My setup.

Greddy FMIC.
Fluidine radiator mounted vertically.
No Ac condensor.
No ducting as of yet.
Power FC w/commander.
Greddy Water temp guage mounted in the filler neck.

I ran a typical water/antifreeze/redline water wetter mix for the last 2 years. I have my Power FC set to put the fans on at 87C. My thermostat breaks at 83C. I typically see running temps on my commander between 83-89C year round including the middle of summer (in NC). My Greddy typically reads 81-86C. I was very happy with this performance but was concerned about cooling for my upcoming HPDE events (having a FMIC). So I made the switch yesterday.

Last night I was out and about and this is what I saw.

Once warm my temps on the commander were between 83 and 86C on the commander. Nothing new - the night was cool and to be expected since the themostat wont let the engine get below 83C. But the surprising thing is that my Greddy read 76C! It NEVER EVER read below 80C running temp before. Not in the middle of winter - never! Now I am making an assumption to explain this:

Assumption: Water flows from the bottom of the radiator out of the top. I dont actually know this is the case but have always suspected it since my Greddy gauge doesnt register water temps until the thermostat starts opening and the temp it registers is always a little lower than the commander temp.

Back to the explanation - My greddy temp NEVER goes below 80C at running, so now it appears with the evans coolant the heat transfer I get through the radiator is improved, cooling the fluid more on its pass through the radiator.

Now this is hardly a comprehensive report - I have only driven the car once since the change. I wanted to post as I wont be driving it for a few days to get more data and I found the fact that my guage was at 76C extremely interesting. I have also never read any hard facts on the coolant on the forum and wanted to see if anyone else has their's setup like mine and had similar results.

Now if my assumption is wrong and the water runs the other way please ignore this entore thread as the only explanation I can see is that I am insane.

(MODS - please move this to the 3rdgen section as I made a mistake posting in the single section - THANKS!)

 

Upon some quick research I found that coolant goes the opposite I thought. I have no clue why I saw that temp last night then. I tapped my filler on the passenger side about midway down (actually used existing plugged stock hole). Is there some crazy coolant routing going on inside that filler neck that would explain my temps? Now I can wait to drive it some more to find out what will be the new normal - too bad I am out of town.


Shawn

 

Strange usually when you switch to Evans your temps should actually be about 5 to 10 degrees hotter not colder...

 

I switched to Evans and temps were about the same (or maybe 1-2 degrees cooler). The big difference is with water I was scared to run without the fans at 96C but with the Evans i'm not worried about it.

 

shawnk... sent a pm to ask you a question... dont want to sound like an idiot on the forum.. thanks
Edwin

 

random thought...the FD's operating temp is around 180F (~83C), 76C is only 169F. there is such a thing as too cold. at a track i'm sure the water temp would come up a bit though anyway.

 

I thought the reason that evans doesn't register as hot as H20/antifreeze is that it doesn't absorb as much heat from the engine.

 

Alright.. I have no idea what is going on with my temps.

I got back in town this afternoon and decided to take the FD out for a while to see what the temps would do. I let it warm up and even got to the fans turning on (87C right now though I think I am going to bring it up to 92C next time I hook up my laptop). My Greddy water temp guage never went above 77C. Sometimes it was as low as 73C. It seemed to run about 10C below my commander temps. Keep in mind the greddy used to run about 3C lower than my commander with nothing else changed except evans. I topped it off just to make sure but it only took a couple ounces (and I did install a bung in the radiator to bleed out the air there). So any one have a clue what I am seeing?

I am extremely happy with the rest of the coolant properties - zero pressure, lifetime coolant, anti-corrosion - and am by no means worried about these temp readings but I would like to understand whats going on.

Shawn

 

I was seeing 85 to 86 C on the Power FC water temp readout with NPG+. This was during Oct 28 (during the trip back from Rx7 Store to Indy). The car belongs to someone else now, so he'll have to give an update on how the Evans NPG+ does during warm ambient temps @ Lime Rock and Watkins Glen. BTW, I noticed the motor warmed up very quickly with NPG+. Probably 5 minutes is all it took to read 85 C?! Also I did not install zero psi coolant caps. They are 15 psi pressure caps, but the NPG+ coolant runs @ very low pressure (7 to 10 psi) with pressure caps installed. As for why your GReddy temp gauge and Power FC don't agree...:shrug: You got me! Why do you have two temp gauges?

 

Evans is great because it does make the car warm up quicker. Nice if you don't have coolant and double throttle in the tb. The only real downside is the increased cost. Anyone up for another group buy?

 

I would if I had the money for it right now...using water wetter and flushing the coolant yearly will do for now.

Steve

 

It pays for itself if you've replaced all the hoses and radiator and the motor is fairly fresh. Jack

 

I've been doing some 3rd and 4th gear tuning in my FD lately. According to my commander, I'm seeing 86C after many, many 8k rpms runs. I was one of the very first to use evans in a rotary, and will never go back to normal coolant. Infact, after the warrenty is up on my Rx-8, I'll be switching to evans in it too. Great stuff, just make shure you guys don't have any contamination. CJ

 

Actually the recommended pressure is zero to 7psi (if any). The heat transfer rate for NPG+ is lower than water (moving less heat away from the engine) to begin with, by pressurizing the system you are reducing the heat transfer rate of NPG+ even further.

 

I asked the Evans tech person about 0 psi vs 15 psi caps, and their response was it was ok to use pressure caps. I suppose the car's new owner could replace the pressure caps with stock 0 psi caps. That's up to him??!!

 

I just snipped the spring out of my .9 cap.

and voila- a .0 cap.

Why put extra stress on the coolant system when you dont need it?

Shawn

 

Zero psi makes Evans NPG+ coolant leaks tough to find...

 

True the coolant should warm-up quicker with NPG+, but the engine metal mass will be slower to come up to "normal" operating temperature. The gauge will give a false indication of this with NPG+, which is easily fixed by waiting a minutue or 2 longer before assuming the engine is fully warmed. Details in my 2 posts on pages 3 and 4 of this thread:

https://www.rx7club.com/forum/showth...6&page=3&pp=15

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Trex: pressure usually will increase the heat tranfer rate, but I don't think it significant factor talking auto cooling systems. With NPG+, I'd run 7 psi with no ast, and zero psi with ast and a 3/32" pill in the hose to the filler neck. Just want to be sure not to create vacuum at rad exit hose, esp in cold weather where NPG+ gets a bit viscous.