Karb. box air filter fitment issues

[Cubieman]

EDIT: I have changed the name of this post as I thought my issue was likely due to an aftermarket air filter but that does not appear to be the case as I have an OE filter now with the same problem. I thought changing the post title might get more input.

I pulled my ITG air filter out for the first time since I installed my Karbonious box back in May and found some alarmingly large sized pieces of gravel in the bottom at the back most part of the air box.
Some were almost bb sized, the pieces were BEHIND the air filter trapped between the filter itself and the "ledge" that the filter sits up against.
I stuck my finger back there with the filter in and there is a small gap, the "ledge" seemed to fill this gap but this is likely where the gravel got in behind the filter.
I recently used 3" brake ducting to bring fresh air into the small rear hole in the air box from the brake ducting in the bumper near the foglight. I plan on making a separate air filter for the back hole using panythose stretched over the hole or something similar so no more debris can potentially enter via this ducting.

Has anyone else noticed a small gap at the rear of the air filter in their Karb. box? Again, I am using an ITG air filter, I think I will see if an OE air filter has better fitment.
I think for now I will find some kind of foam strip I can stuff back there. Those little rocks getting sucked into the engine really wouldn't be a good thing, its possibly already happened for all I know.

[heinzboehmer]

This is what my OE filter looks like in my Karbonius box (got it early March 2020).







There are definitely gaps around the filter, but the lip that is behind it covers them just fine. This pic shows that pretty well:



I also tried to get pictures of what the inside of the air box looks like. Not the best pic, but it does show that the lip is more than sufficient to create a seal:


I don't really see how gravel could get into the air box this way. Do you have any pics of yours?

[Cubieman]

Thanks for the pics, I'll have mine apart in the next few days and post photos of the ITG filter. The area where I have a gap I highlighted in this picture I found on Google.

[benzthis]

try a oe CSL filter.

[Cubieman]

Most definitely.

[Cubieman]

After one drive there was a bit of sediment in the same spot, behind the filter. I think that this is a direct result of my ducting the rear hole down to the bumper brake ducting. Although, a nice fitting air filter should stop any and all debris...I have an OE filter comming.
Any ideas on what I could use for a "pre-filter" to my back hole ducting? Thinking of maybe getting some of that material people put over their ITBs or carbs, or just using pantyhose.

[0-60motorsports]

The ITG is the worst filter you can use. Stick to OE CSL filter and Avoid foam filters like the plague.

[Speed Monkey]

[Cubieman]

The ITG is the worst filter you can use. Stick to OE CSL filter and Avoid foam filters like the plague.

Well belive me its going when the real deal arrives.

[jbfrancis3]

I saw your other post about debris collection, interesting.

I wouldn't put anything over the ITBs (the trumpets). Too much risk of something coming apart and getting sucked in.

Rather, I would get a small piece of screen (cheap way: vinyl screen door material from home depot; expensive way: stainless mesh from McMasterCarr), remove your 3" duct off the brake duct assembly, form the screen (about 6"x"6 piece) around the brake duct opening, hold it in place while reinstalling the round 3" brake duct over top, and re-ziptie in place.

[Cubieman]

...Rather, I would get a small piece of screen (cheap way: vinyl screen door material from home depot; expensive way: stainless mesh from McMasterCarr), remove your 3" duct off the brake duct assembly, form the screen (about 6"x"6 piece) around the brake duct opening, hold it in place while reinstalling the round 3" brake duct over top, and re-ziptie in place.

Yeah, this is what I intend on doing, and the screen will be down at the brake duct inlet for sure. I found that the patching material you would use to do a roof repair on your house looks like it may be a viable option.

[skristedja]

Thanks for the warning about this. I was planning on using the ITG filter for my Karb box, but I ordered a CSL filter after reading this thread.

[Cubieman]

I put an OE filter in today and still have the same issue. The overall fitment is much better than the ITG filter however there is still a pretty good gap right at the back of the box where the filter slants up.
I wonder if my Karb. box isn't out of spec a bit. One thing thing the ITG filter had going for it was that it was foam and that foam would press against the lip on the back side of the filter creating a better seal (I think) there compared to the harder red plastic material of the OE filter.
Where the OE filter slants up the perimeter of the filter isn't really touching the box at all, I am trying to come up with something I can put into that gap. I have some of that foam for sidewalk cracks but worry that it would likely not stand up to high temps and just degrade in general. I am making a long round piece of RTV and may wedge it in there. The lip should stop it from being drawn in behind the filter.
On closer inspection of the Karb. box I don't see how the filter seal up in the back as my box doesn't have a flat spot in that area even, it is curved inward. Its hard to take proper pictures of this.
I could use some ideas of materials for sealing this gap.

[0-60motorsports]

I just installed the OE CSL filter in a karb box and it fit like a glove. Message them on FB and send them pics. I’m sure they’ll reply back and sort it out if need be.

[BBRTuning]

The ITG is the worst filter you can use. Stick to OE CSL filter and Avoid foam filters like the plague.

What in particular makes you say this? Just fitment issues or filtration/flow as well? The ITG filter is quite commonly used on the CSL box particularly in Europe.