Why call it an air filter when it appears to be an air box?

[doraymefa]

The textbooks say to remove the air filter from an engine when laying up and stuff a rag in the exposed vent until re attaching the filter in Spring. I did this and was a little surprised to find that the black filter box is empty.
Should there be some method of filtration in the box and if not why not? I appreciate that there will be a big air flow when the engine is operating at full tilt. Is it a safety device to prevent my tie being dragged into the engine?

Next year should I leave the filter attached and stuff my rag into the open vent at the top of this picture?
Thanks

 

[anoccasionalyachtsman]

It's mainly to cut induction noise (that's what the reverse taper's for), and there's not much dirt getting sucked into a boat engine anyway.

Delighted to hear that you are correctly attired when on board.

 

[DownWest]

[QUOTE="anoccasionalyachtsman, post: 7908275, member: 159476"

Delighted to hear that you are correctly attired when on board.
[/QUOTE]
A tie?? Really trying to remember the last time I saw one on a boat. (Sailing, of course) Maybe on the Thames? Up river, of course.

 

[geem]

It's mainly to cut induction noise (that's what the reverse taper's for), and there's not much dirt getting sucked into a boat engine anyway.

Delighted to hear that you are correctly attired when on board.

Our Perkins M92B has high performance double filtration. A filter inside a filter. Somebody at Perkins Sabre clearly thinks air filtration is important. I have just fitted an air filter to my diesel generator engine. There is always belt dust in the generator case but hopefully not now in the combustion chamber??

 

[anoccasionalyachtsman]

A tie?? Really trying to remember the last time I saw one on a boat. (Sailing, of course) Maybe on the Thames? Up river, of course.

Same here, but I'm thinking we could make more of an effort. I might suggest it to the boys for Wednesday evenings.

 

[Mistroma]

The textbooks say to remove the air filter from an engine when laying up and stuff a rag in the exposed vent until re attaching the filter in Spring. I did this and was a little surprised to find that the black filter box is empty.
Should there be some method of filtration in the box and if not why not? I appreciate that there will be a big air flow when the engine is operating at full tilt. Is it a safety device to prevent my tie being dragged into the engine?

Next year should I leave the filter attached and stuff my rag into the open vent at the top of this picture?
ThanksView attachment 130413

Is it from a Yanmar? I remember reading instructions about cleaning the air filter and also discovering an empty box. I assumed it was just to cut induction noise but was surprised that there didn't seem to be any filter at all.

I usually spray some fogging oil on a tissue and push it into the intake when laying up. Forgot to remove it this year after a 2 year layup and started the engine. I remembered and removed the box to find the tissue partly blocking the intake. A fairly coarse filter had prevented it being sucked into the manifold. I think it consisted of metal slots just inside the intake on the engine, not part of the plastic box.

 

[doraymefa]

Thanks for all replies. I think Anoccasional hit the spot first time explaining that this box helps reduce induction noise.

Like Mistroma, taking the box off and finding it empty was surprising. It is from a Nanni 4.5 (Kubota).

For full effect on Wednesday evenings the tie should be paired with plus twos (once done by default when trying to combine a day trout fishing with an evening race). I am unlikely to repeat as a piper one design can be quite wet and thick wet wool can be quite itchy…

 

[Plum]

Thanks for all replies. I think Anoccasional hit the spot first time explaining that this box helps reduce induction noise.

Like Mistroma, taking the box off and finding it empty was surprising. It is from a Nanni 4.5 (Kubota).

My Vetus diesel engine also has no filter inside the induction silencer and still working perfectly after 24 years. I don't beleive there is any benefit at all from stuffing a rag into the inlet during the winter.

Www.solocoastalsailing.co.uk

 

[Stemar]

I don't beleive there is any benefit at all from stuffing a rag into the inlet during the winter.

There may be

 

[cpedw]

I can't tell from the pic and I don't know the engine but there are devices that separate solid particles from gases by either slowing the gas so the particles settle out (settling chamber) or sending the gas fast round bends (inertial separator). Google has a quick summary of each.

Could your empty box be one of them?

It might also help with silencing but that's not my area.

 

[Mistroma]

I can't tell from the pic and I don't know the engine but there are devices that separate solid particles from gases by either slowing the gas so the particles settle out (settling chamber) or sending the gas fast round bends (inertial separator). Google has a quick summary of each.

Could your empty box be one of them?

It might also help with silencing but that's not my area.

OPs box looks very similar to the one on my Yanmar. It doesn't have a cyclonic sep. design, just some baffles. The air might be swirled around slightly but not enough to remove fine particles. Any heavy objects, nuts, stones etc. would fall to the bottom. Dust would just go straight into the engine. The inside of the box on my Yanmar was very clean when I peered inside after 10 years use.

 

[ghostlymoron]

The textbooks say to remove the air filter from an engine when laying up and stuff a rag in the exposed vent until re attaching the filter in Spring. I did this and was a little surprised to find that the black filter box is empty.
Should there be some method of filtration in the box and if not why not? I appreciate that there will be a big air flow when the engine is operating at full tilt. Is it a safety device to prevent my tie being dragged into the engine?

Next year should I leave the filter attached and stuff my rag into the open vent at the top of this picture?
ThanksView attachment 130413

There's not much dust in my engine room I think the intake filter is more to protect the owner. By the way, surely the appropriate neck wear would be a cravat.

 

[Ian_Edwards]

In 2014, I removed the air filter empty box off my Yanmar 4JH4E and fitted a K&N Apollo air filter.
K&N Filters Apollo Closed Air Intake System - Universal
I clean the filter every spring and it's amazing how much dust it traps, the engine runs for an average of about 150hrs per year.
No real way of knowing if it does any good, but when you work out how much air a 2.2L, 4 cylinder engine uses at 2000rpm, about 2.2 cubic meters per minute, I don't find it that surprising that it collects a lot of dust.