2000 Car Builder's Digest - Auto Racing News

Evans Cooling Turns Up The Heat To Produce Power

SHARON, CT - Steve Pressley of Evans Cooling Systems is a man possessed. His infectious enthusiasm spills out like water from a burst pipe a he talks about the benefits of Evans' non-aqueous NPG coolant, some of them in terms it would take an engineering degree to understand.

His enthusiastic behavior comes as no surprise, since he is the General Manager and a vice President of Evans Cooling Systems based in tiny Sharon, CT. What's surprising is the product itself. It's well regarded in racing circles, but isn't generally well known in the larger marketplace yet. Steve Pressley is working hard to change that.

"The potential market for NPG Coolant is huge" enthused Pressley. "When we explain the advantages to racers, truck owner-operators, fleet managers and the like, the conversation usually ends with them asking me where they can get their hands on it. Once they understand it, NPG Coolant sells itself."

Evans Cooling Systems is named after founder and Chairman Jack Evans, who has enjoyed a long career as a successful performance engine designer and builder. Evans is an innovator, with 16 U.S. and over 60 foreign patents to his credit. His shop was previously named MECCA Development, and their motorsports activities led to the development and marketing of a successful line of racing filters, oiling systems and accessories.

Likewise, Evans' engine cooling systems solutions have withstood the rigors of competition racing, as well as the analytical world of major automobile manufacturers' R & D people with whom Evans has worked closely in the past. By using Evans Cooling Systems' NPG Coolant and their recommended cooling system modifications, anyone can take advantage of Evans' years of development and engine building experience.

While other racing teams tried to keep engines cool with larger radiators and other patchwork approaches, Evans understood that there was a very fundamental problem with the cooling medium. Water wasn't getting the job done because it was unstable for the engine loads and temperatures found in performance and other high-compression engine applications. Here's why.

The high compression and extreme operating conditions inherent in competition and performance engines generates a lot of heat. This heat doesn't saturate the surrounding combustion chamber evenly. Instead, the cylinder head, block and gaskets absorb heat unevenly. Many of these areas of high heat concentrations are backed by cooling passages, which, in theory, are supposed to carry heat away from the combustion area. But in actual practice, this process doesn't always go that smoothly.

Water-based coolants, like a conventional 50-50 mix of Ethylene Glycol and water (EGW), boil around 224 degree F in normal atmosphere. Since engine temperatures exceed that, cooling systems are pressurized to suppress boiling, or vaporization, of the coolant. Each lb. of cooling system pressure raises the boiling point by approximately 3 degree F. Although that keeps the overall cooling system contained, localized overheating within the cooling jacket is the root of the problem.

BRAND OF CHOICE - Evans Cooling System products (below) are used by top race teams (above) in a variety of local and national divisions.

Inside the cooling jacket of a properly-functioning system, heat flows from the hot metal to the coolant. The coolant is circulated out of the engine and passes through a heat exchanger, or radiator, where the heat is dissipated into the outside air.

The coolant, now relived of its heat, is circulated back through the engine and the process repeats itself. But this process starts to breakdown if one of the system components doesn't do its job.

Sometimes the failure is an obvious one, like radiator fins get clogged, or accidentally covered with debris or damaged bodywork. Or the cooling system loses pressure and the water-based coolant starts to boil over. Failures such as these result in your temperature gauge warning you of the overheat, along with visible wisps of steam and the smell of overheated coolant. But more frequently, the failure is more subtle.

When an engine is being run hard, the cooling jacket walls begin to exceed the coolant's boiling point. Vapor bubbles form and break away into the coolant system. This phenomena is called nucleate boiling, and in those early stages, the boiling coolant's change from liquid to vapor carries off heat rapidly and efficiently. The vapor bubbles travel through the system and out to the radiator, where the vapor recondenses to liquid as the heat is carried off by the airstream. So far, so good.

But past the nucleate boiling point, water-based coolants become problematic. As the cooling jacket wall temperature rises further, especially at the hottest locations, the vapor bubbles in a conventional EGW system merge on the hot metal's surface and form a vapor barrier. The super-heated vapor barrier blankets the searing-hot metal and prevents the water-based coolant from contracting it and absorbing more heat. This aggravates any localized overheating problem, and manifests itself as damaging combustion chamber detonation. Meanwhile, all of those vapor bubbles in the coolant stream cause other mischief, like coolant pump cavitation, vapor stalling and vapor pockets.

Jack Evans developed and patented a coolant whose temperature operating range was better suited for this type of duty. Evans used a proprietary formulation of non-aqueous (no water) propylene glycol (NPG) as a pure. coolant. Beside being very stable and essentially nontoxic, its boiling point was up around 370 degree F in normal atmosphere, yet it easily tolerated temperatures down to -70 degree F before thickening to slush.

