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Coolant - What to Use

 
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Rotorhog



Joined: 22 Dec 2005
Posts: 9
Location: Russellville,AR

PostPosted: Fri Feb 03, 2006 8:40 pm    Post subject: Coolant - What to Use Reply with quote

I plan to change out the coolant in my 84 SE prior to the onset of hot weather. In Arkansas, that could be tomorrow! No winter here so far, but the forecast does call for snow Monday... Anyway I'm interested in trying Evans NPG+ instead of the green, orange or any other color stuff. I like the idea of no water in the system to minimize or stop corrosion. Has anyone used this in a basically stock street car in everyday driving? I seem to hear about people who race using it. Any thoughts or experiences good or bad?
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Blake
Been there, done that


Joined: 12 Jul 2005
Posts: 135
Location: Portland, OR

PostPosted: Sat Feb 04, 2006 6:19 pm    Post subject: Re: Coolant - What to Use Reply with quote

Rotorhog wrote:
I plan to change out the coolant in my 84 SE prior to the onset of hot weather. In Arkansas, that could be tomorrow! No winter here so far, but the forecast does call for snow Monday... Anyway I'm interested in trying Evans NPG+ instead of the green, orange or any other color stuff. I like the idea of no water in the system to minimize or stop corrosion. Has anyone used this in a basically stock street car in everyday driving? I seem to hear about people who race using it. Any thoughts or experiences good or bad?


Evans is good stuff. We've been using and recommending it for years. For those not familiar, it is a waterless Propylene Glycol (not Ethylene Glycol) coolant that does not boil until 375+ degrees F. The NPG-R actually goes up to 400 degrees F. And that is at ZERO pressure! Instead of freezing at low temps it just turns to a slush and shrinks in the process (water expands, which can damage the engine). It's also a lifetime coolant, so you never have to change it and you don't have to worry about corrosion cause by water.

There are some theoretical drawbacks if you look at the specs, but they are just that; theoretical. In theory NPG has a lower thermal capacity and does not transfer heat as well. The reality is that ordinary coolant is worse in practice because the engine hotspots generate a vapor barrier from nucleate boiling, spoiling the heat transfer. That means the hottest parts of the engine get hotter while the coolant remains, overall, at a deceptively low temp...until it's too late. Evans bathes the hotspots with coolant which effectively wicks out the heat. Per calorie of heat absorbed NPG gains more temperature, but that improves the efficiency of the radiator (higher temp differential to ambient air). So, the NPG will tend to run a little warmer but the hotspots of the engine are actually kept cooler...and that's the only thing that matters.

We usually recommend running the NPG without pressure, since it doesn't need any and it saves wear and tear on the cooling system soft seals and hoses. You do have to be particularly careful about not contaminating the NPG with water, such as when you are switching from EGW (Ethylene Glycol + Water). Don't forget to drain the heater core. Also, we usually recomend you use Sierra brand ("pet safe") coolant for a few heat cycles between the EGW and NPG. Sierra is an aquious propylene glycol coolant, so it will absorb most of the residual water. Drain all the EGW you can, perhaps blow some compressed air through the system if at all possible, refill with sraight Sierra, run it around for a couple days, then drain and refill with the Evans NPG. Yes, it's a PITA but worth doing.

NPG is expensive. We sell it for $28 per gallon, and at that price we make very little profit. It's hardly worth selling but we believe in the product, so we do it anyway.

There are three basic NPG formulations. NPG, NPG+ and NPG-R. NPG is the original stuff and it's quite thick. Evans made special radiators and water pumps for it (nothing rotary). NPG+ was thinner and we've found that it works fine with the stock equipment, but NPG-R is the thinnest of all and seems ideal for most applications. We sell both the + and R.
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Pineapple Racing, Inc.
(503) 233-3878
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Rotorhog



Joined: 22 Dec 2005
Posts: 9
Location: Russellville,AR

PostPosted: Mon Feb 06, 2006 7:17 pm    Post subject: Reply with quote

Thanks for the info Blake. I wasn't aware of the newer 'R' product. A couple of more questions.

Would it be better to run a lower pressure radiator cap, say 7 psi, rather than 0 pressure? I ask because I wonder if the system is designed to have some pressure in it for seals and such.

Would I expect to see higher temp indications on the stock temp gauge on the instrument cluster?

Thanks again.
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Blake
Been there, done that


Joined: 12 Jul 2005
Posts: 135
Location: Portland, OR

PostPosted: Mon Feb 06, 2006 9:35 pm    Post subject: Reply with quote

Rotorhog wrote:
Thanks for the info Blake. I wasn't aware of the newer 'R' product. A couple of more questions.

Would it be better to run a lower pressure radiator cap, say 7 psi, rather than 0 pressure? I ask because I wonder if the system is designed to have some pressure in it for seals and such.

Would I expect to see higher temp indications on the stock temp gauge on the instrument cluster?

Thanks again.


You can run a low pressure cap, but it's not necessary. Doesn't hurt anything. The stock temp gauge is really just an idiot light with a needle. There is so much center bias, you won't know the engine is hot until it's too late. If you install an aftermarket temp gauge be aware that any location other than stock will read differently. In particular, the gauge will read about 10 degrees F higher at the water pump neck than the stock location in the rear plate, so don't freak out if the reading is high (even with EGW). We've had people come to us after pulling their hair out because the temp is higher than what seems "right" when, in actuality, they were bouncing off the thermostat control point. D'oh! With NPG and an aftermarket gauge, you will see a bit of movement on the gauge in normal operation...sitting at a light it will rise and then it will fall as you drive off. All that means it that it is working. Normal coolant you don't see that so much because of the inefficiency (due to the vapor barrier) of conduction. In other words the hot spots get hotter but the coolant is not carrying it away as well as it should, thus the coolant temps stay more even. The NPG does not deceive you like that.
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Pineapple Racing, Inc.
(503) 233-3878
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