The current toilet drain had a 4" hole bored into an 8" joist - needless to say, the joist was very bouncy and I'd always wondered when I would come crashing into the kitchen on the toilet. I've replaced the joist and I'm looking for an alternative to routing the toilet drain. Straight line to the stack (the stack is the top circle in the pics), is about 3.5 feet. There was no vent in the past.
Options:
1) Run the drain along the same line as the old, but have it drop below the ceiling. Tee into the stack, no vent required. This option requires me to create a bulkhead that protrudes into the middle of the kitchen, which I'd like to avoid.
2) Can I do what I tried to show in the picture below? Can I run the drain in the joist space until almost the wall, put a 90 on it, and wye into the stack? The wye and 90 would be hidden in the bulkhead above the cabinets. Can this be done without a vent? There would be a sharp drop (from the wye), just before the toilet drain enters the stack.