This simple improvement alone solved a lot of problems. The first and biggest problem was localized overheating. With NPG's ability to withstand blistering temperatures without exceeding the nucleate boiling stage in normal atmosphere, it eliminated the need to pressurize the cooling system. The NPG system could operate with no, or low cooling system pressure:

- Imagine no more explosive cooling system failures from a burst hose, or overheating because a minor leak bled off your cooling system pressure. Radiator caps could be removed while the engine was still hot (subject to the usual cautions regarding the handling of extremely hot liquids).

- If a radiator became plugged with dirt or partially covered with debris, the temperature increase would still be safely within the coolant's capacity to handle it without boiling over or damaging you engine.

- Localized overheating became a thing of the past, along with the damaging effects of hot spots and vapor barriers. NPG enters the nucleate boiling phase, but does not exceed that state. The small amount of vapor bubbles that produced recondensed while still in the engine. The NPG Coolant remained liquid and kept doing its job.

- With the significant reduction in vapor bubbles, cavitation and coolant vapor locks were eliminated, improving cooling even further.

In fact, Evans' Cooling Systems NPG Coolant was such a significant cooling system improvement, Jack Evans took advantage of the improved cooling efficiency by tuning his performance engines to run at higher temperatures. Higher compression ratios were immediately possible, as were more aggressive ignition advance curves and leaner mixtures for greater fuel efficiency. Since NPG Coolant reduced the engine's propensity for detonation, higher operating temperatures yielded greater thermal efficiency, more power, and improved aerodynamics (such as smaller grill opening) without danger of detonation.

And that led to further improvements. As engine performance increased, so did the heat. In some applications, when NPG Coolant was used without other system modifications, it absorbed more heat and operated at a slightly higher temperature than conventional water-based coolant. To take full advantage of this, Evans started developing products to increase coolant flow through the engine. Evans Cooling Systems now markets:

- High flow thermostats for most popular domestic performance engines, as well as other racing quality cooling system components like silicone coolant hose, aluminum coolant tubing and no- and low- pressure radiator caps.

- Billet aluminum coolant pump and crankshaft pulleys, both stock and modified ratio designs.

- Aluminum radiators for street and strip, fashioned from aircraft-quality 6061 T-6 aluminum alloy, and offering improved tube and fin design, even over stock "heavy duty" items. Customized fin densities are also available from Evans, to precisely match an engine's cooling needs.

- Cast-aluminum coolant pumps, featuring heavy-duty bearings and seals, air bleed fittings, and larger-distance passages and impellers which provide significant flow rate increased over stock or modified standard parts.

These enhanced performance parts are available from Evans Cooling Systems as individual parts. Evans Cooling Systems has also decided to bundle those components as bolt-on installation kits for racers, aimed at specific engine outputs.

Their first kit was designed for Ford Mustang 5.0 L engines putting out 600 HP or better. The Evans kit contains all of the parts necessary to cool that engine at that output level. Kits for lower-output engines will become available in the near future, and a Chevrolet Corvette kit is in the planning stage.

Jack Evans is a strong supporter of motorsports of all kinds, and the Evans Cooling logo can be seen on everything from NASCAR stockers to Modifieds and Outlaw Sprint Cars. His products prove themselves every weekend on race tracks, circle tracks, road and off-road courses across the country. Details of their racing programs, and about the products themselves can be found on their web site www.evanscooling.com.

A hurdle remains at a few tracks that have a "water only" coolant rule. Pressley said that rule was aimed at Ethylene Glycol antifreeze. But since Evans NPG is essentially non-toxic, and doesn't attack asphalt the way EGW does, it isn't in the same league. Evans NPG is fully accepted by major race sanctioning bodies such as NHRA, SCCA, NASCAR, and AMA to name a few. In fact, drivers who run Evans NPG have already convinced many "water only" tracks to allow Evans' coolant.

If Steve Pressley has his way, the product that's been performing on race tracks for years is about to "go to work" during the week too. Evans Cooling products were recently featured in several heavy duty trade magazines and Evans has opened a Heavy Duty and Fleet Sales office in suburban New York. Evans' work with major engine manufacturers and the U.S. Military has confirmed the benefits of running diesel engines with no- or low-pressure cooling systems and slightly higher temperatures. Improved engine efficiency and cooling system reliability are both enhanced. Lower fuel costs and reduced maintenance make NPG Coolant an attractive cost-effective conversion for truck and equipment fleet owners and owner-operators.

But NPG coolant will still go racing on weekends.