thinking of exploring another option

[BioHazard]

But.... they are huge!

How much do listers weigh again? Take out half the pistons and it's smaller than an iron duke, with a lower torque peak, and more of it. I just wonder if it would run smooth enough? My guess is that it would run quite stable at 1200-1500 RPM with no real need for 1800 direct drive.

[mobile_bob]

removing pistons is not a straight forward proposition, most especially for an inline 6 engine

1. you have balance issues, to contend with

2. you have extreme torsional issues to contend and overcome, otherwise a broken crank will result

3.  you have oiling issues, the crank will bleed off oil pressure through the big end holes, and

4. you will have issues with simply removing the rockers, and pushrod, because the lifters will need to be
retained in order to maintain the oil system integrity

and likely a few other issues as well will come up, some of these and others can be worked around fairly easily while others not so
easy.

for my money, either find a suitable small engine to start with, or cycle the larger engine so that it matches the loads both thermally and electrically
this will likely require some form of battery storage or grid tie, or a rather elaborate management scheme with combination of one or the other.

screwing around with taking out cylinders from an inline 6 or even a v8 is just asking for problems, lots of problems.

other possible problems are ignition related, with crossover arcing because of vacant holes, burnt out distributor caps and rotors (yes this happens if you run
the chevy vortec with a dead hole for any length of time, and can't imagine it would get better with multiple dead holes) coolant flow issues, are likely also to be a problem, with half the engine being cold and the other half hot?

while it is fun to speculate on what is possible, i think it would be more fruitful to work with what is known to work as is, a cogen project that is most successful
is a big enough hurdle to engineer and integrate effectively, without the added layers of complications brought on by trying to alter an engine to run on
half of its cylinders.

my opinion only of course.

bob g

[BioHazard]

The bottom line - you are right, it's much easier to start with an engine that matches for the task at hand.

The problem is there is no such thing. Period. Any engine being discussed for this purpose is going to have to be completely built for this purpose. Nothing will be stock about your engine. If I could buy a water cooled, iron, industrial 2 cylinder high compression NG engine with a built in governor, then I'll take one. I don't think it exists...and even if it did parts would be harder to find than anything automotive. (actually something like an Arrow engine would be absolutely ideal for this purpose, but I don't think any of us can afford one)

The only issue I see with killing cylinders is the engine balance. Sorry bob, but a lot of your concerns are unfounded. Air compressors made from half of a Ford V8 are as common as dirt. They run fantastic on 4 cylinders while pumping with the other 4. The engine would only run smoother with pistons removed. We are talking about an 1800 RPM or less red line. Balance might be an issue, but not one that can't be fixed. I don't see why cooling would be a problem, water would still be circulated through the entire engine block. I used to have an old truck with a 454 that was only firing on 7 cylinders...I drove it more than 10,000 miles like that. I didn't even know at first, and have no idea how long it had been running that way. I took out the spark plug to kill the compression in that cylinder after a while.

It really depends on which engine you're trying to kill cylinders on, and which cylinders. Maybe killing half a V8 would work, but half an inline six won't? I'm not sure, but you also have the choice of removing 3 pistons in a row or just every other one. Or maybe killing half of a four banger would give better balance. Sure, it will take some fiddling around to get it right, and it might not work at all...but that can be said about everything we ever talk about on this board. The commercial availability of "multi displacement" engines in cars seems to suggest there isn't a problem with stress on the crank...especially with seven mains. I also find it interesting that most of the 4 cylinder engines talked about so far, are made from either six or eight cylinder engines cut short at the factory.

If you want 'off the shelf', you need to spend about $100k on a microturbine. Otherwise it's going to be a completely homemade machine with a very custom, one off engine. Just the fact that you need to bump up the compression means you'll have to tear the engine apart and do a custom build if you want efficiency.

[BioHazard]

Hell, who's to say six cylinders is too many anyway? Take a look at what Arrow has to offer...
http://www.arrowengine.com/products/Multi_Cylinder/VR_Series.php
The VR330 is a 330 CI inline six. It's rated at 26 HP at just 900 RPM, designed for natural gas.

Some quick fuel calculations show it's about as efficient as any other NG generator...
http://www.arrowengine.com/Tools/fuelconsumption.asp?engine=VR-330

Too bad I'm guessing they cost more than my house...

[BioHazard]

A bit more research shows inline six engines to be inherently balanced, because the crank throws are 120 degrees apart and the front and back pistons move in pairs. This means killing every other cylinder would result in an engine that is still rotationally balanced, but tends to rock front to back more than a six. This could be a problem in a car at 5000 RPMs, but probably not when mounted to concrete at 1200 RPM.

