Toyota RAV4 Forums banner

1 - 12 of 12 Posts

·
Registered
Joined
·
759 Posts
Discussion Starter #1
Ok I had this idea a couple days ago, but for some reason I can't stop thinking about it. It's only for people with CAI's.

The idea is to take a flat K&N filter (like the stock drop ins) and flatten it out, cut a 3" circle (its wavy, and this way you'll get more filter), and basically stick it in the intake tube. Less restriction, same filtering, would have to be cleaned or replaced more often but you would still have extra discs of filter that cost the same as a new filter all together. I figured the air has less of a path to follow and can go straight to the engine. No more filters, or heat getting to the filter. It would be funny to show someone your engine and them seem confused when looking for your filter... :)

If this seems like a good idea (to you guys) I'll check out HomeDepot tomorrow to find some type of 3" circle (2 pcs.) to hold the filter in place, and I'm still figuring a way to hold it into the tube..

Let me know what you think guys.
 

·
Registered
Joined
·
1,484 Posts
Cool idea. :thumbs_up: But this may not work in reality because you would be starving the engine from getting sufficient airflow into the throttle body.

The large openings of any aftermarket airfilter pods or the factory air box is designed to let unrestricted amounts of air to flow into the intake. The air filter is there to screen out any unwanted contaminants.

The surface area of the filters are designed to trap these particles and still have enough area to let in a sufficient anount of air. The idea that you describe will not have enough surface area (roughly 3" diameter) to be able to trap the particles and still let in the necessary amount of air for your engine to perform.

Also, with the cold air intake scoop that you have created; you will notice that you will be letting in much more dust/dirt/debris than ever before. My enclosed filter pod had a high amount of debris clogging the front of the intake:



Imagine that debris clogging up the 3" area of filter?

Your best bet would be to get the smallest diameter filter pod you can find, and try to enclose it to shield it from the engine bay heat. The K&N X-stream filter pod that I have works well:



Soon it will be enclosed again, like I had it before:








Right now, I am getting some baseline temperature readings from my Scan Gauge to compare an exposed air intake (what I have now), with the enclosed system (what I had before). Once all the data is collected, I'll let you all know what the results are. :D
 

·
Registered
Joined
·
759 Posts
Discussion Starter #3
I dont think there would be starvation of air, the same amount of air is getting sucked in through the 3" tube. Especially since we have enclosed scoops already, the only air that filter is getting is the air from the scoop. I think the regular filters are larger so it lasts longer and is lower maintainance. How big is the stock filter, 6x10 or something? Thats at least 6 filters that you could make for the tube-filter, just would have to clean or change them out more often, but I'm thinking it would have a much larger effect.

I guess I'll test this idea out, I'll run up to HomeDepot later and get something to hold it, I'll just cut off the stock filter type. Since that is white I can see how long it takes before it becomes dark.
 

·
Registered
Joined
·
542 Posts
bigger the surface area the less restriction to airflow! the air will be moving slower when there is a larger area for it to flow through. that means more chance for the crap to stay in the filter & not be forced through by high air flow!!! 7 square inches of filter area is really kinda small if you open the throttle & the engine wants to pull in 6,000 liters (212 cubic feet) of air per min!!!

just my 2 cents worth..
 

·
Registered
Joined
·
759 Posts
Discussion Starter #5
I mentioned it was only for enclosed CAI's. We have scoops leading to enclosed filters where only the air that enters the scoop is forced onto the filter. Its still sucking the same amount of air, and if the engine needs more, it will still suck at the same rate, but this will get it there faster. It will take less time for it to get dirty, but it will also allow less restriction by the air not having to fiddle around throughout the pod, then go through the filter, then realign itself to the tube.

I just got back from buying the parts for the test. 2-3" PVC toilet flanges and 6 nuts/bolts. I'll use my stock air filter and cut out the right size and just stick it in the extra area in the flanges. I'll report back, and take before and after xxx miles photos. Obviously its going to get dirtier , faster. But I think it would be worth the extra couple of minutes to disassemble and check every now and then.
 

·
Super Moderator
Joined
·
1,554 Posts
Derek said:
Soon it will be enclosed again, like I had it before:
Derek,

From that picture, it looks to me, that once enclosed, there would be some serious restricted airflow there... being that the center opening isn't that big, and the sides are mostly blocked so you wouldn't get as much flow...

Just my .02 cents...
 

·
Registered
Joined
·
1,484 Posts
DJ, that is one of the main reasons why I removed it awhile back. I noticed that there was a serious loss of performance from a standing start. But it sure worked well at speed! :thumbs_up:

Now that I have my Scan Gauge and can monitor intake air temperatures in real-time, I can determine whether a mod. done to the intake is having a neg/pos impact. Right now, I have an underbumper air scoop that is hooked up to an air hose feeding straight through to the exposed filter pod.



I'll let you know if this works out alright. Right now it is a toss up between restricted air flow or higher intake air temperatures. :?
 

·
Super Moderator
Joined
·
1,554 Posts
Derek, have you thought about doing the same type of cold air mod with the stock box and a K&N drop in filter??
 

·
Registered
Joined
·
759 Posts
Discussion Starter #9
I'm going to put it together after school today. I'll see how it works out at both from a start and while rolling. I'll use a stopwatch to see the time it takes to go from 0-40, 30-60, or something. I just dont understand how it would be restrictive if the same air is coming through the scoop.
 

·
Registered
Joined
·
1,484 Posts
Good luck! :D You should probably do some baseline data with your old system for comparative purposes. That way, you will know whether this mod. has any benefits or not.

Restrictive air flow might be more long term when built up dust collects. But as you mentioned above, you will check and replace more frequently.

Let us know your results, we are all curious. :thumbs_up:
 

·
Registered
Joined
·
759 Posts
Discussion Starter #11
I'm going to let my engine cool down and check some stuff online, run up to home depot for some inserts inside the flanges to hold the filter better (pretty big gap right now) and then I'll come home, let it cool, and then either later, or tomorrow, go for another run.
 

·
Registered
Joined
·
759 Posts
Discussion Starter #12
Well, this sucks. I got out my old filter and its like 2" thick, I only have enoguh room for about 1". So I cut out the circle and had to find a way to fit it in, and the only way to do that is cut off the bottom which would leave it opened. I just looked and the K&N would work, its only .875", but I'm not sure if I want to buy a stock air filter for 40 bucks just to cut it up, especially if it might not work as well. This either on hold until I can find a cheap filter that will fit, I'll check advanced auto for a thinner filter replacement tomorrow.
 
1 - 12 of 12 Posts
Top