Heated discussion with co-worker today

[magicmike]

We just hired this new sales guy who honestly thinks his shit does not stink. The only problem is that we do not sell toasters we sell custom machine tools ranging from 200k to 1mil or even more. Our machines produce the final geometric characteristics on said workpiece as well as proper surface finish requirements on such workpieces like camshafts (GM, Saturn, Hyundai), transmission gears (GM, Chrysler), Fuel injectors (Siemens, Bosch, Chrysler, Cummins). at any rate. I'm not trying to market my company, I'm just trying to emphasize the fact that we build very specialized expreamly precise machine tools. So, last year our awesome sales manager leaves the company and we hires this new guy which I truely believe was the only guy stupid enough to show up for the salary we stated in the advert. OK I'm ranting about this guy just to make me feel better. now to the point. He apparently worked for some filtration company and subsequently owned his own filtration testing equipment company and today we got into an arguement because he was stating that through "extensive" research he found that K&N filters "HARM" an engine at the cost of creating more power. He was trying to say that because they use a looser filter paper they let particles larger than 20 microns into the engine and thus the arguement began that a 20-30 micron particle of "dust" basically would cause damage or wear even to an internal combustion engine. I was completely floored at this guys stupidity on this one. I dont think this guy understands what a micron is, or isn't I should say. What do you guys think? Am I wrong here or is this guy what i have always thought and that would be so full of shit its coming out of his ears!

[vrg3]

I'm not an authoritative source, but here are my thoughts:

I don't think you can specify a certain size threshold to delineate between "harmless" and "harmful" particles. Given enough exposure, even the smallest particles will wear away at any given surface.

Did he state the hole density of a standard paper filter for comparison?

There's an issue here about how filters work: from what I understand, K&N filters don't work the same way as paper filters. They actually use accumulated dirt to collect more dirt. That is, when you initially clean and oil the filter, it actually allows particles through that are somewhat bigger than the design is meant for. But, many of these particles stick to the oiled filter medium too. The resulting dirt-and-filter-medium matrix then functions as a tighter filter. So if you test a new K&N filter, you'll find that it's not as effective a filter as a properly worn in filter.

[evolutionmovement]

I don't think my K&N melted my exhaust valve, and at 250k, there was little to no wear to any other component. IF what he thinks were true, there are for more things that would cause engine failure before that. What does he think an engine can catch a cold and he wants to filter out viruses? 20 microns would block most pollen. I would think anything much smaller would likely be too restrictive for the engine to breath effectively.

[internetautomart]

a quality paper filter will filter more and smaller particles out of the air in comparison to a cotton gauze filter. They are also "safer" for a MAF equipped car. I say that because many people oil their filter too much and the oil then coats the MAF wire causing running issues.
Part of the tradeoff in filtration vs hp is the decreased flow for better filtration. the difference in flows is minimal at first, but as they become clogged the difference starts swaying in favor of paper.
I wish I could remember where I read the dam test comparison long ago.