I'm starting to think an inline 3 would be the best option, whether you 'make' one or buy one that was built that way. Four is more than you need, 2 isn't enough...3 balances nicely. A 60 degree V6 running one bank of cylinders could be another option. The extra weight and length of the inline six would help dampen some of the vibration a factory built inline 3 might see.

I'm not "allowed" to spin my meter backwards with an engine, thus without a significant investment in batteries and inverters, an oversized unit would be of little use. If I could just fire the engine up long enough to spin the meter to zero I'd use a huge one...but that won't fly with my power company.

I welcome anyone to poke holes in my theory...but I think inline sixes are more common in junk yards than inline threes, and I still like the idea of having 3 spare cylinders you can use later. You could theoretically seize a cylinder or two (been there) and have the engine up and running again the next day without machine work.

[mobile_bob]

let me explain my rationale further

the reason aircompressor conversions work is they retain the rotating components, right down to the use of a modified cam and lifters

without the use of the lifters you will lose all your oil pressure, because of the way an engine's oil system is typically routed.


while i would prefer a 3 cylinder over a 4 cylinder, i would also have to agree that there are precious few 3 cylinders to choose from.

your report of driving an old chevy 10k miles with one plug removed is something i too have had to do in the past, however it doesn't have much
that applies here, in that the rotating assembly is still intact and the lifters are still in place.  my experience was with a 7 cylinder ford 460 and i suspect
yours was an older and not the newer version of the hei ignition, which is likely what we will be needing to work with when it comes to high compression
ratio's if we want to go that route.   the new caps and rotors will crossfire and they will burn out the caps internal traces killing cylinders in operation.
we can probably get around this issue with some work, but why do we have too?

another issue, is one of efficiency,  we can harness up to about 90% max, the remaining 10% is radiated from the block, if we use half a 6cylinder we just doubled those radiant losses,  allowing us a new ceiling of about 80% max.

i will also say this, i don't want to discourage anyone from doing whatever it is that they want to do, however i would be remiss if i didn't voice my objections
if i felt there were problems with the route proposed, leaving a forum member or someone with the possible outcome less than what it could be, or worse a failure due to some problem like a broken crank, or continual ignition issues, or something else.

youj are also correct in the assertion that there is no one engine that is good for everyone, as there is no way to satisfy everyone's needs, let alone their wants.

although i would say that meeting the real needs of a large percentage of folks could be done more easily with a 4 banger, than would be the case with just about any other engine i can think of that is readily available.

lets also talk about efficiency a bit more, as it relates to the cost of this sort of project

we really don't need to spend a fortune making the perfectly optimized engine, because we are not needing to match the mechanical efficiency of any other engine like the arrow or some others, because what fuel that is burned to make mechanical power is only part of the overall target.

so long as the engine is good enough to burn relatively cleanly, i don't care if it is 20% efficient or 30% efficient mechanically, because the balance of the fuel burned will be recovered as waste heat,  that is the beauty of cogen.  depending on what one needs from a cogen, or rather what his focus is, electrical or heat
will determine how efficient the engine really needs to be.

i would assert one needs to look at the engine more as a furnace than a producer of electrical power, mainly because it is about 3x better at making heat than it ever will be at making electricity.

i would also assert that we would have a higher degree of the expectation of success if we choose an engine wisely and use it as it was designed to be used, or as close to that as possible, and not start off with having to heavily modify the engine.

and there is no way i wanna bolt the engine down to a ton of concrete to tame any issues with balance or vibration, an automotive engine was never designed to tolerate those stresses and i would bet my last dollar that anyone that does this sort of thing will be met with much disappointment.

again these are just my opinions, don't let me be a wet blanket
if you are sure of the outcome, and have the time and money to do it, go for it.

i hope you are right, i hope it works out well.
because if you are right, there will be many more options at a time when our options are few.

bob g

[SteveU.]

Interesting topic guys.
In my humble opinion good engine usability begins at a 90 degree V-Twin. Still got 9 working vertical and horizontal single cyinders I use to prove this point. Yes a watercooled 90 degree V-Twin is a new production rarity - but Kawasaki's and Kohler's are out there.
I have two inline 3 cylinder diesels in my life and have had a few Suzuki/GM Sprint/Metro's too. GM insisted on 3 cylinders versus the  Suzuki four cylinders to get the ~15-20 real world efficiency savings from less ring and bearing drag. I have yet to be able to get ANY of these inline 3 cylinders to run on two cylinders.
But my favorite and most used lifetime engine is the watercooled 4 cylinder. I've not yet had an inline 4 cylinder I could not get useable power out with one dead cylinder and only running on 3 cylinders. I've been from 1098 cc's to 2700 cc's on these - best inherent balance is in the 1600-2000 cc range.
No reason with a gaseous fuel to be so picky on engine choice. Use what you've got or use what is common and cheap around you. Even as much as I've learned to hate timing belts especially when as on the newer engines they insist on water pump driving with these (kills the bearings) one of the reasons for the no push rods/overhead cam design was to allow larger in and out gasses flowing valve porting.
Look here at what can be done:
http://www.youtube.com/watch?v=wKMlCqkloF4
DANIEL, woodgas fueling a Toyota OHC 22R 4 cylinder engine belt driving a 3 phase motor for 240 volts 69 amps (16.6 kw).
I have no Grid tie possiblilities or desire so would just go with as small of 4 cylinder as possible.

