Aluminum block vs iron block and BSFC?

[SteveU.]

Sorry Charlie, you are wrong.
To what application, and use, an engine will be put to use has more bearing on your actually used fuels consumption than some BTU's per horsepower hour fancyfi'ing.
B.S.F.C. is a Lab based controlled environment number. Just like our Gov'Mint's EPA mileage ratings.
Your "turbo"; ceramic piston top coatings; must be cross flow heads (why make things harder if you are going to turbo boost anyways??); fewer cylinders must always be inherently more efficient that more cylinders, suppositions are just that: idealized suppositions. Ass-sumptions.

Now you are right that, "you must get out there, do it, run it, measure it." So stop talking and start Doing like all of the active members here.

O.K. You are now strongly leaning toward auto engines, eh?
Ford/Pinto four cylinder 2000 cc SOHC engines. Cast iron. Crossflow cylinder head. Lots of upgrading parts once available - now out there used/cheap. Lots of 2300's had NG kits fitted. Was a Telecom supplied Onan systems standard used engine.
Jeep 4.0 L inline engines. Probably the strongest, stiffest lower end block ever made in a small inline. Lots of distributor to distributor-less ignition possibilities. Lots of currently available upgrade parts. Nope. Not a crossflow cylinder head. One of your compromises choices you will be having to make.
You'd have to make friendly to an Australian fellow like glort and have him ship  you a GM/Holden to get that crossflow "ideal". Or, go back to a rare. rare Pontiac or Willy's early 60's SOHC inline for your ideal domestically. Ha! BMW, Mercedes engines get you there for the big $$$$. Then back to aluminum cylinder heads.
Which compromise you gonna, choose, eh?

And I'd still best you in costs of set up, operation, and maintenance's with the Chrysler 198/225 slant sixes, pumping, generating and mobile applications. I'd cheat. Offloading the coolant and airflow parasitic power robbers.
Back convert it to adjustable rocker arms. With only four main bearings (has a forged - not cast crank) and non-turbo'ed cut in half the oil pumping needs.
Beatcha' by stock-car cheating for end-results.
Actually this is family farmer tech where the year after year fuel use means a real difference in the family's health.
S.U.

[mobile_bob]

it has probably already been mentioned, but how about a dual fuel diesel engine?

the thermoking/isuzu c201 is a 4 cyl engine, that runs forever it seems
my bet is you could either dual fuel one of those or convert one to spark ignition
to burn nat gas only.

or use any number of other 4 cyl diesel engines

those engines are generally very heavy built, relative to a gas engine, the compression ratio is already high enough, and they are not that expensive?

alternatively use 2 or more smaller 1 or 2 cyl diesel engines, that way you can tailor the power to the load more effectively, given your need to have output over a fairly wide range?

without going back and rereading all this, here are a couple more thoughts

it seems to me i read you were asking whether or not you could increase the air to the cylinder and decrease the nat gas and still get it to run... the answer is generally no.

there is a fairly narrow fuel/air ratio where the engine will reliably start and run, getting outside this range will be met with hard starting, loss of power, stalling, misfiring, and possible engine damage, let alone having issues with EPA limits on nitrogen compounds in the exhaust.

if it were me, given what you want to do, i would go with multiple smaller displacement engine's or find a large single cylinder engine from the oil patch that is already setup for running nat gas.

30hp seems like you are looking at pumping a massive amount of water, relative to what most offgridders would have in mind.

bob g

[Number21]

Sorry Charlie, you are wrong.

You know Steve, as long as I've been a member here, I've always thought your posts were generally rude and off topic. This one is no different. I'm trying to have a conversation about the most efficient engine in a specific size, that's it. I should have never told you what I was using it for, I was just being nice, and thought some of you might be interested. There is no "wrong" when I am simply posting thoughts and asking questions. If you think there are wrong questions you should not be here.

Ass-sumptions.

You and Glort are the only ones making ASSumptions. I have not assumed anything, only asking questions. You have certainly made an ass of yourself here. I have not given you enough information about my project to make any assumptions what so ever, but that hasn't stopped you from trying.

The problem here, is that MICRO cogeneration is a dead end, always has been, and this forum is dead, no more than about 4 people ever respond anymore. It's great if you want to share your opinion, Steve, but I'm not going to bother arguing with you about what engine I want to use or why, and I'm certainly not asking your permission, nor do I want your singular advice. Large scale cogeneration, on the other hand, is something that will continue to grow and grow as the years go by, and is an increasingly common subject.

