Repower Options

R_p_ryan said:

I have a Perkins T6.354 but I would opt for a 6bta because they are so common and proven. There are tons of options for the 6bt and you'll be able to find parts and know how if you find yourself in Sitka or San Francisco.

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Dittos here, you will not be disappointed with a Cummins B.
Ski and djmarchand are spot on, running at low power does not hurt these motors, mine often runs all day and night at 1300, sometimes with hours of idling, and there is no problem.
If there is a problem, you will not find a larger distribution network, or cheaper parts in ANY comparable motor.

I have a Mainship 34 with the 6bt that the PO put in to replace a working Perkins for some of the reasons discussed above. But in talking with him I got the sense that he ended up doing more conversion work than he bargained for. Original BW transmission was used, but to do it right the boat needed stringer reinforcements, larger shaft, new prop, new exhaust system, and larger raw water intake. In your case the transmission may fit but probably wouldn't be spec'd for that much torque. So don't overlook the peripheral requirements associated with replacing your existing with something 2x bigger.

I agree that there is little harm in having a larger motor, just don't forget the scope of modification needed to accommodate one.

Boat diesel has some very good tools and resources.

To install twice the amount of power that you need is stupid any way you skin it.

But here's the good part .. I've expressed my opinion and I'll coment no further.

I have a pair of the Cummins 6bt's, turbo but no cooler, rated at 165 HP, run at 1800 rpm. Did a top end at 12,000 hrs, now at 14,000 hrs.

Only thing I would look into changing, is that the turbo hangs at the back end after #6, over the bellhousing. There is an option to center mount the turbo above #3 & 4 cyl's and I think that would have been a better setup. I can definitely see the exhaust temp increase in each progressive cyl from 1 to 6 leading into the turbo, I think a center mount would have balanced the exhaust temps better.

I was wrong.
My apologies to Ski and any others.


The problem is the turbo. I've always been supportive re the turbo engine in boats and many to most have come over to thinking they are OK. But that's a different issue than talking about power in a boat.

When I was shopping for the engine for Willy and was questioning power of several engines my "expert" adviser said to think in terms of engine displacement .. not listed hp. I'll bet a modern engine w turbo would have about 150-200 cu in for a 200hp engine. Despite the 200hp rating the engine would be considered too small. And on the other hand if Bob installed a 200hp NA engine it would be huge .. 500+ cu in.

That brings me back to Bob's boat and reflecting on what I've thought of the GB boats re powering. 117hp in a 40' boat is at least a bit underpowered for a SD boat and would be more appropriate for a FD hull. So I can relate to Bob's thinking a little more power would be a good thing.

So the reman Cummins is more power than Bob is probably going to use but it seems to be a very very good engine and tolerant of some underloading so I agree it would be a very very good choice.

Re other engines FF's IH would cost peanuts compared to the Cummins. And coming in the middle somewhere would be industrial engines like from Klassen/Yukon. Also I think that a turbocharged 150-200 cu in engine would be a bulletproof power choice but personally know of no modern engines in that range. Perhaps Volvo, Lugger, JD and others have that choice in engines. Westerbeke and Vetus are much like Yukon/Klassen type engines but w aluminum manifolds and better paint jobs.

There are probably lots of choices but the Cummins is going to be hard to beat. And may only be bested re cost. But a reman Cummins is no doubt cheaper than a Lugger or a Deere. And the Yukon/Klassen - Westerbeke are probably cheaper than the Deere. And who knows of 150hp engines that could/should be thrown into the pot?

I have found reman and NOS engines to be easiest to price in Boats and Harbors.

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Very interesting FF,
I see a Willard ... inflatable.
And a motorsailer w a 60hp Lugger engine.

There is a huge power range in some marine engines due to turbocharging. The NA Cummins 6B mentioned earlier makes 120 hp. With the same displacement, but apparently a new engine design in addition to the common rail injection, Cummins gets 480 hp out of a QSB 5.9 liter block.


You could almost certainly cruise the NA 120 hp Cummins all day long at 100% of power. But the QSB 480 should be limited to about 240 hp or 50% continuously. The high hp engine does have better metallurgy, much bigger cooling system, piston oil jet cooling, etc that allow it to hit 240 hp continuously and 480 for short periods.


