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Cyclonic pre cleaner - technical info request

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  • Cyclonic pre cleaner - technical info request

    I’m looking for info about cyclonic air pre cleaners for Toyota D4Ds (particular a 120), but this applies across the board.

    More specifically:

    What are engine airflow requirements per Toyota standards or actual measurements? Does Toyota publish this? If volumetric efficiency (VE) is 1.85 (a reasonable guess), airflow would be ~ 2.5 m3/min @ 900 RPM and 9.7 @ 3500 RPM. VE could apparently be 1.5-2.5 so the possible range is large.

    What is an acceptable intake restriction (vacuum) downstream from the air filter, and as a contribution from a pre-cleaner? Operational intake restriction is inexpensively and routinely measured on heavy equipment with “filter indicators” (e.g. see Donaldson catalog). Why aren't these aren’t used on Prados and the like in dusty Oz conditions? Does anyone have experience with these measurements for a Prado D4D?

    Appropriate restriction varies; 20-25 inches-water seems common. Is this a suitable range to indicate changing a D4D air filter?

    Donaldson posts performance data (airflow vs restriction) for some of their pre cleaners. But not the Full View, which is a popular model for Prados. I didn’t find airflow vs restriction data for any other manufacturer. Donaldson pre-cleaners have published upper restriction ranges from ~ 5 - 12 in-water, depending on model and size. Has anyone measured actual performance (restriction at a specific RPM) of installed FullView and TopSpin pre cleaners, or for that matter, any other cyclonic pre cleaner?

    I found the following pre cleaner specifications for airflow (min-max, m^3/min) and size (height x diameter, inches):

    Donaldson TopSpin 002437 2.5-6 m3/min (5.75" x 6.4”)
    Donaldson TopSpin 002426- 6-13 (9.4 x 9 .5)
    Published TopSpin airflow capacities vary between Donaldson catalogs & web sites, and whether units are m^3/min or CFM

    Donaldson FullView - max. 5 m3/min (~7” dia). (I could not find min airflow for FullView models)
    Donaldson FullView - max. 9.5 (~10” dia).

    Engineaire 4-150/465 4.3-13.2. (5.4 x 9.4)
    Engineaire 3-75/250 2.1-7.1. (4.5 x 7)

    Sy-Klone 9001. 2.8-7.8. (4” inlet 5.8 x 8.5)

    The Sy-Klone appears to best fit my driving range, but no advertised airflow range fully covers ##900-3500 RPM. Users consistently recommend going sizing down (e.g. FullView 7” rather than 10”) while many manufacturer and after-market dealers recommend sizing up for maximum RPM. Cyclonic filtering is clearly inefficient at too-low airflows. Airflow restriction increases when flow exceeds the maximum (> 5”-water for Donaldson’s), but does cyclonic filtering drop off at high airflows? I.e., is the maximum airflow specification set by a filtering efficiency standard, by an airflow restriction standard, both, or something else? For most designs, does the relationship between airflow and restriction remain relatively linear at high airflows?

    I know this is a bit over the top, but I found very little quantitative information or actual performance data in the many threads on these pre filters. Let me know if this info is somewhere and I've missed it!
    2008 Prado Grande: ARB + Warn in front, Kaymar rear, Steinbauer, Beaudesert, REDARC, 2" lift, TJM sliders, ARB airlocker, etc.

  • #2
    Toyota (any every other manufacturer) don't put such indicators on filters because most people will never drive through the sort of dust that requires such indicators. Having spent years working on heavy machinery in mine sites/ construction sites and the amount of dust that these machines have to deal with is several orders of magnitude greater than the worst dust you'll ever get driving a car (or at least if as bad the exposure time won't be as long). Any air filter actually functions better with more debris caught in it (up to a point where airflow is restricted beyond what is required for normal operation). I would expect that if you continued to run a modern diesel with an excessively clogged air filter you would gradually lose power until a fault code (idiot light) tripped- I know that all earthmoving equipment that I operated had such a light that was there for people who couldn't be bothered inspecting the filter element at prestart. Unless you intend to operate your car in extremely harsh conditions for extended periods of time I would have thought that a washable filter sock would be the go.


    • #3
      Certainly correct that most people don't drive in extreme dust, but some on this forum do -- one of my recent experiences was Cape York with lots of traffic, including numerous road trains. My understanding is that heavy earth moving equipment often uses sophisticated filtering systems that can include exhaust powered scavenging -- things well beyond what one would even consider for a Prado. There are many reports of bad results with socks e.g. so I don't think they're a good option for sustained, very dusty conditions. Maybe all this doesn't really matter, but I'm still interested to know more about it.
      2008 Prado Grande: ARB + Warn in front, Kaymar rear, Steinbauer, Beaudesert, REDARC, 2" lift, TJM sliders, ARB airlocker, etc.


      • #4
        The Graders I worked on (Cat) did have that but a lot of the other stuff including rollers, loaders, backhoes, moxys and excavators and semis didn't. You're right in that it's an interesting topic and If you're adverse to filter socks then it might be a good idea to carry a spare air filter or two- A pre cleaner would be at the extreme end of solutions and while I've no doubt it would work it'd also probably be pretty noisy being basically right next to your head.


        • #5
          I think I’ll be sticking a cyclonic precleaner on... the extra noise will be drowned out by the rattles and god knows what other sounds the vehicle produces on corrugations and rough tracks
          2018 VX Prado


          • #6
            Despite the lack of specifics, I'll give the pre-cleaner a try. Lots of people like them, and I've been on trips where I knocked noticeable amounts of dust from the air filter every evening. That quantity of dust must impact performance and longevity. Will see about noise and removing the pre-cleaner between adventures.
            2008 Prado Grande: ARB + Warn in front, Kaymar rear, Steinbauer, Beaudesert, REDARC, 2" lift, TJM sliders, ARB airlocker, etc.