FMIC and Coolant Temps

Hey everyone, I wanted to start a thread for my coolant temp situation and gather more input.

I’ve got a Koyorad aluminum radiator and a TR8 FMIC and I still can’t help but feel like my temps are a bit too high. This is mainly reinforced by seeing forum posts with people claiming sub 200 temps under normal driving, which is kind of wild to me.

Today, for example, it was 92 out according to my display in the car. Driving around with the AC off the coolant temps are anywhere from 214-219 and about 205 on the freeway at ~85mph. In itself, this isn’t too worrisome as the fans kick on after 219 to get the temps back down, but it’s annoying when it’s at 219 and I want to step on it, only to see the temps shoot up to 226 during a pull before the fans kick on and do their job.

I’m just wondering if maybe the fins in my radiator and/or intercooler are a problem at this point. I know the fan operates as intended, so no issues there, but I was considering a manual switch for the fan to keep them on when I want. Right now I turn the AC on to manually kick them on, but that seems a bit funny to have to keep doing.

Looking for some guidance and input on maybe some creative solutions for heat management. As it is right now, I could never track this car. If it sits at 219 while city driving, how on Earth could I manage a 20 minute hot lap?

 

So your fans kick on while your on the highway? What have you done to seal off the front end around the intercooler piping?

 

I'm in FL with a CS rad, with sealed off radiator (likely along what Mr EarMgcee would suggest) and I don't cruse above 200 deg F even in this humidity.

Turn the a/c on to ~3 or 4 degrees below ambient and see if it kick on the fan more often.

(Disclaimer I have more cooling going on that just the radiator)

 

This, did you do ducting to replace the stock stuff when you did the fmic? If you didn't it'd explain the temps that or your thermostat has failed. Yes "they normally fail open" well first hand I've had that not be the case in various cars.

 

No, I don't think that's the case. I just think 85 mph is enough airflow that it cools the system just fine.

Front end is basically open since all the plastic pieces are gone. I do have hella horns that block a bit of the sides, but nothing more than that. In the past when I mocked up some pieces to cover the gaps, the difference was negligible, but I'll try it again and see now that I know my radiator fan works fine. I've got some ABS plastic that could be beneficial for making some makeshift pieces to seal the sides.

I also have the air dam, if that counts for anything.

 

Do you have any of the factory skid plate or inner wheel well plastics?

If not you may want to consider replacing those with either OE or a CS skid plate setup.

Have you checked the cooling system for air or exhaust gasses?

 

I have the small plastic piece that connects to the bottom of the front bumper, but that's it. No wheel well plastics or skid plate. I didn't think those ones affected the air hitting the radiator so that's why I only ended up purchasing the smallest plastic piece that goes where the FMIC is.

 

..... Oh Man they do so much for air flow and temps, in a good way

 

No plastics of any kind except that piece I linked. I'll check into the OEM wheel well plastics, but haven't considered a skid plate as that's after the radiator.

The motor has ~2000 miles on it and the cooling system likely has been burped of all bubbles in that time. I've read it's a self bleeding system, so I don't suspect any air bubbles in it, but I can do a double check for any leaks when I park it in the garage again!

You think I could rock the wheel well plastics and still retain a simple quick release bumper?

 

You need all of the ducting to make everything work

The skid tray creates a low pressure area behind the radiator making the high pressure air in front pass through faster

 

^This

Right now all the air is just kind of slamming into the front of the car and nothing is drawing it through your bumper.

 

Also see this thread
https://mazdaspeeds.org/index.php?threads/diy-radiator-ducting-gen1-fmic-woes.5286/

Discussion on bats still applicable
https://mazdaspeeds.org/index.php?threads/bat’s-what-to-do.9313/page-2

I'm not linking all the driving threads I've search
https://www.google.com/search?q=duc...droid-samsung&sourceid=chrome-mobile&ie=UTF-8

Also
https://www.google.com/search?clien...MoQBSgAegQIARAC&biw=412&bih=718&dpr=2.63#ip=1

And also sub 230f is hot sure but fine our fans kick on pretty high Street seeing 240 now it's time to study getting worried and not step on it I know people see that as the upper limit on the track, yes I appreciate that's the track not highway. Also 85mph the rpm range in 6th the car is working not full cruise even 75 is less work on the engine.

Ultimately get your undertray back it should drop things, then look at sealing that bumper up

 

@Mauro_Penguin could tell you a thing or two about under-hood pressures and how to seal stuff

 

Thanks guys! I’ll look at getting some splash shields and an under tray on my car and see how the temps handle. This should be a fun experiment since I have essentially no plastics as is right now.

 

I did a lot of measuring on the engine bay and how air pressure builds up in our cars. Anything over 40mph and you start building engine bay air pressure, which starts lifting the nose of the car the faster you go.

I bet when you go to take datalogs, your steering wheel gets super light to the touch, your hood starts vibrating, and your rear tires start running hotter than the front. It feels like awful torque steer the faster you go.

The BEST thing you can do, throw back on ALL of the factory panels and baffles. You will see significant stability in your coolant and BAT temps.

If you want to go a step further, (because mazda left a TON of room for improvement on this car), seal up the "intake holes" on the front of the radiator support, and seal up the holes on the back of the crash bar. That alone will give you a huge improvement over stock.

If you want details and numbers, they are on my build thread. I'm about to clock in to work and dont have time to look for it. Good luck!

 

Penguin-Mobile -> https://mazdaspeeds.org/index.php?t...-jesus-built-my-hotrod.9305/page-2#post-77373

 

I can second that removing the undertray will make the front end float.i had about 100k miles on my car when I had to cut mine off due to rusty fasteners and immediately noticed that the front end felt way different above 50 mph with no other changes

 

Welp, it turns out that my heater hose connector is leaking. I'm not holding pressure in the system and and I'm thinking that's mainly why I'm seeing the increased temps. I ordered new connectors and will report back with the updated temps.

That said, fender liners and undertray are already on the way.

 

These coolant systems have always been a nightmare for me to burp. I found a vacuum filler at harbor freight that worked wonders to get it totally air free.

 

Do you have a link to the unit from Harbor Freight? Might pick it up just for peace of mind.