Moving Air

spdracr39 · Feb 16, 2013

I am adding a couple of blowers to circulate the air in my engine compartment and I was wondering. Is it better to push outside air into the engine bay or suck hot air out ? I am using two 4" bilge blowers.

Bondo · Feb 16, 2013

Re: Moving Air

Ayuh,... Why not 1 pointin' In, 'n 1 pointin' Out..??

Don S · Feb 16, 2013

Re: Moving Air

Bubba1235 said:
What is the reasoning for it?

Here is the reason http://forums.iboats.com/mercruiser...rives/5-0-mpi-vapor-lock-question-591138.html

Bilge Blowers typically installed so they will suck air out of the bilge.

jimbo_jwc · Feb 16, 2013

Re: Moving Air

Bubba1235 said:
What is the reasoning for it? Most boats have vents designed to exchange the air in the engine bay when they are underway and you really shouldn't have a big heat build up at idle.

Engine off at fuel dock not moving and blowers on moving air in/out for vapor buildup /leaks and brushes sparking in enclosed blowers / starters that aren't marine rated . Google boats that don't follow rules and see results. It happens more than you think .

Don S · Feb 16, 2013

Re: Moving Air

What you might want to try is to put in another blower to suck the hot air out of the TOP of the compartment. Your standard bilge blower is set up to suck air out from low down in the bilge.

tpenfield · Feb 16, 2013

Re: Moving Air

Just curious if the standard blower(s) are not doing enough?

smokeonthewater · Feb 16, 2013

Re: Moving Air

drop the suction hose of any and all bilge blowers lower than any electrical component (starter) but above any bilge water (generally 6" form keel) and exhaust overboard.... push the explosive air out and fresh will come in on it's own.

jimbo_jwc · Feb 16, 2013

Re: Moving Air

Air in or air out is volume / time it takes to replace ,remove for heat or gases fumes temperature differences CFM is all you can get in wattage / horsepower to accomplish your needs . Last one that I learned from made my ears ring and ears plugs didn't help it was 900HP combustion motor from hell 666 amps full load 2450 amps starting current . Happy Blowers to youns .Yes Gravely tractors will give you a hot seat running lean and air flowing .

spdracr39 · Feb 16, 2013

Re: Moving Air

Yes DonS circulating air across the top of the motor was what I had in mind and leaving the original's in place and venting fumes.

Good idea Bondo I hadn't thought of that.

No the original blowers don't cut it.

Thanks for all the input that was just what I was looking for

NYBo · Feb 16, 2013

Re: Moving Air

The biggest reason that blowers are connected to suck air out of the engine compartment and not push it in is to prevent the fumes from being pushed into other connected compartments of the boat. The fumes would escape through any opening in the engine compartment, not just the intended exhaust port.

spdracr39 · Feb 16, 2013

Re: Moving Air

Good point. So maybe I should consider having both blowers suck air out so I can control where it goes.

smokeonthewater · Feb 16, 2013

Re: Moving Air

you also do NOT want a directer stream of air blowing in causing currents that will atomize and broadly distribute any potential fuel or otherwise spread any explosive gasses throughout the engine compartment...... just pull more out and you'll get more in safely

Moving Air

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