IMPORTANT

The water-free formulation of EVANS NPG Coolant and the configuration of EVANS NPG Cooling Systems eliminates coolant pump cavitation commonly experienced with water/ethylene glycol cooling.

EVANS NPG Coolant exhibits completely different heat transfer characteristics from conventional water-based coolants. These differences permit EVANS NPG Cooling Systems to greatly improve the operating efficiency of internal combustion engines. The heat transfer characteristics of the coolant benefit greatly from dramatically increased coolant flow rates and freedom from cavitation, which is contrary to most of what has been practiced over the years. The low surface tension of the coolant and the dynamics of the reduced volume of coolant vapor generated also contribute to the effectiveness of high coolant flow rates.

A Stage II High Efficiency System is a high-flow advancement of the Stage I Basic System and usually will allow compression ratios up to 12:1 for street vehicles and up to 16:1 for race cars (racing requires 104 motor octane fuel). Tests show that elevating flow rates consumes less than one additional HP, small in comparison to gains from reduced detonation & pre-ignition, resulting in usable timing and compression improvements.

The installation of an EVANS NPG OE-type high-flow replacement coolant pump and high-flow radiator is standard when constructing a Stage II system. The currently available EVANS Pumps and EVANS Radiators are listed in the EVANS Cooling High Performance Catalog. DO NOT CONFUSE high-flow pumps with most "high RPM," anti-cavitation pumps. Anti-cavitation pump designs have reduced impeller-fin area or impeller-bleed holes to avoid cavitation at high RPM's by reducing pump draw and flow. EVANS offers an impeller conversion kit which improves coolant flow in many OE pumps.

ALERT: Whenever operating an engine at higher horsepower, compression, turbo boost or load, the engine oil temperature MUST be controlled and kept to a maximum of 250°F by using an oil cooler.

NOTE: In addition to the racing instruction we have found the following modifications beneficial with the use of EVANS NPG.

1. Removal of the thermostat or restrictor from the system.
2. Plug thermostat bypass hose.
3. Install an expansion tank with 7psi cap and a zero pressure cap on the radiator.
4. Install a 1 ¾" OD upper hose neck on the radiator and thermostat housing.
5. Install external lines from rear of the manifold. Bigger is better. Minimum line size should be #12AN or ¾" ID hose.

For technical assistance on these modifications please call us on our support line at (610) 323-3114

OE Pump Speed and Pulley Selection: To obtain full advantage from the Stage II configuration, if an unmodified O.E. Pump is used in place of an EVANS impeller or pump, increasing the speed of the O.E. pump is required. Tests show that regardless of engine type or pump, the following speed to RPM guidelines will assist in the proper selection:

Several pulleys (listed on Page 20) for Stage II conversion are currently available from EVANS. For custom made pulleys; to obtain a price quote and order, measure the diameter of the O.E. lower crankshaft pulley, divide by ratio desired to find diameter of upper pulley. Supply the new diameter, a sample OE pulley, or print, to:

Evans Cooling Systems
PO Box 434
Parkerford, PA 19457-0434
USA

CAUTION

A Stage II System and the related high coolant-flow rates induce dramatic increases in pump draw (inlet vacuum). These increases in vacuum also exist inside the lower radiator hose and can cause it to collapse. This tendency to collapse is further aggravated in hoses with 90° turns or tight bends.

A Stage II System (street or racing application) should always have a lower hose which is either:

1)  reinforced with a coiled wire inside the hose, or 
2)  made up of metal tubing with short rubber connections at the ends.