all i can add from the 2 conversions that i have done is that the Evans NPG seemed to run slightly hotter than conventional coolant did, same day, same car, results in hand.

the Evans does put less stress on the cooling system so no more ruptured hoses and less force on the coolant seals BUT i do believe that the pressure from each side of the coolant seal also helps it retain its seal, now you have combustion pressure overcoming the nonexistent coolant system pressure.

i had 1 of the only 2 Evans customer's car, the coolant seals went out about a year after the conversion. i cannot say that the evans had anything to do with it as the engine was original with over 100k miles but had never had issues prior. the second customer i did the conversion on was more of a test than anything else, the girl drove the car until it wouldn't run anymore resulting in MELTED OEM coolant seals... i wanted to run the Evans for the reason that it eliminates the possibility of ruptured hoses causing the coolant to leak out quickly like a blown hose or water pump would cause, in her case which is why i opted to try and sell her on it. it went into a freshly rebuilt engine and to my knowledge still is having no problems. so end result is incolunclusive as to whether it is good or bad for coolant seals, the old engine may have just been due, new coolant seals have more tolerance.

i don't push anyone to convert to Evans, i do the opposite actually even the there are pros that i believe really could help the rotary engine i just don't see it as efficient for these high need cars coolant temp wise.

 

Take a look. I inspected the rear rotor housing (lost 2 apex seals) and didn't see any of the typical hairline cracks. This engine had 30,000 miles at 12-13 psi running NPG+ from day one. stock twins with M2 large, 850X4, dp and PFS cat back, one oil cooler, Fluidyne radiator. Dynoed at 310 whp, 276 ft-lbs torque by Steve Khan.

DSC_0041-1.jpg?t=1300250271


Another view of the rear housing:
orangerear.jpg?t=1300251433

 

This is the front housing. This housing lost one apex seal but was still producing 3 distinct pulses and 15 mm of vacuum, compression was 95 psi.

orangemotordamagedfronthousing2.jpg?t=1300251350

 

The front oil cover had burned oil (Wal-mart Super Tec dyno 10w30 oil) due to heat in Arizona and coolant temp of routinely 270F in the summer with one oil coooler. I now run two oil coolers with Mobil 1 5w-30 and don't see more than 195F in Northern California and once in a while 240F.

orangemotorburnedoiloverheat.jpg?t=1300251574.

 

My opinion here is that we have on average about 100psi compression and many times that in combustion pressure so 15psi cooling jacket pressure makes no difference.

 

I've been meaning to read this thread, but finally got a chance to sit down and take a look. I do agree Evans isn't for everyone, but what do you have to lose by using it? When I converted mine cost $25 per gallon. I can't believe the prices went up so much.

I wouldn't run anything but Evans in my Rx-7s. I've had the coolant in my car for probably 6 years now with zero problems. There has been a leak in my radiator for some time now which drips occasionally, I'm just now getting around to fixing it. If I had been running a regular pressure cap and regular coolant I wouldn't have been able to drive the car at all. It's not that I wanted to drive around with a leaking radiator, but I just now figured out where it was leaking from.

 

My .02! I see where arghx is going with this. I guess it's time for someone to fill their system with 100% regular coolant to do some comparison test. If both coolants have a high boiling point undiluted, then I see no reason why 100% regular coolant couldn't give similar results to the Evans while being more readily available . I mean could we not run zero pressure with 100% regular coolant as well? I don't see why we couldn't treat cheaper regular coolant just like the more expensive Evans stuff!

 

I run undiluted cheap EG coolant in my daily driver 225k+ miles 2000 protege, I decided to do it after the rad was replaced at around 200k due to overheating due to corrosion using 50/50, changed every 50k.

no difference in daily driver performance but of course it's a 110hp 1.6L 4-cyl so not really comparable.

the car ran a 16psi cap from the factory, still boiled over sometimes on hot days; I could hear the overflow bubbling. No more since running undiluted. I tried no pressure but the fluid expands too much for the factory overflow and I ended up with some air in the rad when cold so I'm using a 13psi cap now, so far so good.

