unless you have deep pockets and dont mind de-cokes every 50-100 hours!
it boils down to the basic's diesels are heat engines and need full operateing temp's evan with rope heaters etc you cant beat a good work out, at the end of the day most are asking them to run on low grade fuel not dino as they were design for by and large.
buy a single or a twin run them at high or low rev's but if want them to last and run well you have to use them how they were designed to be!
if you are going to relay on this set up every day for your needs then its KISS all the way.
less you want to spend a slice of your day mending your genset off grid :-[
it's all well and good building bells and whistles on to a set central heating pumps in the cooling system etc.
but it will go wrong one day and cost you, go back to the start and see what lister did and dont stray too far.
KISS engineering

needenginerunnin
 
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SteveU.

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Re: Which would you choose????
« Reply #11 on: January 25, 2009, 10:13:35 PM »
Hello fellow Steve

You are starting to answer your own questions. You already have an excellent SR2 6.5kw unit for on or off grid baseline use. DO keep this and run it on dedicated dino/bio-deisel. You are now Already proposing to add a second engine/gen  set up. Use this as a "can burn most anything" addition. Whether you run a 10/1 5kw single in conjunction with the SR2 5kw to power your shop or shut the SR2 down and power house loads along with the shop loads when running a 25/2 or 30/2 twin at 12.5-15kw you Are Still going to have two separate set- ups to maintain, repair and keep fueled.
In off- grid generating fuel economy is King. Just check delivery prices on fuel out to the Sticks, the Bush. And used vegi-oil is an Urban fuel source you will NOT be able to get out there. By using two smaller sets and you could stretch  5,000 gallons of fuel out to 5 years versus only 1-2 years with a single big 15kw setup. Something to really think about. Urban fueling can be a weekly endeavor, or at a worst, a single phone call away. Out in the sticks it something you'd best do once a year to last for the whole rest of the year. You learn it gets very cold and dark when you run short of fuel and with snow, ice, blown down trees, mud and road wash outs no delivery trucks will be coming for months. So that 20 gallons US hauled in by 4-wheeler or snowmobile can last you either 2 weeks or 4 days untill you have to do it again. Gets old real fast.
The second most important off-grid factor is a balanced triad of Reliability/Serviceability/Parts Availability. No one of these is more important than the other.
The people with two 6/1's or a 6/1 and a 12/1 have thought this all through.

Regards
SteveU.
« Last Edit: January 26, 2009, 06:33:37 PM by SteveU. »
Use it up. Wear it out. Make Do, or Do Without.
 Electrodyne 12vdc. AC MeccAlte 8.5kw
John Deere 950 w/Yammar 3cyl IDI; Peterson 21" sawmill w/20hp Kohler v-twin; four Stilh chainsaws,  Stilh weedeaters; various Kohler, Onan, Honda, Briggs, Tecumseh singles.

SHIPCHIEF

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Re: Which would you choose????
« Reply #12 on: January 26, 2009, 04:20:43 PM »
Lister SR2 6.5 Kw!
I've got one too. These are very good, and have powered many off grid homes & farms in commonwealth nations.
They can be set up as Start-O-Matics. Mine has a Lima 12KVA 12 wire alternator that can be configured  single or 3 phase and lots of voltage choices too. Incredible unit! :D
I'm converting my home standby from Listeroid 25/2 12KW to SR2 6.5 Kw. I'll keep both for a while, then if all goes well the 25/2 goes to another property.
Ashwamegh 25/2 & ST12
Lister SR2 10Kw 'Long Edurance' genset on a 10 gallon sump/skid,
Onan 6.5NH in an old Jeager Compressor trailer and a few CCK's

ronmar

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Re: Which would you choose????
« Reply #13 on: January 26, 2009, 04:40:38 PM »
Your needs sound like you need 2 generators.  One large enough to run your shop tools will probably be way too large for the typical house.  This is not good for the engine and is not especially efficient for the reasons stated.  If you are going to be out in a rural setting, you will probably want a tractor.  A 3 point hitch mounted generator powered by the tractor might meet the needs of the shop loads depending on how much you need to run them.  I have seen one interesting setup where the generator is mounted inside the shed.  The owner backs his tractor up to the shop wall and connects the driveshaft to the generator head thru a small sliding door in the wall when he needs to run that generator...  When he is done, he drops the driveshaft and drives the tractor away.  This would leave you with a small single cylinder diesel properly loaded to meet the long term running loads of the house.  My personal ideal offgrid setup would include a battery bank and inverter.  This would keep the generator properly loaded and store energy in the batteries so the generator didn't have to run all the time.  It also leaves the door open to future solar expansion...

Good luck on your project.
« Last Edit: January 26, 2009, 08:31:55 PM by ronmar »
PS 6/1 - ST-5.

diesel guy

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Re: Which would you choose????
« Reply #14 on: January 26, 2009, 06:49:25 PM »
billswan,

Bump clearance is similar to injection timing, there is no one setting that is perfect. I wanted to keep the bump clearance and slightly retarded injection timing conservative for maximum durability at an expense of some fuel economy.

If the engine is used for standby use, you can get away with a tighter bump clearance and advanced timing for maximum fuel economy, with reduced durability.

I set the bump clearance somewhere around .035 on the 14/1 when reassembled, the pump timing is set at 16 degrees BTDC.

The 14/1 is a Power Solutions ( Jkson) and the 16/1 is a Metro.

Here is 14/1 specs similar to the Jkson:

http://www.slowspeedengine.com/engines_lg_techspecs.htm

http://www.ameerrajkot.com/htm/engines/14_cbw_di.html


Here is the 16/1 similar to the Metro:

http://www.ameerrajkot.com/htm/engines/16_cbw_di.html


Diesel Guy