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Old 04-05-2013, 04:19 PM   #21
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Mark,
Do you see the curves in post 19? That is exactly the same curve I referenced to get the info on post # 15.

I agree w that Marin. When I was looking at VWs I asked the service mgr at a VW dealership how much trouble the turbos were. He said they rarely give trouble. I wouldn't hesitate to buy an electronically controlled turbo.
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Old 04-05-2013, 04:33 PM   #22
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It's a Bruce Roberts 44' boat with a 48,000 lbs displacement. The designer recommends 120 to 175 hp. I tried to narrow that down to 150 - 175 to compare engine types.
I would say that 120 is more than plenty, a 100 is enough, 80 would get you by just fine.

Not if you add some high power accesories syuch as a pair of big alternators and hydraulics...then 100-120 probably would be perfect.

This is of course you are willing to run the boat right around hull speed. If you routinely go 1-2 or more knots above hull speed then the 150-175 range is probably more suitable.
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Old 04-05-2013, 04:45 PM   #23
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Manyboats, the owner's manual is showing crankshaft horsepower, while the charts show both that and propeller absorption horsepower. By the way, my engine's governor limits speed to 2400 RPM although the engine is rated for 2500.

Railroads were known to detune -- remove the turbocharges from their diesel-electric locomotives -- when they were permanently assigned to less-demanding roles. If you don't need it, why have it?
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Old 04-05-2013, 05:05 PM   #24
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You can detune a turbo motor but I believe it is a lot more complicated than just removing the turbo and bolting on another airfilter.

Better to get a smaller turbo engine that you are using the turbo (probably a much more efficient engine)....modern wet turbos last as long as most boaters will need them. The ones on my Cat 3208's were 25 years old and had over 3500 hours n them and were just fine. Some of the work trucks I've used have 10-15 year old turbos and over 225,000 miles on them.

In a clean environment like most bilges..they should definitely last....
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Old 04-05-2013, 08:31 PM   #25
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I would say that 120 is more than plenty, a 100 is enough, 80 would get you by just fine.

Not if you add some high power accesories syuch as a pair of big alternators and hydraulics...then 100-120 probably would be perfect.

This is of course you are willing to run the boat right around hull speed. If you routinely go 1-2 or more knots above hull speed then the 150-175 range is probably more suitable.
I agree w that completely if the BR 44 is actually a FD hull. I don't know the boat.

Mark if you want that 100 rpm you can have the governor adjusted. Most governors are adjusted to 2 or 300 rpm above the rated speed.

Before anybody removes a turbocharger one should know ALL the details re the differences between the turbo engine and the NA. They may have different camshafts, compression, injectors, timing and numerous other things. I wouldn't recommend it.
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Old 04-05-2013, 08:44 PM   #26
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One cannot get a non turbo 2013 JD 4 or 6 cylinder today due to Tier iV requirements. Try to get one without the aftercooler, the headache maintenance item on either.
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Old 04-05-2013, 08:52 PM   #27
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I wouldn't remove the turbo. Most of the companies make the same engine without the turbo already, they derate the hp. It just doesn't have enough hp without the turbo for this application.

It looks like the Deere engines have the older 6cyl line and the now have the next generation 4cyl line that makes similar hp by using newer/more technology. It's really not a choice of a 6cyl without a turbo and a 4cyl with a turbo. They both have turbos.

I was really interested if any one had some good advice on why I shouldn't do the 4cyl.
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Old 04-05-2013, 09:07 PM   #28
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"I was really interested if any one had some good advice on why I shouldn't do the 4cyl."

I don't.
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Old 04-05-2013, 09:10 PM   #29
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Mark if you want that 100 rpm you can have the governor adjusted. Most governors are adjusted to 2 or 300 rpm above the rated speed.
Don't need/want it. It would add virtually nothing to the boat's performance, further ...

JD has five ratings for its engines: M-1 through M-5. The 4045DFM70 is rated M-2, meaning it can be operated up to 65% of its potential load factor continuously but can exceed this up to one-third of the operational time. (Load factor is defined as the rate of actual fuel consumption in relation to maximum fuel consumption.) 65% for this engine is around 2100/2200 RPM. At those RPM, the Coot has reached hull speed.
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Old 04-05-2013, 10:59 PM   #30
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Is your 4045 a turbo?
Yes, it's a 4045TFM75. It puts out 135HP. I saw this same engine at the boat show rated at 225hp.

