How hot is TOO hot?
 

Today was the first hot day I've ever driven my FD in. I'm paranoid about the thing overheating and I always watch my aftermarket temp gauge like a hawk. I have extra concerns since I installed an upgraded SMIC and ducting for it. The lower portion of the IC duct covers a good portion of the radiator flow. I have a Koyo radiator. Normally when driving I see temps well below 190 degrees that hold steady. Today I was driving around 65 mph and it was over 90 degrees outside, A/C was not on. My temps started eeking closer and closer to 220 and eventually crossed it, heading ever upward. The OEM gauge was reading about dead center at this point which is "hotter than normal". At this point I had reached my exit and started travelling on a slower road and snapped my running lights on to activate the fans which brought the temps back down to around 200.

I'm not used to seeing temps higher than 220 in any other car and I'm really afraid it's just going to keep going higher. Is this normal behavior and am I being paranoid? Is there a legitimate problem with having I/C ducting blocking the radiator fans? Anyone else have this problem with their upgraded ICs/ducts? At what temp should I really start to panic?

Drivin' the DSM tomorrow, it stays at 185 deg in all conditions.

change the thermostat quick like....rotary shack makes a 160deg thermostat...either that or completely remove the thermostat to constantly ciruculate the cooling system fully

dont remove the t-stat, you will actualy run hotter

if you dont belive me try it, howver have some $ set aside to replace your warped engine internals when you find out i was right

I replaced the thermostat with a brand new OEM one about around when I bought the car 6 months ago and went over it with a fine toothed comb.

have you done the fan mod yet?

Please quit posting this crap....you are WRONG!


Armitage: Are you running the undertray?

If I remember correctly Mazda gives a normal operating range of 158-221F. Their fan turn-on ranges suggest that they really do not worry about running around 220F degree ranges.

Some people who track their cars, running sustained high RPMs and moderate boost, report water temps in excess of 235F degrees.

In my touring with a stock size radiator and single oil cooler I did a run a couple of weeks ago, up a steep, winding canyon road at 92 F ambient temps. Most of the cornering and acceleration were in 2nd or third gear. By the time I ran the 3 miles to the top of the canyon my PFC water temp indicated 110C or 230F. Of course, i need to mention that I had left the air conditioner on. When I repeated the same run in 70F ambient temps and with the air conditioner turned OFF, the water temps got to 100C or 212F.

When I road raced my R1 FD with stock radiator and dual oil coolers I was ignorant of the inaccuracy of the dash water temp gauge and since the FD does not have an oil temp gauge, I simply did not worry about temps. I raced the car for two full seasons in 94-95 on some very hot CA days and never had any problems. The same motor is still in the car with the new owner and has not missed a beat yet (only has 30 some K miles on it today, total).

So, while I do not like to see water temps over 200F, I think that ocassional trips to 220 - 230 probably will not hurt it.

Albert

Edit: Having said all that, your temps do seem too high if you were only cruising on some highways, vs. running steep uphills in low gears. I have the M2 SMIC with ducting that severely restrict air flow out of the radiator. It is a compromise, I guess that I have to live with. I relocated the battery just so to open up a nice large area to allow radiator air to flow. The other side is pretty blocked by the SMIC air duct and the M2 intake box.

No, not yet, whenever I see it getting hot I flick on the running lights. I plan on getting a PFC soon which I hear will allow you to setup your fan temps.

Yep, only thing I'm missing is the tranny cover thing which my car didn't come with. I am assuming at this point that the I/C ducting may be the problem since it does block a good amount of airflow coming off the radiator.

I think someone mentioned that in stock form the fans come on at 226 degrees.

I installed the upgraded radiator for the express purpose of being able to track my car on hot Virginia days and not worry about temps, but if the temps keep creeping up at 65 mph on the highway what are they gonna do at 120mph at the track under constant WOT/boost? Argh.

I get much higher temps in stop and go traffic than at 65mph or 120mph. 120mph is about twice the air flow over the radiator as 65mph.

For tracking be sure to use some good dual oil coolers. Oil cooling plays a large role in the total cooling of the rotary engine. When I raced SCCA GT class Mazdas we found that oil cooling was almost more effective for the total engine cooling than water. We could get by with relatively small water radiators but, needed very large oil coolers.

