Changing a running car to Evans is a big old pain in the dick. You have to get absolutely every last drop of water out of the system, which is alot more dramatic than you might think. I'm not telling you not to try it, just to be extra careful with it.

 

have I missed a thread about this evEns stuff? What is it? Last I heard the best track setup was distilled water with a bottle of water wetter added in. Does this trump that? I'm mostly pissed that my huge mishimoto radiator isnt keeping things cool, and the pathetic little heater core made when I was 8 years old is able to keep things in check. Is this because of where the heater core is getting it's coolant? I need to buy begi's racer reroute.

 

You aint kidding about price for the EVANs stuff:
EVANS PREP FLUID from Aircraft Spruce


EVANS NPG + COOLANT FOR ROTAX ENGINES from Aircraft Spruce

No real threads on MT regarding it Curly. Only a few out of date ones on the pointy forum. It looks like Jason has tested it but didn't fully commit to an endorsement.

Chris

 

I think there is a really good clue to your problem in this statement. Where do you think the water is going? It is possible that it is going out the exhaust, but lets assume not. So where can it escape? there could be leaks, but I am sure you have covered that. So that leaves one path, past the rad cap, into the coolant reservoir. Is there coolant in there when you stop? I doubt it.

So here is my theory, your coolant is like American beer (FN near water) so let us say it has a boiling point of 220 deg f at zero pressure. Your rad cap, I hope is good and adds 17 psi+- to the system again raising the boiling point, lets say its 250 deg now. For arguments sake, lets say combustion temp is about 1000 deg. That is a huge demand you have put on the coolant in the cyl head. I have no doubt that the coolant is boiling in there, which dramatically increases the pressure in the system. The pressure looking for a way out finds the rad cap and overpowers it, pushing some coolant out to the reservoir, allowing the steam to find its way to the rad cap, which finds its way to the reservoir boiling/blowing the coolant out of the tank. The more this happens, the more steam is produced in the head. Steam does not absorb heat very well, and so cyl head temps start to rise and the problem gets worse.

Yes water transfers heat better than antifreeze. Antifreeze however has a higher boiling point than water. The fix here may be as simple as adding to a 50/50 mix. (that's chemically about the best boiling point you can get with antifreeze) A higher pressure cap if available will also raise the boiling point higher.

Evans coolant has a boiling point of 370 deg f, at zero pressure. The pressure in the head is higher than that due to pumping action and coolant flow. They recommend a zero pressure rad cap, and a higher temp thermostat! The reason for the higher temp stat is so that the temp differential between the coolant and the metal in the head is lowered, allowing it to absorb heat easier. The higher temp of the coolant raises the temp at the rad, creating a wider temp differential to ambient air, thus removing heat easier.

There are other benefits to the higher temp, ultimately increasing the ability to make power and reduce detonation, but that is a much longer discussion.

Ron

 

I have never used it, but was considering it. I talked to a few guys who were running it, and said it worked well. Then they pulled the motors and noticed it was eating the head. Seems it likes to disolve aluminum.

 

That's a pretty good write up Ron.

That's weird since EVAN's recommends an aluminum radiator with it.

Chris

 

Well same ol overheating at MSR last Friday. It would usually start creeping up around 10-13 minutes into the session (heater on and no warm up). So I would do a slowww cool down and try to get one last hot lap in, most times it would be checkered half way through.

I replaced the thermostat thinking it was getting slowly stuck closed. Did a long idle and started getting warm. I also noticed my AC fan (siliconintakes.com 10 incher less than a month old correctly wired in parallel) stopped working.

Next step is pressure testing the system to look for leaks, then a leak down.

Chris

 

did you do any ducting on the front? Seal it up if its not done already. I may take my car to boostlogic for some metal fab work. I only needed the fan in 2 sessions and I have 30% anti-freeze. What about your oil cooler again?

 

UPDATE: I had a hole in my Godspeed, it vibrated against an AC bracket. I had it repaired and it was still leaking (I don't think the shop fixed the other hole the first time though). Reinstalled and it was still leaking. I installed the passenger side fan to tight against it and it was making contact with the radiator. Had it fixed again.

I did not notice any overheating on Saturday except when I hit the Hot Pit. This was with ambient temps in the 70s and 80s.

I just bought a digital Autometer coolant gauge and two senders. I am going to test temps for the front and rear with the BEGI racer reroute (heater outlet to top rad hose).

My next step will probably be EVANs.

Chris

 

Chris,
If the front water neck is blocked-off, don't expect an accurate reading in the front of the head with that nasty water-neck sticking out...no water moves through it. You should make a plate at the head and put the sensor there.

You don't need it though if you block the front of the head because water at the front of the head will always be cooler than at the rear.

 

Might want to hold off on Evans. I had a prototype radiator in my car at SOW on Friday that was pretty promising. Going to do further testing in 2 weeks, but I think a 30 degree drop is not out of the question.

 

Maniac92,

Have you sealed the heat exchangers yet so air can't bypass them? Makes a world of difference if you haven't. If you have I missed the thread or post, sorry.

 

Fixed for ya. What do you have now in terms of ducting?

 

What are your readings for water and oil on the track? Average and peak?

 

The front water neck is stock right now. I got an extra one to drill and tap the top for a temp sensor.

I want to see what kind of temp differential there is with the BEGI reroute. I'm pretty sure the T into the top radiator hose is not allowing enough flow through the rear (it should be a Y IMHO).

Is it a double pass? If I went with a bigger/better/different radiator I would probably try one of the circle track double pass radiators that M2CupCar has recommended. It's also the best bang for the buck after the Godspeed/Chinese stuff.

They are sealed ala TrackdogRacing's Intercooler kit. 2 small panels on each side, top of the radiator and bottom of the mouth. While not 100% boxed in, I'd give it a 4 out of 5.

The front is boxed in and I'm running the belly pan as well. Two "hotrod" ducts on the hood behind the radiator would probably yield a significant improvement at speed, I would prefer to not have to cut the hood.

I'm not debating the merits of a proper/ideal reroute. I want to see the actual data for the mods I have now and then switching to EVANs. I don't think that the Miata community has given it a proper shakedown with enough Data to back up any conclusions.

Chris

 

Although the TDR kit is an improvement...when you seal it up like mine, you get to run in 90* heat without ever turning on the fan...with 300whp.

 

Do the sealing, and then measure the radiator coolant and air inlet and outlet temps.
I did before changing to the TDR ic, and came to the conclusion that there was insufficient airflow.

 

Truly sealing those exchangers should make a big change as Hustler states. He's been a big supporter of this. After doing it myself I understand why.

Jason, are you are saying, after sealing you saw decreased flow? Sealing it should lower the pressure in the engine bay giving you a larger differential. Should have seen increased flow.

 

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Our Coolant Re-Route is a REAL reroute and will certainly help you in your quest for cool track temps.

We have many happy clients!

 

No. I've always had sealing, but the TDR ic increased flow big time.