First, I hope you have solved your problem with your plants. I have one plant that I had to bring back from being over nuted. It is about ready but it will not be as good as the first 2.
My space is 84 cubic feet. I am venting with a 110 CFM fan and intaking fresh air with a 90 CFM fan.
My fresh air comes from the garage as I said and it will soon start to heat up. Even now, I am having "daytime growing " temps reach 80-83 degrees in my space when the outside temps reach 70 or above. Soon, 70 will be the low temp, not the high so I have got to solve the heat problem. In the past I have not grown during this time of the year for this very reason.
I may just put an AC unit in my space and try to vent its' heat out into the garage. I have been studying the situation and this might be my best choice. I have a small "entry room" that is off of the main grow area. When you crawl into it, it is angled from the floor up to about 4 feet in height and might have just enough room for me to set an AC unit in, box off the back of the AC and vent it into the garage.
I think I can hide an exhaust fan hole easier than I can a big box with an AC in it. Once again I have a lot of teenagers in and out of my house so I need to be very careful.
Good luck with your plants.
Peace to all