Thermostat Temp. Question 195 vs. 160
 

Is there a problem going with a say 160 degree t-stat vs. the stock temp? Is that to cool? I live in Phoenix and now during the summer, it's around 115 during the day. Needless to say, the engine gets really hot! The car is all stock for now, it runs great! I was thinking about putting in a cooler t-stat. I've done coolant flush with water wetter and 50/50 mix... I'm thinking a new radiator is what I need, but wanted some feedback on single best cooling mod you can do...

Any help is appreciated...

Do you have an aftermarket temp gauge?

If not, get one of those first so you can see what temps you are actually seeing.

If you have one, what temps are you actually seeing?

Sorry, I don't have an aftermarket temp gauge yet. I plan on getting one, but just haven't yet. The stocker is moving up slightly when I'm driving home at around 5 pm and 110 degrees. The needle is not quite halfway between middle and "H", but maybe a quarter of the way up there. It's starting to scare me of all the talk about over heating rotaries, so I want to do something about it.

What do you think is the single best cooling mod I can do?

If the stock temp gauge is moving, then your car is definitely getting too hot. A few cheap things that will help are:

1. Drive with the parking lights on. This will cause your OEM fans to activate at 210F rather than 230F.

2. Seal the gaps around the sides of the radiator so that air is being forced through it rather than around it. Duct tape works, and racers have reported that this lowered their temps by as much as 10-20 degrees F.

3. Replace the filler neck cap (use OEM Mazda, it's $15-20) and the pressure cap on the AST (use a Stant 16lb cap). If your cooling system isn't pressurized, it will boil at a lower temperature.

4. Clean the oil cooler, and make sure the fins are straight. Oil performs a LOT of cooling in rotary engines.

5. Replace the thermostat, personally I'd rather drill 2-4 small (1/8") holes in a stock thermostat than pay the extra money for a non-OEM thermostat. I've heard that the 2nd Gen RX-7's and possibly Miata's have thermostats that open at lower temps, but I'm not sure if this is true or not.


As mentioned, install a temp gauge so you know how hot you're getting, and under what conditions.
-s-

The stock temp guage isn't linear, and is pretty worthless. Get an aftermarket gauage ASAP. Also, if you still have the plastic AST, get an all metal one.
Then, IMO, do the simple things first. You've already flushed with new coolant and WW, but where you live, consider a ratio with more water than the 50/50 mix. And no offense, but don't overlook the obvious. The radiator can get pretty dirty between the AC condensor. Also check the oil cooler(s). I also think that switching to the FC thermoswitch would do more good than swapping the t-stat. It will turn the fans on sooner. Search for "FC Thermoswitch" for more info. Buy some cheap upholstery foam and plug up any gaps around the radiator/condensor. After that, you can still consider an aftermarket (larger) radiator.
There's also the FAN MOD which will run your fans for ~10 minutes after shut down. Won't do anything for engine cooling, just reduce underhood temps.

Putting a cooler thermostat in the car will not make it run cooler. If you're having overheat problems the thermostat won't help.

To expand on what Damon mentioned, the OEM thermostat is fully open at 203F. This is assuming that your original thermostat is working properly. Like I mentioned, replace your radiator caps first, because they're more likely to be the culprit.

-s-

Thanks Guys!!! Do we know of any write-ups on "sealing" around the radiator or is it pretty straight forward?
Also, where can I buy the Stant AST cap that scotty305 is talking about?

Ok, now a noob question, cleaning the oil cooler... Are we talking about just the outside of the cooler and making sure the fins are straight or something internal?

Search under "Damian" he's got a good thread on extreme radiator ducting with picture on where to seal gaps in the underbelly.

also, search under "damian" for the oil cooler cleaning. Its amazing the before and after pictures he has.

Yeah, nothing complicated. I just used some foam 2 to 3" thick, cut it a little oversized and stuffed it into the gaps, which will be obvious.
Almost any parts store...Advance Auto, Autozone etc. will carry them. 13 psi for stock. If you still have the green plastic stock AST, they are prone to failure. Most aftermarket metal ones will come with the appropriate cap.
Yes. I use a pressure washer, or garden hose nozzle. Just be careful not to get TOO close and end up flattening the fins. I think they make "combs" to straighten them, but I just use a small plastic pick. It can be a little tedious the first time.