Albert

With the stock rad and IC, I was pushing 210-220F after 2-3 auto-x runs, and the undertray was required or else.

I didn't really panic until one time when car started backfiring constantly. The temps we around 230F, because I got stuck in a traffic jam on a really hot day.

Presently, with my Koyo rad, stock IC, no A/C condenser, and a 90% h2o coolant mix, it says between 160-200. I had to run over a dozen runs back-to-back to get the temps up to 210F (test-n-tune). The undertray doesn't make much difference.

I don't worry about overheating anymore (at least not for the engine :) ).

If you are running that hot on the freeway, that is not normal. Last summer, I drove back from an autocross in 100+ temps. Coolant temps stayed around 200 degrees.

I suggest that you hook up your fans to come on earlier. That will help on the freeway. Also, make sure that your radiator is well sealed around the edges. You want to make sure that air is forced thru the radiator, and doesn't escape around it.

Heres something really simple that will give you 20 degrees. When your car starts getting hot turn on the heater full blast through the defroster. The heater works as an additional heat exchange, you may think its stupid but I speak from experience. I track my FD regularly in the summer. Thunder Hill here in NorCal gets plenty hot. I get under 200 by running the heater when I need to. Try it.

That does make some sense being that the engine coolant is used to warm the air.

104 celcius (220F) is where i'd start to worry. I never see over 95F even on hard runs and 100 degree weather.

I have always thought this was common knowledge. I mean I even learned this in drivers ed back when I was 16. But hey, good advice none the less.

i apologize i was merely being sarcastic no hard feelings, i do run the RS 160deg tstat...works wonders! :icon_tup:

^^This makes me suspect your radiator ducting, or lack thereof. At higher speeds, air will try to flow around the radiator rather than through it (especially with a Koyo, which uses a core that is too thick IMHO). How are you sealing the gaps around the radiator?


In my car (stock radiator, stock ducting, stock IC and airbox, with miniature PC680 battery), turning the A/C on will decrease coolant temps, even at 80mph. This tells me that the fans are the most effective at pulling air through the radiator even at such high speeds, especially since the A/C condenser is adding heat in front of the radiator.


Since your car cooled down when you turned the lights on and activated the fans, that means your radiator is working properly when it has enough airflow. Remember that the stock ECU doesn't turn the fans on until ~230F. If you want your car to run cooler than that, I'd look into the fan switch mod or the FC thermosenswitch.


Here's something I just discovered: the OEM thermostat isn't fully open until 203F.


What is your water/coolant ratio? If it's warm outside and the car won't see freezing temperatures, the FSM recommends 65% water / 35% glycol. In hot weather, I think 80/20 is a better blend since the water transfers heat so much better than glycol (and the 13psi pressure cap will raise the boiling point above 245F, even for pure water).



-s-

Hrm, maybe you've hit the nail on the head. I have nothing sealing the gaps around the radiator. I was going to fab up an airbox on the passenger side to draw cold air thru the gap for my k&n's.

So the I/C ducting that's blocking exit airflow from a large portion of the radiator isn't as important as sealing the gaps around the radiator because the fans work as they should? Maybe I'm barking up the wrong tree. I was hoping to get some other people's experiences using big I/C ducts over the rad fans.


About 40/60 coolant/water.

Remember that lower A-F %'s WILL cool better, BUT they will cause greater coolant pressures when hot, possibly hastening heater-core and radiator end-tank, coolant-seal, and/or hose failures.

He responds to Scotty:

I feel like the Rodney Dangerfield of this forum (straightens ties, twists neck)..... I get no respect I tell ya. No respect!! ;)

Sorry, your quote was all the way back on page 1 so I didn't include it ;P Thanks for the help ;)

Sometimes people need to hear things three times before it sinks in, Adam. To be honest, I barely noticed that you mentioned radiator ducting, since it was the last post on page 1.


-s-

One thing I just remembered now that I am ready to change my 50/50 coolant mix to closer to 80/20 is that the coolant does act to lubricate the water pump. So, if you take most of it away there may be a lack of water pump lubrication.

I will go out and get a water pump lubricating additive to put in just to be sure. I always used such in the racing engines when we ran 100% water and glycol based coolants were prohibited in cars (for crash spill effects on the tracks).

Albert