This weekend I measured and did some research on CAI and cowl intake design. Also researched the differences between aftermarket air filters and OEM paper filters. Knowing what I know now, it would make me cringe to see K&N style filters being ran in dusty offroad conditions. In one of these test, the K&N passed 18x more dirt than a stock paper filter. For a race car with a specific tune and engine rebuilds I could understand the benefits using a high flow/ lower filtering media but I just don't think its a good idea for our trucks where we want the engine to last as long as possible and a lot of us drive in dusty conditions on a trail for example.
I don't want to throw on a snorkel and use the stock airbox because of the snorkel look, so I'm thinking a cowl intake might be the next best thing and maybe better in some regards.
Like I said I've been geeking out about this and this is some more data I've dug up:
Efficiencies:
K&N 96-99%
AFE Pro DRY S 99.2%
AFE Proguard 7 99.7%
Volant/Donaldson Powercore G2 99.97%
Stock Paper Filter 99.91-99.96%
K&N Air Filter Review - Debunking the Myths (and why OEM is better)
https://www.bobistheoilguy.com/airfilter/airtest1.htm
S&B Intake w/ Donaldson Powercore G2 Filter - Chevy and GMC Duramax Diesel Forum
I'm really leaning towards using the Volant/Donaldson Powercore G2 filters for my cowl intake, seems to be the most offroad-proof filter and Donaldson makes a ton of air filters for industrial equipment so I'm betting they know what they are doing. With a cowl intake setup, I'll need to make my own enclosed/waterproof aluminum filter box next to the firewall. Buy some aluminum tubing and install the MAF sensor and vacuum lines. The cowl intake will be more protected from water than the factory intake in the wheel well where it is more exposed now that I've trimmed the plastic around it. Also, moving the intake backward in the engine bay means it will tip less into the water during a deeper crossing when the front tires initially dip down and your truck is sitting at a forward angle. The cowl has a drain for water and the intake tube will sit up off the base of the cowl an inch or two basically right beside where the cabin air filter draws air from. The only thing is the cowl vents are still located under the hood when you close it so I might need to add additional vents on the outside of the cowl under the windshield for fresh air.
The new air box will basically be right here, I could almost make the factory one work if I was okay with using a filter that fits the factory box:
While I had the intake system off I did some snooping and noticed something that I thought was odd. Some pitting on the butterfly valve and weird gunk behind it. So I removed the throttle body and took a peek.
Backside of the valve:
Inside the intake:
I thought it might be bad but I did some research and turns out it's a normal thing for an engine.
Today I also replaced the cabin air filter and while I was there I decided to try and fix the clicking blower motor that it's had ever since I've owned it. Basically when the motor was on low it clicked slowly, and on high it clicked faster and louder. The click was very audible whenever the motor was spinning which was pretty annoying
(Dislaimer: I made this process up as I went with very little research. I had no idea what I was doing most of the time, just trial and error. I'm a mechanical engineer not an electrical engineer!)
The solution: Pull the motor and fan assembly out and take it apart to see if I can find debris inside making the click and clean it a little. It wasn't very straight-forward to take apart without breaking it so it took me a while, there are some guides on youtube for how to take apart GM or Ford blower motor/fan assemblies which was mostly identical to the Toyota part which really helped. Anyway, finally got it apart and inspected the brushes, with the brushes out it didn't click when spinning it by hand. The commutator was perfectly smooth so I re-profiled the brushes to reset their wear and put them back in. Not much better. I noticed when I plugged the bare motor in and turned on the AC in the truck, the motor wouldn't click when I pushed down axially on the shaft. There was a clip on the back of the motor that held the shaft on on that side, but it allowed it 3/16" of play back and forth. I slid the clip up on the shaft so that it had maybe 1/8" of play front to back and plugged the motor in and turned it on; silence! Blew out all the brush dust, reassembled and reinstalled everything and turned on the AC. What a difference, instead of hearing clicking I only hear the sound of air in the vents like it's supposed to be.
Anyway, we'll see how long that fix lasts, if it comes back I'll just have to buy the $120 motor/fan assembly from Toyota.
The guts:
After reassembly it was nice and quiet! Dance you little squirrel-cage, dance!
I'm too busy/lazy to get off my ass and make one for the 4th gen... also it's been 90*+ for a month so... yeah. lol
I make do with 360 on my main and if I really need to get work done I boot up ye old windows computer for inventor.
