This is my set up
Increasing airflow is about the only thing you can do short of adding a portable air conditioner (which has problems of its own.)
Do you plan on moving these outdoors? You are going to need a whole lot more room and a ton of more lighting if you plan on flowering these indoors.
Haven’t had any problems with 8 plants in a 2x4 area yet short 4 week veg. Then switch to 12/12 and cover canopy with trellis net. Plus Lst and topping to make them grow more horizontal than vertical.
If you’re ok with leaving the top cracked, and turn your fans towards the opening. I grow in a small closet in a 70yo, dilapidated house (it looks nice tho!) With the heat wave, I could easily hit close to 90°, but my fans are all in the back facing the door, and I leave it cracked a couple inches. I do have a portable AC, that I’ll turn on if heat is bad, but they introduce humidity. And are noisy AF.
87 is ok. In flower or veg.
? Not for me or any grower I know indoors. 72 to 80 is my target range with 77 being dialed in on the thermostat.
You will need an air conditioner, sad but true. It’s only going to get hotter in the weeks to come.
Sit there in summer all the time indoor. No issues. Total B.S. cannabis cant handle that. Find 1 area cannabis grows naturally that has a perfect temp. Perfection can be sought but home growers rarely achieve it. Info was given from actual grow experience with temp ranges up to mid 90 at times with big HLG lights. If cannabis can only grow in such a small temp range many could not grow.
My first grow I couldn’t control temps . As high as 95 degrees. She grew lol
Lol, I’ll stick with tried an true non bs science. Soil and water temps is another consideration at higher temps so are fluffy buds.
Plants outside basically shutdown in high heat. If I was the OP I would read up on this more.
Good luck and happy growing
Each to his own. Tried and true to me is done it myself and observed the results multiple times over multiple years.
Happy growing.
You can regulate your temps I assume @Storm the op can not. Me thinks with it only getting hotter in weeks to come that the best advice would be for him to install an ac. Wouldn’t you agree?
If not, what’s your advice on his hot and getting hotter situation? As I just don’t see letting the temps run wild as a viable option.
What say you?
Just be aware that you will need to exhaust a portable AC outside of your grow space. They put more hot air out the back than they put cold air out the front of the AC unit.
Chased temps years. When hps/mh was tough. I am in the south and we are sitting triple digits. Found steady under 92 is workable. Extra airflow. Watch watering. Ac in lung room and good exchange is only solution i found that works steady. Removing drivers ftom tents if detachable. Sometimes just cant get down to low 80 or high 70. I used to stress it. Now i just deal with it instead of chasing it. Lights on overnight instead of daytime. I upgraded to es300’s instead of my HLG because of much better heat levels. Same horsepower each tent. Ac in tent I personally dont suggest. Lung room yes. If spikes are under 90 I have never had an issue. Mid 90 for a short time no issues either. Switching to lights at night can get you 5 degrees at times. Just me. I have found fightin for a range smaller than cannabis can handle is just non essential worry.
Do as you wish. Not gonna argue with you. I will just keep growing successfully for my medical group and trust in results over anything else. Good luck in your grows.
Hey hey… be nice. Each of your styles is fine for each of you.
And somewhere something got miscommunicated. He wasn’t saying @Storm cant regulate his temps. He was saying OP can’t. Tomatos Tomatoes.
Now back to OP… I think you‘ll be fine. Yes OPTIMAL temps are 74-84ish… but with that goes humidity, intensity (lights), and nutrient solution strength. Optimal being the operable word.
Weed can and will grow at 60-95 just fine. A bit slower when not OPTIMAL, but it will grow. Just like it’ll grow at 77 degrees and 90% humidity, but it’ll also grow mold. So there’s that…. But it grows.
Point is, new user, needs help. Not to watch two decent experienced growers measuring forearms. 
Id suggest moving the hotter of the two lights to yhe top. I yhink he said 600w on bottom. Heat rise naturally. The other plants sit above yhe top of the light. Just thinking of yhe bottom of the clothe pots getting direct heat on the bottom of their roots from bottom 600w light. Just spit balling. Leave the fixin for the pros
That’s what I was thinking switching the light but the 200w that I have on top produces way more heat than the 600w on bottom and the top is only at 50% whereas the bottom is at about 75% and still isn’t as hot.
I’d be curious to know what are your leaf temperatures are doing. But for now, how hot is the air going into the tent?
In any case:
Anyone can outflow a setup like that just by moving the intake fan to a second exhaust fan in parallel to the first one (side-by-side), & then giving them both enough intake area to reach max flow when they are both at 100% power.
You might even be able to outflow your current setup simply by getting rid of the 4" intake fan, & giving the 6" exhaust fan enough intake area to reach max flow when it is at 100% power.
What 6" fan do you have?
Are there any more restrictions that the exhaust fan is seeing, such as a restrictive carbon filter or ducting?
I have a Vevor ac inline fan that’s currently running at 100%
As for restrictions I have a carbon filter attached and the fan blows hot air out through the exhaust duct meant for the bathroom on the other side of the wall. There’s also a 6 to 4 inch reducer on the fan and then a 4 to 2 inch reducer on the duct for the bathroom exhaust.
This was the original design it’s a bit different since now there’s the 6 inch inline fan but you get the idea.