But back to the OP's needs. A remanned Cummins 6BT 210 hp engine should cost somewhere in the low $20Ks with everything new. Transmission, mounts, adaptation of stringers, etc are all extra. I will bet that is competitive with a JD 4045, a rebuilt Lehman 135 or Perkins 6.354, etc. With all due respect to Eric, a marinized industrial engine leaves me a little cold. You might save a few bucks but if the **** hits the fan I would prefer to discuss it with Cummins rather than a PNW marinization shop.


The other alternative mentioned above is a JD 4045, NA if the 80 hp is ok or mildly turbocharged if you need more power. That engine should be able to run 100 hp continuously if turbocharged. The shorter engine will leave more room in the engine compartment and it is a balance shaft 4 cylinder so it should be smooth.


David

Jeff F said:

I agree that there is little harm in having a larger motor, just don't forget the scope of modification needed to accommodate one. Boat diesel has some very good tools and resources.

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The OP's motor, assuming a 6 cylinder, is about the same footprint as the 6BT. BTW, Art DeFever loved torque and cubes for offshore work. Low cruise RPM (1400 to 1800) with reserve power for big seas when needed served him and his 1,600 or so vessels designed very well.

David,
I'm shocked. The rebuilt FL and 6-354 Perky would cost as much as a new 4045JD? Who would buy the old engines?
I hear you on the "industrial" connection. I prefer it though as I get a custom marineazation that way. Got a steel manifold, remote lube oil filter, bronze Jabsco seawater pump (via belt), pre-wiring, lube oil extractor and other features I've forgotten. And I have no reason to doubt the engine itself isn't excellent. And re "**** hits the fan" I'd rather deal w the old Klassen team than Cummins. I've seen first hand what they've done in northern Canadian and southern Alaskan waters over the years. But Bob or the average customer wouldn't have that benefit .. but the force would still be there .. at least w Yukon. But no offense David and in the general marketplace your point is well taken.

Being able to run the NA 120 Cummins at or near WOT would be essentially the same as getting a more powerful engine for Bob or anyone else walking this trail. Would be a big advantage to a single 36 or 42 GB as well.
I would think the turbo JD would have a bit better fuel burn running the turbo w a little boost. Think so? Fewer cylinders usually = greater efficiency also .. gas & diesel engines alike.

Please excuse my ignorance - but is a belt-driven raw water pump common? Is there any consensus on electric raw and fresh water pumps? I see lots of people changing out the belt driven for an electric one for race applications but I don't how that translates to the marine world.

With all the aftermarket options for marinizing a 6BT it seems a customized one would be preferable to a stock marine 6BTA. I might be totally off the mark, but I would consider the different exhaust manifold options, a titanium-plate heat exchanger similar to the CAT, and some of the other "best of breed" options. I would definitely opt for an oil change pump that pulls from the drain plug on the bottom of the sump (I'm particular for getting that low-lying sludge out and my Perkins requires me to suck it out from above. It drives me crazy to see 1/4" of old sludgy oil in the bottom of the pan).

I wouldn't go Frankenstein or anything like common rail, but I'm just a do-it-yourselfer and I've seen some of the compromises on stock engines that I wouldn't make. As many can attest on the forum, I loathe my raw-water cooled iron exhaust manifold.

Here's another discussion re 6BT vs 6BTA: http://www.boatdesign.net/forums/diesel-engines/cummins-6bt-vs-6bta-46297.html

On another thread some one said that TAD would rebuild a Perkins 6.354 for $10,000, call it at least $12,000 with surprises. A rebuildable core will cost several grand. So say $15,000 for the Perkins and it is still rebuilt, not new.


A new JD 40455 is something south of $20,000 but not much, maybe more than the rebuilt Perkins, but less than the remanned Cummins.


You know and trust Klassen, so I can't argue with that.


David

David,
You mean TAD Roberts? And would that be Canadian$? That could be a buy as it would be about $7,000 USD. Thats what I paid for my mitsu w all the options. I've seen 6-354 engines on Craig's List for peanuts.

I was hoping FF would tell us about the IH. What do you know David?

Eric: I think David was referring to Trans Atlantic Diesels, Inc. in VA. They're know for Perkins parts and service but sell and are knowledgeable on other makes also. Good customer service.

TAD for perkins engines, perkins diesel, perkins marine, perkins parts, perkins generators, perkins service

What about a Kubota 99hp marine engine by Beta Marine. Seems like a very solid, easily available parts that don't cost an arm and a leg. I personally don't see a need for more HP than this, but then that's just me.

First, I hope all of the US members had a great Thanksgiving. I sure did.

