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#11 Priscilla II

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Posted 21 February 2018 - 02:48 PM

The largest sucker of air in the engine compartment is the fresh air intake manifold.

How about just a old fashioned stand pipe with a 75mm flexi hose directly attached and do away with the air filter.

Heat exchanger should be sufficient in keeping things cool so more interested in adequate engine air supply.

Have sound proofed where I can and given the correct required volume of air is quite a bit I am not happy with just nooks and crannies and gaps to provide.


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#12 Island Time

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Posted 21 February 2018 - 03:29 PM

Indeed, there should be proper air intake ducts.
Air filter - do you mean the engine air filter?
I'd not do away with that! I know some boats don't have them, but that's dumb. A filter will help provide the engine a long life. I know many have crap filters, and IMO an upgrade from a foam filter to a proper washable filter like a k&n is worthwhile.
A good idea is an air duct that can be shut off in case of fire...
A really good engine room has intake ducts with salt scrubbers, shut off hatches, and is quite airtight otherwise...
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#13 Priscilla II

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Posted 21 February 2018 - 04:06 PM

A really good engine room has intake ducts with salt scrubbers, shut off hatches, and is quite airtight otherwise... 

And there I was thinking that the end was in sight for my engine replacement project....


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#14 wheels

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Posted 21 February 2018 - 04:52 PM

 

A really good engine room has intake ducts with salt scrubbers, shut off hatches, and is quite airtight otherwise... 

And there I was thinking that the end was in sight for my engine replacement project....

But have you got an engine room or an engine box? Big difference. An engine room can allow for a very decent and dangerous fire and having the ability of starving it of oxygen is beneficial to putting the fire out.

 

The largest sucker of air in the engine compartment is the fresh air intake manifold.

How about just a old fashioned stand pipe with a 75mm flexi hose directly attached and do away with the air filter.

Heat exchanger should be sufficient in keeping things cool so more interested in adequate engine air supply.

Have sound proofed where I can and given the correct required volume of air is quite a bit I am not happy with just nooks and crannies and gaps to provide.

 

I am not sure what you are actually trying to achieve. Are you preempting you might have a problem with heat? or do you actually have a problem with heat or not enough air for the engine intake?
 


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#15 Chloe

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Posted 21 February 2018 - 06:00 PM

The way I see it is that most boat engines are sucking in warm/hot air all the time. with an external Air intake to the engine with filter your engine will get colder air. However that is easier on launchers than yachts.  


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#16 Priscilla II

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Posted 21 February 2018 - 06:35 PM

Wheels, the old diesel just sat tucked away in the rear end of the yacht with little thought given to fresh air intake.
I have upgraded the diesel to a Beta 3 cylinder and now looking for a simple solution to provide fresh air to the intake manifold without having to resort to a electrical blower.
Heat is manage by the exchanger so I am going to head for a ducted intake with a stand pipe tucked up in the back of the cockpit

Surprisingly most of the yachts I have seen have no dedicated fresh air intake system and a few have blowers to just cool the alternator.
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#17 Fish

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Posted 21 February 2018 - 08:01 PM

The Beta installation manual has a good section on this.

Effectively you just have a hole in the engine box, and to manage noise you make a baffle. Most yacht engines manage fine by being open underneath to the bilges, the draw in sufficient cool air from there. The engine box itself suppresses the noise. You will be surprise how effective and appropriately designed baffle is for suppressing noise break-out while letting air in.

 

Just out of interest, how does your new Beta go on the noise front, what size is it, and what did you pull out?

 

I have been looking closely into re-powering with a Beta. Unfortunately non of the engine suppliers provide dBa levels for their engines. Most claim there engine is the best / most balanced / has the best injector pump so therefore is the quietest. With all of the EC conformance testing, power analysis etc, it is beyond me that they can't provide a standard dBa rating.


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#18 wheels

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Posted 22 February 2018 - 05:36 AM

Thanks for the clarification. The engine sucking hot air certainly does mean you lose Hp. But like most sailboats, you rarely use all the Hp available anyway. The Engine can be a big help in sucking in the Hot air in the box and allowing colder air to enter the box. Make sure you have a vent somewhere in the Box wall to replace the air the engine is sucking up. The heat comes off the Engine block and exhaust manifold, so the heat exchanger is not helpful in reducing the heat in the box.


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#19 Priscilla II

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Posted 22 February 2018 - 08:09 AM

Fish, I replaced my aged 17hp 2 cylinder marinized Kubota with a 25hp Kubota based Beta.

Quite a task which included a new larger fuel tank, complete engine bed, exhaust system, electrical wiring, prop and battery management etc....

Basically I have turned my old log of wood sailboat into a launch and realistically the total speed gain achieved from old to new is about 1.5 extra knots when motoring to wind and tide.

Got sick and tired of beating home up the harbour at 3 or so knots which in my view has more tidal flow due to the harbour being constantly stolen by POAL. 

In fifteen years of ownership the old Kubota received one birthday and never let us down, however now we have a smooth modern quieter? more powerful donk and its red as well.

I use diggers onsite frequently that have similar Kubota power plants and they run and sound like the ducks nuts .

The only weakness in the Beta conversion is the aluminium heat exchanger casing so keeping the pencil anode refreshed is important.

I do not like Volvos not only because they are green.

Yanmar was my first choice but price and layout saw me go Beta.

I have sound insulated only the removable engine compartment front/companion steps and sound wise we are happy, I do like to be able hear a engine run.


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#20 Aleana

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Posted 13 March 2018 - 04:29 PM

My production boat has extractor fan fitted as standard in the engine room. The original Jabsco unit recently died so I replaced it with a identical TMC 4” in-line blower but after 3hrs use the fan blade flew off. A few days later Burnsco swapped it another TMC (on the advice that TMC is normally good kit) but exactly the same thing happened to the new unit after 30 mins.

So I returned it for a refund and will never buy another item if TMC kit again.

So stick with Jabsco is my advice although as someone else said they are all quite noisy.
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