Engine compartment diesel fan

[raptorheli2]

Hi all,

I have a boat with 200hp turbo diesel on outdrive. The engine bay is well insulated and only maybe 1.5m cubed, to say it gets toasty in there would be an understatement!

Id like to put a fan in there to help get the temps down.

The boat has basically a full side to side air tunnel to pull air in/out, the turbo is very close to the one on the stbd side of the boat.

I'm wondering if I put an extractor on the port side of the engine bay and a hose down under engine if that is a good setup to keep temps down and pull air in too from the turbo side.

 

[aerobat]

I,m thinking about a similar setup .

While running i think the engine sucks WAY more air thru the intake ports than any fan can do , so probably there is a lot of forced ventilation inside the engine bay and a fan will not change much .
.
But things get toasty when you shutoff the engine so any forced ventilation stops while the engine continues to radiate heat .
Running a fan some time after shutdown will probably significantly reduce the ambient temperatures inside the engine bay .

I,m just unsure if the engine cares its toasty inside after shutdown , so if the installation work and fan noise is worth it .

 

[Alicatt]

We have 2 big turbo diesels in our boat and it does get a bit toast under the floor, we have a blower on the aft port side of the engine bay bringing in cold air and an extractor on the forward starboard side removing the warm air.
The blower and extractor are coupled with the port engine ignition switch, so I turn it on a minute or so before I start them and leave the ignition on after I have stopped the engines, yes it is a bit noisy when the engines are off

 

[Refueler]

I know my engine is gasoline - but because of that - I have a 'blower' that I am advised to run for up to 5 mins before starting the engine - to remove any gasoline vapours that are hanging around in there ...

The blower is a standard 12v NOEX fan fitted into the stbd side engine vent casing ... with separate switch .... it does not depend on ignition switch ... as long as battery main switch is ON ... I can operate the blower.

Why do I explain this ? For OP - if you think that the heat is probably after engine off - then my setup would suit you - you can switch on the blower as you shut down engine ... and leave running while you have your Sundowner .... or even have a timer switch on it ?

 

[raptorheli2]

I will be putting whatever I put in there on a timed relay for post ignition off.

Keep the ideas coming though, happy to consider all options.

 

[Momac]

I dont think a fan is going to do much for engine bay temperatures. Getting into an engine bay with hot engines is best avoided.

 

[Grubble]

I know my engine is gasoline - but because of that - I have a 'blower' that I am advised to run for up to 5 mins before starting the engine - to remove any gasoline vapours that are hanging around in there ...

The blower is a standard 12v NOEX fan fitted into the stbd side engine vent casing ... with separate switch .... it does not depend on ignition switch ... as long as battery main switch is ON ... I can operate the blower.

Why do I explain this ? For OP - if you think that the heat is probably after engine off - then my setup would suit you - you can switch on the blower as you shut down engine ... and leave running while you have your Sundowner .... or even have a timer switch on it ?

Same as on my boat. I always open the engine hatch before starting the engine to check things like belts and oil so there is plenty of air for the blower to suck in.

 

[Alicatt]

Same as on my boat. I always open the engine hatch before starting the engine to check things like belts and oil so there is plenty of air for the blower to suck in.

I have to lift the floor in the saloon to check the engines, oil, raw water stop cocks, belts etc.etc. and that happens before I turn on the ignition.
It is the one big downside of having two big engines under the deck, shifting the furniture and rolling up the carpets, etc.
Once the floor is lifted then you have to start the engines and let them idle for more than 2 minutes to check the oil level, the dipstick goes to a separate sump that is higher than the main sump under the engines and the scavenger pump has to be running to lift the oil to the upper sump.
Totally unintuitive

 

[raptorheli2]

ofcourse it will make some difference, I'm not expecting it to bring it down to ambient.

 

[Seastoke]

What make of boat , I thought most boats had fans.

 

[raptorheli2]

Aquador

 

[aerobat]

I dont think a fan is going to do much for engine bay temperatures. Getting into an engine bay with hot engines is best avoided.

On my last boat ( a gasoline mercruiser 5.0mpi ) there ineed was a noticeable difference if you ran the blower after shutdown or not and then opened the hatch .

 

[ss2016]

Hi all,

I have a boat with 200hp turbo diesel on outdrive. The engine bay is well insulated and only maybe 1.5m cubed, to say it gets toasty in there would be an understatement!

Id like to put a fan in there to help get the temps down.

The boat has basically a full side to side air tunnel to pull air in/out, the turbo is very close to the one on the stbd side of the boat.

I'm wondering if I put an extractor on the port side of the engine bay and a hose down under engine if that is a good setup to keep temps down and pull air in too from the turbo side.

I have a D6-400. At full chat it's consuming order of magnitude 1 cu m/sec. So in round numbers you will be consuming 500 litres per sec. I don't think your fan will be able to compete! The engine is sitting there at 85 to 100C so of course it's hot.
Open the hatch and leave it before going in.

 

[raptorheli2]

You are kind of missing the point here, any air is better than no air.

my engine consumes 14000cfm, I'm not looking to feed the turbo. It clearly can draw enough air in as the boat runs. It is what fan setup to pull SOME hot air out.

 

[LittleSister]

my engine consumes 14000cfm, I'm not looking to feed the turbo. It clearly can draw enough air in as the boat runs. It is what fan setup to pull SOME hot air out.

But when the engine is running it will be pulling hot air out far more effectively than I imagine your new fan can do, and I suspect when you are powering along the turbo will be pulling air in 'backwards' through your new fan, regardless of its efforts.

The new vent fan would be beneficial for cooling purposes, I would have thought, only for a period after the engine is shut off, and perhaps also when you are at low power berthing etc. after a run (when the engine is really hot but the engine is drawing in relatively little air at tickover-ish revs).