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Old 11-11-2015, 03:20 PM   #21
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This is all very interesting.
So what did that 1/4 turn do to performance?
I never turned screw. I do not know if the present owner has turned the screw.
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Old 11-11-2015, 05:52 PM   #22
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Turning the screw depends on the injector pump. Some 'screws' adjust the travel or stops of the pump stroke length. Others have individual capacity adjustment per cylinder. And CRD engines have a computer that adjusts everything based on everything. They have sensors for intake air temp, exhaust temp, and torque sensors. Some have knock sensors to adjust the timing to limit engine knocking.

I don't think I would turn a screw a quarter round unless I knew what it did on the inside.
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Old 11-11-2015, 06:04 PM   #23
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"The ratings M1 to M4 are for the exact same engine, only change is the service setup required (tranny and prop) for the desired service."

I have a different turbo than the Diamond series, which might suggest its more than just the ancillaries that are different?
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Old 11-11-2015, 11:32 PM   #24
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Downrated HP?

On the power plant in my 'other' boat I have 2150hp EMD-12-645s X2.

The model is rated at 2150. It has a turbo.

The lowest model (using the same exact block) uses just air blowers (NO turbo) and is rated at 1950.

The model after that has larger blowers and is rated at 2025hp.

The model with the highest HP has blowers AND Turbos and wrings 2350HP out of these blocks.

All this is measured at 900 RPM.

So the difference in rating comes from the factory. I am suspect of 'someone' who says 'they have Derated their engine'. It's not that simple.

Pulling back the throttle stops is not 'derating'. It just taking it easy on your engine.
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Old 11-11-2015, 11:43 PM   #25
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There's some iron ballast.

The turbos are around 3' in diameter. The air boxes are 3' square.
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Old 11-11-2015, 11:46 PM   #26
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I am suspect of 'someone' who says 'they have Derated their engine'. It's not that simple.
Perhaps "someone" has been following this and will comment.
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Old 11-12-2015, 12:06 AM   #27
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There's some iron ballast.

The turbos are around 3' in diameter. The air boxes are 3' square.
Great stuff.
What are they pushing and what are the insulated lines on the back wall/bulkhead?
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Old 11-12-2015, 12:17 AM   #28
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Actually, if de-rated properly it allows you to 'over' prop (more pitch) and aim for a design point lower on the engine's power curve, using more of the available power and torque at lower RPM. This usually puts you in a slightly more efficient operating regime in terms of specific fuel consumption (grams of fuel / hp/ hr) as an added bonus. Nice thing to do if you're not obsessed with top speed, and further points to this being a 'proper trawler'.
Most engines are offered at several ratings, with pleasure boats being allowed to squeeze more power out at higher RPM since they don't do it for as many hours as commercial operators. The downside there is you're 'required' by the mfr to prop the boat for that top RPM, which means less pitch, which means you get less out of the engine at that mid-range RPM you actually prefer to use.

Boy Chriscritchett, you have succeeded IMHO, in collapsing the massive discussion on over wheeling with this response. All that you write in a concise manner is what I had been attempting to state over several post regarding propping with over size wheel while still maintaining a cushion of 400/500 RPM to WOT. At this setting the boat is obtaining hull speed at a very, very quite and comfortable sound level, close to fuel burn of similar engine/hull configuration running manufacture recommended wheel which is reflected in operating RPM range and corresponding fuel burn. With my over wheel application I burn approximately a quart more than the other example. Acceptable for the results, he is screaming along at 1800 RPM against my 12/1300 RPM at the same hull speed. Good trade off, Thanks for the post.
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Old 11-12-2015, 12:23 AM   #29
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Downrated HP?

The shot of the side of the engine? On the aft bulkhead is the 4" and 6" bilge, ballast and fire lines. All painted either white or red.

The insulated lines on the overhead are the potable hot and cold water lines insulated so they don't freeze in the winter when the faucets are shut off.

Currently pushing 100,000 bbls of diesel. 4,200,000 gallons
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Old 11-12-2015, 12:47 AM   #30
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The shot of the side of the engine? On the aft bulkhead is the 4" and 6" bilge, ballast and fire lines. All painted either white or red.

The insulated lines on the overhead are the potable hot and cold water lines insulated so they don't freeze in the winter when the faucets are shut off.