If you had bothered to take a look at the info I posted from Arrow engines, you'd see there is a huge difference in fuel consumption among NG engines. They rely heavily on load, speed, and air flow. Simple things like a crossflow head, turbochargers, compression ratios, and load ratios, have a big impact on the BTU per horsepower consumed. The information is easy to see on a graph from just one engine with varying loads. Your suggestion of a big six cylinder running slow is a bad one, that is not an efficient way to run any natural gas engine. You will find if you read the fuel consumption graph on a 6 or 8 cylinder engine, at 25% load, it burns more fuel per horsepower than at 75% or 100% load. Thus a more heavily loaded 3 cylinder will use less fuel under the same load. Slower engines also have worse BSFC numbers, because the cylinders have more time to absorb heat. And Arrow published some very specific fuel consumption information comparing an inline 4 and inline 6 without crossflow head, and with crossflow heads, the crossflow heads make a substantial difference on the same engine in the same application. Same with turbos. A company like Arrow would not be experimenting with crossflow heads and turbos if they didn't actually do something important. It's not rocket science, the information is highly published and easy to read. I would have to be really stupid to chose an engine that burns 12,000 BTU/HP when there are engines available that burn less than 7500 BTU/HP. That is an INCREDIBLE difference in efficiency! Yes, inline 6's are great motors, and I love them, but they are not efficient on natural gas without crossflow heads, and they are also not efficient at partial load. An inline 6, pushing 30hp or less, will be in the 12,000 BTU/HP range.

So stop talking and start Doing like all of the active members here.

What an incredibly stupid thing to say. I only asked this question 8 days ago. My timeline for getting this done is absolutely none of your business. And the vast majority of what is talked about on this forum is theory that is never actually put into use. With that kind of attitude I'm not going to bother to come back and share my results. This kind of attitude is why this forum is dying...or pretty much already dead. "All the active members here"...what "active members"? Have you seen how dead this forum is? Most of the people that still post here don't even have an operational cogen system!

And I'm willing to bet a thousand dollars that those pinto/Onan engines you speak of were never optimized for natural gas, and wasted a shit ton of fuel. Fuel efficiency was likely one of the last things they had on their mind. Even today, small automotive engines used in generators for natural gas are not usually optimized for the NG, they are simply low compression gasoline engines fitted with a mixer. If you are a telecom company, gas is cheap, waste away. I am not a telecom company.

If you want to make any further replies here:
The subject is highly efficient variable speed 30hp natural gas engines. Nothing else is acceptable to talk about here.

[Number21]

it has probably already been mentioned, but how about a dual fuel diesel engine?

the thermoking/isuzu c201 is a 4 cyl engine, that runs forever it seems
my bet is you could either dual fuel one of those or convert one to spark ignition
to burn nat gas only.

or use any number of other 4 cyl diesel engines

those engines are generally very heavy built, relative to a gas engine, the compression ratio is already high enough, and they are not that expensive?

alternatively use 2 or more smaller 1 or 2 cyl diesel engines, that way you can tailor the power to the load more effectively, given your need to have output over a fairly wide range?

without going back and rereading all this, here are a couple more thoughts

it seems to me i read you were asking whether or not you could increase the air to the cylinder and decrease the nat gas and still get it to run... the answer is generally no.

there is a fairly narrow fuel/air ratio where the engine will reliably start and run, getting outside this range will be met with hard starting, loss of power, stalling, misfiring, and possible engine damage, let alone having issues with EPA limits on nitrogen compounds in the exhaust.

if it were me, given what you want to do, i would go with multiple smaller displacement engine's or find a large single cylinder engine from the oil patch that is already setup for running nat gas.

30hp seems like you are looking at pumping a massive amount of water, relative to what most offgridders would have in mind.

bob g

Thank you, Bob, for posting something extremely useful, as always. If only we had 10 Bob's around here.

I have considered duel fuel engines, but, I need to calculate the total fuel consumption, including diesel, and decide whether it's worth the increased cost of diesel. Diesel cost more but I also think it makes the natural gas side burn more efficiently, so it might equal out. My gas rate is only $0.52 per therm, and offroad diesel is around $1.60/gallon right now. Diesel will likely rise, while gas will probably stay the same for the foreseeable future. It's also nice because my engines would continue to function on full diesel in the event that natural gas supply is disrupted, however unlikely that is. I also might be able to burn some of the waste oil I produce.

And you are absolutely right, I need several smaller engines working together, that can be turned on and off independently, not one giant machine. That has been the entire subject of this post, and a few people can't seem to get it through their heads. Too bad there are only 4 people on this forum....

let alone having issues with EPA limits on nitrogen compounds in the exhaust.

Just to be clear - if I could find an engine that ran economically on old tires and ground up baby whales billowing black smoke, I would. I have no EPA concerns of any kind.

[glort]

I have not given you enough information about my project to make any assumptions what so ever, but that hasn't stopped you from trying.

You also haven't given enough information for anyone to really help you here.  Carrying on about BSFC endlessly is not the be all and end all you make it out to be as several now have tried to tell you but you seem to have a Fixation on it and frankly are giving me the impression you are more interested in what you want to hear rather than real solution's and facts to what you want to do.

