An attempt to sort out the snorkel pre-filter debate

[filcar]

Interesting results so far, especially with the Uni filter ...

https://www.youtube.com/watch?v=zQc8d1HEEP0&feature=youtu.be&fbclid=IwAR1p0fOM8270Uh8CxKIVoizn0AkJ0zaaWlk7Wnf0_5-BfetulI-4HJFKFSM

[MarkGU]

Here is my take on pre filters.
As some of you will know, i enter the Variety bash every year.
During the week away we travel along some of the most dustiest road know to mankind 
I run the standard air filter on my Wolseley 24/80 with the sides cut out of the air cleaner housing for unrestricted air flow.
I have made my own pre filters form foam pre filter material bought from Autobarn.I cut out the right length & width form this material, glued the two ends together and after a pre oil of the filter it goes on stretched around the standard air cleaner element.

After each day of travelling over 500k's a day of outback roads, it gets changed for a clean one ( i carry one clean pre filter for each day). I an literally squeeze out the "mud" from each pre filter like its custard.

Now, after the week of this dust the standard air cleaner element is still white in colour like it has never even seen dust.

So, do pre filters work?? You bet your left one they do.I run one for my diff breather & my auto gearbox breather.
And no, made absolutely no difference to the running of the car nor did it restrict the carby in any way.

Just my 2 cents worth from actual experience.
  

[HKB Electronics]

They are a compromise, they guy in the video is talking but acceleration times and restriction to air flow. When I hit the dirt 1/4 mile times are not my interest, keeping dust out of the engine is so when I hit the dirt I install a cyclonic unit and a sock.

I found with the cyclonic unit if I used the size to suit the engine it caught little dust, I then decided to go with a unit that was on the small size for the engine, it catches a lot of dust compared to the first. Yes it introduces more opposition to airflow but I'm generally not trying to race anyone when I'm on dirt. Main air cleaner element after 1000's of K's on dirt is still like new. Cyclonic unit gets empty daily, couple of spoons full of dust comes out of it, sock changed around once a month and it is usually pretty dirty too. All that would have been into the standard filter if the other two weren't there.

[Hoyks]

Anything that can give the standard filter an easier time has to be a good thing.

I did a fair bit of reading up on snorkel head cyclonic things when I was researching dust extractors for work.

The cyclonic heads work best when the air going through is at a constant velocity. So you need to pick the head for the engine capacity and working RPM.
Air speed past the head of 80km/h or more creates a lot of turbulence and messes with the laminar flow and their efficiency. Really good for tractors and earth moving equipment that get a set at a constant RPM for hours, not so much for 4x4's unless its slow going.

https://www.donaldson.com/en-au/engine/filters/products/air-intake/accessories/pre-cleaners/

[Craig Tomkinson]

I do not know about the Snorkel pre filter never used one, Having said that after what Mark has said if I was doing more driving on dirt roads in convoy I would give one a go, But just a observation  on my old 80 the first few trips up to Weipa the snorkel rubber hose connecting to the filter was buggered, in around the 1000ks of dirt up and back the filter was stuffed each year, So I hooked up a new rubber hose from the snorkel to the filter, the next trip up and back the filter was fine, So I mite make one up to or buy one if not to dear, Craig

[Traveller]

I found with the cyclonic unit if I used the size to suit the engine it caught little dust, I then decided to go with a unit that was on the small size for the engine, it catches a lot of dust compared to the first. Yes it introduces more opposition to airflow but I'm generally not trying to race anyone when I'm on dirt.

I agree. My first 4x4 was an old petrol 2.4l Hilux that had a small Donaldson fitted in heavy dust conditions. It caught so much dust that I had to empty it a couple of times a day. I now run a 4.2l turboed Patrol with a bigger Donaldson that does 3/5ths of nothing. Where the small one would have a lot of dust swirling in it when driving, the bigger one has hardly any, and I swear you can see the dust going down the snorkel. I went to Donaldson and had a chat to the guy there and he maintains I have the right size for the motor, and even muttered it might be a bit small for the job. I think the problem lies in the fact that usually the motor isn't working hard enough to get the cyclonic effect working, and as HKB states, a smaller size is needed.