## Engine Air Filters

## from the

## Tayana List

In an earlier post "Perkins needs more air" Harvey advised me to check the air filter after I found the engine space needed to get rid of heated air (still working on that)!! Anyway I checked and Harvey was right. I had a spare and installed it and now we can run faster. I use a Donaldson Duralite filter ECC06-5001. It is easy to install and seems to do a great job. What other air filters are people using on the Perkins?

Nick DeRocher July 2005

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Hi Nick,

I didn't know that you could put an air filter on a Perkins. The standard setup is a domed metal fitting with a screen inside that attaches to the air intake. It is not so much a screen as a circular piece of metal with hundreds of round holes in it. Although a filter would add more protection, it probably is not needed on a boat. You can see a picture of one at ftp://tognews.com/Perkins_4_108_Models . Look under Perkins Engines and then "4-108 in a sling.jpg".

Wayne V-42 C/C RESTLESS July 2005

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Wayne

You are probably right about not needing this air filter but when I changed it and looked at how dirty the filter was, I was surprised. When I climb down into the hell hole, I am always surprised at how much stuff is floating around in the air and I keep this space pretty clean.

Nick DeRocher, S/V Paul Martin Hull #118 July 2005

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Does one need an air filter on a boat?

Answer: Just as much as when operating a farm tractor in dusty field.

Normal 'clean' ambient air typically contains 30,000 particles (0,03-2µM) per cubic foot. Compress that number (compression ratio of ~ 12:1) and you get 360,000 particles per cubic FOOT. Airborne dust and debris circulates globally on the wind currents, and doesn’t stop at the waters edge. The Sahara routinely covers the Caribbean Islands, Alps (yellow snow) and central Europe with dust. "Loess" from the Rocky Mountains routinely falls on the east coast (including airborne spiders), same reason why the Yellow River in China is yellow. Ever wonder why archeological excavations are so deep into the ground, why not simply found on the surface? or why the Great plains are so flat? ...... airborne particles, gazillions of them.

The reason all those helicopters crashed during the attempted 'rescue' of the US hostages in Iran in 1979 ..... they removed all the engine air filters to save weight.

If you add an air filter, choose the largest surface area DRY filter you can fit. The largest surface area will give the lowest particle velocity through the filter media and will allow 'dwell time' for the particle to adsorb to the filter structure. K&N is the 'usual' manufacturers of aftermarket engine air filter/housings.

regards, Rich Hampel July 2005

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Our Yanmar 4 cylinder diesel has no air filter as such, just a perforated can with a fine mesh screen wrapped around it. The screen becomes fouled with oil and dust after a season of use but is an easy thing to clean with soap and warm water. Maybe a paper or fabric air filter would not last in the wet environment on a boat(?).

Bob Kirbach Walk About July 2005

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Paper automotive air filters are micro cellulosic fibers bound with an epoxy-like wet strength resin. Such filter media is commonly used to filter liquids. Fabric is very poor choice due to lack of 'open space' in the structure; plus the fabric fibers aren’t 'bonded' thus they tend to 'unload' debris under high operating pressures when the fibers 'flex'.

Rich Hampel July 2005

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Really? I thought that some of the best filters (such as K&N) used fabric media soaked in oil. What am I missing.

Philip McConnell Tayana 52 #35, Alejandra Fernandina Bch, FL July 2005

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K&N is the 'usual' manufacturers of aftermarket engine air filter/housings.

Rich Hampel July 2005

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Good information. Any specific suggestions for WHICH K&N filter can simply bolt onto a Perkins filter riser?

Regards, John Kalpus Prudence San Diego July 2005

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What you're missing is a lot unsubstantiated of 'sales-hype' based on industry standards abandoned in the late 1950s.

