Most fuel efficient diesel engine?

[kaseycoleman93]

I am hoping to narrow down what engine to use on my generator build. I'm planning on using a ECP28-S/4(15kw 240v 60hz) or possibly a ECP28-M/4(17kw) depending on the feedback I receive here. Here are my 2 questions:

Which engine would you choose based on prior experiences? Most important for me is fuel economy. Load will generally be around 6-7kw. Perkins, kubota, isuzu, deutz, mitsubishi? I'm hoping to be close to .5 gph. The goal is to have power as cheaply as possible when it's all said and done.

Second question, is using a generator end that has a larger output capacity going to use more fuel spin, at all loads? A 15kw will be more than enough for my needs, now and future. The 17kw is only slightly more cost.

Thanks for any and all input.

 

[sumpower]

All diesel engines consume approximately 0.054 gallons per horsepower per hour,
So a 10 HP diesel consumes about .54 gallons per hour.
Choose any diesel engine that has good local support and consumable parts (oil filter, air filters) availability.

Any difference in fuel consumption with a slightly larger gen head will not be noticable.

 

[Hedges]

Generator directly supplying (probably variable) load?
Or generator feeds inverter/charger, shuts off when battery full? This should allow more efficient operation.

Will you want heat? The waste heat is probably 2/3 of the total energy.

 

[kaseycoleman93]

Generator is directly supplying(baby steps ). Hopefully we aren't too far from a good solar setup.

 

[Hedges]

Running 24/7? How much will loads vary?
If not a steady load, consider including an inverter/charger such as this:

Battery Inverter Solar Cabinet: (QTY 2) SMA Sunny Island SI-6048 w/ Warranty | eBay

These cabinets were designed and built by DC Solar. If you use the cabinet as-is there are only 2 connections required to have a functioning system (battery connection and solar panel connection). This setup will generate power even when there is no connection to the power grid.

www.ebay.com

Or any of many others discussed on the forum.

Generator runs during hours when it won't disturb you, shuts off and lets batteries carry the load.
This could mean getting a larger generator you find a deal on, quickly charging batteries.
Or smaller one, with inverter supplementing power from battery when necessary.


Some of these trailers come with diesel generator.
Batteries presumably trashed. You would want LiFePO4.
And more PV panels eventually.

https://sfbay.craigslist.org/sby/hvo/d/san-jose-solar-trailer-115kw-with-11kw/7758000007.html

 

[Brucey]

I find this site to be helpful they tend to show fuel consumption rates at least for the diesels, no affiliation

https://www.centralmainediesel.com/

 

[kaseycoleman93]

Running 24/7? How much will loads vary?
If not a steady load, consider including an inverter/charger such as this:

Battery Inverter Solar Cabinet: (QTY 2) SMA Sunny Island SI-6048 w/ Warranty | eBay

These cabinets were designed and built by DC Solar. If you use the cabinet as-is there are only 2 connections required to have a functioning system (battery connection and solar panel connection). This setup will generate power even when there is no connection to the power grid.

www.ebay.com

Or any of many others discussed on the forum.

Generator runs during hours when it won't disturb you, shuts off and lets batteries carry the load.
This could mean getting a larger generator you find a deal on, quickly charging batteries.
Or smaller one, with inverter supplementing power from battery when necessary.


Some of these trailers come with diesel generator.
Batteries presumably trashed. You would want LiFePO4.
And more PV panels eventually.

https://sfbay.craigslist.org/sby/hvo/d/san-jose-solar-trailer-115kw-with-11kw/7758000007.html

Currently it will not be charging battery's, only powering the home. Loads will vary a little, depending on hot water heater and dryer cycling but a/c and other things will be constant. It's hot here in Texas so our 2 ton ac never kicks off during the day for most of the year.

 

[Hedges]

The goal is to have power as cheaply as possible when it's all said and done.

Generator is directly supplying(baby steps ). Hopefully we aren't too far from a good solar setup.

a/c and other things will be constant. It's hot here in Texas so our 2 ton ac never kicks off during the day for most of the year.

People running diesel generator have calculated $1.00/kWh

PV panels are available new for $0.20/W +/-, also used.
Hardware or GT PV comes to $0.50 ~ $1.00/W, labor for turn-key install adds $1 to $3 more. But you can DIY.
Amortized over 20 years $0.025/kWh for hardware. That would be 6 months break even with diesel.

An off-grid system with battery I don't have as easy an estimate for.

Most of the time, you'll have more sun when there is more heat load. I think you can save a lot of money in a short time with a PV/diesel (autostart) hybrid system. Most of the work is mounting PV panels. Laid on the ground would work but you need to secure against wind. Start with no PV panels, and as you add more the generator will run less and less.

