But have you run the compression test yet? Or a leakdown would be even better.

Don't waste time with ancillary stuff when a likely, logical path has been outlined. I guess that's just what we do while we hope against hope.

OEM fans are very thick tho, won't really fit with a 50+mm thick radiator.

I think the real trick with the OEM fans and radiator is that they seal up amazingly well so every morsel of flow is forced to come through the radiator. I noticed when I first put on spals that by default they don't seal up the area between the fan and the radiator and they aren't exactly pressed up against it either. Unless you completely shroud off the area between the fans and the radiator, they will be almost completely useless no matter how powerful they are.

I riveted together a fan shroud out of aluminum sheet and aluminum 90 degree angle pieces (it's like an L that's 1" on each side) and I don't overheat even without the undertray. It was probably under 20 bucks in home depot parts and a few hours of elbow grease and it helped a bunch.

I don't know much about NA things. I fit the oem fans on a 52mm radiator in my old MSM, though.

Spals are good though. Do that.

Also, do what the guys in this thread are telling you. Check compression, you should see (I'm guessing the middle 2) at least one cylinder with really shit numbers.

I know you guys like to focus on the fans, but once you're moving they really shouldn't add much cooling. With really good ducting I'm only running the smaller A/C fan and it only kicks on when sitting still. Fans aren't a substitute for good ducting.

With that said pretty sure OP has a major issue involving cooked engine parts.

Especially once you stack an intercooler in front of the whole mess, the shape of a miata front end doesn't allow for much airflow through the radiator at speed.

But i agree. OP has bigger problems.

One more data point about airflow. Literally the only good ducting I have installed right now is between the fans and the radiator and my coolant temps are usually EXACTLY at the fan activation temperature (90 C) unless it's raining or something. This proves to me that properly ducted fans help... but it also shows that without ducting/undertray, the fans are the only thing moving air through the radiator.

And yeah, I will put some quality ducting up front, I just haven't gotten around to it yet.