pomanferrari

iTrader: (1)

It got up to 110 F today. Wanting to see how NPG+ performed in this weather, I went for a drive with boost up to 14 psi. Temperature climbed rapidly with the PFC commander reading 110 Celsius while my Autometer (sensor at the filler neck) was reading 230F. Didn't datalog but the high temp didn't seem to bother the car (given that I moved the ignition retard at 105C to 110C). The instrument gauge didn't budge at all from it's 9 o'clock position.

All I can say is, it's hot but bearable given that I don't have AC either.

PhoenixDownVII

Wow, 230F, you let it run that hot? Do you have a fan switch, btw?

POS7

I live in Hawaii and I dont see temps over 90. Usually temps are between 85-87 (on stock rad). Of course I run the fans constantly after temps get up to 80 degrees.

110 is hot btw. The only time my car ever got up to that temp was when my thermostat was shot.

1QWIK7

iTrader: (33)

holy cow, 110 is HOT!

i'll most likely be inside chillen in the A/C and you're out?? and driving too??!!

wow, you must have been sweating your gonads off..

Mahjik

iTrader: (1)

Evan's will show warmer coolant/water temps (than normal coolant/water mixtures) which is really a good thing. That means it's absorbing more of the heat from the engine.

Trevor

I used to run it in the Stealth. The specific heat of it is lower than water. That means that the temp of the NPG+ will go up more than water when it absorbs the same amount of heat.
An example:

Specific heat of water at 176F is 1.00 btu/lb/F whereas NPG+ is 0.64 btu/lb/F.

Both systems start at 176F

Dump 246 btu's into an 8 liter reservoir (17.6 lbs of water/ 19.2 lbs of NPG+)

NPG+ will end up at 196F
50/50 antifreeze and water would end up at 192.2F
Water will end up at 190F

They all absorbed the same amount of heat.

Of course higher coolant temps don't matter much with the NPG+ when it doesn't boil until 370+F. I decided to get away from it and redesign the system to work well on water because:
- I was tired of hearing my fans running all the time
- Occasionally my coolant temps were high enough where the A/C would turn off automatically
- NPG+ isn't cheap
- NPG+ isn't locally available
- NPG+ expands more than water...my overflow tank was just a hair too small to deal with the overflow & still have enough capacity to refill the system completely as it cooled.

With all that in mind I'm in the middle of doing the 7 up to work well on conventional coolant...a water wetter, 12.5% anti-freeze, and distilled mix. It hit 108F here yesterday so I tore it up and started installing a rotary extreme dual 34 row oil cooler kit. I still need to install the new Koyo radiator and fab some ducting to seal it all off.

Mahjik

iTrader: (1)

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/why-shouldn%92t-everyone-use-evan%92s-npg-coolant-99933/

7racer

hmmm...I wasn't aware of that.

I just switched to NPG-R

I'm still doing some work on the car during some runs for bedding in my 99 spec brakes my temps never got past 96 C on a Texas 98 F day. This is without and undertray (I'm going to place it back soon or after the repaint). But it is with a PFC with fans coming on early, 99 spec fans, and CWR oil coolers.

What conditions did the coolant temps get that high? Stop and go traffic?

tmiked

Not true at all. Just advertising hype.

EFS.O

Hey poman,on another note,are you satisfied with the vw electric pump?i was thinking of doing the same for the bloddy heat soak...

POS7

Mahjik, is it proven that it absorbs addtional heat from the engine (hence the increase in temps)? I always thought that higher temps means higher overall temps period. I wasn't aware that higher coolant temps could be a result of greater absorption from the engine.

Perhaps you can enlighten me, or if not I can do a search

weaklink

so at what temp do the coolant seals warp?

Trevor

NPG-R? Haven't heard of that...do tell.

A/C only switched off while going 84 mph in 6th on the highway when it was 100+F outside. That was just as much my fault as the NPG+'s. I installed a front mount IC without any kind of ducting (even removed alot of the stock stuff). After I switched back to conventional coolant my temps were only like 14F lower...still over 221F on occasion when both the fans on the Stealth come on high. Only after that did I fab some nice ducting (if I do say so myself) and temps dropped quite a bit. Since I installed dual Setrab oil coolers on the Stealth in 85-90F ambient coolant stays pretty much at 176-186F except for in stop and go. Then I see 197F max when the fans start regulating temp. It's great not having to worry about water or oil temps. I hope I can do the same with the 7.

Mahjik

iTrader: (1)

Evan's is designed to run hotter and absorb more heat from the engine so it can carry the heat to the radiator. In this case, the higher temps shows that it "should" be more effective.

There are many articles around the web discussing it. And easy Google search using these key words "evans coolant absorb heat" will pull back some information for you to help see if it's an option for you.