If a particle exists in a liquid regime (oil bath or oil soaked, etc.) then it takes about ten times the 'work' and ten times smaller retention 'pore' size to do the exact same filtration if the particle was 'dry' and filter was 'dry' ---- dry gases are more easily (by a whole 'magnitude' - log10) filtered than mixed aerosols or liquids. This is because a particle in a gaseous/air/dry atmosphere is in a very high 'energy state' (oscillatory brownian motion); not so in a liquid regime. A dry particle is easily removed not just because of physical size of the particle but chiefly because the *amplitude* of the natural vibration of the particle - usually larger than the 'pore' of such filters. For example a 0,03µM particle is easily captured by a filter that has 0,1µM 'pores'. For liquids it takes a 0,1µM filter to remove a 0,1µM particle (to 100% efficiency).

Simple speak: DRY filtration is a magnitude more efficient in retention efficiency (both by weight removal and size) than 'wetted' filtration.

Secondly, such 'liquid'/flooded filtration: 1: easily re-entrains particles downstream (low values of 'adsorption') due to 'unfixed' particles already captured; 2. are only efficient at a narrow single operating condition - rapidly losing efficiency of capture if the flow is lower OR greater than that narrow single design point; 3. The 'residence time' of capture is typically very small (velocities too high). If the velocities exceed the design point, all the liquid/oil (now bound with agglomerated particles) now are vulnerable to 'extrude' through the device or re-entrain back into the gas stream. That’s why the auto manufacturers abandoned oil bath filters in the late 1950s - they only removed rocks sticks and feathers, didn’t capture the important submicronic particulate, and when full of crud emptied themselves down the carburetor. The consumer equivalent of such an argument is the biologically dangerous "'Rainbow' Vacuum Cleaner".

Use DRY and use a LARGE (surface area) filter that you can fit. And for folks like Charlie and Harvey - be sure to change that face mask immediately when it becomes wet.

regards, Rich Hampel July 2005

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The largest that will fit, you can use aluminum manifold 'flex' tube to do the connection. The flex tube is cheap compressed 'aluminum foil' - auto parts store stuff. You’ll probably have to 'concoct' an adapter to the air inlet of the engine, hose clamp stuff, etc. K&N only makes the 'container'. Like most 'automotive' type filters the filter 'media' is made by a few technical grade paper mills.

regards, Rich Hampel July 2005

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--Another thought .....

"Browse" just about any auto salvage yard, then you’ll be able easily match a common brand/shape of replacement filter element. Might even be able to 'match' the plastic inlet duct that attaches to an automobile injector air throttle plate body. Any standard size old auto air filter assembly would probably be larger than the maximum aspiration needs of a small marine diesel.

Regards, Rich Hampel July 2005

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Rich and all: I use the Donaldson Duralite filter ECC06-5001. It is a canister type that fits right on. If you have trouble finding Duralite this number will cross reference with other filter types.

Try: https://dynamic.donaldson.com/webc/WebStore/search/item_detail.html?section=10084&item=15089
Nick DeRocher, S/V Paul Martin Hull # 118 July 2005

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Our air filter is:

Duralite Donaldson

ECC08-5002-DC1250C
215mm diameter

165mm height

We added an alloy tube to the intake - this filter is quite large – lays back horizontally toward the rear of the engine.

Jon McLeod July 2005

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Jon,

Mine is quite compact, round and sits on top of the intake. It's about 6" in height and about 6" wide. I have changed it underway and it is easy. I do find that my engine oil looks less black when I change it at 100 hours.

Nick DeRocher, S/V Paul Martin Hull # 118 July 2005

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A common cause of black smoke coming out the exhaust as you increase the RPM is lack of sufficient oxygen to the engine. Calder says that if you have black smoke, the first thing to check is the air filter. (Of course, I found the passage in Calder only after the event! Sailing/motoring with Richard and Karen Genet, on their T-52, black smoke started coming out at about 1500-1800 RPM. Richard tracked it down to an almost completely occluded air intake filter. After washing it in solvent, problem was solved).

Harvey July 2005

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I don’t know the 4-108 but if you give me the cubic inch displacement of the engine and max. possible rpm, I will calculate a minimum sized (surface area) filter set (or if you have specs for the maximum CFM aspiration numbers - even better). The most destructive particle size will be about 5-15µM so most grades of automotive filter media will be OK but one must be sure that the velocity through the filter is correct so as to allow sufficient 'dwell time' for capture, etc.

regards, Rich Hampel July 2005

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