Repower Question - Repurpose Deere Genset as Propulsion Engine?

Hello - I have been looking more seriously this year at repower options for our trawler and I'm curious if it's possible to repurpose a constant speed generator engine to propulsion?

Specifically a Deere 4045AFM85 constant speed at @121 KW which would be about 160hp.

If it's already configured as a marine genest (heat exchange cooling) would it take much to convert to variable speed? I can keep our current MG502 2.1 gears so it should mount up pretty easily.

As to the repower itself - we have a pair of 8.2's (225hp) that have been great. We love the boat and plan to keep her so I want to consider better options for long term maintenance over the next 10-15 years.

Already priced out Cummins Reman 210 6bt which would fit just fine and top out the budget, but also researching potential RTO of smaller common rail engines (4045, Volvo D4) as we would love to gain a bit more space in the engine room and possibly be bit quieter than the 6bt's. Mechanical Yanmar 4LHA could also be an option but may not be as smooth at hull speed from what I've read.

I would like to keep at least 150hp on each side - even though we'll cruise at hull speeds most of the time she will get up nicely at about 13 knots.

Thanks!

I have a 4045 and it's a great engine. Imo, there are a lot of unknowns converting a constant speed generator engine to propulsion. My guess is that you would need to talk to a Deere dealership that services both. What tier engine is this? Is it computer controlled?

Ted

My guess, and it is just that, is that an older completely mechanical engine would be easier to repurpose than a common rail engine.

There's a governor in the injector pump. It's probably different for constant speed.

Ditto on talking to a JD dealer.

A good and competent JD dealer…

I can't answer but I just just thought that the cooling system may have to be upgraded.

THe existing MAY be designed for the heat load from a gen engine operating at 1800 or even 1,200 revs.
If so then the question is if the cooling system is adequate for an engine that may well be working harder thus producing more heat than working as a generator.

Of course you will need a raw water pump unless this unit is a marine generator.

THe other thing that comes to mind is the injector pump will need some reworking to allow for variable speed.

You should talk to a good dealer or a distributor. Sometimes getting ahold of the two parts books will answer a lot of questions.

JD dealer is on the list to contact and a dive into the parts catalog too. Believe it is electronically controlled - all the AFM references I could find are, that made me wonder if it can be a program setting.

More to come - thanks

Sailing Uma, one of those millennial sailing channels, bought a smaller generator engine as a bargain. They were unable to cost effectively convert the injection pump and governor. They ultimately converted to electric drive. Might be worth researching their channel. It's been a couple years but I seem to recall they made a gallant effort to convert a generator engine.

Peter

I talked to a friend who is knowledgeable in both JD propulsion and generator engines. In short, mechanical engines are fairly easy to convert. Electronic engines are not. There are barriers to conversion in place both by OEM and EPA regulations.

Peter

I'm finding out similar information. Thanks for all the feedback.

The research continues...

this seems like a good idea on the surface but maybe one of those mods that is designed to save money in fuel that cost 20 times the potential fuel savings...and nobody is happy..

I'm curious what has you considering this path? The 4045AFM85 is a current model engine. Are you looking a new engine that just happens to be set up as a generator engine? Or are you looking to pull an engine from an operational genset? Is it a question of cost, or of availability?


You have some responses from people who seem to have dealer-level knowledge. I do not, but I do have one of these engines in my boat. The throttle control is electronic, so I would expect the constant speed to be maintained by some external controller commanding the engine speed. It seems to me that the engine package itself should be the same.


I'd be real interested to hear exactly what's different between a propulsion vs generator variant of this engine.

twistedtree said:

I'd be real interested to hear exactly what's different between a propulsion vs generator variant of this engine.

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One of the difference would be the computer software. On my engine 4045TFM75, there were 3 HP ratings. To change between the 3 ratings only required reprogramming the computer ($800 +/- 7 years ago). While I'm sure there's different software for constant low speed generators, there may also be a different computer. The computer and wiring harness might not have the provision for an external speed control as the engine computer might control those functions.

Ted

Have you priced out the NA Beta Marine? Regarding the JD 4045 don't the mechanical injector ones use a Stanadyne injector pump? If so and governor equipped that would be about $2,000 each before install, filters etc.

As mentioned by Clectric the coolant pump and HXer require checking out to assess if they match up to a non genset JD marine propulsion engine. If not, add a few more thousand per engine.

Whether Beta, JD or 4 cylinder Yanmar you'll have a lighter boat but likely not have the speed of the 8.2s.

If there is a specific engine being considered, a picture of the sticker on the top with all the option codes would tell the whole story. Those option codes will spell out the exact engine config and can be matched up against a propulsion engine.


Generator engines and propulsion engines are subject to different EPA requirements, and as such need to be separately certified. But if you set that aside for a second, I really question what material differences there might be. Maybe the generator engine has no throttle input and is programmed to always and only run at 1800/1500 rpm. Or maybe it uses the exact same throttle input as the propulsion engine and expects an external controller to command the desired rpm, just like a propulsion engine. I don't know. Other than that, I don't know why it would be any different assuming it's set up for sea water cooling. But I think the option codes would answer all of this.

I bought an 18 year old Lugger generator 6 cylinder about 160 HP, and rebuilt the motor compete and they converted the governed fuel pump to a throttle arm with no problem at all.

Have you thought about removing the engine(s) and using your generator to power an electric motor for propulsion?

I've been thinking about it as an option but haven't done much research on it. Since the generator uses less fuel than the boat engine, could it power an electric motor to drive the transmission or propeller? Just a thought!

ABL said:

Have you thought about removing the engine(s) and using your generator to power an electric motor for propulsion?

I've been thinking about it as an option but haven't done much research on it. Since the generator uses less fuel than the boat engine, could it power an electric motor to drive the transmission or propeller? Just a thought!

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Any time you convert power to a different form, the conversion isn't 100% efficient. Converting diesel engine power to electric costs efficiency. Converting from electricity to power with an electric motor also costs efficiency. This is all predicated on having the most optimal electric motor to propel the boat.

Ted

It also takes a lot of electronic controls to regulate speed and direction of the electric motor. It's not as simple as controlling a single speed motor. And you're switching a few hundred amps. I had diesel electric tugs of about 1500 hp. Generators and motors were 250v DC. I enjoyed the setup, but used more fuel and maintenance than straight diesel drive.

Back about 20 years ago PMM had an article on diesel over electric on a trawler. It was going to be the next great thing. I believe it was a Grand Banks that was repowered. But then they never had any follow ups on it. Don’t really know how well that repower worked out. But if it really worked out well I think we would be seeing a lot of diesel over electric trawlers now.

ABL said:

Have you thought about removing the engine(s) and using your generator to power an electric motor for propulsion?



I've been thinking about it as an option but haven't done much research on it. Since the generator uses less fuel than the boat engine, could it power an electric motor to drive the transmission or propeller? Just a thought!

Click to expand...

Lepke is spot on about the complexity of the control system. O C Diver has it right on efficiency. And consider it takes a given amount of power to move the boat a certain speed. Main engine direct drive or diesel electric, it doesn't matter. You will not see any reduced fuel consumption in typical recreational trawler use.

Diesel electric can offer some benefits. For example ships that have widely varying power needs. Say 1000 HP at the low end to 5000 HP at the high end. They might use multiple Diesel generators to drive one or two propulsion motors. Varying the number of generator sets online to meet the total work load. But those ships need to spend a majority of their working time at the lower power demands to even begin to make the complexity and costs worth it.