I must be search challenged... pretty sure this information is already here on the form many times over, but I can't find it, so... I got the information below from ChatGPT. Can anyone confirm these numbers are realistic--or not?

Running only modest upgrades: Fluidyne rad, dual oil coolers, Efini turbos, etc.

Thanks!

Oil Temp Range (°F) Zone Notes < 160 °F Too Cold Oil not up to temp; moisture/fuel contamination risk. Avoid high RPM.
160–220 °F Safe Ideal for most driving; full viscosity and good lubrication.
220–250 °F Caution Common in spirited/track use; still fine short-term if using quality oil. Monitor closely.
> 250 °F Danger Viscosity breakdown accelerates; risk to bearings and rotor seals. Reduce load or pit.
> 280 °F Critical Rapid oil breakdown; serious engine damage likely if sustained.

 

Here's my favorite subject reference for rotary engines...

Mazda Competition - Recommended Temps and Pressures

BTW, I measure a delta of ~20-25°F pre and post oil coolers.

 

Not sure what cooling info you are specifically looking for but the FAQ thread has all the best coolant threads listed.
https://www.rx7club.com/3rd-generati...l-links-68640/

 

A good synthetic oil should easily handle over 300F. Dinosaur-based, IMO, the chart is correct with 275F max for safety.

What is best for the engine, since the oil does almost all of the rotor cooling, would be a bit lower.

 

Rotaries last much longer with cooler oil temps. I don't think I've ever read about damage or an issue from low oil temps in a rotary.

 

The probablem with this document is that it specifies oil pan temperatures which are always significantly higher (I think in the old VARA RX3 I supported it was a ~20-30* delta) than where most oil temps are probed these days. Still good info just skewed.

*edit* Drats! you mentioned that and I was doing the typical internet thing of assuming what else was said. My apologies.

 

It is best to measure oil temps in the pan/pre cooler.

You never only measure water temps post-radiator; and you shouldn't do it for the oil temps either.

0.02

 

Thanks guys for sharing your thoughts. A couple more questions?

Stop and go traffic, A/C load, brutal ambient temps: seems to run way too close to dangerously hot. I'd like to maximize cooling even at the expense of performance.

• Has someone developed a replacement sending unit to make the stock temp gauge useful? Or, why not--Is it impossible to do so?
  
• On a budget... tried a
  radiator cap with a thermometer it it
  radiator cap with a thermometer it it
  . Pretty sure this measures the water temp at it's absolute max, true? It seems to match the oil temps spot on, rather than the lower numbers described above.
  
• Using Royal Purple Purple Ice with ~50/50 antifreeze mix, erring on the side of water... the Ice didn't seem to make any difference. Is there something better to try?
  
• Hate to be a noob, but how do you measure the temps at different points, "pre and post the oil coolers," for example? Multiple sending units installed? Using vampire taps on the lines?
  
• I just reversed the car's AST delete with an aluminum OEM-style tank after learning air pockets are a real possibility when changing the coolant in an FD and then seeing that ASTs are commonly used on track cars in general. The FD had one from the factory--a bad one sure, but a good one seems like cheap insurance. Is there some downside I'm missing?
  
• Using a vented hood... does that actually help, or is it just a false reassurance? (Having tried comparison testing, hoping not to go to the trouble.)

 

- Best bet is to get a real temp gauge, I don't know of anybody that has placed one in the cluster aside from standalone builds. Water temp, oil pressure and boost gauges are a pretty regular thing for these cars as they are lacking from the factory, oil pressure from the factory has its faults and known failures (I personally lost an engine from a bad pressure gauge, my fault for not adding an aftermarket one sooner and just living with a dead gauge.)
- Don't bother with that cap. Use a high quality factory cap, I've seen those thermometer ones leak and its not like you will be running outside to pop your hood at every stop light.
- Not sure where you live but in hotter climates we tend to use 75% water to 25% coolant because water does better at cooling than coolant and we don't have to worry about the freezing. Coolant is just being used as an anti-corrosive factor at this point. I just did a video on my youtube channel on this a couple months ago. IMO, if you plan on keeping the car, Evans coolant is the way to go and then you can also run a pressureless system.
- Aside from installing sensors in all those locations, there is no real good way of going about it. Unless you are trying to diagnose a flow issue or something, this is overkill, just grab a laser gun to measure input/output when you need. If you have the standard aftermarket temp gauges, its up to you to decide where you want to place them.
- This AST question is a rabbit hole and there really is no wrong answer from the looks of it. I am one of those that tends to stick with the Mazda engineers and thing that there has to be a good reason why the manufacture decided to spend $X on a part times tens of thousands of vehicles rather than saving money which is what they like to do more than spend money. But on the other hand, there are people here that have been running AST deleted for well over a decade with good results. Maybe its just better at keeping the system bled, so if you are thorough with your initial bleed and don't have air left over, AST delete may be fine. If you have trouble bleeding, AST is probably the better option but it still won't fix a poor bleed, just help with the very small amounts.
- Vented hood helps a ton with underhood temps, but not for engine cooling. Your engine cooling is almost entirely based off your heat exchanger setups and how efficient they are. Vented hood helps evacuate hot air but does nothing to send ambient air to those exchangers.

The factory Mazda cooling system is good enough for a lightly modded car for fun use. Maybe not for sustained track use (which it can be ok for a stock car as proven by their initial testing.) I'm in Florida with a factory cooling system. It is an R model so I do have dual oil coolers but the factory system has been able to keep up with autox style driving, air conditioning etc. in the heat of summer. Standing still has the largest impact in cooling on a factory car, I can see my temps rise, especially oil temps while in stop and go, the minute you get airflow over the coolers, temps drop considerably but everything always stays in safe range. Remember, coolant temp of 220 degrees is considered normal operating temperature from the factory. Most of us like to stay in the 185 degree range for longevity though which is why we do the fan/thermister type mods.