first step is to create a solid. it should be closed from both sides
second step is to create an air intake as a solid tube too, and move it a lil bit into the first solid
then go to solid > fillet edge > fillet edge and fillet the edge of the airintake
now the most important step: go to solid > boolean two objects and select the both solids you have created before, by rhight clicking the mouse you can choose which part of this operation you need...should looking like at the link...
now create another one tube as a solid an skew it a lil bit. then place it llike at the pic. it should intersect with the other solids you have created before
now do again the boolea operation of two objects like in the step 4
thats the way i would do that. of course its no exactly the shape you has, but with a litle more work you can reach it.....