Like the title says, just wondering if anyone's had any o-ring trouble since they switched to Evans NPG+? I've read in past threads how evans is supposed to prevent the uncontrolled localised boiling of coolant that leads to warping. I'm very interested in switching to Evans only I'm not sure how easy it is to come by in the UK. Could Evans possibly be the solution to what seems to be the major cause of rotary death? What do you guys who are running the stuff think?

 

wtf is evans npg+???

 

A substitute for glycol based coolant. Do a search; there's lots of info.

 

Evans NPG+ is great in my book. Ran the stuff for 2 years in Texas heat...including a few track events...and never had any problems at all. The engine is as strong as ever.

If you can't get it locally, be sure to stock up on it. You can't put water in your system if you happen to lose some. This is the most concern I had with the stuff so I always kept a couple of gallons around.

 

I just started using NPG+. Reason was I lost 2 motors due to coolant seal failure. The coolant seal is fine for the 2nd gen turbo but not 3rd even though the coolant seal was supposedly better in the 3rd gen. All things being equal, my suspicion is on the coolant and/or coolant system unable to control heat being generated.

A secondary reason was that none of the pressure caps (3 OEM and 10 Stant caps) that I've used were able to keep its rated pressure for more than 3-6 mos. Because the difference b/w 16 psi and 13 psi is about 20 degF in boiling point, the seals could have been damaged w/o me even knowing it due to localized boiling.

Hence my experiment with NPG+.

NPG+ has some strange characteristics though. It has 1/3 less thermal conductivity; more viscous; takes on heat and shed them much faster than EG/water mix. Because of these characteristics, flow rate must not be decreased and radiator should be thicker by 20-30%.

I like it very much for the fact that it doesn't boil at operating temp and is not dependent on the cap to maintain rated boiling point.

I don't like it b/c it's $25/gallon.

 

I'm not sure if you mistyped or just don't understand Thermal Conductivity.

Evans has 1/3 less thermal conductivity, that means it takes on and sheds heat much SLOWER than standard coolant.

 

I'm defo gonna give evans a try. I've got my coolant system drained out for winter so as soon as the spring arrives I'm gonna track some down. Gonna fit an up-rated rad and change my coolant hoses over the winter months. Dya recon I'll still need to flush with sierra coolant if my system's been dry for a couple of months? The sierra's probably just as hard to come by as the NPG+.

 

Sierra is dirt cheap...I would think you could find it somewhere local. Maybe not there.

I think you should flush it with Sierra though. There are many places within the engine and heater core where coolant will be trapped. That old stuff is NOT compatible with the Evans.

It isn't cheap...but you won't need to flush your system next winter. Evans is non-corrosive and can stay in the system a long time as long as you don't have other issues. (coolant seal issues, etc.) Also, be sure to run Evans at a lower pressure. I put a lower pressure rad cap on my alluminum AST (7psi) to take some strain off the coolling system. You can convert to zero pressure if you want...but I had a leaking problem when I did that.

 

Really? Where was it leaking from? I really like the idea of running a zero pressure cooling system, it must drastically prolong the life of the coolant hoses etc. Still, you wouldn't want to waste any of that stuff, what with it costing $25/gal! (God only knows what it'll cost over here in rip-off britain!).

 

Evans IS glycol. Just like sierra, with some snake oil stuff supposedly added. You can just run 100% sierra and save a lotta $$$. A bottle of aftermarket cooling system additive every year or so wouldnt hurt.

 

Well, I attempted to modify my old cap...and ended up leaking from there. It seems that Evans also expands a bit more than water/coolant mixtures. The 7psi cap was my quick and easy fix. It is likely that the problem I was seeing was my own fault.

After I converted to Evans I never saw over 105C on the hardest track days in 100F temperatures. This was the only conditions I saw the leak...tossed the 7psi on and haven't had a problem since.

 

So why are we to assume this stuff would be better than water/antifreeze?

 

The main thing that I like about it is the 350F+ boiling point. Zero localized boiling potential which is probably the first major cause of warping within a engine.

 

But it will increase you oil temperatures, sure it will help with localized boiling and corrosion, but high engine and oil temperatures aren't a good thing.

 

The point is you can run any antifreeze 100% and have a similar effect.

NPG = propylene glycol = Sierra
NPG+ = propylene glycol + ethylene glycol = Sierra + Prestone

Higher engine temperatures a good in some applications (higher efficiency) but not in rotaries. Localized boiling is a selling point only, localized boiling absorbe the latent heat of vaporization from the immediate surface on which it occurs. One could make a good argument in favor of localized boiling as well as against it. However, when it occurs in the water pump it is cavitation and a bad thing.

 

How did you come up with these conclusions? Did you do a chemical analysis or a spectrographic analysis?

 

If I were to go by the logic of your argument, localized boiling is good because it indicates that the vaporized liquid has absorbed the heat.

Then why in the world do we need a pressure cap and prevent boiling for water/EG?

Don't like Evans? Don't use it! Or at least don't spread misinformation.

 

A pressure cap is use to allow a higher operating temperature of the entire cooling system. (Higher efficiency, remember ?)

I have nothing against Evans or Sierra. They are just not the cure-all some ppl represent them to be.

There was ZERO misinformation in my post. I wish it were true for everyone else.

 

No , I read the freakin Evans web site. Several ppl have asked for MDS on the NPG's. To my knowledge no-one has received them, even though their availability is required by law.

 

Evans notes that 'controlled' localized (nucleate) boiling occurs with NPG+. Nucleate boiling is great until it gets excessive, then u have DNB or departure from nucleate boiling, where a vapor cloud hovers over the hot spot and surface temps jump up there.

NPG+ has poorer heat trans props vs eg+w. The fluid does warm up quicker than egw, but with less net heat transfer (btu/hr), giving a false indication of better heat transfer.

As long as the bulk fluid temp in the block is low enough, the egw will work fine. if it can't be kept low during sustained high loads, then DNB will result in overheating, and NPG+ would work better at those high bulk fluid temps.

 

I think if your RWD F3D gets to DNB with NPG or EGW you are FUBAR.

But thats a few too many TLA's .

 

I run :
75% distiled water
25% Dexcool
1 bottle of REDLINE water wetter
M2 all aluminum radiator
1.3ATM Gant cap with out the AST.
PFC fan points of /86/86/88.

No problems here in Houston summer with over 320rwhp.

 

Sounds like a good setup. My car doesnt like sitting in traffic in the Houston summer.

 

Your conclusions are unsupported in that NPG is Sierra and NPG+ is Sierra + EG. The website does not state taht NPG is Sierra and et al. NPG is a form of propylene glycol and NPG+ is another modified form of PG.

That's like looking at Prestone website and concluding that Prestone is alcohol and then implying that you could put alcohol into a car as coolant. Not too unscientific and therefore I submit to you that it's tantamount to misinformation.

Like I said, if you have evidence-meanging facts that lead to these conclusions, let us know.

I'm curious too. I know that the $25 per gallon includes marketing but hey why do people buy Mercedes and BMWs when they're so unreliable?

 

Why Dexcool? Not better heat transfer? Longevity?

There was an article in C/D a year and a half ago about how it's unsuitable for older vehicles not designed for Dexcool. Dave at KDR saw 3 cars running Dexcool that had coolant seals damaged - see lightning in a world of thunder.