Interesting information on non OE air filters...K&N etc

[Silver CL55]

ISO 5011 Duramax Air Filter Test Report - MotoWiki

 

[dog68]

Interesting, no k&n for me then.

 

[SavMan]

Wow didn't think it would come out as good as that, the K&N flows 50% more than the next best on test and more than double the worst offender.

 

[bolide]

the K&N flows 50% more than the next best on test and more than double the worst offender.

Where do you get those figures from?

Nick Froome

 

[SavMan]

Where do you get those figures from?

Nick Froome

Restriction to flow, the devil is in the detail. This test is concentrating on how much dirt the filter stops, the downside is they restrict flow.

 

[Silver CL55]

Just what I was thinking!

Interesting, no k&n for me then.

 

[bolide]

the devil is in the detail

It is indeed. Unless you're looking at a different set of figures to me, at 350 CFM the K&N produces a resistance of 1 inch Hg and the AC Delco around 2.7 inches

That does not mean that the K&N flows twice as much

One point made is that all the filters flow enough air for the engine. Additional air ≠ additional power if the filter flows enough air

The rest of the figures are illuminating. The K&N filters poorly and reacts badly as dirt builds up. It flows lots of air but, for 99.99% of engines, more air ≠ more power

For the other 0.01%, if the air filter is the limiting factor on your power output then a better intake system design will gain you far more than fitting a K&N

Nick Froome

 

[SavMan]

It is indeed. Unless you're looking at a different set of figures to me, at 350 CFM the K&N produces a resistance of 1 inch Hg and the AC Delco around 2.7 inches

That does not mean that the K&N flows twice as much

One point made is that all the filters flow enough air for the engine. Additional air ≠ additional power if the filter flows enough air

Nick Froome

OK - let's put it another way the K&N has half the restriction, problem I see with this is that they only measure up to 350 CFM which is not a lot.

My engine is currently capable of 750 CFM and that's just a restriction I have in the supercharger inlet. If I can remove that my heads are capable of over 650 CFM each so do I care if I have to clean my filters more often and may get 1% more dirt not in the slightest.

 

[SavMan]

I do agree with your comments on the inlet design, hence why many opt to change from standard drop in filters to induction type kits.

Don't get me wrong I don't support much of what is said on "performance filters" I just find tests like these a little misleading as it is testing against a standard engine.

Just took a look at some of the US forums that have owners that have modified the Duramax most of these are running twin turbo's that flow in excess of 1300cfm.

 

[moonloops]

One point made is that all the filters flow enough air for the engine.

That there is the golden nugget, if the engine parameters are satisfied with a Fram air filter from say halfords, then fitting expensive aftermarket filters and induction kits will yield no improvements until you start properly tuning the engine. IMHO

 

[Dieselman]

The air filter is usually the least restrictive part of an intake system.

 

[bolide]

OK - let's put it another way the K&N has half the restriction

At 350 CFM, slightly less than half. I think the point is that the difference in restriction isn't relevant as they each flow enough air

Given the choice of two air filters that each flow enough air which one would you go for? The one which is massively better at filtration and costs less or the one with lots of marketing behind it?

Nick Froome

 

[SavMan]

At 350 CFM, slightly less than half. I think the point is that the difference in restriction isn't relevant as they each flow enough air

Given the choice of two air filters that each flow enough air which one would you go for? The one which is massively better at filtration and costs less or the one with lots of marketing behind it?

Nick Froome

Me I would bolt 2 new turbos with an intake to match, I can pretty much guarantee that the standard filters would not be able to flow enough or fit my custom intake

I do appreciate what you are saying and drop in filters are unlikely to achieve any real gains on a standard engine. They achieve exactly what's needed for modifying to achieve maximum performance, if I could get away with no filters I would.

 

[millo777]

Do K&N filters still need to be oiled regularly? I remember reading several stories of people getting this very wrong and the excess oil from the filter damaging the maf. I'll stick to the MANN filters from ecp.

On a similar note, my local MB dealer has a large pos display next to the parts counter. On 1 side are cutaways of genuine MB parts, and the other side are cutaways of Bosch after market parts. This, I gather was supposed to convince customers to buy genuine parts. It has done the opposite. The air filter and oil filter are clearly identical!

 

[Dieselman]

Me I would bolt 2 new turbos with an intake to match, I can pretty much guarantee that the standard filters would not be able to flow enough or fit my custom intake

I do appreciate what you are saying and drop in filters are unlikely to achieve any real gains on a standard engine. They achieve exactly what's needed for modifying to achieve maximum performance, if I could get away with no filters I would.

What pressure drop are you seeing across the filters and how much over the complete intake system?

My guess says the filter drop is negligible compared to to the rest.

 

[jaymanek]

Wonder which company paid for that test then

 

[SavMan]

What pressure drop are you seeing across the filters and how much over the complete intake system?

My guess says the filter drop is negligible compared to to the rest.

Did not test with original filters I had already fitted BMC filters combined with the standard intake it was 0.1 bar, I had the same view that the problem was the intake. My new one was built and now I have zero pressure drop but I am about to go to the next phase which is modifying the supercharger internally as well as the supercharger inlet to see what gains are there.

 

[Dieselman]

Did not test with original filters I had already fitted BMC filters combined with the standard intake it was 0.1 bar, I had the same view that the problem was the intake. My new one was built and now I have zero pressure drop

You will with a finer scale manometer, however having seen a reduction from 0.1Bar should help quite a bit.

See if you can mount the intake so you see positive pressure before the charger. That would help as the pressure will rise as speed does.

I think we should turn you car into a test mule...