Evans Cooling Systems' vice president Steven Pressley checks out Rick Bells Busch North car, which Evans campaigns for research and development. (Karl Fredrickson) A little known fact of history is this: Not long after cavemen discovered fire, it started to rain. That's when our pelt wearing ancestors discovered something else. They found out that water has an incredible ability to remove heat. The world has changed a lot since then, but water has remained tough to beat as a coolant. Until now. Maybe.

Jack Evans of Evans Cooling Systems has been involved with racing for years. He's the man behind Mecca, the successful brand of oiling components.  For the last 15 years he's been working on a non-water-based coolant called Non-aqueous Propylene Glycol, or NPG.  Evans and his company's vice president, Steven Pressley, feel their product offers plenty of benefits to stock car racers.

Here's why. As good as water is, it has limits. First, it boils at 212 degrees. Your engine doesn't boil over (or over-heat) when you see 212+ degrees on the gauge because your cooling system is pressurized. The pressure effectively raises the boiling point.  For every pound of pressure your system is under (you can tell how much by looking at your radiator cap), the boiling point is raised by about three degrees. If you're using a 20-pound radiator cap, the water will boil at around 272 degrees.

Even so, seeing a consistent 185 degrees of water temperature on your gauge doesn't mean there is no boiling occurring inside the engine. There is, and that's a good thing. The metal temperature of your block, and especially of the heads, can be very different from the number you see on the water temperature gauge. Metal temperatures, often called surface temperatures, vary. Some areas are drastically hotter than others.

These areas, referred to as "hot spots," can usually be found around the combustion chambers and exhaust ports. Some hot spots can reach 400 degrees Fahrenheit or more, even when your cooling system and engine are fine.

When your cooling system is doing what it should, it works something like this. Water comes from the radiator at a temperature of say, 180 degrees, and is pumped through the block toward each of the heads. When the water comes in contact with a 400-degree hot spot, it boils almost instantly at that spot and turns to vapor. This process is called nucleate boiling.

Heat energy is required to turn water into vapor. When nucleate boiling occurs, heat energy is removed from the surface metal, effectively cooling the hot spot. (Ever pour water on something you just welded?)

The water pump forces coolant to keep flowing, so incoming liquid surrounds and washes away the water vapor bubbles. The cooler water causes the vapor to condense (turn back to water), and the cycle begins again.

If nothing ever went wrong with the cooling system, water would be near perfect as a coolant. Unfortunately, lots of things can and do go wrong with cooling systems. Mud from a dirt track can clog the radiator, water pumps can quit, and even hot-dog wrappers have been known to foil a race-winning effort.

Anything from outside the system can disrupt the delicate balance of nucleate boiling.  As a result, incoming water may not be cool enough to make the vapor bubbles condense.  If the bubbles can't turn back into water, you'll see the temperature gauge climbing.

Then the situation inside the motor gets ugly. "The vapor bubbles stick to the cylinder-head cooling jacket," said Pressley. "More bubbles form and stick. Then more. You can see this phenomenon with a pan of water boiling on the stove: little vapor bubbles stick to the bottom.

"The vapor begins clinging to the metal of the cylinder head. Now there's no heat transfer.  The metal is getting hotter because there's a vapor barrier [insulating it] and the liquid is going right by.  You [can] start to develop a hot spot [in the combustion chamber] that causes detonation.  Your driver will say when the motor gets up to 220 or 230 degrees of water temperature it loses power."

Cooling specialist Art Lentini has just started working with NPG coolant.  He said, "From what I can see at this time, it would be good in long races, especially long dirt races where the front of the car will get a little plugged up.  If it does what they say, you could run more compression and you won't get distortions in the block and heads." (Karl Fredrickson)

The likelihood of detonation increases with engine temperature.  You may not hear the motor detonating—especially with open headers—but you can usually feel it losing power. After that, more obvious effects of overheating appear, including steam from the engine and water out the overflow. Blown head gaskets, cracked heads, and even more expensive engine problems aren’t far behind.

Mike Maietta Jr. was using water as a coolant when a crushed air duct caused his motor to overheat. He finished the race, but his motor could have been finished, too. (Robin Hartford)

The Evans Cooling System offers an advantage: its coolant has a boiling point of 370 degrees before pressure is added to the system. The coolant will support nucleate boiling at the hot spots, but those vapor bubbles will condense back into liquid at much higher temperatures.

Pressley said, "Even if you get to a point where you're running 220, 230, 240, even 260, you still have that 100-to-120-degree temperature differential between the incoming liquid and the vapor bubbles. So the vapor bubbles collapse."

What does that mean to you? Well, let's put two identical race cars on a heavy, wet dirt track. Driver A has water in his radiator. Driver B has Evans' coolant. Both drivers' radiators get blocked with mud. Both drivers are going to see higher coolant temperatures on their gauges. Eventually, both will have engine problems.

"It's hard to continue racing when you see real high temperatures on your gauge, especially when you're paying your own motor bills," said Brett Hearn.  Evans' coolant gives him the confidence to finish. "Our intention is to be around at the end of the race no matter what." (Karl Fredrickson)

The difference is that Driver B (with the Evans coolant) will be able to race longer before having engine trouble (either detonation or overheating). His coolant has a much higher boiling point, so his vapor bubbles are still condensing. Meanwhile, the water bubbles in Driver A's car are increasing in number, leading to overheating and reduced engine performance.  Will this make a difference in the race (or the championship)? Maybe.

