BEST 400W hps grow room

whats up guys? im a pretty expirenced cfl/ outdoor grower and this year ive decided to move up to an 400w hps. i have a few questions tho..

1. Room size 2ft wide, 4ft long, 6ft tall...is this enough room for 4 plants that will be put into flowerin around 15 inches tall?
2. I will be having fans blowing in at the bottom and at the top 4 inch ducting on both sides that connect to above outside the box with 4 inch inline boost fans..is that enough to keep it cool? with that said the hps has a remote ballast and temps in room will be around 70 all the time
3.If this will not keep plants cool enough what about moving it to my garage since its starting to get a little cold out?
4. Any suggestions

please comment back, id really appreciate the tips, thanks guys.

also this will be for veggin...any ideas? biggest concern is the grow room size, would my size room be good enough for decent yeild on 4 plants or should i make it smaller or larger?
thanks

i have the exact same set up. I live in n.cal and temps outside are near 70 mark and I'm having a cooling problem. Can u get 6 inch ducting?

Size is fine. Just prune and top you'll be fine and garage is an uncontrollable environment. I might keep it inside to control your environment. Hope that helps.

sweet man im from the east coast, but you said you have cooling problems with the two 4 inchers? whats your temp/humidity looking like, and thanks bro i appreciate it

and also would i put the inlines at the exhuast holes or put the ducting in and install the fan a few inches up and yeah i can get 6in ducting..would that be more benficial

a couple of pieces of advice, concentrate on cooling your light, that will solve a big part of the problem because the light un cooled with heat up a tent QUICK, get a cool tube or similar air cooled reflector, you will be glad you did.

also, make sure to vent the hot air from the fan outside you tent, also keep any electrical item outside as well (ballasts, hydro pumps, etc)

If the passive intake doesnt work, you can always add an active intake face to bring in fresh air.

Lots of options, feel free to check out my log (its in my sig) for an example of what I am saying, My temps are a stable 75 average

I would use those 4 as mothers and just do a full SOG and make use of every CM of that grow space. The yield from 4 plants squished into a 4x2 is gonna be bad compared to a 4x2 SOG.

thanks guys i appreciate the help, i built the box today im almost done. you say 4x2 will effect yeild? would 4x3.5 be more beneficial aka better harvest? i plan to flower when around 15" so should i widen up the box a lil more
?

A small closet space like that is going to require an air cooled reflector, like captainkush said.