Evans NPG?

[Supracentral]

I know this is slightly off the "lubricant" trail, but I'd still like to check for your opinion.

What do you think of Evans NPG (http://www.evanscooling.com/catalog/C_npg1.htm) as opposed to traditional water based coolants? I've been a fan of straight distilled water with Redline Water Wetter for summertime track use, but this stuff sounds interesting. Do you have any experience with it?

[jdub]

This is interesting SC...I don't have experience with it, but you did peak my interest.
A couple of things I gleaned from reading about the NPG cooling system:

- It uses Propylene Glycol...a close relative of Ethylene Glycol you find in standard coolant

- It's designed for use in a non-pressurized system and may require the Evans radiator, coolant pump


In a pressurized system like on the Supra, I'm not entirely sure this would work well. Pretty much everything I've read says the max ratio of coolant to water is 60/40 to 65/35. I suppose you could convert the Supra coolant system to non-pressurized, but it just may be more trouble than it's worth.

JetJock did a good write-up on coolant at MK III Tech:
http://www.mkiiitech.com/forums/viewtopic.php?t=859

I do know that you would have to thoroughly flush the system to change over to the NPG. I also know Propylene Glycol is an organic hygroscopic compound with a definite affinity for water. It is non-toxic (in contrast to Ethylene Glycol) and is actually used in some cosmetics, food additives and "personal lubricants"

It looks like it gets pretty viscous as it cools, making it harder to push through your radiator...probably ok for warmer climates and the reason Evans has an "NPG friendly" radiator and coolant pumps in stock. It doesn't look like NPG will flow well enough on a street car at low speeds in a cold climate...a race car is a different story.

From what I've read, it's a poorer heat transfer medium than the water based coolants...that would make your temp gauge read higher even though there's no danger of boil over (NPG boils at 370 deg F). Another reason for a bigger radiator with very good air flow. The stock Mk III ECU might not like it either...when the coolant sensor detects temps over ~100 deg C, ignition timing is retarded (I can't tell the exact temp and how much from the book I've got) to prevent knock when above idle (IDL off). Also, the A/C will cut-off under high temp conditions. There's no way I know of to "tell" the stock ECU that the motor is not over heating. Of course, if you're using a stand alone, these points are not an issue.

Hope this helps ;)

[bwest]

Back in '97 or '98, I tested the Evans before it went to market. This was before they had specific radiators or water pumps. Infact, I don't know if the fomulation that I used is the same as what they sell now. But what I did notice through normal everyday usage is exactly what jdub speculated above. The motor ran warmer in low speed traffic, as well as warmed up faster when cold. I also noticed that freeway driving and fast mountain driving yielded more stable temps. This is all subjective data gathered driving a 1988 Thunderbird turbo coupe, but that is what I noticed. Back then I got it for free, don't know that I would pay for it today...

[bobiseverywhere]

The Prestone Low Tox is a propylene glycol based formula.

http://www.prestone.com/products/antifreezeCoolant.php

As far as i understand it, There is nothing Better then water for a liquid heat transfer medium.

I know the Water Wetter and the Royal Purple stuff help, but they are all still based on the idea that you have allot of water in your system with a minumal amount of Antifreeze for best performance

[CyFi6]

http://www.evanscooling.com/html/npgPls.htm

They now have this NPG+ which they say can be used in any stock cooling system without modification. Any thoughts?
.
Its also surprisingly affordable (around $30 a gallon, about the same as Toyota red (although with Toyota red you only need half the system capacity))