I started down the path Mark went on, and wanted the non turbo engine. The engine dealer talked me into the 135. Given that I was replacing a 120, and I was going from a 6 to a 4, it seemed like the safer bet.

I think the smaller engine would have been fine, and in the end would have cost less to install. JD is very strict on back pressure. I ended up ripping out the entire exhaust system and going to a 4.5" system.

That said, I don't have any concerns about the turbo or the electronics on this engine. It's an industrial engine, not a light-duty engine like you get with the higher RPM Yanmars. One of the advantages of the electronics is that I get a fuel flow meter and engine load readout as part of the package.

Marin, I know from other posts that you're not afraid to do the green thing. I don't think you can buy an EPA rated engine that's non turbo.
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Old 04-06-2013, 12:17 AM   #31
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Marin, I know from other posts that you're not afraid to do the green thing. I don't think you can buy an EPA rated engine that's non turbo.

No, I've got nothing against helping out the environment. That's one reason that we'd love to get rid of the Lehmans. But, despite the good advice my engine friend has given me, I just don't want turbocharged engines. If for no other reason than I hate the sound of them.

At this point I have no idea if a re-power is in our boat's future or not. One possibility that is probably not at all cost effective is to get a pair of engines from overseas where EPA regulations do not apply. Or perhaps a pair of the Luggers we like can be unearthed somewhere. Or whatever. It's a bridge we don't have to cross yet so it's not something I'm going to spend any time thinking about.
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Old 04-06-2013, 12:28 AM   #32
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Why all this talk about horsepower? Who cares about the horsepower rating (and # of cylinders)?

The spinny thing in the back moves our boats through the water. The power developed in the engine is provided to the propeller via the gearbox and shaft in the form of torque.

So one could say that torque moves your boat through the water, not horsepower. Horsepower should be thought of the measure of torque over time. HP=T x rpm/5252. Torque and horsepower are joined at the hip by this formula. Keep in mind that torque and speed can be measured, horsepower is then calculated.

So what, you say. Well, my point here is that lots of different combinations of the two measured variables can create the one calculated variable. (Read that sentence again, there will be a quiz later)

RPM matters (and do people get excited about engine rpm on this forum or what?) Because rpm it is directly linked to the pitch and diameter which make up the efficiency of the spinny thing. And propellers can only be so big, can have certain variables of efficient pitch, have so much swept area, and can only rotate so fast before they cavitate. Also gearboxes can be somewhat limiting in ratios relative to the engines manufactures and reliability of gearboxes are also affected by its thermal efficiency.

Throw in the mass of boat, block coefficient, waterline length, plus available engine room height and width. Don't forget shaft centerline height is relative to your motor mounts. Oh, shaft diameter and length (torsion is our friend and enemy) too. Any parasitic loads like dual alternators or a hydraulic pump?

You can have lots of fun figuring out which engine, gearbox and propeller combination is right for you boat. Then I suppose you can go ahead and see what the rated horsepower is. It won't matter much though, because, you'll never really use it, as it is at WOT.
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Old 04-06-2013, 12:49 AM   #33
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Good post, NS, thanks. But you left out another variable regaring horsepower, one that has always bothered me.

What kind of horse?

Take our engines for example. Ford Lehman, 120 horsepower at 2,500 rpm. So is this 120 Clydesdales? Or 120 Morgans? Or, God forbid, 120 Shetlands? Because depending on the kind of horse, 5252 may not be the right number to use. Perhaps if it's a Clydesdale the number is more like 3535. Where the Shetland might be 8585.

Because the kind of horse your formula is related to is going to make a hell of a difference in the torque available to turn the spinny bits at the back.

Actually, it seems to me that any discussion of horsepower is absolute rubbish because so far as I know, nobody knows what kind of horse it was that served as the "model" for one horsepower way back when. Who says 5252 is the actual correct number? Because if they used a Percheron, for example, well, 120 horsepower can really move something, right? Our wussy Lehmans take on a whole new image if they are 120 Percheron power.