 

by Evans own numbers, a 24% decrease in specific heat. I'm not going to do that on a car that already has cooling problems. Coolant is a poor heat exchanger compared to water, but for our purposes it doesn't freeze or boil. That part isn't debateable. The question is whether it is worth it to reduce the heat exchanging capacity in order to gain the benefits of an extremely high boiling point. I argue no.

yes another one of my main points. I personally don't agree with running 100% undiluted coolant of any sort. But if you are going to do it, why would you buy very expensive stuff that you can't even find? Evans coolant is the cooling equivalent of ProActiv solution, the very expensive (by volume) mail-order face wash you see in commercials. It's supposed to be revolutionary but it's just a couple conventional ingredients mixed together and marketed as proprietary.

 

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I guess you could get fancy with technology if you wanted!

I simply increased my radiator size (26x19x3) and have always had low coolant temperatures with NPG+ and then straight Sierra PG.

Why do this when water or water/coolant mix is proven to work?

The rotary has the combustion process in one location without the other 3 strokes between to cool the area and so has a very localized hot spot in the engine that causes water or water/coolant to vaporize.

In rotary engine development ('60s ~100hp engines) Mazda found rotor housing temperature near the leading spark plug to be 400F @ WOT 7,000rpm.

Many high performance engine applications have some system to relieve vapor from the cooling system.

Where is this vapor coming from and and what are the effects of vapor on cooling the localized hot spots that cause the boiling?

That is the question/issue that people using high boiling point 100% coolant are addressing.

The issue of adequate overall cooling is easily addressed even with the lower thermal transfer capacity (specific heat) of 100% coolant.

 

Ok so whats up with this stuff? I really like the idea of running a zero pressure system.....but i'm also using a hybrid intercooler converted into a Radiator... I want to run evans because I won't have to worry about the corrosive properties of running 50/50, but at the same time I don't want to be out on the track with Temps over 95 Celsius.

Any new findings guys?! Who here tracks their cars in 95F+ summers and run NPG/NPG+?

 

I run evens on all my customers cars, Best stuff out there. Its so nice to pop the motor and not see crud and rust everywhere . Your side irons will love it, no corrosion on the retaining walls of you water seals, That tend to collapse dew to damage done by rust etc. You will need to run a 7 psi cap. do not run 0 pressure cap..

Thanks
Chip U

 

Hmm thanks chip. I'm gonna give it a shot. Should I try the NPG or the NPG-R the lower viscosity race stuff?

 

I'd also like more clarity on the higher operating temps with Evans before jumping aboard... is this trade off worth it for the higher boiling point?

 

Your thermostat and cooling fans control the coolant temperature.

You will only have a raised coolant temperature if your cooling system can't handle the added load of the lower thermal transfer properties of Evans or 100% PG coolant.

If this is a problem you can increase the size of your radiator or cfm of your fans.

 

Use the normal npg stuff. It is my understanding that the R formula is not lifetime.

 

I never have to guess where Raymond stands ... got to admire that.

I used NGP+ in my first FD. The thing ran at 300F, on the freeway, AC on, 100f day on a small hill. I converted back to 50/50 and never crossed 210 in the same situation. I know, the NGP doesn't boil, vaporize and loose it's ability to transfer heat. I just wasn't comfortable with higher temps. I ultimately decided to convert back to 50/50 as I wasn't solving a specific problem and didn't want to risk introducing a new one.

If Evan's solves a problem for you great, use it. If not, ask yourself why you're changing.

My .02c

 

Anymore updates I'm just about to put this stuff in but am have second thoughts...

 

I bought a 13B-RE many years ago, and when I opened it up, the corrosion on the irons was so bad, it caused the engine to lose compression. After replacing the irons, I switched to NPG+ primarily to prevent corrosion. I have a very large circle track rad in my car, so I didn't notice an increase in coolant temps. While using NPG+, I ended up detonating and breaking an apex seal. I repaired everything, put it back together, then I warped the apex seals. I was running a lambda of .78 at approx. 13 PSI, datalogged.

