ok i've searched here and googled it but i am having trouble finding micron ratings for a '89 GQ pre cleaner ............. the reason i ask is because that is the only air filter i am using ATM because of the way my intake is for a factory GU turbo set up on my GQ. I have been told that the micron rating is the most important thing relating to air filtration and i tend to agree and i really don't want to replace another TD42 ......... any ideas?
thanks in advance
DAN
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micron ratings on paper filters
Dan,
micron rating is part of the issue. The other components are air to cloth/filter ratio, face filtration velocity and construction format of the filter itself. I have spent a lot of time in the application area of fliters with vacuum and positive pressure air system over the years and these all have to be considered. Unfortunately for an automotive application we are screwed to some degree as there is never enough filter area avail to satisfy the ideal situation, and the filter media is cheap and configured for frequent replacement.
You get good life from a filter by slowing the velocity of the air and dust thru the element. The faster the air, the higher the impact speed of the solid particles on the fibres and the more chance they will not be stopped or 'filtered' by the media. This is the first consideration, so find a filter with the greatest area of contact. If you can lower the incoming dust load as well, like the cyclonic re filters by donalson, these help with the big particles, but don't work at reducing the smaller stuff to a great degree.
Second look at the material it is made from. Air filters generally utilise a principal of a dusting or light cake of dust on the outer filter to act as a crude pre filter. A filter functions normally with a small build up. The first time you crank up the engine with a new filter is great for the breathing of the engine but the filtration performance drops off temporarily until the outer layer is established. I am not saying you are passing material into your engine or damaging it, just that the filter needs to 'clog up' to a minor degree internally to allow the filter cake to establish.
The micron size sets your lower particle size for free passage thru the element. The filter cake assists in this determination because its very difficult to manufacture an element with say a 2um filtration rating and have it still breathing freely after it has travelled all day in the dust.
Some filters are marketed as 'washable'. From my experience in industry, this is a play on words. When you have a matted fibre construction that is permeated with dust, then wash it out, the solid turn to liquid and mud and the fibre format collapses, trapping the material. Even the most expensive industrial filter manufactures are yet to offer a filter that returns to greater than 90% of original performance when new - and these units are of much higher quality media than we get in our automotive air filters. For me, its a new filter each time, as they are cheap to replace.
I have used the finer filter oil foam elements to great effect, but also been caught by leaving them go too long and get so dirty they slow things down. I don't use them any more - just prefer to change the filters regularly and just keep on top of the conditions under which I drive. Another thing to watch is periods of driving in very dry dusty conditions then into either very wet or moist weather. the water vapout is still in the air, and it ends up in the filter, clogging it up. I have had a filter go from new to covered in mud in 48 hours of changed conditions.
Anyway, here ends mu 'sermon', others may have different thoughts, but this is based on my experience over time. Hope it helps.
micron rating is part of the issue. The other components are air to cloth/filter ratio, face filtration velocity and construction format of the filter itself. I have spent a lot of time in the application area of fliters with vacuum and positive pressure air system over the years and these all have to be considered. Unfortunately for an automotive application we are screwed to some degree as there is never enough filter area avail to satisfy the ideal situation, and the filter media is cheap and configured for frequent replacement.
You get good life from a filter by slowing the velocity of the air and dust thru the element. The faster the air, the higher the impact speed of the solid particles on the fibres and the more chance they will not be stopped or 'filtered' by the media. This is the first consideration, so find a filter with the greatest area of contact. If you can lower the incoming dust load as well, like the cyclonic re filters by donalson, these help with the big particles, but don't work at reducing the smaller stuff to a great degree.
Second look at the material it is made from. Air filters generally utilise a principal of a dusting or light cake of dust on the outer filter to act as a crude pre filter. A filter functions normally with a small build up. The first time you crank up the engine with a new filter is great for the breathing of the engine but the filtration performance drops off temporarily until the outer layer is established. I am not saying you are passing material into your engine or damaging it, just that the filter needs to 'clog up' to a minor degree internally to allow the filter cake to establish.
The micron size sets your lower particle size for free passage thru the element. The filter cake assists in this determination because its very difficult to manufacture an element with say a 2um filtration rating and have it still breathing freely after it has travelled all day in the dust.
