I'M TRYING TO AVOID POSTULATION AND CONJECTURE WITH THIS THREAD. IF YOU HAVE DONE THIS CONVERSION AND HAVE TIPS AND ADVICE PLEASE POST. IF YOU HAVE NOT AND ARE JUST INTERESTED IN SAYING WORDS PLEASE REFRAIN. THERE IS CURRENTLY NO SINGLE GOOD POST FOR THIS CONVERSION. IT IS ALSO SOMETHING THAT A LOT OF RX7 PEOPLE CONSIDER. SO THE MORE GOOD INFO IN ONE PLACE THE BETTER. THANKS!

Hello! I am switching to evans npg? coolant. I am curious about the do's and dont's. I have searched and found no concrete information regarding making the switch or the required changes that are necessary for the physical parts of the cooling system.

I have read that flushing all the water out is important. Good, no problem. I have heard that it runs little to no pressure. Thats fine. I have heard that some people dont run a thermostat. I cant imagine why. That would effect your warm up times. Which wouldnt be ideal. I have heard that some people remove their ast. This sounds like it should be an ok thing to do. Given that this coolant shouldnt steam or cavitate it shouldnt need the ast to remove the "air" that is introduced by those two conditions.

The best way to remove the ast from what i understand is to run the turbo 2 lid to the fd cooling neck. It has an overflow outlet that you can hook up to the fd's overflow tank.

Since cavitation isnt an issue with this coolant is the remedy waterpump still a good idea or is it overkill and just another thing to spend money on? If you move the coolant around too fast it could lower its ability to pull heat from the engine parts.

What are your experiences with this?

 

I switched to Evans 8 years ago and never looked back after 2 engines in 60K miles failing due to overheating using the green ****. search under my name and you will see that I am also running a VW VR6 electric auxiliary water pump to ensure no hotspots after shut down. I have never had to replace the Evans NPG+ coolant and to this day it is still reading 0.08 volts. It has gone as high as 128 degrees Celsius from me torture testing the car in 118 degrees heat at 1bar of boost in Arizona
but that didn't seem to bother my motor. It did overheat the oil so a second cooler is a must.

Do use the Sierra to start the conversion process, run for a few days and then drain, after draining, use a shop vaccuum to remove remainder. Make sure you clear out the heater core.
Do run a low pressure 7psi cap
Do run a Koyo or Fluidyne in any case.
Do add a couple of 1/8 inch holes in the thermostat.
Do run a second oil cooler.
Do carry an extra bottle of Evans in the car.

Don't need to change water pump at all.

Our car has two weak points: (1) the cooling system and (2) pre-ignition. Fix (1) by running Evans. Fix (2) by running a water injection system.

My car is bullet proof even at 16 psi running Alberto old motor (which had 20K hard track miles).

 

I have been pondering this too.
How do you get all the "prestone" out of the system?.I own an FC.
also Curious if the Evans is "slippery" like normal coolant feels?(you know,if you get it on your hands it's like a slick feel.)
Subscribed.

 

pomanferrari

Thank you for such a great reply! Good to hear you are having such a positive experience with the evans coolant.

I'm curious, why do you drill the holes in the thermostat? I have heard of people doing that to aid in the bleeding process.

Do you still run the ast? I have heard of people deleting them even with out switching to evans. I believe this to be a mistake. Due to the rather impressive ability to hot spot in the coolant passages around the spark plugs, you can rest assured that a standard coolant water mix will boil at that point. Which is exactly why there is an ast in the stock cooling system. The ast aids in the removal of the vapors and air bubbles that are created by that boiling. But with the evans it may not be necessary. At which point you can move your pressure cap to the top of the coolant neck with the use of the turbo 2 parts.

I have a completely empty (with all new components including heater core) so i may skip the sierra step. The prupose of which i understand to be getting all the scaling and rust removed from the cooling system. Given the fragile nature of the oem cooling o-rings, do you think the sierra treatment is safe? I employed the use of the pineapple viton cooling system o-rings for my build after loosing my motor to the stock ones. So i may still consider it.

Thanks again for responding!

 

To assist in increased flow when the car is cold. The viscosity of the coolant is higher than the green stuff so it would need the holes to keep the evans coolant moving.

I agree but my AST is a much larger stainless steel AST.

