Air box to reduce noise on my 4108?

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pcatterall

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Just re-read the thread on fitting a Marine Power engine. I would like to try the idea of reducing noise from my 4108 using the air box idea and I know there was some interest from others.

My ‘filter’ is the fairly common doughnut type just a push fit onto the (60mm?) pipe.
The air box from rover 400 series was mentioned as a possibility and I guess I could just order one from one of those on line scrappy chaps ??
has anyone had success with other airboxes.
I have a fair amount of space around and above my filter and would like to mount it direct rather than using a bulkhead and hose.
 
Arcady said:
" The air box from rover 400 series was mentioned as a possibility and I guess I could just order one from one of those on line scrappy chaps ??"

Or - you could stump up $450 for one of these: http://www.foleyengines.com/products/specials/walker-airsep-only-449
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Quote from the link above "Finally, it recycles the unburned fuel back into the oil pan via the dipstick. All in all, a huge step forward in making your marine engine nicer to be around."
What is that all about? Surely unburnt fuel should go back to the tank. As in pump excess. I would not think fuel should be fed into the oil pan as it will dilute the oil and possibly cause too much oil in sump so burning oil and overflow. Am I missing something here?
As for an inlet air muffler I would think that sealing the engine room except for a small air intake would do the same thing. If not any box coupled to the intake with a small air inlet hole (60mm) perhaps lined with sound deadening material would do as well. Marine engines don't have a filter as such becuase there is usually not much dust around. olewill
 
William_H said:
Quote from the link above "Finally, it recycles the unburned fuel back into the oil pan via the dipstick. All in all, a huge step forward in making your marine engine nicer to be around."
Marine engines don't have a filter as such becuase there is usually not much dust around. olewill
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My engine returns about 20% of unburnt fuel back past the injectors to the tanks so that would fill the sump in minutes. I recall that the old listers in some of my building plant would leak fuel into the oil & the operators would think they had enough oil when in fact it was dirty black fuel

My volvo has a filter on the air intake ( I assume that is what you are referring to)& i would be surprised at some not having one
 
William_H said:
Quote from the link above "Finally, it recycles the unburned fuel back into the oil pan via the dipstick. All in all, a huge step forward in making your marine engine nicer to be around."
What is that all about? Surely unburnt fuel should go back to the tank. As in pump excess. I would not think fuel should be fed into the oil pan as it will dilute the oil and possibly cause too much oil in sump so burning oil and overflow. Am I missing something here?
As for an inlet air muffler I would think that sealing the engine room except for a small air intake would do the same thing. If not any box coupled to the intake with a small air inlet hole (60mm) perhaps lined with sound deadening material would do as well. Marine engines don't have a filter as such becuase there is usually not much dust around. olewill
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Agreed - it's an odd claim to make. I had presumed it was simply a crankcase vent - but that's not how it reads.

Isolating the engine in it's own soundproof (and waterproof) compartment is an admirable aim: it has both sound-deadening and safety advantages. However - as discussed in another thread (http://www.ybw.com/forums/showthrea...ith-a-Marine-Power-Chinese-46bhp-diesel/page4), creating a fully-isolated compartment is not necessarily easy. I am impressed by the claimed 8db - 10db reduction in noise by the simple expedient of fitting an airbox on the intake. I now plan to look at this on my 4.108!
 
If you want to strangle your engine go ahead, if you want quiet ride get some earplugs, remember these engines require AIR to run, they get lots when running on a road but not a lot when stuck in a slow moving ill ventilated box.
 
omega2 said:
If you want to strangle your engine go ahead, if you want quiet ride get some earplugs, remember these engines require AIR to run, they get lots when running on a road but not a lot when stuck in a slow moving ill ventilated box.
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The fact of the matter is that Perkins or resellers offered many different types of air filter for this exact engine depending on use: desert sand / dust, grain chaff dust, wood dust. There are oil bath types, plain foam, metal gauze, labyrinth style traps. The 4108 was such a popular engine and could be found in just about any type of stationary or vehicular machine. I dare say, as you elude too, that just stuffing a filter on top may be detrimental but considering that the engine does have filter options I would have thought that this is taken care of in the design of the filter.
 
BlowingOldBoots said:
The fact of the matter is that Perkins or resellers offered many different types of air filter for this exact engine depending on use: desert sand / dust, grain chaff dust, wood dust. There are oil bath types, plain foam, metal gauze, labyrinth style traps. The 4108 was such a popular engine and could be found in just about any type of stationary or vehicular machine. I dare say, as you elude too, that just stuffing a filter on top may be detrimental but considering that the engine does have filter options I would have thought that this is taken care of in the design of the filter.
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Yes I agree, you have to stop rats and seagulls getting through, but "NO AIR" "NO GO", not much dust, sand, or chaff in any boat I know of!
 
omega2 said:
Yes I agree, you have to stop rats and seagulls getting through, but "NO AIR" "NO GO", not much dust, sand, or chaff in any boat I know of!
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Maybe you are just not familiar with engines and their ancillary components. Engines with air filters are not starved of air and the Perkins engine has been fitted with lots of different styles of air filter. If the OP wants to fit one because he thinks it will reduce air induction noise (the actual point of the thread) then a good look around eBay, Land Rover restorers and anywhere else that flogs off old Perkins engines should come across an air filter that may reduce induction noise without restricting air flow.
 
BlowingOldBoots said:
Maybe you are just not familiar with engines and their ancillary components. Engines with air filters are not starved of air and the Perkins engine has been fitted with lots of different styles of air filter. If the OP wants to fit one because he thinks it will reduce air induction noise (the actual point of the thread) then a good look around eBay, Land Rover restorers and anywhere else that flogs off old Perkins engines should come across an air filter that may reduce induction noise without restricting air flow.
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https://youtu.be/ujHlhON9-S8?t=34 sorry did not hear that!!
 
if you go down the route of fitting directly on the intake, beware of the cold start flames ! Thermostarts are sometimes a bit, well "bonfirey"
 
omega2 said:
Sorry I got the idea you were putting me down
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No, I wasn't, just contributing to the thread, sorry if it appeared that way. Personally I think time an effort spent on quality sound insulation and a dedicated engine box would be more beneficial than an air filter at reducing noise. An earlier poster suggested an 8 to 10 decibel noise reduction due to fitting an air filter, thats the equivalent of a watch ticking, not worth it at all.
 
BlowingOldBoots said:
No, I wasn't, just contributing to the thread, sorry if it appeared that way. Personally I think time an effort spent on quality sound insulation and a dedicated engine box would be more beneficial than an air filter at reducing noise. An earlier poster suggested an 8 to 10 decibel noise reduction due to fitting an air filter, thats the equivalent of a watch ticking, not worth it at all.
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I always understood that knocking 10 decibels off the top of a noise level was actually very noticeable
 
Daydream believer said:
I always understood that knocking 10 decibels off the top of a noise level was actually very noticeable
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I guess this is correct because I think increasing decibel levels are not liner, so a reduction would be more noticeable from a loud starting point.
 
Knocking 10dB off a level reduces the power by a factor of 10.
3dB is half power, so 3dB + 3dB +3dB +a bit; gives you a half of a half of a half, i.e. an 1/8th, and a bit.
Noise is not a linear scale but losing 10dB is a significant reduction.
 
Thanks guys. I have spent quite a bit of time effort and money on fitting insulation and it has made a difference. I was attracted to the info on the early thread and, indeed, 10 decibles quieter would be great.

I am also aware of issues if I restrict the available air.

Thanks again
 
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