Remember.  Evans' NPG coolant will not lower the temperature you see on the gauge. It can, however, raise the temperature at which severe engine damage starts.

Pressley conducts their performance R&D with a variety of race cars.  The common practice of adding water to the cooling system may become as extinct as adding water to your battery. (Karl Fredrickson)

If  you're  using  water,  you may be ready to pull in from leading the feature when your water temperature gauge reads 230 or more. According to the folks at Evans, temperatures of 300 degrees are not a problem when their coolant is properly used. In fact, they usually replace water temperature gauges with oil temperature gauges because they read a little higher.

Water has several advantages, including that it won't catch fire.  The Evans system can, although Pressley said it's no more likely to happen than with conventional antifreeze. (Karl Fredrickson)

"Some ARCA guys have gone up to 270 and won races," said Pressley. "The oil temperature is going to want to follow the coolant temperature. So, if you intentionally go there, have your oiling system in line.

"We have approached 300 without cooling problems, but when we do, we are afraid of other problems like underhood temperatures and charge air/fuel density. There are other things to worry about.

"But if you are leading with four laps to go and the water temperature is 260, keep going. We've had racers tell us they've finished races after they've spit the belt off the pump."

Brett Hearn, a regular winner in the DIRT series, has been using Evans' coolant for over five years. "In the environment we race in, we're always worried about plugging up the radiator," said Hearn.

"On Labor Day we ran a track with a lot of cinders. They'd just got done running the horses. We found the tight cored radiator took a lot of cinder even though it didn't look dirty at all. It was plugged solid.

"We couldn't understand why it was running hot, but the coolant gave us the insurance to run without [overheating]. It ran well over 260 degrees for a long period of time. We finished the race and did a minimal amount of damage to the engine. That's the kind of insurance I'm looking at." It shows.  "Our DNFs last year were minimal. A lot of that is due to these kinds of considerations."

The product has also given Hearn's crew the confidence to restrict air flow to the radiator intentionally. "This system has allowed us to keep the front of the car closed up [for aerodynamics] even at the Syracuse mile. It's a place where we are on the floor almost all the way around the track."

But wait, there's more

Since NPG raises the point where detonation begins to occur, compression ratios can sometimes be raised. That can make more horsepower. "Even if you have a higher liquid temperature, you can actually have a lower metal temperature of the cylinder head's critical areas," said Pressley. "That's what lowers the [potential for] detonation." 

The company claims NPG is essentially non-toxic, so unlike conventional antifreeze, you can drink it by mistake without injury. So can your pets. Still, if you run out of coffee and beer in the garage, don't crack open a jug of Evans coolant. Evans claims it is also environmentally safe.

There are other safety advantages.  NPG normally operates with a minimum of cooling-system pressure, so burns from spraying coolant are less likely. "I've taken a rag and removed a cap that looks like it would be under pressure, but it's not," said Pressley, who admitted he's had fun doing that in crowded pit areas.

Along with other cooling system modifications, Evans designed their own water pumps.  The design includes a large impeller cavity (visible in the lower pump).

"We either run zero pressure, or on some racing applications we'll run a low-pressure cap, like four to seven pounds." It is still a good idea never to remove a hot radiator cap in case something goes wrong.

NPG has antifreeze qualities, so you can leave it in your engine year-round.  Unlike the conventional antifreeze, this stuff won't attack asphalt.

A new impeller design represents a substantial departure from stock and currently popular high-performance designs. (Karl Fredrickson)

On the other hand

Like a beautiful woman with a dorky laugh, there are downsides to Evans' coolant. Wrecks happen and this coolant is only slightly quicker to clean up than regular antifreeze.  It's also flammable. "It burns like Sterno," said Pressley, who discussed the situation of one racer who said the coolant caught fire on his dirt car.  "Since they weren't running an overflow can, they left the fitting for the overflow line open on the intake manifold's water neck-cap combination. So the coolant sprayed onto the headers."

That team's engine builder confirmed the story. He explained that many dirt track racers let their overflow spill to the track. He said their problems started with a defective conventional-style radiator. When the coolant was pumped out of the fitting, it had a direct shot to the headers. Pressley claimed that, when properly handled, their coolant is no more likely to catch fire than regular antifreeze.

Clearly, overflow cans are necessary with this product. "You must consider the expansion tank," said Pressley."  A lot of people just use it as a puke tank, but it's an important part of the cooling system."

At $20 per gallon, you won't want to dump out the Evans coolant like water, anyway. "The NPG, like anything else, expands five to eight percent when it gets hot," said Pressley. "You need a reservoir to hold it, so when [the engine] cools back down [the coolant] can go back in."

If  your  own  overflow  tank  is  a  taped-up old sports-drink bottle, consider a manufactured one. "If your expansion tank is under the hood," Pressley said, "we suggest you use aluminum because of all the heat in there.

"We offer a one-and-a-quarter and a two-quart expansion tank. We just want a little bit [of coolant]  in there when it's cold to know the rest of the system is full.  It should  be half-full when it's hot. Expansion tanks are $75 to $100."

Evans recently began offering specialized radiators and water pumps for people who can benefit by tailoring their cooling system. You can probably enjoy the basic benefits of Evans' coolant simply by replacing the water in your conventional equipment.

SOURCE

Evans Cooling Systems, Inc.
Engineering Center
255 Route 41 North
Sharon, CT 06069
860/364-5130 Fax 860/364-0888