MFI airbox connections
 

On my 72 there are three connections. One that comes from the right side of the engine compartment which is the oil breather hose. One that is smaller and comes from the left side of the compartment and I think this is the tank vent? And one that come from the middle of the engine shroud, what is the purpose of this hose?
Thanks

One from the MFI temp sensor --I think.

every thing is here http://forums.pelicanparts.com/porsche-911-technical-forum/269190-ultimate-mfi-resources-thread.html

oops, I just re-read your Q ... see http://forums.pelicanparts.com/porsche-911-technical-forum/299053-tank-ventilation-mfi-diagrams.html

the short of it is, engine shroud air purges the charcoal filter.

If I were to remove the stock air box and go with this setup RENNSPORT RACE MFI-FILTER: A high performance air filter for Porsche 911s with MFI - RennSport Classics I could install catch can for the oil breather (easy), but where be the best place for the remaining left over vents? Maybe one side of the base plate of the rennsport?

Ok, I'm an absolute moron at times. My engine has been out of my car for so long that for some reason I thought that was connected to the airbox, duh!
Ok, so back to the one last gas vent hose that connects to the back of the mfi box, since I'm going with the filter setup above, should I tee that hose and vent it into both plates, or just use one side?
Thanks

Yeah, that's a good Q. I dunno whether to Tee or not. With another car, I was amazed by how much the gas fumes (purging from the tank) could mess with the intake mixture. (flood on start-up)...but that was a different set up (Cayenne).

My loose reasoning says that the charcoal filter purging will a be fairly slow event - mostly air, not much gas fume. And, any building of static fumes (eg sitting in a hot parking lot) will vent back out the airfilter.

I also expect that many people just disconnect it. ...let the fumes vent to the air.

I read a bunch of past posts and it does look like a vast majority either shoves it in the crease at the firewall, or snakes it into the left rear fender and forgets about it. But being the environmentally inclined person that I am, ;) I feel I should do my due diligence and connect it at the filter. Hmmmm, what to do.

yeah, and that environment happen to be the engine bay . . which draws air (for heat) to the cabin. (that could get stinky)

Anyway, what I would do... I would hook it up to the stock air cleaner :cool: ... or to just one bank if the stock system wasn't there. :)