If you have a dry system then no need to do the Sierra step. Sierra is just a pet friendly coolant that has basically the same ingredients as Evans but w/o the stability additives. Sierra will absorb excess water so that when you install Evans it will be a clean install. Do vaccuum out your heater core though.

I lost two motors due to warped rear housing then rear seal failure. I can only pin this on microboiling with the green stuff. No more gurgling sound after shutdown, no more fear of rear o-ring seal failure

 

Why does the coolant need to flow when the car is cold? I thought that was the whole point of the thermostat. To keep the coolant stationary to allow the engine to reach operating temps?

 

That is my question exactly. The viscosity of the coolant shouldnt effect how the thermostat functions should it? By allowing fluid to flow through the radiator before the temp is capable of opening the thermostat will make the car warm up slower is all. Any more info about this modification would be appreciated. Thanks!

 

I tried evans about 10 years ago and both my oil and water were easily 5c higher and my car was lapping at least a second slower. Probably robbed the car of 10 hp.

Why put something in hot running rotary that causes it to run hotter given other alternatives

I'd rather control my AI, water and oil temps with good coolers and ducting and keep it simple.

 

Exactly.

Internal temperatures goes hand in hand, higher coolant temperature means higher housing temperature, higher EGT's, higher oil temps but also higher apex seal temps, all detrimental to engine components.

High engine block temperatures also have negative impact on volumetric efficiency, so its direct loss of power. Competition manuals have recommended coolant temperatures in range of 70-90°C for a reason.

 

Fritz..... has evans changed their formula since then? 10 years seems to be a pretty long time. Goodfella-Rich swears by the stuff. I know you track your car more frequently..but maybe you just had a bad experience with a different formula evans?

 

I tried evans about 10 years ago and both my oil and water were easily 5c higher and my car was lapping at least a second slower. Probably robbed the car of 10 hp.

Why put something in hot running rotary that causes it to run hotter given other alternatives

I'd rather control my AI, water and oil temps with good coolers and ducting and keep it simple.

The theory behind why it is a better alternative to water or water with PEG coolant is that its higher boiling point keeps it from vaporizing at the localized hot spot around the spark plugs, therefore transferring more heat to the coolant.

If overall oil/water temperatures are higher that is easily addressed by adding larger heat exchangers or otherwise improving their function.

Its not as easy to lower the temperatures at the localized hot spot by other means though you can see how Mazda has done this on their race engines.

You may want to try 100% PG coolant if you have symptoms of overheating the spark plug area of the rotor housing such as cracked spark plug holes, flattened sides on the apex seals, carbon marks on the rotor housing around the spark plugs or appearance of lack of lubrication in this area.

Though these symptoms are also synonymous with the heightened combustion temperatures of detonation, so of course make sure that isn't your issue as well.

Another really nice benefit is the ability to run low/zero pressure cooling system. There is much lower chance of leaks in such a system and when it does leak it is a dribble. If you have a large bridgeport cut into the coolant groove it will stress your seal here much less as well and if it fails only suck coolant in with engine vacuum.

I haven't noticed any difference using Evans over 100% Sierra Pet Safe PG coolant which is readily available and inexpensive.

 

^exactly what I wanted to hear.

 

Any straight coolant will cause your car to run hotter or be less efficient and cause more wear and tear on everything.

Glad you heard what you wanted

 

I understand which is why I gave it a go years ago but why not install proper coolers and have the car tuned properly. Fix the problem not the symptom.

 

^ I have dual 26 row mocal's... and a custom radiator to help battle heat, I'll have a good tuner and most likely run evans coolant. Your actually the first person i've heard complain or say anything negative about evans.

 

I love Evans...... Scrub/DannyMac has been running it for like 7 years. I converted a few years ago and never looked back, my brother is running it and we have several customers with IRP-warrantied engines running it.

Benefits?
* zero-pressure cooling system--no more burst hoses, 16 psi caps to control the boiling point, coolant seeping from small seams, afterboil
* lifetime use, no need to flush your coolant yearly
* much higher boiling point, minimizes localized micro-boiling
* Icing on the cake is less chance of detonation.... guys racing bikes have been advancing their timing safely once they converted to Evans for many years

I swear my FD runs better with the Evans in it, I heard the change in the exhaust note. Call me crazy, but I'm sticking to my story

Only real drawback is needing to carry a bottle with you. But when you're running 0 pressure, you shouldn't have any leaks anyway. Plus all my buddys run it too, so there is always a lot to go around

The higher cost is quickly absorbed by the fact that it's lifetime. I haven't run an AST for about a decade now regardless of the coolant in my FD, to address that point.

