If I floor it getting on the highway and hold 80 MPH I heat up to 195F +. If I slow down and stay out of the boost I cool back down 185F. At that speed I would assume that my fan is not necessary and I should be able to stay cool.

If I get on it for any period of time I start to heat up. I definitely think this will be a problem during autoX this summer.

My turbo glows red after running hard but cools down in 5 minute of idle.

I have a koyo radiator, new NA s4 water pump and housing, good radiator hoses (new OEM but no spring to keep from collapsing), OEM cap (original), and OEM thermostat (new OEM), under tray in place, cooling plate on top, new 3000 CFM electric fan (installed correctly).

I measure temps just below the thermostat with an autometer gauge while driving and a two wire GM for my haltech and data logging. I have a S4 street ported 13bt with a TO4E 57trim turbo with a 1 AR Turbine. I run 15 psi boost max. I do run a FMIC that blocks air flow but at low speeds and idle I run at 180F-185F. I do not think my timing is too retarded. My AFRs are between 11 (high boost) and 15 (no load with O2 correction). I cruise at 13 afr to 15 afr. I run 80% water 20% coolant. Aluminum NA hood no vents.....

What else can I do?

Is this just the price of more power?

Should I measure temps elsewhere?

Could aftermarket hoses and radiator caps help?

Many people run with a FMIC without problems right?

 

Sounds like you did everything you could do. Plenty of guys run FMIC with no overheat issues.

All I can think of is to try and see if you need to bleed an air out of the system, maybe get a vented hood (helped me more in traffic vs running hard but who knows)

some people like to put water wetter in there.

I don't think new hoses or cap is necessary so long as you are still holding pressure.
anyone else?

 

I tried water wetter, it made no difference. I noticed by system seems to have high pressure, I think maybe my cap is sticking shut and not letting normal expansion of the fuild. I ordered one from mazda should be here Thurseday. I have the spring type cap with the recirculating tank.

Any other idea? Different pulleys? Does any body make a performance water pump? I heard S4 are not as good as S5 (you can see the difference in fin design) but I need one that fits my waterpump housing and front cover (both S4).

 

So after wasting a day data logging I did the smart thing and went and pick-up a coolant system pressure tester from advanced auto parts.


It has all sorts of adapters and tests caps and systems


Tested my system, with the part below and found a few leaky radiator hoses (pressurized to 15 psi and dropped slowly looked for leaks and listen for hissing)


Then I tried the radiator cap, and it held no pressure. I bought cheap to hold me over until Mazda delivers a new one and tested it and it held 13psi. It's nice to find a smoking gun.


Then I when and test drove the same route as I did when I data logged and it stayed rock solid at 180F. I even did multiple pulls on the back roads and never got high enough above 180 to read on my gauge (182 I would guess).

So if your car heats up above 3000 rpm, but cools down below 2500 rpm you should check your radiator cap! My guess is the system reaches full pressure at 3000 rpm and that’s when the cap screwed things up. Below is the data log of my car when it was getting hot, peaked at 202F

 

^^ That's awesome.