If the temp needle hits the "H" how hot is the water temperature?

I did a search and cannot find an answer.

 

It's DAMN hot. I'd say probably anywhere between the 220-240 F mark.

 

too hot...bye bye hot

 

Really damn hot the needle on the gauge cluster should be considered a dummy gauge by the time you can tell your too hot with it its usually to late I hate that damn gauge. I was reading 101C on my PFC and the gauge needle was just above the half way point so if it got all the way to the H thats is pretty freakin hot.

 

It is something over 230 Fahrenheit

 

hot enough to warp your apex seals

 

I have hit 109C (about 230F) and the stock gauge never moved. I seem to recall another member saying it swung to H at a little over 240F.

 

What about half way between C and H? There is no way it can be 120 degrees between C and H (240/2)

 

What is the temp limit for the rotary? I'm working on getting an after market temp gauge, but it will be useless if I don't know what too hot is.

 

Well the fans kick on, on a stock a FD (no PFC) at 100c. So with that, you could expect normal driving temps to reach around 105c pretty easily or higher during WOT or spirited driving. I personally like to keep the temps down below the 95c mark. I would think that a FD operating constantly above the 110c mark would be getting way to hot as far as street driving is concerned...tracking a car would probably see much higher temps around the 115c to 120c mark but I wouldn't recommend letting temps stay that high on the streets.

 

This is the reason why I'm asking

Could it be a bad thermostat??

 

I wouldnt let it get above 105 on the street. I've seen as high as 109 on the roadrace course and the motor was fine.

On the street with the 500R setup my temps have yet to get into triple digits, even when flogging the car.

 

Yes and probably is, but it could also be the water pump or your fans not kicking on and etc. But I would start with the thermostat since it's really cheap, fairly easy to replace and if it never has been replaced it's probably a good idea to go ahead and do it anyway.

 

In the good old days when I was tracking mostly stock FDs I'd let the PFC go to 112 which is about the point where the stock gauge starts to move.

I think the conversion is 1.8 x 112 + 32 = 233.6

so at around 234 or so the stock gauge will start to move which is a good time to take it easy hehe.

At 245 and higher for an extended period (probably as little as 5 minutes) you risk the chance of warping the aluminum rotor housings. The aluminum cools faster and the iron is thin when really hot but cools unequally across the face and then compression on the aluminum housing unevenly and warping can accur. Well atleast that's my take on it Basically even though 245 isn't that hot it's crazy hot for a rotary and can permanently damage your engine.

 

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/big-fat-fd3s-cooling-thread-571088/

 

Your gauge in the picture is reading about 240 F

If the temp reaches the white line below hot that's about 250F

Reading "H" is about 260 F

Don't ask me how I know this so well

FWIW I've had various FDs hitting 240F many a time but I've always backed off and let the motor cool down and never had a problem. I had one motor that probably saw spikes of 240F at time for several years and dozen of track days... however it did eventually die of a bad water seal.

However, as Fritz mentioned above... continual operation at that temp is not good.

My general rule of thumb is if the stock temp gauge moves off the standard centered position AT ALL back off the throttle ASAP and do a cool down lap.

If you are seeing these kinds of temp on the street then something is wrong with your cooling system most likely.

 

The thing is, on the highway, it drops down to about 1/3rd between C and H. Only during city driving, it goes up.

 

I think now is a great time for an aftermarket water temp gauge.

 

or a pfc with commander

 

https://www.rx7club.com/showthread.php?t=571088

scroll down a bit and youll see a pic of the gauge and around what temps are what... its the Big Fat FD cooling thread

 

I've never heard of warping an apex seal.

Engine housings warp. Apex seals chip, break, or shatter.

 

I caught that too. The apex seal *springs* can warp with extended time hot EGTs.

 

I suspect your gauge might have been "linearized" where it might actually be accurate and move along with the temps you are seeing. The FAQ thread has links to Robinette and Ciriani's site where you can get info on the linearization mod.

 

Could be the fans or related to the fans. Higher speed has air flowing over the radiator without the need of fans...slow city driving doesn't generate a whole lot of natural airflow, so the fans are needed to create that airflow. Broken fans (or fans that aren't switching on correctly) might cause temps to go up when speeds are down. Just a guess

 

.