Eric; Thanks for the info on Yukon/Hatton and MER. I will have a conversation with them and Seaboard Marine as I get closer to pulling the trigger. BTW, mine is a full displacement hull, so I'm guessing 8 knots (+- a bit) is hull speed.

And thanks to everyone else for your opinions and experience. At this point, it kind of comes down to the 6B/BT or one of the 4045's. I'm kind of surprised no one tossed in the 4BT. I see TAD has 4BT3.9 rated at 150hp. Any issues with this one, maybe vibration?

I see the 6BT rear turbo model has the same footprint and height as my existing Ford Industrial/Iveco, 40" length x 30" high. The center turbo model is about 9" taller and may be too tall. This is a liner boat and the engine room is pretty tight. With a 10Kw Westerbeke and a 10Hp Baldor electric come-home motor, real-estate is a premium.

John Deere specs shows the 4045's to be 35" length x 36" tall. So it's 5" to 6" taller than the 6BT, but it should still fit. It is only 5" less in length than the 6BT.

I reconsidered part my position on trying to stay away from turbo and electronic/computer engine systems. I have 4 street vehicles that are turbo diesel and all are computer controlled. I have never had a turbo failure on anything, and I know that even if a turbo fails, I can still limp in. But I would still rather stay away from electronic engine systems. I have a real "ghost in the machine" phobia. While I have never had a problem with the Dodge Cummins PU, VW TDi or diesel Mercedes, the Jeep CRD Liberty was a nightmare from the beginning. Poor electrical/mechanical engineering by Chrysler and VM Motors trying meeting US EPA regulations made this great little engine sick and it failed often. I spent a lot of time and $ undoing their mistakes. So rather than having the same potential problems, I'll just stay away from the electronic controlled engines.

Thanks everyone.

Bob

remwines said:

And thanks to everyone else for your opinions and experience. At this point, it kind of comes down to the 6B/BT or one of the 4045's. I'm kind of surprised no one tossed in the 4BT. I see TAD has 4BT3.9 rated at 150hp. Any issues with this one, maybe vibration?

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The 4BTs are better than they originally were as far as vibration. When I was waying options on the repower, I considered a new reman from Cummins. Talked to my local Cummins dealer who is also a friend. His comment was that they had made significant improvements in the 4BT, but the slow speed and idle vibration were still significant. When they sell new motors, they always run them in the shop before doing the install. Some of the 4BTs will still walk across the shop floor from the vibration. If I had gone with a Cummins, it would have been the 6BT solely for the low end smoothness over the 4BT.

Ted

freshalaska said:

What about a Kubota 99hp marine engine by Beta Marine. Seems like a very solid, easily available parts that don't cost an arm and a leg. I personally don't see a need for more HP than this, but then that's just me.

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I like Beta Marine engines a lot for sailboats. They are well engineered with good placement of maintenance components, an installed oil change pump, etc. And they work with you to fabricate engine mounts that will drop in. It also helps that their US east coast shop is a few miles down the road from me in Arapaho, NC. Stanley Feigenbaum is a prince of a guy and knows marine engines backwards and forwards.

But for this application I would be leary. From the drawings the 3.8 liter engine looks like it does not have a water cooled exhaust manifold as it looks like it is insulated. The 3.3 liter 80 hp engine might be a better choice because it is not insulated but that may be pushing too close to its hp rating for continuous use.

The OP reported that his boat weighs 30,000 lbs and is a full displacement hull. A good rule of thumb is that FD hull with an engine of 1.5 hp per 1000 lbs or 45 hp in this case will push a boat to hull speed, in this case about 8 kts. The OPs data indicates that his hull may not be as efficient as that or it is heavier than he thinks, or both since he gets 6.9 kts at 1,900 rpm on his current 117 hp engine. That is about 60 hp and probably double what a good FD hull will require to make that speed.

So all the more reason to go with a bigger engine. The JD 4045 4.5 liter engine or the Cummins 6BT 5.9 liter engine remain my top choices.

David

Renewed my subscription to BoatDiesel and have studied 'til my eyes blurred. The more I read, the better I like the Cummins 6B. It looks to me to be the logical and nearly direct replacement for the 335 cid, NA, Ford/Iveco engine. I have a lead on a Cummins 6B, NA, 115hp, with the same transmission that is currently in the boat. I will be having a conversation with the seller tomorrow. This is a new old stock, 25 year old complete engine with Velvet Drive. Any recommendations before I contact the seller?

Thanks.

Bob

Buy it

Sounds like a match made in heaven. Where is it?