I did a lot of research at that point and came to the same conclusion as arghx.

Aside from the corrosion prevention, another selling point was supposed reduction or elimination of "nucleate boiling". In theory the hottest sections of the rotor housing cause the coolant to boil in that region. Once the coolant becomes gaseous, the heat transfer becomes even worse, creating a hot spot in the combustion chamber that leads to detonation.

I don't know if this is true, but I do know that I switched back to 50/50 H20/EG, and haven't had a problem running the same 13 PSI for 4 years.

Even if NPG+ doesn't cause overall higher temps because your cooling system is large enough to compensate, I believe that the lower specific heat is detrimental. Except where there is nucleate boiling (assuming it even exists), NPG+ will result in certain regions of the engine running hotter since it can't pull away the heat that water can.

Are there any high tech racing classes (i.e. ones where they have real engineers who make data-based decisions) where glycol coolant is allowed that have cars running NPG+?

There seems to be a convenient lack of data on this, since most high dollar sanctioning bodies don't allow antifreeze and most low-dollar operations run on hearsay.

 

To throw out another option:

Engine Ice Hi-Performance Coolant - Home

Seems to me Engine Ice is the best of both worlds. The higher temps of Evans have always bothered me on a rotary. I'll be testing Engine Ice versus my regular mix of 70% water/30% coolant to see if it performs as advertised. I've spent a bunch of time on the phone with the CEO of Engine Ice and he's a very knowledgable chemical engineering type. Engine Ice has been around for a bunch of years, mostly in the motorcycle market. They have over the past several years begun to sell into the aftermarket auto performance niche.

I won't have the car together until January at best but we are going to run my regular coolant setup and then do runs with the Engine Ice to log comparisons. I'll then do some track events and see what temps are like. Will post them up in my build thread.

 

That stuff is propylene glycol too. I don't see how it's significantly different from Evans. If you read the FAQ, it mentions "On top of the many featured teams and athletes we also have some secret factory teams using out products, but we can't really talk about that". Sounds like a red flag to me.

They do mention Edge Motorsports. Interestingly, I can't find a good website for them.

At least Evans admits their product may result in higher operating temps. Engine Ice claims lower temps, which is illogical.

 

Should have posted more. Engine Ice is a blend of propylene glycol, distilled water, and then "secret stuff" including proprietary anti-rust inhibitors and dissimilar metal agents (motorcycle engines have this issue too). They've been working on the formula for about 20 years.

So, unlike Evans, Engine Ice will not raise the operating temps of the car (as it includes water which has the highest temp reducing props) but will significantly lower them or at least that is the claim. It has to do with the "slickness" of the product, whatever that means. They described it as the same properties of water wetter. It will also not cause rusting in the engine. It also operates under pressure so if you want zero pressure, then it's not the product for you.

Heard about Engine Ice from a mechanic in Asheville NC that races a Subaru STI and he has been using the stuff for a number of years.

Hope this helps.

 

LOL, so the CEO of the company selling you a product says it is good and you should use it, what a surprise.


All that stuff is is premixed antifreeze with some super secret additives.

It is a form of RV antifreeze, nothing new, and nothing special.

 

pomanferrari,

The dark carbon stains are from not cooling the plugs well enough.

This is what breaks the apex seals.

We can also tell that you were running the triangle of the seals on the right side of this housing.

If a cooling medium could absorb more heat in this area it would lessen the hump.... and subsequent snapping of the apex seals over it.

This is the essence of arghx's well reasoned and documented argument.

Barry

 

That is like saying Evans is nothing more than some of the super RV antifreezes as it too is based on propylene glycol, right?

I do know the Engine Ice guys mix all of their ingredients inhouse so it's not some RV stuff. And I think it's pretty cool I can ask for the CEO and he will speak to me for over an hour about my cooling issues and how Engine Ice may help. Great customer service if you ask me. They've also offered to give me my money back if it doesn't work as described which also pretty cool.

I will test it and post up the results one way or another. Just thought I'd throw it out as an option.