I was checking out ebay and found an interesting thermostat by "billion". It say that it will open at 160*f (race version) and the other one is 170*f (street version).

Since rotarypronge to overheat and have a high engine bay temp... is anything bad can happen from running water temp @ 160*f (for street driven)??

 

You should only use an OEM Mazda thermostat, period.

 

Not sure I buy the "rotaries are prone to overheat" since in my experience, they don't.
The "high engine bay temps" would be primarily due to the exhaust manifold and a thermostat won't change that.
Absent compelling evidence to the contrary, I'd stick with stock.

 

alright, I am using stock thermostat and i have an extra one that I'LL USE THE NEXT TIME I AM DOING COOLANT FLUSH.

But MY QUESTION: is there any bad side effect for running rotary with coolant temp only 160*f??

 

I don't know, I guess you'll have to try it and see.
Don't forget to also posit the corollary to your question..."Are there any advantages running cooler than stock?"

 

The ECU (stock or aftermarket) depends on very specific engine parameters to operate properly. If you use a 160 degree thermostat, the engine will take longer to warm up, and could even stay below proper operating temp (180*) during normal driving. Mixtures will be richer at the very least, which is not going to help mileage or performance.

Use OEM thermostats only.

 

no its only 10*F differnce when i got my car tuned they did that they put 160*f thermostat in my car and it was fine but also i live in florida and it is super hot down here lol

 

The only advantage that i can see (or think of) running cooler water temp than stock is that if u autocross ur car and running redline almost at all time.

 

So this is closer than what i was looking for...
My haltech was tune for 180*f (water temp), so i can potentially running rich (richer) by lowering my water temp.. or will my haltech adjust to the cooler water temp??
AGAIN I AM RUNNING OEM THERMOSTAT...I WAS JUST THINKING WHAT CAN POSSIBLY GOES WRONG IF YOU ARE RUNNING COOLER WATER TEMP.

 

yes. because its only the thermostat, it runs cold when you're just normally driving, so you loose MPG, when you step on the gas, the coolant temp just goes right up to where it would be with the stock thermostat....

so if its running too hot when you're driving hard, this thermostat won't help

 

A cooler opening thermostat is not "improving" your cooling at all, its just delaying the inevitable overheating if that is a problem for you. All it is doing is letting more water flow at a cooler temperature. It flows the same amount of water as the factory one (the flow is what does your cooling). It is a band-aid at best. A radiator improves your cooling. Water jacket mods improve your cooling. A thermostat does not.

At worst, it is doing a number of things. As already mentioned, if the ECU detects that your car never gets up to temperature, it is never going to perform correctly and mileage and power will suffer. Additionally, from a thermodynamic standpoint, a cooler engine is using the energy of combustion to worthlessly heat up the coolant (remember, that coolant is 20 degrees cooler and is happy to absorb more heat) instead of using that energy to make actual power. There is a reason that most cars run as hot as possible (180 degrees is COLD, you don't even have to worry about boiling, most cars run at 210 or more), its mean less energy is spent heating up the block (and therefore the coolant) and more of it is used to make power.

 

180 is the normal temp... but i did seen it goes to 210 or even a tat more than that when the car is being driven really hard (and outside temp quite hot). I just didnt want to push the car even harder... risking blowing the motor.

 

Im new to the whole rotary thing so i could not say yes or no its bad or good but i do know i had a 11.1 compression stroked 350 and in a truck and it ran fine for almost a year and i pulled the motor and stuck it a 16 foot speed boat and and trashed the heads in about 2 hours due to way cooler temps cause i was running off fresh lake water as a radiator, and also it opperated worse so id have to get one it to heat it up and thats when damage started happening ( this was my first boat i built in case anyone calls me stupid )