Some filters are marketed as 'washable'. From my experience in industry, this is a play on words. When you have a matted fibre construction that is permeated with dust, then wash it out, the solid turn to liquid and mud and the fibre format collapses, trapping the material. Even the most expensive industrial filter manufactures are yet to offer a filter that returns to greater than 90% of original performance when new - and these units are of much higher quality media than we get in our automotive air filters. For me, its a new filter each time, as they are cheap to replace.
I have used the finer filter oil foam elements to great effect, but also been caught by leaving them go too long and get so dirty they slow things down. I don't use them any more - just prefer to change the filters regularly and just keep on top of the conditions under which I drive. Another thing to watch is periods of driving in very dry dusty conditions then into either very wet or moist weather. the water vapout is still in the air, and it ends up in the filter, clogging it up. I have had a filter go from new to covered in mud in 48 hours of changed conditions.
Anyway, here ends mu 'sermon', others may have different thoughts, but this is based on my experience over time. Hope it helps.
the reason I am curious is because almost anyone I talk to has a different opinion 
and having spent a fair amount on the turbo rebuild and fitting the thing I really want it to last and old mate from MTQ (he rebuilt the turbo and supplied all oil and water lines etc) said that the turbo would damn near collapse the factory paper pre-cleaner in the old oil burner .............??
and having spent a fair amount on the turbo rebuild and fitting the thing I really want it to last and old mate from MTQ (he rebuilt the turbo and supplied all oil and water lines etc) said that the turbo would damn near collapse the factory paper pre-cleaner in the old oil burner .............??Dan,
sounds like a camp fire outburst to me!
As the filter clogs up, the flow decreases thru it - and a turbo is not what you would call a 'positive displacement device', so whilst it continues to spin, it just gets less air to pass thru it, so on that basis I would say its highly unlikely to suck the filter element apart - never seen it happen, even on very high negative pressure vacuum pumps.
I am not familiar with this pre filter, but if I was looking at an industrial application I would specify the cubic meters of air/min the filter will have to pass, and also the negative pressure it will see and of course the max temp so the density correction can be made as the filter selection will be done in SCFM(standard CFM). Armed with this, you can start talking hard facts with any reputable filter supplier. They will ask what the contaminant load is likely to be, which is pretty well impossible to say, and perhaps the overall size of your preferred element.
No doubt an experienced filter guy will know the sorts of parameters regarding 'typical' dust loads or be able to tell you an expected life.
What does MTQ recommend for a filter or is he just saying its too small - and leaving you to make the decision? I am sure this sort of thing has been done many times before, so would not expect it to be too difficult to sort out. I can't help with specifics unfortunately.
sounds like a camp fire outburst to me!
As the filter clogs up, the flow decreases thru it - and a turbo is not what you would call a 'positive displacement device', so whilst it continues to spin, it just gets less air to pass thru it, so on that basis I would say its highly unlikely to suck the filter element apart - never seen it happen, even on very high negative pressure vacuum pumps.
I am not familiar with this pre filter, but if I was looking at an industrial application I would specify the cubic meters of air/min the filter will have to pass, and also the negative pressure it will see and of course the max temp so the density correction can be made as the filter selection will be done in SCFM(standard CFM). Armed with this, you can start talking hard facts with any reputable filter supplier. They will ask what the contaminant load is likely to be, which is pretty well impossible to say, and perhaps the overall size of your preferred element.
No doubt an experienced filter guy will know the sorts of parameters regarding 'typical' dust loads or be able to tell you an expected life.
What does MTQ recommend for a filter or is he just saying its too small - and leaving you to make the decision? I am sure this sort of thing has been done many times before, so would not expect it to be too difficult to sort out. I can't help with specifics unfortunately.
the advice is greatly appreciated PBBIZ2 
old mate from MTQ uses an oiled K&N filter in the pre-cleaner assembly and the original paper element in the filter box that normally lives on top of the engine ?? The guy who tuned my truck (swafftec industries) actually races a turbo diesel gq ( and is getting stupid numbers out of it !!! maybe it's the NOS 
) and told me that he still hasn't found a filter that he likes yet ???? although I'm not racing mine I really don't need fine dust etc running through it ( does anyone ??)
old mate from MTQ uses an oiled K&N filter in the pre-cleaner assembly and the original paper element in the filter box that normally lives on top of the engine ?? The guy who tuned my truck (swafftec industries) actually races a turbo diesel gq ( and is getting stupid numbers out of it !!! maybe it's the NOS ) and told me that he still hasn't found a filter that he likes yet ???? although I'm not racing mine I really don't need fine dust etc running through it ( does anyone ??)filter
Thanks for the info Phil, as this is relative to my TD42 engine swap too.