Regards
Steve Unruh

[mbryner]

I don't know anything about this topic, so don't beat me up too much.   Biohazard gave a link to the Arrow engines.   I notice they have single cylinder oil-field engines w/ huge flywheels and rate below 10 hp @ 400-800 rpm.   Looks like a modern-day gaseous lister.   Appears perfect for woodgas, NG, LPG....   Are they just really expensive?   

[mobile_bob]

i would be shocked if you could by any of the arrow engines, even the singles, new for much less than 10 grand

however i haven't check into one in a very long time.


going back to the cutting off half of an inline 6 cylinder or half of a v8
to what end?

we can get 4 cylinder engines fairly easily between about 1.3 to 3 liters just about anywhere.

the reason i like the pushrod engine's is based on their ability to make more bottom end torque
where generally the overhead cam style, requires much more rpm to get into the gains made possible by this design.

the former statement of course is a general one, and this is not by any means all inclusive.

as for comp ratio, i don't see the need to go over what is commonly available, with engine's available with 9:1 that is good enough
by me, and likely would present fewer problems down the road than one optimized for natural gas running 15:1 ratio.

with some of the enigne's available with low miles from the bigger salvage yards  for ~300 bucks, why not just use em like the top fuel boys
did with the hemi's in the 50's,,, where they pulled salvage  engines on monday-thursday , then mounted them with blowers and nitro on friday, saturday
and ran them till they puked, and went and got another one.

granted they might only have gotten a few runs out of a junkyard engine, however i don't think we will be asking the same sort of performance as don garlits did back in the day.

it lust seems right to use what is widely available, relatively inexpensive, and readily adaptable to our application, that way more of us can work with a specific engine, or family of engine's, leaving us the ability to develop all the ancillary parts without having to reinvent all the varied wheels  involved.

if that makes sense?

what i am not suggesting is going out and buying an engine if you already have an engine such as an inline 6 you want to remove cylinders from, or alter in some way,, however if you are faced with going out and buying an engine, why buy one that needs anymore alteration than is necessary?

bob g

[SHIPCHIEF]

Why are you guys beating your heads against the wall?
ONAN made tons of these engines. Lots of boats had water cooled MCCK 6.5 gensets. 1800 RPM.
I have a few CCK air cooled units, in 4 Kw and 5 Kw.
MCCK engines are higher Kw rated than the air cooled ones because they can carry away more heat.
They are sized right for house hold Co-Gen.
I'm having a hard time finding the high compression heads, but a web ad for them has a nice picture and CC volume, so I can weld in and mill a standard set to get the compression ratio up. (from 5.5:1 to 7:1)
with a condensing exhaust heat recovery system, total power plant efficiency will be over 90%, heck you could get an EnergyStar rating!!
My house has an oil fired hydronic heat system. It has an old Crane 'Sunny Day' cast iron sectional header boiler. I'm going to change it out for a natural gas boiler. The Zone Control heat system has the possibility of back feeding heat from the Co-Generator, so even if it doesn't add enough heat to the house, the boiler could fire and supply the remainder.
Although we get several power outages per year, the natural gas has never had a failure in over 50 years. My son Peter completed his Natural Gas powered back up generator last week. It's an ancient ONAN 705CW 7.5 Kw plant, an opposed twin like the later models, but with removable cylinders (!) It carried the whole house and shop with ease. No fuel tanks, no mess, no smell, and with the motorcycle muffler, very quiet (out side). 

[BioHazard]

Don't get the wrong idea bob...I'm not trying to fight, like I said, feel free to poke holes in my theories. That's why I post them here first. As for mechanical efficiency, I want as many kilowatts as I can squeeze out of a therm of gas - because I have a much greater need for electricity than heat.

Are they just really expensive?  

That would be an understatement. Search "Arrow engine" on ebay.

Why are you guys beating your heads against the wall?
ONAN made tons of these engines. Lots of boats had water cooled MCCK 6.5 gensets. 1800 RPM.

