Blower in the Engine room

[JulianGullsway]

Hi this was a thought I had recently, and I 'am no expert in engines, I can bleed our Perkins 4108 with my eyes closed and do general yearly maintenance, but that's where it ends! We are going to the Med next year and I was planning because of the excessive heat putting a fan in the engine room for when we have long windless passages, even in the UK after a long run on the engine it creates a massive amount of heat what with the sound insulation etc Crazy or not? also paper filter on the air intake will it reduce noise?

[GordMay]

NOT crazy, at all!

Caterpillar has a good application guide on Diesel Engine Room Ventilation:
➥ Cat-Engine Room Vent

Or ☞ http://www.cashmanequipment.com/User...entilation.pdf

See also Yanmar Help, for additional information on the subject:
➥ AIR VENTS

See also:

➥ http://www.cruisersforum.com/forums/...-it-37561.html

➥ http://www.cruisersforum.com/forums/...wer-42656.html

[Dhillen]

An engine room should have a blower. This is mainly because diesel engines use a phenomenal amount of air and a steady flow of fresh air to the engine will allow it to run more efficiently. It should also help with your "heat" issue but that, I believe, is secondary in importance to giving your engine the environment it needs to keep it (and you) happy.

There are 12v and 24v blowers on the market for just such a purpose. I have found them to run well and last a long time, properly installed. This will mean attaching properly sized ducting from the blower to the outside (usually back to the transom area) and enough venting into the engine room to complete the air flow.

Cheers.

Dhillen

[zeehag]

bluestocking--if i were adding those i would do one of each--intake and exhaust for adequate air flow

[Dockhead]

For anyone interested in why diesel engines use a "phenomenal amount of air" --

the reason is that they are unthrottled, so they pump through basically the same volume of air as you get by multiplying the displacement by 1/2 rpm (unless the engine is turbocharged and on boost, in which case it's even more). So a 2000 cc engine running at 2000 rpm will be pumping 2000 liters per minute, or two cubic meters! That's a lot of air!

Petrol/gasoline engines don't do the same because they are throttled, which creates a partial vacuum whenever the throttle plate is partially closed, reducing the mass of air going through the engine.

[S/V Alchemy]

Good explanation, Dockhead.

I will be going the blower route. If you are motoring, it doesn't take much juice.

[JulianGullsway]

Thanks Gord, some good info and reading, I was planning on just putting in x 2 bilge blowers x 1 in x 1 out, they should hardly drain any power as we have solar wind gen and will only be used during the engine running so it will pay for its self so to speak, I hate using the engine on passages however wind in the Med seems to be either famine or feast, Thanks Dockhead I had no idea how much air diesel used.
Thanks all for your invaluable information

[zeehag]

diesels are essentially air pumps.

[atoll]

i was working on a large yacht,70 ft a few years back in the med and red sea with 2 blowers in the engine room,both acting as extractors,the engine room was allways very hot,as it was well sound proofed and sealed,with vents to the bilge for air flow.

one day i decided to switch the wiring around on the extractors and turn them into blowers,bringing air into the engine room...............hey presto the engine room after that was a good 10c cooler,and the fuel consumption dropped by 2liters an hour!

[Jim Cate]

Originally Posted by atoll

i was working on a large yacht,70 ft a few years back in the med and red sea with 2 blowers in the engine room,both acting as extractors,the engine room was allways very hot,as it was well sound proofed and sealed,with vents to the bilge for air flow.

one day i decided to switch the wiring around on the extractors and turn them into blowers,bringing air into the engine room...............hey presto the engine room after that was a good 10c cooler,and the fuel consumption dropped by 2liters an hour!

Well, Alex, think about it...

The two extractors were just adding to the amount of air required going into the engine room. If there was any restriction in the intake, there would just be more pressure drop in the room, making things worse for the engine(s).

Good call on your part, mate!

Jim

[roverhi]

The engines won't be effected by the amount of air in the engine room as long as it is not sealed air tight. The issue is temperature of the air. The higher the temp, the less dense and less oxygen the air contains. Extractors will draw hot air out of the engine room and the lowered pressure will replace it with hot air from somewhere else in the boat unless there is an intake vent above deck level. Should need only an air extractor fan as long as you have an equal sized intake that draws air from the coolest spot on the boat. That is not at deck level.

Having said the above, have had two boats with no mechanical engine room ventilation and they've run just fine in the tropics. Just opened the lazarette hatch, which had a halfheight bulkhead open to the engine space, for ventilation. Ran fine even when the lazarette hatch was closed, as well.

[CaptTom]

I'm no diesel expert, either, but...

As Zee points out, a diesel is just a big air pump. There should be good natural ventilation into the engine room, assuming the boat was designed by someone who knew what they were doing. When running, the diesel is moving a lot of air into the vents, from outside, and through the engine room.

The little 12V blowers like you see on a gasoline inboard or I/O can't possibly move any significant fraction of the air the diesel will move. And in a 24V system you probably have an even bigger diesel.

So it's hard to see how they can make much difference at all. Atoll makes a good point that a high-power vent (in a big boat) may make things worse, actually fighting the engines for air. My guess is the diesel will easily overpower the little 12V blowers we're likely to have.

I can see running the blower to cool down the ER after running the mains. If I have to work on the engines while hot, I just point a regular room fan down into the ER from the saloon. I'm struggling to see the value in running a blower while underway, pointing in or out.

[HopCar]

CaptTom beat me too it. The engine is moving massive amounts of air into and out of the engine room. The typical small engine room blowers will have no effect at cooling while the engine is running. Might be nice to have once the engine is shut down so you can make it more comfortable to work on the engine.

[HopCar]

Damit, I'm supposed to be selling stuff! What's wrong with me?
Yes you must have blowers and lots of them!
Buy them here: Blowers & Fans

[scoobert]

everyone is correct. adding a blower will not affect cabin, or engine operating temp.
add more insulation is best. and a blower after shutdown will help cool it down.