If you're using Evans NPG+ coolant, what are your normal operating temperatures with the engine warm, and after "hard use"?

The reason I ask is because the stock temperature gauge in my car was "weighted" towards the center so as not to "alarm" the user when coolant temperatures rose. It was supposed to stay in the center until it "really meant it", then skyrocket to the Hot mark, often after it was too late to do anything. Great design.

There's a modification you can perform which will remove the center weighting, but it also changes the scale of the gauge, apparently. A couple resistors in a simple arrangement will recalibrate the gauge to specific temperature ranges, and I want the middle gauge area to be normal operating temperature with Evans NPG+.

The "hot" mark and overheat mark (and warning light) can then be calculated, so I have some idea of what they really mean. Evans claims that NPG+ doesn't boil until 375 F, which doesn't help much. I'm assuming that normal operating range is probably 180-185 F, and that "too warm" is probably 250-260 F for other components, if not for the coolant.

Any help would be greatly appreciated. Thanks!

 

jimlab,

Evans will still provide excellent engine protection at temperatures as high as 260ºF. Of course, coolant temperatures in that range, while increasing thermal efficiency, usually provide a significant hit to volumetric efficiency as that heat is transfered to the intake charge.
If you can keep the NPG at 220º +or- 10º you will hit a happy medium. I've tested NPG in engines running extremely high static compression ratios and running on 87 octane petrol. The stuff works.
Is this something Mark has talked to you about?

Take care,
Chuck Riddeck

 

Mark recommended using NPG+, but hasn't told me what to expect as far as operating temperatures with my package.

I want normal "cruising" temperatures to be approximately the half-way point of the gauge. A particular resistor value which puts 180 F at the midway point will read "hot" at about 245 F, and "overheat" at roughly 270 F. At least the warning buzzer would come on at that point.

I'm just wondering if that's a realistic range for everyday use of Evans NPG+. If the normal operating temperature is higher, I can compensate, but it will move everything else up the scale as well.

 

This stuff has intrigued me for quite some time.

Chuck,

Sorry this question in a bit vague, but does it make enough of a difference in detonation resistance to enable higher compression on a pump gas blower motor? For example, a high compression supercharged stock LT1 prone to detonation in the first place.

 

A realistic range would be anywhere from 200-260ºF. I personally have tested NPG on engines with up to 16:1 compression and coolant temps close to 300ºF, oil temps of 240ºF, with no signs of pre-ignition. You need a very high rate of coolant flow to operate efficiently at that level but it should be reassuring to know that a well designed cooling system using NPG, will operate at those temperatures safely.

So, realistically... 230-260ºF. This scares many people but much of that fear comes with a lack of understanding in how cooling systems work in the first place. Nor do they understand the shortcomings of conventional H2O based coolants.

Stephen,

There have been numerous tests performed... by myself and many other automotive engineers. I could quote you numerous examples of engines I've worked with or have heard/read about which could not run without pre-ignition before the conventional coolant was replaced by NPG. Most of these engines were and are developmental... which usually means they are on the ragged-edge performance-wise.
Without getting into the technical aspects to your question.... your answer is... Yes. NPG will raise the pre-ignition threshold of any IC engine and is especially effective in high-heat force-inducted engines... especially the reverse-cooled LTx engines.

I refuse to debate the issue as I have on message boards in the past. I will however answer any pointed questions that might be of help to you. I don't get paid to recommend Evans to anyone so you can maybe see my point here.

Take care,
Chuck Riddeck

 

OK, I'm sold! Evans it is

I pity the fool with the audacity to debate with The Great Chuck R.

As always, thanks for the great info

 

Do you actually see higher operating temps on the guage due to the fact that NPG is pulling alot more heat out of the CC ? Just trying to get some insight on why actually an NPG cooled car does run hotter vs. a conventional coolant system .

Also , given the low pressure requirements of NPG should the only other thing I need to do is replace the cap with a low pressure cap and remove the T-stat ? I do run a CSI H20 pump with a stock LT1 radiator . I see Evans sells low pressure pumps( gen 1's) and radiators , thats why I ask .

Thanks

 

So after the introduction of NPG+ to the equation, all of a sudden the gauge reads 230-260ºF during typical opration and that's considered normal?