 

 

Btw, each car seems to react to Evans a bit differently depending on setup and driving environment. I can tell you my coolant temps were largely unchanged, but with my R1 oil coolers, 99 front and R-magic ducts my oil temps did raise something like 20 degrees F higher under all conditions. Still manageable and nothing 'dangerous.' Stepping up to the SBG dual 26 rows (which I planned to do anyway) with proper ducting brought them back down.

Don't forget you can safely lap at higher water temps with the evans..... if you search you'll find a few old threads, with some guys claiming hot-lapping with temps at 125ish C for an extended period IIRC. Also if you back out of the throttle for even half a lap the temps come down fairly quickly, which didn't happen for me with 50/50.

 

been running it since 2004-05 timeframe and about 30k miles, never changed. Stock non-drilled thermostat, lower seal removed from stock cap (zero pressure) and dual 19 row mocal (CWR kit) oil coolers

I've drag raced, drifted, road raced and plain stupid abused it on the street at 18 psi on the stock seq twins. Got it up to 114 C once during uphill run in 90+ degree weather in PR. Never had any problems.

I converted by first removing the thermostat and running without it for some time while flushing with clean water. Did various cycles like this until water ran clear. Then added straight PG Sierra and ran like that for a few days. After that I ran Evans Prep fluid for a few days. And finally drained and filled with NPG+. Never touched the cooling system again.

 

I used all kinds of different coolant green to orange to red nothing worked i still had engine overheating and housing damage.
in the end Evans NPG + was what worked for me. No more gurgling after shut down with a 7 psi cap. Try that on your regular coolant and 7 psi cap and see how long your engine will last.

 

I'm not saying anything bad about it I'm simply saying you don't need to use it nor do you need to use water injection or half the other BS that's been deemed as essential to keeping the rotary alive.

Rich would put liquid gold in his car if he thought it would help it run better.

 

 

Yes, liquid gold nano particles!

Okay, its actually copper or silver nano rods....

Look into that, it breaking technology for heat transfer that will REALLY help the rotary hot spot keep cool.

Stolen from Wiki-
Nanofluids
...

Some significant improvements are achievable; e.g. silver nanorods of 55±12 nm diameter and 12.8 µm average length at 0.5 vol.% increased the thermal conductivity of water by 68%, and 0.5 vol.% of silver nanorods increased thermal conductivity of ethylene glycol based coolant by 98%.[8] Alumina nanoparticles at 0.1% can increase the critical heat flux of water by as much as 70%; the particles form rough porous surface on the cooled object, which encourages formation of new bubbles, and their hydrophilic nature then helps pushing them away, hindering the formation of the steam layer.[9]

Note the talk of the pesky steam layer- thats that fubars cooling in the rotary hot spot and causes stock FDs to boil their coolant cruising and require an AST.

 

The main problem with the rotary is that it is 30 year old technology and to keep it alive while being on parity with alot of the newer cars pushing an easy 400whp means that you have to run water injection. And something like at least 30% (from an informal poll in the forum 6 or 7 years ago) of the rotary engines have rear coolant seal failure means that there is a real defect in the cooling system.

I have owned my 7 for almost 20 years and it's only after I started using Evans and running water injection that I finally lost that feeling of trepidation (you know the feeling, sh*t is my engine going to die if I get on it?) every time I'm on boost and it's over 90F ambient. It got so bad that I had a fifth engine built by Howard just in case my 4th engine (with Evans and water injection) was going to go boom again. Fortunately, it has been 3 years + routine 17 pounds of boost on California 91 octane gas without any failure. Now the biggest problem is remembering to go into my garage and spray WD40 on Howard's built motor and turning it several times every six months (to keep it from locking up from sitting in storage).

That peace of mind is something that LS2 owners are used to but did not happen to me until I had these so called "bandaids".

I assume that you have never blown an engine? If true, I need a lock of your hair for good luck. On the other hand, if you had blown at least one, permit me to chortle at you ( no offense intended).

 

Evans, Use it, it works ..

But for real, it has no water , the cast plates will love you for that, the retaining walls on your inner coolant seal wont rust and give way in time. All in all the Evans is a good switch the benefits are there.

A good set up on your rad fans and Evans... she will run like a champ...