Thanks guys!!! I'll try these things and get some gauges done, Boost, and Temp and see what happens before I go spending money on a radiator, maybe a downpipe instead is my future... :)

I guess you did say your car was stock. If you've still got the pre-cat, definitely get it replaced...soon, with a good Downpipe. Have it heat-coated or put header wrap on it . Peformance and reliability...one of the best "bang for the buck" mods there is.

Thanks for the info guys!!!

I'm not thinking radiator any more for increasing my cooling. I'll do a downpipe, radiator ducting, and more agressive mixture with water, maybe a 70/30?

I was also thinking about trying to find a used or new R1 stock dual oil cooler setup and put that in my car... Do I need the whole kit or can I just get one since I already have one on the car? Just curious...

I also live in Arizona. I had a lot of over heating problems until I put a fluidyne radiator in. I have OEM caps and thermostat. Since this upgrade 3 summers have passed and I have not got too hot yet.

Thanks for the reply K-man... I was thinking bigger radiator before this post, but the majority says to do other things, so maybe a new radiator, maybe not...

If I have $1k to spend on my car, what to do first?

Any one know this company or have this t-stat? https://www.rhdjapan.com/shop/cart.p...t_detail&p=809

Also, they're selling a brand new PowerFC + Commander for $680. Isn't that a good price?

I wasn't saying NOT to replace the radiator, just that replacing the t-stat wouldn't do you any good (unless it's bad), and there are many other inexpensive things to do for better cooling than just replacing the stock radiator.
If you've got 1k to spend, replace that pre-cat with a good, heat-coated and/or wrapped DP, put on an aluminum AST, get a boost and temp guage and the other stuff mentioned above. Then, if you still feel the need, replace the radiator with a larger aftermarket one. Do a search for what's available. You'll still have a lot of money left over to buy gas, and enjoy the car while learning more about it before doing any performance mods. :)

Yea, that's part of the problem... I want to do performance mods, but it's my daily driver, so I need to make sure it's reliable and be ok in the AZ summer. So, cooling first, then performance, then looks.
Will a cat-back help with engine temps too? I wanted to do the downpipe and cat-back at the same time, but maybe the downpipe first and aluminum AST and gauges first... So many decisions to make and I want it all!!!

Here's what I would recommend:

1. Maintenance (new OEM t-stat, new OEM coolant caps, coolant flush with better water mix)
2. Close up openings around the OEM radiator
3. Downpipe
4. Aluminum AST

Check your radiator during your 'Mainenance'. Make sure the fins aren't all smashed in. If the fins are ok, leave the radiator replacement for later. If it's just all beat to crap, go ahead and replace it with a Fluidyne or PWR.

I haven't checked the condition of the radiator or the oil coolers. The car only has 25k miles on it, so I assume there in good shape, but I guess I should get under it and take a look. I was thinking dual oil coolers too, what do you guys think about that too?

Can you buy a downpipe already coated? The ones I've been looking at, don't say... RX7Store or Pettit? Which one's are a direct fit without any problems?

IMO, in stock form, you shouldn't have any overheating problems just driving on public streets (track driving is something else). IMO, you need to find out what temps you really are running, then handle the OEM stuff first.

While we don't have as many 100+ days here in the Midwest as you, we do spend most of the summers in the upper 90's with a few trips in the 100's. My car never had a problem cooling itself when it was stock, just driving on public roads, during those conditions.

I just think I'm playing in a totally different field then you guys in the midwest. Here it gets up to around 115 during the day and with the sun baking off the asfault streets the air going into the engine has to be higher than that. The car hasn't overheated yet, the fans do thier job, but the stock gauge does move upwards and that scares me. So, before I do some performance stuff, I want to make sure it stays cool and reliable for driving in those conditions. That's all... Not too much to ask, right??? :)

I used to live in Tempe so I'm well aware of the temps there compared to here. Trust me, it's not as different as you might think. ;)

The first thing (which I forgot to mention) is to get an Aftermarket Temp gauge. Without it, with any changes you'll do you won't really know the benefit (or non-benefit).

Really? I used to live in KC, MO for about 6 years. I'm from MO originally, so I know what you're talking about, with the humidity and all that...

So, from what I can gather, I'm thinking Aluminum AST, Aluminum Rad, foam ducting work, dual oil coolers, gauges, rad cap, and ast cap...
All of this for less than $1k??? Maybe???