No, I won't be spending millions on this project, I find that quite laughable. I suppose it might approach near a million when I'm all done.

Really? That's amazing! You are going to build 20 factory units/ homes with Hydronic heating and cooling and everything else for under $50K per unit?  I'm no builder and I live in a different part of the world but I think if you can do that anywhere in a first world country, you are doing something incredible!
Here in Oz it cost you $100K just to build a granny flat by the time you get approvals, certifications, electrical, plumbing and everything else and they are only 1-2 Bedroom places with a max of 60 SqM.
If you can knock out full size homes with Hydronic heating and cooling for under $50K each let along everything else this project would need such as roads, utilities to these places, planning approvals and certifications and the other myriad of costs involved in a 20 building project let alone the cost of the buildings themselves, Then I think you are going to be a very wealthy man indeed.

If you have some sort of magical trick up your sleeve to accomplish that, it will be amazing, if you don't and are naive enough to think you can pull off that major Miracle without some sort of magical trick, then I think it's more than laughable that you think you can.

If you want to make any further replies here:
The subject is highly efficient variable speed 30hp natural gas engines. Nothing else is acceptable to talk about here.

I have considered duel fuel engines, but, I need to calculate the total fuel consumption, including diesel, and decide whether it's worth the increased cost of diesel.

Sorry, Diesel engines are not acceptable to talk about here apparently but as you bring it up..... 

Just to be clear - if I could find an engine that ran economically on old tires and ground up baby whales billowing black smoke, I would. I have no EPA concerns of any kind.

then why aren't you looking at engines that run on waste oil? You are not going to find a more economic fuel than free now matter what your efficiency.

In any case, if the arrow engines are so good on NG, just go buy one of them.

Too bad there are only 4 people on this forum....

Please feel free to ask your questions on other forums. I certainly won't be offended and I'm quiet sure the other 3 people here won't be either.

Good luck with your project and let us know what you come up with once your project is up and running and what the final cost of your grand plan ends up being. .

[Number21]

If you want to make any further replies here:
The subject is highly efficient variable speed 30hp natural gas engines. Nothing else is acceptable to talk about here.

then why aren't you looking at engines that run on waste oil? You are not going to find a more economic fuel than free now matter what your efficiency.

In any case, if the arrow engines are so good on NG, just go buy one of them.

Waste oil is not free in industrial quantities anywhere in the world, never has been, and never will be. If it was somebody would buy it. Arrow engines do not meet the qualification of low cost and readily available. Does not mean a similar engine could not be built from automotive stock. Arrow engines are great examples because they publish a lot of really accurate, highly detailed fuel consumption information focusing on natural gas.

As for your other comments, I'm not even going to begin to have a conversation here with you about real estate, and you definitely have no idea what I'm doing, and no knowledge of construction prices in my area. If you can't stay on topic find somewhere else to post.

[Tom T]

Ok I have been off line foe a while  got back on and found a complaint that some one thanks things are getting out of hand read through all posts  so every  one just settle-down back up take a deep breath or two or more if needed and be nice or this thread will be locked.     Tom T.

[EBI-WPO]

Been reading this with some interest, mixed with a small amount of dismay. It's true that interest/participation is down compared to a few years ago. Someone always comes along with out of the box thinking, and a lot of true innovation has resulted, along with some true dead-ends. There is a lot of hard earned knowledge available from some true innovators on this site, and it should not be taken lightly, no matter how much you may disagree. As advice is asked for, advice given should be taken, sometimes for face value, sometimes with a grain of salt, that's all......past that, it's ones own decision, HOW to act on it. It's a FORUM, not a fight club.

I do have a question for Number21's lineage, have you been a member here before? Some of the arguments/outlooks sound painfully familiar.

Just sayin'......

Terry

[glort]

Waste oil is not free in industrial quantities anywhere in the world, never has been, and never will be.

Ummm, sorry mate WRONG again.  You can get all you want FREE where I am, always could.    It5's so free in fact, some people will pay you to take it!

If it was somebody would buy it.

HUH???
If it was free, why would someone buy it??
IT"S FREE!!   

Arrow engines do not meet the qualification of low cost and readily available.

Well I can't speak for your definition of low cost, but it took me about 30 sec to find a heap of the things at what I consider very reasonable prices for what they are and there is certainly no argument about freely available.
There seems to be more than any single entity could want, in any size they made.  They are as readily available as anything else you can buy. Pay your money and take them away. Dunno how more readily available they can be than that?

I had never heard of them before but clearly, although somewhat specialized, they are neither rare, hard to get, unique, hard to get parts for and there is a ship load of them around. They are the staple of an entire industry by the look of it and also a very tried and proven engine going back decades so I'm not sure what you would need to test and muck around with for your needs.  They have obviously been used for pumping and generating for a very long time.

Either you are very short of a quid or haven't  looked too hard for these things.