Currently pushing 100,000 bbls of diesel. 4,200,000 gallons
Cool, thanks for showing us your rec room.
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Old 11-12-2015, 06:49 AM   #31
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Derating an engine is done at the manufacturer, unless you replace the injection pump with a different rated engine model, which would be an expensive move. Also, if you know the internal mechanics of an injection pump (Fuel Injection Engineer) you could adjust the power / torque curves. My older brother was a diesel fuel injection engineer and he could do it. Average joe turning a screw is setting the throttle limits, changing where it stops the throttle / rpms.
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Old 11-12-2015, 01:42 PM   #32
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Who cares, really. Whether runnning a 3208 at 210 or 150 it should live a long life. Neither rating will stress it at all.
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Old 11-12-2015, 01:50 PM   #33
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Who cares, really. Whether runnning a 3208 at 210 or 150 it should live a long life. Neither rating will stress it at all.



Especially with the boat in FL and the questions coming from non-buyers very far away.
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Old 11-12-2015, 03:12 PM   #34
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Who cares, really. Whether runnning a 3208 at 210 or 150 it should live a long life. Neither rating will stress it at all.
The rating does not alter the stress on the engine. a candle burning twice as bright lasts half as long.
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Old 11-12-2015, 07:21 PM   #35
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Most stanadyne rotary pumps have an internal allen screw that can be adjusted to increase or decrease fuel flow/pressure to the injectors. It has nothing to do with the throttle stop. The 3160 had a smaller front balancer bore than the 3208, among other things. I was not aware that it was a liner block. I have never heard of "thicker liners and smaller pistons" used in derating a diesel engine. While I agree on the bigger wheel at lower rpm argument, that is not really "derating" as much as it is "rerating". Or using the available power of a lower setting more efficiently. As long as you are ok with resetting the max rpm to this new lower rpm, and not exceeding it, you'll do fine. The easiest way to derate a diesel engine (within reason) is to take some pitch out of the wheels.
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Old 11-12-2015, 08:21 PM   #36
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@hawgwash. Look back at post 12. That's your answer.

(W/o any technical changes to 3160. ). Right there the person who wrote this is uninformed

(210HP downrated to 150.). Really??? With NO changes to engine!!!

This person does not actually know what is/was done to engine.


To derate an engine means more than just lowering throttle, crimping down on fuel injection pump, or changing prop.

I would like to think this is 'broker speak' for make stuff up.
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Old 11-12-2015, 08:58 PM   #37
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@hawgwash. Look back at post 12. That's your answer.

(W/o any technical changes to 3160. ). Right there the person who wrote this is uninformed

(210HP downrated to 150.). Really??? With NO changes to engine!!!

This person does not actually know what is/was done to engine.


To derate an engine means more than just lowering throttle, crimping down on fuel injection pump, or changing prop.

I would like to think this is 'broker speak' for make stuff up.
In fairness to the owner/seller, he said the 3160 became the 3208 without any technical changes.
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Old 11-12-2015, 09:24 PM   #38
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Don't screw around unless you know what you're doing. That is, if you've no fear of the unexpected. Which could be bad or good. OK, take you choice. Do it, do it, do it. Do not expect me to follow, however.
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Old 11-12-2015, 09:38 PM   #39
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Old cat pumps are really easy to change. Never fooled with 3160/3208 pumps much.
3406B cat at 400 hp come out three turns on the right screws and it will make 600 on the dyno.
No one I dealt with ever wanted less power but two turns the other way would certainly reduce horsepower ...easy as can be.
P style pumps on a cummins are easy. Rotary pumps less so. But pretty much any non computer engine drop the pump at an injection shop and tell them what you need assuming you have a good pump shop and you should be good to go.
Computer Controlled engines can be changed too. It is all about what software you have in your laptop. You can tell the engine it is 300 hp or 600 hp ( 60 series Detroit for instance) it does not care just a different fuel map.
Now with all that said -yes there are engines (cummins for instance) that have a huge number of cam and piston changes in the same block to make different horse power ratings so it is not always about just the amount of fuel. Oh... And sometimes there are turbo changes so it is a complicated subject but...
Each engine made is almost never made with just one horsepower rating.
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Old 11-13-2015, 12:11 AM   #40
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Downrated HP?

The engine generation was 3160 first. The 3208 came after. The 3208 was the 'souped up' 'new' variant. This engine you are looking at never was 'Derated'.

Look up cat 3160. You can find this info on several websites for engine info and lines as they were produced.
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