For those who may remember, quite a while back I decided to test some 300Tdi air filters.

Well I haven't finished analysing the efficiency data yet, but I thought I would post the DP results.

First the filters:

Left - Right:
Discovery 300Tdi K&N (thanks SSmith)
Defender 300Tdi DONALDSON - used for 20k km on dusty roads (thanks rick130)
Defender 300Tdi Coopers (OEM) NEW (thanks rick130)
Defender 300Tdi K&N - initially supplied with 20k km worth of dust (thanks rick130)


And also a 3.9V8 (RRC) K&N (thanks Hobie18) - you will notice that this is about the same diameter as a 300Tdi filter, but about half the length. Yet a 3.9L V8 would flow A LOT more air than a 2.5L Tdi - what were the engineers thinking...

So now for the pressure drop results - should be self explanatory???


So - the first conclusion we can draw is that V8 owners should switch to a TDI filter!!!

The 2nd conclusion is that K&N filters definitely have lower pressure drop - but at what cost (wait for the efficiency results) - when they are clogged, that would be a different story, but 20k km worth of dust isn't a lot in the scheme of things.

However the most surprising conclusion, was that a Donaldson (cellulose fibre (paper)) filter element with 20k km worth of dust in it, has a LOWER DP than an OEM (Coopers) filter does when NEW!!!

This can be explained by 2 things:
(1) Notice in the picture above, that the Donaldson uses expanded metal for the outer mesh, which has a high open area, whereas the OEM filter uses a drilled plate, which has a lower open area, and even dome closed areas. NOTE - all filters were tested without the plastic cyclone, which may make the DP curves of the 2 filters slightly closer.

(2) The Donaldson has deeper pleats, which means there is more filter material in the element, therefore lower average velocities and less restriction. It also should mean that the donaldson filter has more dust capacity (so your Donaldson element still has life in it rick )

Efficiency curves will be coming soon!

Good stuff Ben.

Who wants to start a book on how much (or little) dust the K&N's let through ?

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Just a comment - the assumption that a 3.9 V8 would have a higher airflow than a 2.5 Tdi is not necessarily correct (it may be, but not necessarily).

For a start, if we assume that they have the same maximum rpm, just to simplify things, and at full power there is no throttle restriction on the petrol engine, then the amount of air taken in by each engine will be proportional to the swept volume, everything else being equal. But it is not equal - for a start, around 8% of the volume going into the V8 cylinders came out of the injectors, and is the flow restriction of the valves the same? (I don't know the answer!). But the BIG difference, is the turbocharger, which is pushing air into the diesel at a higher pressure. Again, I don't know the answer, but I strongly suspect the diesel, after taking this into account, is pushing more air in at full power than is the V8.

And in any case, diesels are unthrottled at all times, so unless you drive the V8 wide open all the time, the amount of air going into the diesel will easily exceed that going into the V8 on an average per kilometre basis. So perhaps the engineers did know what they were talking thinking. Of course the air cleaner size was probably really determined by how much room was left in the engine bay!

I look forward with considerable interest to the filtration results.
John

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JDNSW
1986 110 County 3.9 diesel
1970 2a 109 2.25 petrol

Great stuff Ben! I'm looking forward to the results also.

I'm betting the K&N lets in more dust that a Defender door seal.

Gday John, I would have thought that 92% of volume came out of the V8 injectors.

Seriously though, I would expect it to be much less than that in terms of volume. I thought that they ran about 14.7:1 air:fuel based on weight rather than volume.

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EDIT - I stuffed these calcs up. see below...

Slunnie - great line Funny you should say that - when I was running the tests using small particle sizes (on the K&N), I had to double check I was measuring on the correct side of the filter, as the concentration was hardly changing...

There should be some sort of grammatical ban on using Defender and door seal in the same sentence!

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Roger

Land Rover Owners Club of Australia (NSW Branch) Inc.

"Experience is something you don't get until just after you need it."

I have measured the pressure drop at full throttle on a clean 3.9 OEM filter at about 11 inches of water including the snorkel piping, and interestingly to me anyway about 0.5 inches positive at 80Kmh.
In other words a poofteenth.
So either the Tdi filter is an overkill, or they expect tdis to be used on dirt roads more.
I can tell you " from the heart of my bottom" that there is no room to put a Tdi filter under the bonnet of my 3.9 anyway.
I tried modifying a Commode door filter and that wouldn't even fit.
Regards Philip A

I ran that damn thing for 20,000km.....
I wonder how much I've shortened the engines life.....

No wonder Jim Attrill in SA stuffed his engine using one of those for 80,000km...

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