That would be great, if I can find a junkyard that has a pile of them out back for $300 each. I have been looking on ebay and craigslist for just one, and have yet to find it. Parts? I'm sure many can be ordered from the internet...but for how much longer?

I'm sorry but I just don't think ANY other engine MFG can compete with GM or Ford for engine and parts availability, prices, and long term support...

What we're looking for is the "350 Chevy" of cogenerators. The 350 has been in continuous production since 1955, all around the world. Parts are available in any country for peanuts. The engine has been used in everything from cars and trucks to boats and planes and even generators and other industrial uses. It's just too big for what most of us need...

[BioHazard]

I've really been studying the Arrow 4 and 6 cylinder engines and I wish I could afford one. That will never happen. I can however copy it.   Their literature is an interesting read for a generator geek. Something noteable, the 4 cylinder engine comes with an optional balance shaft that "greatly reduces vibration", while the inline six does not get the balance shaft because it doesn't need it. (their 4 cylinder is 4.2 liters) About the only thing I can't copy are their wet cylinder liners, but I don't see that as being very important. For a governor they use either a mechanical unit gear driven off the front of the engine, or newer models come with an electronic version. I like their CDI distributorless ignition system. They also have a newer cross flow head for their engines, which claims a 6-8% increase in efficiency over the older head. Most of that stuff could be fitted to an iron duke.

http://www.arrowengine.com/Literature/VR_Series.php

Inline six would be overkill for most houses but it's probably the smoothest running/longest lasting engine you'll find. I think it might be the right size for the new shop I'm planning. My boat has a 1.6L inline six, too bad it's a 2 stroke, that would be great in a 4 stroke.

Maybe I'm overcomplicating things, but you're talking to a guy who cleaned and sorted 50 tons of gravel by hand for a barn floor...because it was too dirty.

[mobile_bob]

Bio

i don't think you are over complicating things at all, as a matter of fact having this discussion likely will work out at least some of the
kinks and at least lead us to what likely will be the best group of alternative engines for this use.

otherwise we end up using what we got, and maybe that won't be the best use of our time and resources.

i have found this to sadly be  on of lifes truths, often times when i try to use what i have and get in a hurry, the end result is somewhat less than
what i had hoped for.

then when i look back that part that i had on hand that saved me 300 bucks in first cost, turned out to cost me many times that in the end
and then even more over the life of the finished product due to lower efficiencies and other problems.

i guess what i am saying is, one would hopefully gather from discussions like this one that perhaps he might be better served to use an iron duke
rather than a pristine vega motor he either has or can pickup for free from a buddy down the street.  i know this is an extreme example, but i think it
illustrates the point.

even if we conclude from this discussion or another , that perhaps removing rods/pistons to reduce displacement as being not the direction to go, perhaps
we still learn something from the discussion that might be useful somewhere else down the road.

besides i don't think anyone can be anymore "anal retentive" than i am.



for me at least i think i have boiled it down to the following engines

the iron duke, the volvo, or perhaps the topaz/tempo 2.3 from the automotive world, each has its strong points i guess.

i am also considering putting in a coin op laundermat on the opposite corner of my property, laundramats are useful in town and there no longer is
one in the little town i am relocating to. this would do two things for me,

1. i could get commercial nat gas rates, which cuts the cost ~30%

2. laundermats need lots of hot water,

3. the waste electricity could be moved over to my house for direct use.

4. i might even make a couple dollars off the laundermat from normal operations?

that was one thought anyway.

another was building perhaps a 6 plex housing project of high efficiency units, where i could rent them and include the utilities,
and balance the demand between the cogen and the utility company.

i think there would be enough heat load year around to supply me with paid for electricity as a waste product of the system, certainly
in the winter months this would be so, and the cost of rent includes the cost of the nat gas anyway,, and i am not sure but i might also
qualify for commercial rates.

another alternative is the shop idea like you have,
if i put in a repair shop it can probably pay for the cogen operation and i can borrow some of the work products for the house
and have the shop/business write off the cost.  this is a little sticky, but if setup right probably could be done in an irs friendly manner.

in the end however in my opinion the holy grail will be a continuous operation absorption chiller that can provide A/C from the waste heat
of the cogen, that would make the unit vastly more efficient over the balance of the year where cooling is needed more so than heat.
if we ever get there, then we have really arrived in my opinion.

bob g

[Henry W]

A gas turbine? http://cgi.ebay.com/TURBINE-GAS-ENGINE-GENERATOR-SET-/200436078003?pt=BI_Generators&hash=item2eaaebd5b3

[rl71459]

What kind of fuel can a gas turbine be run on?