25 year old complete engine with Velvet Drive. Any recommendations before I contact the seller?

Find out how hard it is to locate a complete gasket kit.

You might want to run it before installation to see if there are leaks.

If engine has not run in 25yrs, oil seals can bond to their mating shafts, then rip on a micro scale on first rotation. Sort of like how impellers stick in housings while in storage. Might happen, might not. 25yrs is a long time. Might want to put a new crank seal in the flywheel housing, that one is hard to do once in the boat.

Injectors and things in injection pump can stick while sitting too.

Get engine thorougly checked out and bench run before buying.

What Ski said. As one of the boat diesel experts he would tell you the same there.

Since I won't need to install it right away, I planned on replacing crank seals as well as both shaft seal in the transmission. I also figured on pulling the injectors and spraying oil mist in the chambers before rotating the assembly by hand. I also planned on replacing all hose and belts, and keeping the old stuff on the boat as spares. One other thing that may be of concern are the valve springs. Those that have been compressed for 25+ years may be weak. Maybe lift pump as well. Any thoughts on that?

I do plan on running it in the shop for awhile prior to installation. It will require a riser and possibly difference rear mounts. My current assembly has the mounts off the flywheel housing and new assembly rear mounts are off the transmission.

I have not yet gotten back to the to checked the gear ratio on the current transmission. The new transmission is 2.57:1. Will this gear ratio work for my boat? Boat: 40'x13'8", 30,000 lbs full displacement with 25x19 three blade prop.

Thanks guys. I'm off to strike a deal

Bob

remwines said:

. I also planned on replacing all hose and belts, and keeping the old stuff on the boat as spares.
I have not yet gotten back to the to checked the gear ratio on the current transmission. The new transmission is 2.57:1. Will this gear ratio work for my boat? Boat: 40'x13'8", 30,000 lbs full displacement with 25x19 three blade prop.

Bob

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I would not recommend keeping old hoses and belts aboard as spares. If they are 25 years old chuck them. In another ten years when you need them, they'll be useless.
You need to check your current tranny ratio.

I plugged your new hp, rpm and transmission ratio into boatdiesel's calculator and it came up with the exact prop that you now have. Also calculator says 7.1 kts at 1,800 rpm and 2,100 rpm to hit a hull speed of 8.2 kts. I would take these performance values with a grain of salt vs a vis my earlier comments about your hull shape and weight. Those issues only affect your prop sizing by an inch or so however, so you are in the ball park.


Sounds like all will work out well with that engine and transmission.


The only thing that would make sense before buying it is to bar it over to make sure it isn't frozen up. I wouldn't start it without doing all of the work below.


Be sure to get Ski's full advice about prepping the engine for first startup: hoses, seals, impeller, injector rack free, bar over the engine, rotate with starter for a few seconds with start solenoid off to lube galleries, etc.


David

[I would not recommend keeping old hoses and belts aboard as spares. If they are 25 years old chuck them. In another ten years when you need them, they'll be useless.[/QUOTE]

Yeah, what was I thinking?


Thanks David for running the numbers for me. I am still working a deal with the seller. The engine is about 2,000 miles away, but fortunately we have a fairly knowledgeable relative living close who is going to look it over before I buy it. Once here, I will freshen it up and seek advice on getting it ready for installation.

Thanks all.

Bob

One other thing that may be of concern are the valve springs. Those that have been compressed for 25+ years may be weak.

No problem , diesel RPM is usually too low to bother.

After operation just take a look to see if any are broken.

Now if it was a 9500 RPM Ducati ............

Wow, a lot of good advice here.

The only thing I'd add is that those early two-valve "B" series Cummins were loud, even idling. They're wonderful engines, uber-dependable & efficient and economical to service, especially due to the availability of spares for things like injection nozzles and lift pumps from the automotive world (a friend with a 210 hp 6BT marine engine has found that '96 Dodge pickup application is very nearly a universal fit). If you don't mind the noise, go for it!

The lifetime before overhaul is so long as to be effectively infinity.

Cummins offers reman engines which they can legally sell as "replacement" engines for older ones, complete with factory warranty, new wiring harnesses and as-new performance and longevity. They are never a bad choice.

That new-old-stock engine sounds pretty ideal to me, at the right price. I do agree that all the old rubber components should be replaced immediately, just due to age. You might as well do front and rear main seals now because it's so much easier to do before installing the engine.

Will you keep us posted as you cruise up the passage to Alaska? I'm envious.

Onward!

J.S.