But if the horse chosen to be the model for one horsepower was, say, an all-flash-and-dash-but-no-staying-power quarter horse, well then our two Lehmans don't really amount to much on the power scale.

So while I appreciate your torque explanation, NS, it seems to me that you first have to define just what kind of horse your forumula is based on before your you can start calculating with torque and rpm. Right?
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Old 04-06-2013, 12:57 AM   #34
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I thought horsepower was based on the "miniature" horses used in English/Welsh mines, and not the large Clydesdales or even medium sized "quarter horse."
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Old 04-06-2013, 01:06 AM   #35
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Pretty sure James Watt used mill ponies walking on a turntable and then uprated it to horses.

Also keep in mind he was selling steam engines and not horses...

Even so, he got his name attached to two units of power.
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Old 04-06-2013, 01:12 AM   #36
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Hmmm. Wiki says brewery horses. Very appropriate for my boat.
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Old 04-06-2013, 01:32 AM   #37
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Hmmm. Wiki says brewery horses. Very appropriate for my boat.
Well this changes everything. Have you seen a brewery horse? They're frickin' enormous. Think Budweiser Clydesdale when you think brewery horse. In England before trucks (sorry, lorries), they used horse-drawn wagons to distribute beer. Stacked to high heaven with casks. Same idea as what you see in Munich during Octoberfest. Big-ass wagons loaded with beer casks being pulled by four or more giganic horses all tricked out like pimpmobiles.

If that's what Watt was using, then no wonder the British thought a piss-ant (by US standards) 120 hp, six cylinder Ford Dorset diesel was a gynormous powerplant suitable for the semi-tractors of the day (the day being the late 50s).

We've had it all wrong. We've been laughing at the measily power put in things like E-Types and Morgans and Austin Healeys and MGs and Land Rovers but we had no clue that when they say "68 horsepower" over there (the hp of my 1973 Land Rover), they mean 68 brewery horses, for God's sake. The biggest, baddest, strongest horses God or Allah (or both of them together) ever made.

This casts a whole new light on the British and their engines. I'm gonna treat our FL120s with a whole lot more respect now.
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Old 04-06-2013, 01:41 AM   #38
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Hmmm. The first steam engines were used in mines to pump water, not to haul beer. I'm skeptical of this "brewery horse" theory.
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Old 04-06-2013, 01:47 AM   #39
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Nobody said anything about steam engines hauling beer. Just that Watt used brewery horses as his power model. Which makes sense because the mine horses were little bitty things bred for the purpose and would not be something one would select as representative of the power of a typical horse. A friend in the UK raises "mine horses" as a hobby and you can put the damn things in the back of a car. I can't see Watt or anyone else using them as the basis for a power figure.

Here's the explanation probably referenced by NS----

Horsepower (hp) is the name of several units of measurement of power, the rate at which work is done. The most common conversion factor, especially for electrical power, is 1 hp = 746 watts. The term was adopted in the late 18th century by Scottish engineer James Watt to compare the output of steam engines with the power of draft horses......

"Watt found by experiment in 1782 that a 'brewery horse' was able to produce 32,400 foot-pounds per minute." James Watt and Matthew Boulton standardized that figure at 33,000 the next year.[10]

Most observers familiar with horses and their capabilities estimate that Watt was either a bit optimistic or intended to underpromise and overdeliver; few horses can maintain that effort for long. Regardless, comparison with a horse proved to be an enduring marketing tool.
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Old 04-06-2013, 07:26 AM   #40
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A 3 cylinder or a 6 cylinder will be smoother than other configurations , even if they install a balance countershaft .

IF you can obtain cruise power with no turbo , the engine will eat a bit more fuel, but save thousands in turbo maint.

KISS is for a reason!

The Deere engines can be bought factory rebuilt at way!!!! under the "marine " price from the tractor folks.

A rebuilt Twin Disc and the next 10,000 hours (assuming some maint and PM) should be easy.

For a 6 cyl I would get an International 360 or 466 , mechanical for cheap , long lasting and smoooth!
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