Engine air intake & vent design

[tashmoo2]

1. The air intake is on the outside hull amidships on my boat. It looks like intake on many of the DE pictures I have seen lately have intake in cockpit. This seems like much better location.

Will a 6-71 NA with supercharger draw air in from the cockpit. is engine noise back through the vent hose and issue?

2. Who makes an inline DC vent fan for continuous service?

 

[F/V First Team]

Most any blower motor will do, usually they say "heavy duty" or "for continuous use"

I think I have a couple of 4 inch ones on the shelf if you're interested.

 

[8943post]

Maybe I'm wrong but I thought NA Detroits were naturally aspirated not supercharged.

I don't have an answer to your question but I'm more concerned with salt intrusion into the engine room that will eventually cause corrosion on anything metal. Is there a way to inexpensively filter the incoming air? I think this is what you're trying to do as well.

 

[tashmoo2]

Super charger is a really a blower (2 lobe Roots type).

If blower is pulling a vacuum on the intake side then it should suck in air from anywhere. I was wondering where most intakes are locate on DE boats now.

 

[CEShawn]

I like them on the outside of the hulls, yes salt can be a concern. Look at all the carolina boats that have them on the outside of the hull. I've had them on two boats now and really can't say much about the salt intrusion. Just make sure you put a couple 90's in there. You can really quiet the boat down if you plug up all the little noise intrusions from the cabin, etc. So many times on boats you can hear the engine drawing air from the cabin with that high pitch whistle etc. When a boat is tweaked in, it makes those multiday trips much easier.

I've been debating putting in an air vent on the stern of the vessel, with a drainage box back overboard. I really like to vent under the cockpit and do not like like the noise. Best thign I've noticed is open up a hatch in your cockpit and that engine noise you'll get in the boat. Granted you can cut down on the noise with 90's, or so I believe as I've always seen them there but also have to imagine it cuts down on the air flow to some level but to what level never been able to get anyone to dial it in.

Sadly, two downeast boats I've had, have had problems with the cockpit deck and people keep pointing to not enough ventillation back there, yes the wood was glassed boat sides, etc.

 

[8943post]

Super charger is a really a blower (2 lobe Roots type).

If blower is pulling a vacuum on the intake side then it should suck in air from anywhere. I was wondering where most intakes are locate on DE boats now.

Most DE boats draw engine air in from intakes located under the washboards. There are several builders onsite here who can do a better job of answering your questions

 

[snowstorm]

Maybe I'm wrong but I thought NA Detroits were naturally aspirated not supercharged.

I don't have an answer to your question but I'm more concerned with salt intrusion into the engine room that will eventually cause corrosion on anything metal. Is there a way to inexpensively filter the incoming air? I think this is what you're trying to do as well.

all 2 stroke detriots are super charged. they have to be as they dont have any intake valves. only exhaust 4 per cyl. unless its really old. they have intake ports in the cyl liners that is forced in by the blower. may also be turbo charged

 

[MDI45]

I personally like the way Wayne Beal did his engine ventilation...with 45 degree panels at each corner of the stern

 

[Stinkpot]

I personally like the way Wayne Beal did his engine ventilation...with 45 degree panels at each corner of the stern

Kinda like this....? The panels stop about 4" below the washrails and allow air to be drawn into the bilge and to the engine. In my case, these are in addition to an intake grate below my aft steering station in the cockpit.