7racer

NPG-R has been out for awhile. It's not as viscous but you do have to change it so its not "lifelong" like NPG+

http://www.evanscooling.com/main25.htm

technonovice

I still believe in standard coolant and water...ok...and water wetter. Eliminating mechanicial and engineering deficiencies (ducting, larger radiator, oil coolers... etc) are better than band aid solutions.

pomanferrari

iTrader: (1)

Yes. I am happy with it as it keeps the coolant circulating. I can see the stock gauge dropping immediately (showing that metal temperature is declining) while the VDO gauge is around 250F.

KevinK2

Not quite true. See my post here:

https://www.rx7club.com/forum/showth...&highlight=npg

pomanferrari

iTrader: (1)

Before NPG+, I was running 70/30 (water/coolant) and in 100F using a Fluidyne, in traffic 15-20 mph, I was seeing 230F at the TB coolant hose.

With NPG+, in 110F, in traffic, I was seeing 221F. On boost, I was seeing 230F so it's not really that hot. BTW, the knock reading were well under 70, air temperature was 67C in traffic and 55 on boost to 14 psi.

The strange thing about NPG+ is that on the highway at 90F, my temperature doesn't drop down below 100 C (212F) even if I'm in 5th at 80 mph. In contrast, with 70/30 water coolant, at 95F it's 185F. I think that the Fluidyne core is too thin to dissipate heat.
I think a Koyo would drop the temperature even more.

To ensure that I pass the emission in AZ (IM170) which is more difficult than the one in Virginia (IM240), I used datalogit to switch the fan on temp at 110C and reduced boost to 0.5 bar. Car passed with 50% of applicable limits. The high temperature of the coolant doesn't seem to bother the engine at all under the emission dyno. I have gotten the NPG+ as high as 135C (280F) w/o ill effect. By contrast, I think my seal let go at 250F using 70/30 b/c as soon as my VDO gauge showed 250F, my OEM meter gauge shot up past the half way mark. After that, it was a the dreaded gurgling sound then a new motor.


FWIW, VW Passat VR6 runs at 240F or 116C in steady traffic.

Mahjik

iTrader: (1)

Actually, it is (in a non-technical way)... The fact that water/coolant gets to the point where it begins to boil (at which point it isn't absorbing any more heat). Evan's runs hotter with a higher boiling point allowing it to absorb more heat.

turbojeff

iTrader: (30)

Evan's doesn't absorb more heat from the engine unless the standard coolant is boiling.

Evan's is worse at absorbing heat (engine side) and worse at rejecting it (rad side).

That is why you might see higher coolant temps.

I agree Evan's is a band-aid solution. Fix the root of the problem, rad size, rad ducting, etc. Typical problems with FDs running hot is the factory set the fans to come on a 221F. Switch to a FC (89-91) thermoswitch and the fans will come on at 195F.

Mahjik

iTrader: (1)

Note the post above yours.

I wouldn't say it's worse at absorbing heat, but it does retain more heat by design.

I don't run Evan's, not sure if I will with the new rebuild either. However, from the select few that do run Evan's on the forum, I don't think I've ever run across any of them having a coolant seal failure (or housing warpage) even at the higher temps. Just food for thought.

the_glass_man

iTrader: (2)

I hardly see Evans as a "band aid" solution. It's got a higher boiling point, and can be used at lower pressures which puts less stress on the cooling system. The fact that it's a lifetime coolant and won't corrode are pluses in my book.

KevinK2

In non-technical terms, NPG+ is worse than egw in removing engine heat, until you reach the extreme limit (ie: 100F track days) of egw. Most get a hint of this fact of NPG+ when driving with moderate load, with t-stat controlling temps at the same value as their old egw mix. They find oil temps are now higher, since the NPG+ is removing a smaller % of the total heat load to the oil and coolant.

regarding boiling, BOTH transfer the most heat when a controlled amount of local boiling is going on (called nucleat boiling with phase change), and depend on it. But for egw to work at 250F, without excessive boiling (ie DNB or departure from nucleate boiling) you would need a 25-30 psi rad cap.

Related point for hpde tracking an FD in 100F+ weather:

YOU WANT ALL HEATED COOLANT TO BE COOLED!

1) the heater core takes a large, unregulated flow of hot coolant from the back of the engine and bypasses the rad. either put a pill/restrictor in this large line, or run full heat at the track with ducts pointiing away from you.

2) fully heated coolant goes through 10mm hoses to the ast, and bypasses the rad. If you use an an aluminum ast, put a 5/64" restrictor (pill) in the inlet line. (stock ast has the flow restrictor in the exit nipple).

3) the TB line also bypasses rad, so plug it/ remove.

4) run a stock type 3-way t-stat, that shuts off the bypass loop as the t-stat opens up. I think a larger throat 180F GM 3-way t-stat could be modified to work, for more flow.

Mahjik

iTrader: (1)

By design, Evan's is retaining heat. I'll look to see if I can find the white papers again but Evan's believes that engines run more efficiently when they are "at temp". Evan's does retain heat to keep the engine from being too cold where it's not as effective.

Good or bad, that's what it's designed to do. Whether that is a good application for a rotary, that's another question. For street use, IMO it's not worth it. For track use, that may be an application in which it works well.