Help choosing an air filter please

Rivers & creeks

Rivers & creeks

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There were a couple of threads last year about how fitting a decent air filter significantly reduced the engine noise. The new to us engine is in place and I need more than the bog standard filter it came with. It has no breather into the filter and a 75mm apature, what would you recommend? The engine cc is just under 4l and it's normally aspirated.

Apart from doing the job of filtering the air I'm looking for something that will cut down on noise and so maybe a vehicle unit would be best?

Many thanks for suggestions!
 
Thanks, they are OK but the threads in the past were about noise reducing boxes, those K&N filter elements are great filters but not designed to reduce noise.
 
Here is the thread I did about using a Ford Ranger airbox:

http://www.ybw.com/forums/showthrea...ith-a-Marine-Power-Chinese-46bhp-diesel/page4

I took measurements using a sound level meter to show the difference. I think a few others are using similar filters but not posted any results yet.

I am very pleased with the low noise level and performance from the MP446 - its in a different league to the old 4108 it replaced, as I was reminded when I took the old girl out for her first run of the season last week.

I should add that my airfilter is remote (1m) from the engine under the cockpit so I this will help the noise, and also avoids it drawing in warm engine from the engine. (there isn't room in the engine bay for it anyway)

K&N type clamp on filters won't do anything for the noise but will provide better filtration.
 
ianj99 said:
Here is the thread I did about using a Ford Ranger airbox:

http://www.ybw.com/forums/showthrea...ith-a-Marine-Power-Chinese-46bhp-diesel/page4

I took measurements using a sound level meter to show the difference. I think a few others are using similar filters but not posted any results yet.

I am very pleased with the low noise level and performance from the MP446 - its in a different league to the old 4108 it replaced, as I was reminded when I took the old girl out for her first run of the season last week.

I should add that my airfilter is remote (1m) from the engine under the cockpit so I this will help the noise, and also avoids it drawing in warm engine from the engine. (there isn't room in the engine bay for it anyway)

K&N type clamp on filters won't do anything for the noise but will provide better filtration.
Click to expand...


The K&N filters may actually make the noise worse if fitted to a standard airbox. They, generally, flow better so provide less restriction to airflow. I think of induction noise as an exhaust in reverse, OK there are A LOT of problems with that but its simple. What we need to do is add some baffling to damp the pulses. This will have a detrimental impact on performance so a compromise is a remote airbox. This provides some baffling effect from the pipework, as long as we dont get any tuned lengths, and the small additional restriction will provide a lot of sound dampening. ianj99's idea looks lovely and obviously works well. The cool air intake would do no harm for performance either although there may be a tiny penalty in the longer lengths of ducting but I would guess that this would be pretty small. Not worth worrying about.
 
ianj99 said:
I should add that my airfilter is remote (1m) from the engine under the cockpit so I this will help the noise, and also avoids it drawing in warm engine from the engine.
Click to expand...

blxm said:
The cool air intake would do no harm for performance either
Click to expand...

Thread drift alert... These two statements caught my attention. The air filter on my little Beta diesel has a 'trumpet' which ends very close to the exhaust elbow so I assume it is drawing in quite warm air when the engine is up to temperature. Is this causing loss of power/efficiency or doing any harm. Should I rotate it away from the heat source?
And as a follow up question from my untutored point of view, why is cool air better? I would have instinctively said the opposite.
 
alahol2 said:
Thread drift alert... These two statements caught my attention. The air filter on my little Beta diesel has a 'trumpet' which ends very close to the exhaust elbow so I assume it is drawing in quite warm air when the engine is up to temperature. Is this causing loss of power/efficiency or doing any harm. Should I rotate it away from the heat source?
And as a follow up question from my untutored point of view, why is cool air better? I would have instinctively said the opposite.
Click to expand...

Although certain limits apply, cool air is generally more dense. Greater density equates to more oxygen for combustion. More oxygen, more power.
 
Cool air is denser than warm air, so you get a greater amount of oxygen in the same volume. On a high performance engine this can have quite an effect, on your engine less so, but probably still worth doing IMO

Cool air also flows better than warm air :)
 
As has been said cool air, more dense and therefore more available oxygen. However, this is only realized at full power as below that we are deliberately restricting power delivery. I guess a slight efficiency improvement may be a result. However, I suspect in our installations the effects are so small we would be hard pressed to notice. I would rather have a quiet motor :)
 
I ordered the Ford Ranger kit, all in with a nearly new box, new filter cartridge and a silicone elbow it came to £80. The cool air issue is a bit of a red herring as it's been said that it really only applies at near to WOT levels. But the main thing is that my engine is the most effective engine room cooler I have, so I want it extracting the hotter air.
 
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