Best air filter for OBS 7.3?

BajaSurfRig

Active member
I just recently purchase a 96 F350 CCLB 7.3 4x4 and it came with a Napa 6637 filter. I find myself in some pretty dusty conditions on occasion and am curious what the best filter out there for filtering in those conditions with a 7.3 is (I don't want to dust my turbo or engine). I would like to make the AIS severe duty filter (for the late 99 to 03) fit but don't really want to do the trimming that is required for it. I just ordered a donaldson 6637 along with a Riff Raff pre filter cover for an upcoming trip. My fear is that there is no box around the filter still and that one bad splash through a creek crossing could do some damage. What do you guys recommend?
 

Superduty

Adventurer
I have the AIS severe duty on my 99 7.3 Compared to the stock filter it is a beast. I am not sure there is a better option. The 6637 looks like a good option, but the AIS still looks superior. I am not aware of what trimming and mods need to be done to fit the AIS in the OBS, but for peace of mind it may be worth it.
 

Chorky

Observer
Following - as I REALLY want to do this as well


I just recently purchase a 96 F350 CCLB 7.3 4x4 and it came with a Napa 6637 filter. I find myself in some pretty dusty conditions on occasion and am curious what the best filter out there for filtering in those conditions with a 7.3 is (I don't want to dust my turbo or engine). I would like to make the AIS severe duty filter (for the late 99 to 03) fit but don't really want to do the trimming that is required for it. I just ordered a donaldson 6637 along with a Riff Raff pre filter cover for an upcoming trip. My fear is that there is no box around the filter still and that one bad splash through a creek crossing could do some damage. What do you guys recommend?
I was considering the Donaldson AIS also as it's the best one out there - But even with the fender trimming I still have read somewhere there was clearance issues with the hood??

I have the AIS severe duty on my 99 7.3 Compared to the stock filter it is a beast. I am not sure there is a better option. The 6637 looks like a good option, but the AIS still looks superior. I am not aware of what trimming and mods need to be done to fit the AIS in the OBS, but for peace of mind it may be worth it.
Can you elaborate on what the trimming mods are?? I wonder if there is another unconventional option they have probably a standard industrial cylindrical style system that you could just mount where the existing filter box is. It might also allow for a pre-filter if you were ok with the 'snorkel' type look :-/


UMP or get a Donaldson catalog and install a canister or cartridge style yourself.
One question though would be finding a way to hook up the airflow sensor (its on the bottom of the existing box kind of tucked away some. No doubt that would cause a change in fuel mapping though.
 

BajaSurfRig

Active member
Thanks for the input guys. It is worth getting an S&B intake box (to protect the filter from splashing of water) and running the donaldson blue cone + prefilter on the inside of it? Unfortunately it looks like it is near impossible to fit an AIS intake on an OBS 7.3...
 

Chorky

Observer
Thanks for the input guys. It is worth getting an S&B intake box (to protect the filter from splashing of water) and running the donaldson blue cone + prefilter on the inside of it? Unfortunately it looks like it is near impossible to fit an AIS intake on an OBS 7.3...

Well I have heard of people running the Donaldson AIS on the obs fords, but unfortunately of all the forums I've seen talking about it, nobody did a write up - so that's a bummer...

Just curious, what intake/filter are you talking about using? Links?
 

BajaSurfRig

Active member
Awesome!! I'm looking forward to seeing it.

I just got back from the trucks inaugural Baja run. I couldn't get the AIS set up to fit without more trimming then I was willing to do....

I ended up going with an S&B Filter with cotton cleanable filter...

https://sinisterdiesel.com/i-164994...eN1zWnMjzXLuBG6wvIpJiUjUrUzwvPmRoC5vgQAvD_BwE

It did a great job on this trip where I did around 300 miles of dirt roads with lots of silt beds. Still not as good as the AIS but it works.
 

Chorky

Observer
I just got back from the trucks inaugural Baja run. I couldn't get the AIS set up to fit without more trimming then I was willing to do....

I ended up going with an S&B Filter with cotton cleanable filter...

https://sinisterdiesel.com/i-164994...eN1zWnMjzXLuBG6wvIpJiUjUrUzwvPmRoC5vgQAvD_BwE

It did a great job on this trip where I did around 300 miles of dirt roads with lots of silt beds. Still not as good as the AIS but it works.

Oh no! How much trimming was needed? I'm wondering if its something I might try....

I'm glad your other option worked out ok though
 

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