Cooling Options
 

Hey everyone - long time lurker, first time poster (I think).

So I have a cooling issue on my TDR supercharged Miata. It is fine for autocross and general cruising, but what I have found is that extended higher RPMs build up the heat load significantly. e.g., 4krpm for 10 minutes or so will build up to about 220*. When I let off the accelerator, they drop back down fairly quickly to around 200-205*. Running with the heater on drops temps by 5-10* so that has been my goto when I start seeing the temps get up to 215*.

Here are the relevant details on the car:
94 Miata with 1.8l factory engine (about 20k miles on it) - located in Atlanta, Georgia
Megasquirt DIYPNP (have adjusted cruise area to run closer to 14.7 instead of 15.2 - helped a little)
TDR supercharger kit with Intercooler and included ducting modifications to underpan
QMax coolant reroute with 195* thermostat
TDR radiator, filled and burped
Stock fan shroud and fans
PS&AC (not using AC, but would like to, living in ATL)

Car is fine at idle, so I think the thermostat and fans are fine.

I have read a lot of the discussions on here about this issue, and I am trying to figure out my next steps. Based on what I have been reading, I can see a few options - but want to get opinions on the following:

1.) Currently, I am running 50/50 with Amsoil coolant booster. I know I can change that mix to be more water-based, so I can aways go through and figure out a more "ideal" mix and still keep it from exceeding the pressure-adjusted boiling point. It's free, so I'll probably do it next. But I'm not sure how much improvement to actually expect here. Any experiences on the size of measurable change based on changes in coolant mix?
2.) I could add a hood vent. Right now, I am using a big part of the hood to display a large rice-y decal I made of Speed Racer, so it would have to be an asymmetrical vent on the driver's side, and probably look kind of goofy. I'm not totally opposed to this, but it's not my ideal choice. I think it would probably solve the problem, so I may end up having to go that way anyway.
3.) TDR offers an oil cooler kit that mirrors their SC oil cooler. I expect this would help, but I don't know by how much. Any experiences on the size of measurable change based on installation of an oil cooler?
4.) I am already kind of interested in installing a RS front spoiler and a splitter. I expect that doing this will improve air flow into the radiator, and that might be enough - but not sure if that might actually make it worse. I've seen other car forums where people say this make a huge difference, but obviously that's very vehicle-dependent. Any experiences on the size of measurable change based on installation spoiler/splitter?
5.) I've thought about water injection, but seems like that would be a PITA to maintain, and not sure how much impact that would actually have on the temps. Not really a useful option IMHO, but letting you know I have thought about it.

Thoughts?

Thanks in advance. Images for fun. Yes, the garage is a mess. :-) Thanks!

https://cimg1.ibsrv.net/gimg/www.mia...81f010ee61.jpg
https://cimg2.ibsrv.net/gimg/www.mia...1290b2afa6.jpg

I also run the same kit but i ditched the supplied radiator for the super miata cross flow and i have zero issues.
a cheaper less intrusive solution would be to seal the radiator with more ducting,make sure air has nowhere to go other then the radiator. block off all the gaps around the radiator.
https://www.miataturbo.net/race-prep...-thread-79930/ read this thread.

My engine is N/A at the moment (been considering a Rotrex), but I did notice a pretty substantial improvement in my temperatures on the track when I switched from 50/50 coolant to a pure water coolant. I'd definitely recommend using water in the summer.

I also saw some improvement in temperatures when I switched to running primarily E85, but that may not be feasible depending on where you live.

Hood vents

Yep, good thread/writeup. I found that and a number of others. They have the same article here: NA NB Cooling System Performance (supermiata.com).

Yeah, I'll try that approach as the easy/free option first. Thanks!

Have you wired your fans to run in parallel? I can't quite tell if this is an issue at a stop or cruising.

Whats your timing in this area? What MAP is this happening at? Post your tune.

Also, as an NA, you should have set your coolant temp calibration to the RX7_AFM option, not "Mazda". However if anything this change may just bring temps up.

Fans are normal config. This is when cruising at 4k or above for extended period of time. Car is fine at idle/stopped. Peaks at 205ish and fans take it back down to around 195ish.

Timing is around 50* @ 4K & 45kpa load.

Thermistor calibration is -10=9kOhms, 20=2.5kOhms, 80=320Ohms

I'll post the tune when I get a chance. Working off two laptops right now, and the Tuner Studio laptop is having network issues.

Right now, I am looking at adjusting cooling mix and tweaking ducting on passenger side (I think I can probably create higher pressure in front of the rad/IC with some minor adjustments). I am thinking oil cooler might just be throwing money at it. Also thinking about if/how to do an extraction duct that I won't regret every time I look at it. Finding some good ideas here and there, but they still look less attractive to me.

I'd be interested to know what happens when you take 10 degrees out in the area you're having issues. 50 sounds like a lot to me. Change your coolant sensor calibration the the RX7-AFM preset, looks like your settings are a bit off.

-15. FI engines typically run smaller spark plug gaps which limit the afr. Low 15’s does not require more then 35 degrees of advance.