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So I was looking at the pictures of the stock passenger turbo inlet elbow that @MWILD posted and it made me wonder if there was something I could use to swap it out. The stock elbow narrows down a lot with the built in fins that either try to swirl the air or cut down on the noise to the stock airbox.
He took a couple measurements of the turbo side which was 2" id and the airbox side which was 2.25". It looked liked it was pretty close to a 45 degree bend so I searched around and found a 2.25 to 2" reducer elbow with a 45 bend. It has 4.5" long legs and looked like it would fit. I got the elbow and thought there might be a chance it could suck itself a little flat under high boost conditions so I found some 2" exhaust pipe and 2.25 pipe that I planned on inserting into the legs to help prevent any chance of it sucking flat.
The fun part was removing the stock elbow with that spring clamp that holds it on the turbo. You can't squeeze the clamp enough with normal pliers or plumber pliers enough to get it off the raised ridge on the turbo inlet. I could get it to move and rotate, but it wouldn't come off. I tried some vise grips which grabbed it the same amount as the other pliers but still not enough to get it off. I finally tried turning the vise grip adjusting screw (with the other pliers) to tighten it up more and that was the secret to getting the clamp expanded enough to pull the elbow off the turbo inlet. I tried a quick test fit of the reducer elbow and it was not going to be long enough (about 1-1.5" short from seating on the turbo and the airbox). Since I did not want to put the stock elbow back on at this point, I decided to cut the reducer elbow along the 2.25" section and insert a length of 2.25" exhaust pipe with some clamps. That actually gave it a little better angle to seat the reducer on the turbo and airbox fully so no risk of it coming loose.
It's not pretty, but it's securely attached at this point. I added a zip tie to hold the coolant line and make sure it did not rub on anything. While I had the stock airbox out of the truck, I looked inside and noticed the "skirt" area at the bottom of the inlet and found that the tube width is wider than the opening at the bottom of the skirt so it might be restricting air at that point. I decided to grind down the skirt area to help open it up a little but still maintain that tube for potential water diversion. I will say that when I was washing the airbox out to clean all the plastic grinding material, that little hole in the bottom of the airbox does not drain water very fast so even with the stock airbox, any significant water intrusion will take time to drain and will most likely still get sucked into the filter/intake going to the turbos. Here's the stock airbox from a picture I grabbed here since I forgot to take one, you can see the skirt area that flares out at the bottom of the tube.
My modified airbox with the skirt removed. I could barely get 2 fingers under the stock airbox with skirt but I can now get 3 fingers under that tube now with the skirt removed.
At the time I did these mods, I found a Roush lid and filter on Ebay and grabbed them. So far with these changes, it feels to accelerate a little better and this tank of gas is .75-1 mpg better so far but I don't trust the stock computer so I'll update when I do a fillup with real numbers.
At this point, I'm pretty happy with how it seems to be working better than stock so I may not get an aftermarket CAI. One thing I did find after looking around some more, HPS makes a 2.25 to 2" 45 degree reducer elbow that has slightly longer 5" legs and that might actually be able to reach from the turbo to the airbox but it might be really close and I would want to make sure there is enough of the reducer clamped on to each end. I can't say if the mods made the truck any louder because I have the MBRP Overland cat-back exhaust and that is louder than stock.
He took a couple measurements of the turbo side which was 2" id and the airbox side which was 2.25". It looked liked it was pretty close to a 45 degree bend so I searched around and found a 2.25 to 2" reducer elbow with a 45 bend. It has 4.5" long legs and looked like it would fit. I got the elbow and thought there might be a chance it could suck itself a little flat under high boost conditions so I found some 2" exhaust pipe and 2.25 pipe that I planned on inserting into the legs to help prevent any chance of it sucking flat.
The fun part was removing the stock elbow with that spring clamp that holds it on the turbo. You can't squeeze the clamp enough with normal pliers or plumber pliers enough to get it off the raised ridge on the turbo inlet. I could get it to move and rotate, but it wouldn't come off. I tried some vise grips which grabbed it the same amount as the other pliers but still not enough to get it off. I finally tried turning the vise grip adjusting screw (with the other pliers) to tighten it up more and that was the secret to getting the clamp expanded enough to pull the elbow off the turbo inlet. I tried a quick test fit of the reducer elbow and it was not going to be long enough (about 1-1.5" short from seating on the turbo and the airbox). Since I did not want to put the stock elbow back on at this point, I decided to cut the reducer elbow along the 2.25" section and insert a length of 2.25" exhaust pipe with some clamps. That actually gave it a little better angle to seat the reducer on the turbo and airbox fully so no risk of it coming loose.
It's not pretty, but it's securely attached at this point. I added a zip tie to hold the coolant line and make sure it did not rub on anything. While I had the stock airbox out of the truck, I looked inside and noticed the "skirt" area at the bottom of the inlet and found that the tube width is wider than the opening at the bottom of the skirt so it might be restricting air at that point. I decided to grind down the skirt area to help open it up a little but still maintain that tube for potential water diversion. I will say that when I was washing the airbox out to clean all the plastic grinding material, that little hole in the bottom of the airbox does not drain water very fast so even with the stock airbox, any significant water intrusion will take time to drain and will most likely still get sucked into the filter/intake going to the turbos. Here's the stock airbox from a picture I grabbed here since I forgot to take one, you can see the skirt area that flares out at the bottom of the tube.
My modified airbox with the skirt removed. I could barely get 2 fingers under the stock airbox with skirt but I can now get 3 fingers under that tube now with the skirt removed.
At the time I did these mods, I found a Roush lid and filter on Ebay and grabbed them. So far with these changes, it feels to accelerate a little better and this tank of gas is .75-1 mpg better so far but I don't trust the stock computer so I'll update when I do a fillup with real numbers.
At this point, I'm pretty happy with how it seems to be working better than stock so I may not get an aftermarket CAI. One thing I did find after looking around some more, HPS makes a 2.25 to 2" 45 degree reducer elbow that has slightly longer 5" legs and that might actually be able to reach from the turbo to the airbox but it might be really close and I would want to make sure there is enough of the reducer clamped on to each end. I can't say if the mods made the truck any louder because I have the MBRP Overland cat-back exhaust and that is louder than stock.
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