I'm just trying to pick an accurate midpoint to recalibrate my gauge to. Would you say that 230 would be a reasonable choice, or in a street car with a built 11.8:1 compression 396 (big solid roller) would the "normal" operating temperatures be even higher? What do temperatures reach when on the throttle for reasonable amounts of time?

And finally, what is considered the overheating point for NPG+? I know that the Evans site says the boiling point is 375ºF for the liquid itself, but I wouldn't expect that you'd see temperatures anywhere near that in even hard street driving or, say, from a highway roll to top speed, right? So what would be considered "bad" as far as a temperature high enough that the engine would be "upset" about it, even if the NPG+ coolant wasn't?

Thanks Chuck!

 

Is the basic reason that NPG+ temperatures are higher because it is able to pull more heat "into" the coolant? In other words, it's more effective at cooling the engine and absorbing heat from the components it is passing by, therefore the temperature of the coolant is higher, but it is not an indication that the engine is running any hotter than normal? And in fact, if the coolant is more effective at absorbing engine heat, shouldn't the engine itself be a little cooler?

Thanks!

 

When I switched to NPG, I noticed 10-15 degree hotter temps in the summer time as per my Scanmaster.

 

I can probably kill two birds with one stone here...

You're correct Jim. I don't know if you are familiar with the term "terminal molar heat" (TMH). TMH is the ability of a fluid to draw heat from a surface and is usually expressed in BTUs. Water for instance has a TMH of roughly 9,350 units where as the propylene used in NPG has a rating close to 15,000 units. Therfore it's not too much of a stretch in seeing the effectiveness of propylene's heat transfer abilities.

That said, you will see higher "coolant temps" and better thermal efficiency overall. The temperature of the "engine itself" while an issue, is not the most important. What is important is how effective the coolant is at thwarting nucleate boiling temperatures. Localized boiling (at hot spots) is the issue that needs addressing, not necessarily overall engine temperatures, if that makes any sense?

This should also answer Derek's question on this matter. And yes, that's all you need to do Derek. A cap of 5-8psi will do fine.
As for your guage.. yes, I'd target it at 230ºF. I run NPG in all of my performance engines, the 434, and my two Mopar engines. Extended blasts usually put me close to 250ºF but I have never seen an ounce of coolant loss or any signs of detonation or pre-ignition. An "overheat" temp is a much more difficult thing to answer but you are right in your assumption that the engine will lose out before reaching anything close to NPG's boiling point. Fuel octane, gasket issues, there are a plethora of variables that arise before you ever reach the "terminal point" of the coolant.

Take care,

 

Thanks Chuck!

Would you recommend a 5-8 psi cap over a 0 psi cap? I'm going to have to run some sort of in-line filler "neck" on the upper radiator hose, since my radiator has no cap and is positioned at an angle in the car (stock configuration for the 3rd gen. RX-7).

JEGS sells a filler neck fitting that has an overflow tank fitting, and I was just wondering which cap (and pressure level) I should run with my LT1 for the street.
http://www.jegs.com/cgi-bin/ncommerc...01&prmenbr=361

Thanks again!

 

When after replacing with the NPG and noticing the higher op temps, I wrote them to see what their responce would be to this. I had saved the e-mail they sent but somehow it got lost. The answer I got was basically what Jim questioned in his last post and Chuck reaffirmed, and it was a woman speaking to me. I had questioned that if my PCM programming was to give me a little more spark advance with lower temps would good was their product doing me. She aswered that the company was working on programming to compensate for this. She did say to try to lower the temp the PCM was reading was to take the stat out and put a core plug in the hole in the waterpump that recirculates the coolant back thru the block, the one the stat plugs when it opens and get a bigger radiator. I tried this, except for the radiator, but no difference except it took longer to get up to temp. I think the common thinking is to run as cool as possible for more performance but listening to Chuck not so. I've thought a couple times to replace it but the **** costs so damn much.

 

I was told to use a 7 psi cap because of some problems with the 0 psi one. Can't remember what they were.

 

Use a cap rated from 5-8 psi. Any in that range will be satisfactory.

Take care