Heat concerns on new growbox

I found an old cabinet in my basement that I'm making into a grow box. You can see a diagram of it below. (As you can tell.. I'm no artist) For starters I installed 3 26watt 1850 lumen CFL's. I've discovered that if I leave it closed with the lights on it can get as hot as 87F. If I leave the doors open it drops to 75-78F with lights on but its not really feasible to do this 24/7. With lights off its about the same both ways, it stays 65-70F. Is this going to be way too hot especially if I add additional CFL's? If so, would adding C02 into the equation make this setup usable?

Is the diagram the plan for the box or is it what you currently have?

That many fans for a couple of low wattage CFLs seems overkill.

I'd have thought a high CFM 120mm PC fan (say 100CFM or so) for exhaust and a passive intake diagonally opposite it, should be sufficient.

This is what I currently have. The thing is I started with one passive vent and one exhaust fan. The temps were way out of control so I added the additional fans hoping it'd help bring down the temps. It helped somewhat but I still see upper 80's. Considering the grow doesn't have to be very stealth I'm starting to think it'd just be easier to pick up some B&W Poly and 2x4's and build myself a grow room in a corner of an A/C'd spare room. For whatever reason this box seems way too insulated to use. Its solid wood.. no idea what kind. Its kind of a pain spending the last couple days modifying it but oh well.. live and learn I guess. I took out two CFL's to see what would happen and temps have already dropped to 75F. Each additional CFL seems to add 5 degrees to the box.

i just got a couple 120mm computer fans, they are about 55CFM each, but they are the quiet type, so i dont know if you could get a higher CFM out of a 120mm fan.

i've always herd that you want more fans on the intake side the the exhaust, but i dont know if that was because of cooling or just air circulation.

what type of CFL are you using? I know the 3000k bulbs add a decent amount of heat and the 6500k shouldnt add very much heat and if your vegging at this point then you want bulbs with a high light temperature(cool white)

the "Scythe Ultra Kaze 120mm Fan 3000rpm" moves 133.60CFM at 45.90dBA - that's almost 3 times the air your other 120mm fan moves, so they vary a lot in performance.

I'm using the same set-up for the 1st time...cfl's..I have a problem with 24 hr. lighting. I also just cut a vent hole in the top of box and a vent in the bottom..Heat rises, and as it does and vents out the top it pulls cooler air from the bottom...It works fine for 2 cfls. I've got no heat problems at all. If you use more lights or stronger lights, it won't work..

As of right now I'm using 6500k 26watt cfl's. It really looks like this box is a bust. One CFL will work, my max temp was 77F but anything more and the temps are insane. I bought 10' x 100' of poly online today for $100. I've decided to just turn half of a guest room into a grow room. Heat will be much less of an issue and I'll also be able to throw 15-20 CFL's into it if I want eventually.