DaveInDenver
Middle Income Semi-Redneck
gjackson said:I've got to agree with GT. I've done thousands of miles in Africa including hundreds (I'm not joking) that included bull dust or fesh fesh, and my air cleaner (K&N in a 110) wasn't close to capacity when I cleaned it (with no snorkel). And I only cleaned it twice in 30,000 miles. The argument that you get cleaner air is dependant on what type of car you are in and where the air pick up is. In the 300tdi 110 it is in a very good place for convoy work. For other makes, I don't know. It's one of those arguments that seems to make sense for everyone, but every car maker puts the air pickup in a different place, and will get different air flow. There is no blanket statement that will work for everyone.
Snorkels for me would be for dust primarily. The air intake on my Hilux is behind the left side headlight, which is about 6 inches higher than the stock ECU location and alternator, probably a good foot higher than the starter. I've raised my axle breathers to spots higher than the air intake, so my low point is really the tailpipe. Although since the bend in the intermediate pipe between the muffler and tailpipe goes up and around the axle, the real low point is actually roughly equal to the top of my tires.
BTW, I put in a K&N right after buying my truck and around 10K miles later when I tore into the engine to replace the timing chain, noticed that my intake was filthy with a fine dust. I started doing used oil analysis and was surprised at how much silica they found (around 65 ppm). That level is usually considered severe duty and usually means really short oil change intervals. I typically follow ~4K intevals on Castrol Syntec.
I promptly went back to stock Toyota filters. I now get around 5 to 10 ppm silica. The K&N certainly didn't clog like my stock filters do. But, it appeared that the reason it wasn't dirty is that it does not do a particularly good job at stopping the fine dust. As it is I replace the filter about 2 or 3 times a year, which I'd rather do than keep ingesting dirt. I recommend to everyone I know that uses a stock-fit K&N to have an analysis done (really everyone should do them periodically). Compare the silica numbers with a good traditional filter (cheap thin-paper Frams don't count) and a K&N, since silica is just a measure of how much external dirt is being sucked into the engine.
To be fair, I also noticed that the stock filters fit more snug into the air box than the K&N, so I could have been sucking dust around the edges of the filter, too. But I'm careful to wipe a coating of grease on the frame before putting a filter in, so I'm not sure that I was getting all that much coming around the edges.