K47 filter w/ 4" tubing

[drag sgt]

For anybody who has upgraded to 4" tubing on their air box, did you retain the factory A1300C filter? I have a picture saved where somebody hacked off the end of the factory elbow and placed it inside the silicone 90, but I'm hesitant to destroy it. Will the factory filter stretch over a 3.75 or 4" aluminum tube, or is there a different ACDelco filter with the same dimensions and larger opening?

 

[dbrannon79]

Not sure about the factory elbow since I don't have one, but my filter is fitted over the end of a iirc 3" sewer PVC elbow. the bell end (larger) is what the filter is fitted over and the other end is smaller kinda like a street 90 the rubber boot to the turbo fits over.

what I would do is take a good measurement of the filter ID and head down to the local hardware store and measure various pipe fittings. Lord knows I've done lots of hackery like that finding something that works without destroying NLA OEM parts!

 

[ak diesel driver]

I turned down one end of a 3" abs coupler for a friend

 

[Will L.]

Something I haven’t been seeing that surprises me- more guys getting factory air boxes from junkyard on brand new dmax/cummins/powerstroke that are built to flow enough air for 970 pounds of torque & 475hp. Call me silly but that should support 99% of 6.5 alive.

 

[dbrannon79]

Something I haven’t been seeing that surprises me- more guys getting factory air boxes from junkyard on brand new dmax/cummins/powerstroke that are built to flow enough air for 970 pounds of torque & 475hp. Call me silly but that should support 99% of 6.5 alive.

finding a d-max, cummins , powerstroke in the jy is as rare as hens teeth around these parts!

 

[MrMarty51]

finding a d-max, cummins , powerstroke in the jy is as rare as hens teeth around these parts!

Wonder if there might be some in ebay ? ? ? ?

 

[DieselAmateur]

in GM's infinite wisdom, the stock filter for the K47 has a diameter of 3.75". An uncommon/ difficult to find size but not impossible.

What I did was get a piece of 3.75" outside diameter aluminum pipe off ebay along with a 3.75" to 4" silicone 90* hose from intakehoses.com

The 4" was to match the inlet on a HX35/40. I had to trim down the 3.75" part of the silicone elbow to gain clearance between the air box and battery but it did fit with the turbo in stock location.

If using the factory turbo you'd need to go in reverse from 3.75" to 3"

I tried the PVC pipe adapter route but my underhood temps were hot enough to melt/ distort the plastic enough for it to come undone

 

[dbrannon79]

Hadn't thought about it till now, but an exhaust shop can take an elbow in stainless or steel and expand it to fit the filter. maybe even put a ridge in it for the filter box too.

 

[Will L.]

You could do it from metalwork, but the metal will heat up from the engine heat. Imo the solution with the silicone 90°s seems far better to have good airflow and block the heat at the same time.

 

[MrMarty51]

Hadn't thought about it till now, but an exhaust shop can take an elbow in stainless or steel and expand it to fit the filter. maybe even put a ridge in it for the filter box too.

The largest the muffler shop here can do is 3” but I’m not sure if they can expand it to 3” ID.

 

[drag sgt]

Something I haven’t been seeing that surprises me- more guys getting factory air boxes from junkyard on brand new dmax/cummins/powerstroke that are built to flow enough air for 970 pounds of torque & 475hp. Call me silly but that should support 99% of 6.5 alive.

Anecdotally, from what I've seen online of GMT400 engine swaps, a surprising amount used a 6.5 K47 box. I don't own a copy of the 6600 conversion guide but I assume there's at least some light fab work required. LB7 boxes are just as expensive as K47s but much newer boxes that take the stubby round filters are really cheap.



I need to finish cleaning up my cuts but I'm using a 6" long piece of 3.75" aluminum intake/intercooler tubing that I cut down to just under 3" in length. The flared side goes into the silicone 90* and clamps down well. I have dual post batteries and converted to using the top posts when I made new battery cables so I shouldn't have any space issues with the boot.