 

[kaseycoleman93]

People running diesel generator have calculated $1.00/kWh

PV panels are available new for $0.20/W +/-, also used.
Hardware or GT PV comes to $0.50 ~ $1.00/W, labor for turn-key install adds $1 to $3 more. But you can DIY.
Amortized over 20 years $0.025/kWh for hardware. That would be 6 months break even with diesel.

An off-grid system with battery I don't have as easy an estimate for.

Most of the time, you'll have more sun when there is more heat load. I think you can save a lot of money in a short time with a PV/diesel (autostart) hybrid system. Most of the work is mounting PV panels. Laid on the ground would work but you need to secure against wind. Start with no PV panels, and as you add more the generator will run less and less.

I appreciate the suggestions, but for now I'm focusing on getting a fuel efficient generator put together.

 

[Backtrack8189]

I have experience with quite a few little diesel motors. Kubota have some the of the most dependable designs. They hold a premium price over the other brands, because those in the know prefer them. They are very fuel efficient. They are found in light plants, diesel generators, and small equipment like commercial mowers.
There is an off the shelf generator that i recommend that mostly meets your specs and uses a Kubota 4 cylinder diesel. Now the price has doubled in the past 4 years, and i would build my own over paying this, but im okay with used diesels and chinese genheads.

The motor that comes with that powertech is a Kubota V1505 which is a 4 cylinder 1.5 liter engine. 4 cylinders is a bit quieter and smoother in a diesel, but they waste a bit more fuel if you aren't running them at 100%.

You might be able to run a Kubota B1305 which is a 1.3 liter 3 cylinder and put out enough power. Keep in mind, you need to pull a spec sheet for an 1800rpm version to get the rated KW or horsepower output at 1800rpm. for the best fuel efficiency, step down to a B1105-T which is a 1.1L version with a turbo.

As far as the genhead, it is good to oversize as more spinning mass gives you surge capacity and longevity, but does increase fuel consumption as the motor has to spin that stator that weighs more. I have the same dilemma in my home built RV generator. I have a B1005 currently mated to a marathon Pancake. Its very fuel efficient as the entire genhead weighs under 100lbs. I can get an 11kw AVR for around $1100, but it weighs almost 300lb.

 

[Brucey]

People running diesel generator have calculated $1.00/kWh

This seems on the high side, if we are just considering fuel costs and not lifetime costs of generator, the prime power rated generator that Backtrack linked is rated at 12kW with 1.1 gph.

Assuming $4 per gallon of diesel, $4.40/12= 36 cents per kWh. That's cheaper than some peoples peak grid charges. Still have to pay for the gen tho, but fuel costs don't seem that crazy.

 

[Chispas]

Modern diesel engines need to be run under load or, over time, serious problems can occur, including fires. It's recommended that the minimum load for extended periods isn't bellow 30% and some manufactures recommend at least 50%.

Load will generally be around 6-7kw

Is that peak or constant ?

 

[kaseycoleman93]

I have experience with quite a few little diesel motors. Kubota have some the of the most dependable designs. They hold a premium price over the other brands, because those in the know prefer them. They are very fuel efficient. They are found in light plants, diesel generators, and small equipment like commercial mowers.
There is an off the shelf generator that i recommend that mostly meets your specs and uses a Kubota 4 cylinder diesel. Now the price has doubled in the past 4 years, and i would build my own over paying this, but im okay with used diesels and chinese genheads.

The motor that comes with that powertech is a Kubota V1505 which is a 4 cylinder 1.5 liter engine. 4 cylinders is a bit quieter and smoother in a diesel, but they waste a bit more fuel if you aren't running them at 100%.

You might be able to run a Kubota B1305 which is a 1.3 liter 3 cylinder and put out enough power. Keep in mind, you need to pull a spec sheet for an 1800rpm version to get the rated KW or horsepower output at 1800rpm. for the best fuel efficiency, step down to a B1105-T which is a 1.1L version with a turbo.

As far as the genhead, it is good to oversize as more spinning mass gives you surge capacity and longevity, but does increase fuel consumption as the motor has to spin that stator that weighs more. I have the same dilemma in my home built RV generator. I have a B1005 currently mated to a marathon Pancake. Its very fuel efficient as the entire genhead weighs under 100lbs. I can get an 11kw AVR for around $1100, but it weighs almost 300lb.

Thank you for the great information! I am leaning heavily towards Kubota. I was about to go look at a v1903(23hp @1800) but you have me second guessing myself. Is it too big? I will expand my search to include those models you listed. Thanks again!

 

[kaseycoleman93]

Modern diesel engines need to be run under load or, over time, serious problems can occur, including fires. It's recommended that the minimum load for extended periods isn't bellow 30% and some manufactures recommend at least 50%.

Is that peak or constant ?

That would be the load it would see 75% of the time. Doesn't include hot water heater, dryer, or water well and septic.
I am able to consume much more power occasionally to prevent wet stacking. But I'm thinking with a 15kw, 50% load should be good to stay on top of it?