I am going to experiment with the GQ prefilter arrangement and look at altering the filter inside to a K&N and fit larger inlets and outlets. The main reason behind this is the lack of room to fit anything in the engine bay with all the other essential crapola in there.
I have a modified 2.8 filter housing with K&N filter and it has served well, but is ridiculous to service in the cramped location.
I know the standard prefilters are small and restrictive for the volume of air reqd for the turbo, however K&N make some high flow small footprint filters which look to be the goods. Down side is the small surface area leading to clogging if the conditions are bad
My thoughts were to use the standard Donaldson ram head on the snorkle for highway and the Donaldson cyclonic prefilter for dirt (although the ram head turned backwards is very effective too if you forget the cyclone head!!).
Then, with an easy to service filter arrangement under the bonnet, carry a spare filter to swap it out if the conditions warrant.
I am going to experiment with the GQ prefilter arrangement and look at altering the filter inside to a K&N and fit larger inlets and outlets. The main reason behind this is the lack of room to fit anything in the engine bay with all the other essential crapola in there.
I have a modified 2.8 filter housing with K&N filter and it has served well, but is ridiculous to service in the cramped location.
I know the standard prefilters are small and restrictive for the volume of air reqd for the turbo, however K&N make some high flow small footprint filters which look to be the goods. Down side is the small surface area leading to clogging if the conditions are bad
My thoughts were to use the standard Donaldson ram head on the snorkle for highway and the Donaldson cyclonic prefilter for dirt (although the ram head turned backwards is very effective too if you forget the cyclone head!!).
Then, with an easy to service filter arrangement under the bonnet, carry a spare filter to swap it out if the conditions warrant.
Dan,
all this sounds like we are heading towards a sensible solution. The racing guys have high duty cycle loadsfor short periods of time and no doubt are right onto their maintenance. The finer filter style units work really wel when they are clean and they do have a better capture and filtration media. Its two layers thick, and gooped up with a pulsing oil membrane. If you examine the second layer of the filter its rare to see any dust on it. I stopped using these as said because they got me thinking along the lines of set and forget, which ended up neglecting the air system until it was a negative on perfaormance, instead of changing the filter more regularly.
Also, the high face velocity is countered by the increase media depth. As long as you stay on top of the cleanliness aspects then the oiled foam type are good in my view. The paper elements come down to all the parameters I have mentioned, and when its dusty, you just need to change them more regularly.
Good luck
Phil
all this sounds like we are heading towards a sensible solution. The racing guys have high duty cycle loadsfor short periods of time and no doubt are right onto their maintenance. The finer filter style units work really wel when they are clean and they do have a better capture and filtration media. Its two layers thick, and gooped up with a pulsing oil membrane. If you examine the second layer of the filter its rare to see any dust on it. I stopped using these as said because they got me thinking along the lines of set and forget, which ended up neglecting the air system until it was a negative on perfaormance, instead of changing the filter more regularly.
Also, the high face velocity is countered by the increase media depth. As long as you stay on top of the cleanliness aspects then the oiled foam type are good in my view. The paper elements come down to all the parameters I have mentioned, and when its dusty, you just need to change them more regularly.
Good luck
Phil
h
Hmmm, I have read that the pre oiled foam filters are not so good for the turbo engines as they can tend to suck themselves down and flatten thus restrict flow. Which is why the riceboy turbo cars run paper or K&N type.
Of course this would depend on surface area, and its dirtiness to a large degree.
Oh dear, it seems that the more you find out , the more you realise there is a lot more to know and we havent entered the black majic world of negative flow dynamics yet......
One thing for certain is that the maintenance MUST reflect the application. So easy to maintain is a good starting point
Of course this would depend on surface area, and its dirtiness to a large degree.
Oh dear, it seems that the more you find out , the more you realise there is a lot more to know and we havent entered the black majic world of negative flow dynamics yet......
One thing for certain is that the maintenance MUST reflect the application. So easy to maintain is a good starting point
Derek,
when you go the donaldson, go the 10" dia unit, not the 6". The 6" doesn't have enogh air flow rating for even the 2.8 in my mind, having purchased one and looked at the amount of large material carried over onto a new filter.