 

[Chispas]

That would be the load it would see 75% of the time. Doesn't include hot water heater, dryer, or water well and septic.
I am able to consume much more power occasionally to prevent wet stacking. But I'm thinking with a 15kw, 50% load should be good to stay on top of it?

The engine manufacturer should be able to tell you about this, but one way would be to fit an exhaust manifold temperature probe, an EGT, something that Diesel Landcruiser owners do, but they're more concerned about overheating.

 

[Backtrack8189]

Thank you for the great information! I am leaning heavily towards Kubota. I was about to go look at a v1903(23hp @1800) but you have me second guessing myself. Is it too big? I will expand my search to include those models you listed. Thanks again!

A 1903 would be a good size for 15kw. All my suggestions would be to be the most fuel efficient, but 15kw would be about all those motors would reliably handle. I would like to have some unused output to not the load the motor as much.

 

[Backtrack8189]

That would be the load it would see 75% of the time. Doesn't include hot water heater, dryer, or water well and septic.
I am able to consume much more power occasionally to prevent wet stacking. But I'm thinking with a 15kw, 50% load should be good to stay on top of it?

I agree that diesels need to be worked however I have seen light plants have 30,000 hours in them and still run. Many times they don't pull over 50% load and just idle for hours on end.. I think if you run a warmup and then charge a battery or go over 30% load often, you are good. Also, consider running 2 stroke oil mixed 128/1 with your fuel and it will lubricate the cylinders from being washed with fuel.

 

[kendive]

I have one of them U.S. G.I. 3kW Diesel Generator MEP-831A single cyl diesel inverter generators. I don't know what it uses for fuel but it seems to run forever on a small tank of fuel.

I picked it up for about 400 bucks and fixed it up and runs like a champ. It's really just a backup for the cabin that I mostly run on solar.

 

[ksmithaz1]

This seems on the high side, if we are just considering fuel costs and not lifetime costs of generator, the prime power rated generator that Backtrack linked is rated at 12kW with 1.1 gph.

Assuming $4 per gallon of diesel, $4.40/12= 36 cents per kWh. That's cheaper than some peoples peak grid charges. Still have to pay for the gen tho, but fuel costs don't seem that crazy.

Let me know how that works out for you cause I would be stunned if you can get real costs under $0.60/kwh. Maybe if you get a free generator with free lifetime maintenance, powering an optimal load 24x7. Otherwise I think you are dreaming. @Hedges $1.00/kwh sounds pretty close to the mark, maybe $0.75. Further you can't run a generator 24x7x365, you have to shut it off periodically, thus if you want reliable output, you need at least 2, and they will need to be sized sub-optimally to meet peak demand in a generalized scenario. Totally wasteful if not a backup/minimal output/operation/maintenance scene, the local power company can generally produce drastically less expensive reliable power on demand at scale. If you could realistically do it for less big companies would already have platforms to make it happen. The guys that run Wal-Mart are not stupid, thus to the contrary, they make sure the local power company can provide power at their desired levels for their stores before they will build. This is also why a lot of EA charging stations are in Wal-Mart parking lots. If they could throw a couple generators in the back lot and save money, they would in a heartbeat.

Solar OTOH, can be used as a supplemental or primary source, requires very little maintenance, and once installed will continue to put out power for a very long time. The drawback is it takes a lot of real estate for the panels. Today, I would never consider creating any kind of generator only power plant for continuous use unless there was no other option.

Micro-atomic plant might be interesting.

 

[Chispas]

Also, consider running 2 stroke oil mixed 128/1 with your fuel and it will lubricate the cylinders from being washed with fuel.

A proper old school tip but yeah, good advice.

 

[wpns]

Another vote for a DIY hybrid generator, which you can then build into a fully solar system with the generator for backup.

 

[Brucey]

Also, consider running 2 stroke oil mixed 128/1 with your fuel and it will lubricate the cylinders from being washed with fuel.

Never thought to do this but will start on my mowers Yanmar 1.3l 3 cylinder, got some Motul 800 2t we use in the chainsaws and backpack blowers.

 

[Chispas]

It's a normal here to winterise your own Diesel as the refineries leave it as late as possible to add the antifreeze additives to their stock & us folks up in the mountains can get caught out. A litre or 2 of old 2 stroke mix is added to a tank of Derv. The 2 stoke oil is good for lubricating the injector pump. Older diesels were designed to run on high sulphur diesel & a bit of 2T oil isn't a bad thing.

 

[Hedges]

I finally bought Stanadyne diesel additive. Found one that is conveniently a bottle per 30 gallon tank.
I will be using that year round, for pump lubrication.

 

[Brucey]

I finally bought Stanadyne diesel additive. Found one that is conveniently a bottle per 30 gallon tank.
I will be using that year round, for pump lubrication.

I do use Pri-D in my mower to keep it from growing anything.