Pet hate hearing the 'black magic ' statement. Absolute rubbish unfortunately, permeated by those within the vacuum application industry to try and cover their butts when something they design doesn't work, because they didn't know what they were doing to start with! I have worked with plenty of guys like this - they take the old 'bigger is better' approach without knowing what they do.
Believe me, its hard line engineering fact 100%, no magic or guess work.
The comment regarding the foam filters is a good one - I can see how an unsupported foam element that is laden with dirt will be pulled flat under high negatives, which you might approach if the element is totally clogged, OR, the surface area is way too small for the air volume. The K&N and other paper elements obviously are better supported and with the pleated finsh wont suffer the fate. I also tried one of those finer filter snorkel socks over the inlet of the snorkle - man, what a mistake. The fuel consumption doubled I reckon. Sure it save 10c of filter life but cost $100 more in fuel.
So what do you do? More filter area is best, so perhaps the K&N or similiar, a good large cyclonic pre cleaner and thorough anal maintenance.
I accept the comment about the oiled foam unit, but have not noticed this on mine - ran one in a Diahatsu and a 75 series troopy - seemed to do the deal ok. Have not personally run a K&N as the cost of the units was always too high to swallow.
If you only have a set volume to fit a filter into, its going to be a compromise eaither way.
when you go the donaldson, go the 10" dia unit, not the 6". The 6" doesn't have enogh air flow rating for even the 2.8 in my mind, having purchased one and looked at the amount of large material carried over onto a new filter.
Pet hate hearing the 'black magic ' statement. Absolute rubbish unfortunately, permeated by those within the vacuum application industry to try and cover their butts when something they design doesn't work, because they didn't know what they were doing to start with! I have worked with plenty of guys like this - they take the old 'bigger is better' approach without knowing what they do.
Believe me, its hard line engineering fact 100%, no magic or guess work.
The comment regarding the foam filters is a good one - I can see how an unsupported foam element that is laden with dirt will be pulled flat under high negatives, which you might approach if the element is totally clogged, OR, the surface area is way too small for the air volume. The K&N and other paper elements obviously are better supported and with the pleated finsh wont suffer the fate. I also tried one of those finer filter snorkel socks over the inlet of the snorkle - man, what a mistake. The fuel consumption doubled I reckon. Sure it save 10c of filter life but cost $100 more in fuel.
So what do you do? More filter area is best, so perhaps the K&N or similiar, a good large cyclonic pre cleaner and thorough anal maintenance.
I accept the comment about the oiled foam unit, but have not noticed this on mine - ran one in a Diahatsu and a 75 series troopy - seemed to do the deal ok. Have not personally run a K&N as the cost of the units was always too high to swallow.
If you only have a set volume to fit a filter into, its going to be a compromise eaither way.
b
Interesting about the 6" diameter cyclonic filter. Of course this is the one I have. Now I have another job to sort out!
Sorry I called your pet hate up. But negative flows (as opposed to pressure) are very confusing, hard to calculate and any minor bend or weld dag inside the pipe seems to alter things. Sometimes trial and error is the only true test.
As you say, not always is bigger better as sometimes air velocity is better than outright flow. And given that most road 4wd engines dont run full power for long periods the flow at that level of performance is probably not that important.
I agree, I have had no troubles with the foam filters on my non-turbo cars either and they worked well. (Apart from a backfire in the carby and the filter caught fire) I did see a performance increase on my brothers turbo hilux when he went to a K&N over the Finer filter though.
Agreed about the compromise. All the calculations might show it to be right, but if you cant get it under the bonnet its not helpful at all.
Sorry I called your pet hate up. But negative flows (as opposed to pressure) are very confusing, hard to calculate and any minor bend or weld dag inside the pipe seems to alter things. Sometimes trial and error is the only true test.
As you say, not always is bigger better as sometimes air velocity is better than outright flow. And given that most road 4wd engines dont run full power for long periods the flow at that level of performance is probably not that important.
I agree, I have had no troubles with the foam filters on my non-turbo cars either and they worked well. (Apart from a backfire in the carby and the filter caught fire) I did see a performance increase on my brothers turbo hilux when he went to a K&N over the Finer filter though.
Agreed about the compromise. All the calculations might show it to be right, but if you cant get it under the bonnet its not helpful at all.
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