| Below
follows a general introduction to Evans NPG and the coordinated components
designed to deliver maximum efficiency when used with NPG. While this is
a brief "technical" overview, it covers many of the most common
questions and benefits of an Evans NPG Cooling System. For additional information, please read our NPG Benefits pages - for a general explanation of Evans NPG - please read the text in our Technical Information page and our FAQ page. For Complete Evans NPG Installation instructions - Please read the online install guide in our Operational & Technical Information pages. |
COOLANT
 |
Evans NPG Coolant will transfer 27.5% more heat energy than water in your race engine, due to NPG's molar heat of vaporization and high saturation temperature. |
|
Evans
NPG is the best choice for racing engines. . |
WATER PUMPS
|
Evans
Performance Pumps have the highest GPM flow rate, lowest drag of any pumps
available. . |
|
Evans
Small Block and Big Block Chevrolet pumps features a 4.4" O.D. impeller. . |
|
Other
high flow pumps are possible alternatives, pump speed increases could be
necessary. . |
PUMP SPEED
|
Coolant
pumps reach maximum GPM flow by approximately 4500 rpm. . |
|
Keep
your pump speed between 4500 rpm and 6500 rpm for maximum flow and lowest
drag. . |
RADIATORS
|
Design
a radiator best suited for your application - Call Evans Technical Support. . |
|
Aluminum
large tube radiators work best, core type determined by HP and application.
. |
|
Air
management can be used to control system temperatures and aerodynamics. . |
|
Cross
flow designs work best, double pass designs are not recommended due to flow
restriction. . |
RADIATOR CAPS
|
A
7lb. cap is recommended when using Evans NPG to seal the system. . |
|
Evans
NPG will work at zero pressure with an expansion tank. . |
|
Never
put the cap in the upper hose or thermostat housing which is the high pressure
side of the system. . |
THERMOSTATS & FLOW RESTRICTORS
|
Not
needed, they reduce the coolant GPM flow through the engine and radiator.
. |
EXPANSION TANKS
|
Expansion
or "surge" tanks work well as a fill point & location of your pressure cap.
. |
|
Expansion
tanks must always be plumbed into the suction side of the cooling system,
(lower hose, pump inlet, radiator tank). . |
|
Evans
NPG uses a 7 lb. cap maximum. . |
HOSES
|
Hoses
should not restrict coolant flow. . |
|
Upper
hose should be a minimum of 1 1/2" I.D., 1 3/4" I.D. recommended. . |
|
Lower
hose should be at least 1 3/4" I.D. metal tubing or reinforced suction hose.
. |
|
Hoses
with loose springs should have them clamped or tie wrapped in place. . |
EXTERNAL LINES
|
Very
useful. . |
|
They
are used to change the distribution to lower the metal temperature in problem
areas. . |
|
Lines from the back of the intake to the thermostat housing and inlet hoses from the pump to the block or cylinder head are beneficial. They do not add to the overall GPM flow though the engine. |
AIR BLEEDS (depends on component location)
|
Air
bleeds help remove air trapped in your cooling system. . |
|
Evans uses an air bleed in all coolant pumps. This allows any air trapped in the impeller cavity to escape ensuring maximum coolant flow at initial start up and continuously through operation. |
|
Engine
or radiator air bleeds purge the components of trapped air. . |
FANS
|
Mechanical
pump driven fans draw twice the air CFM as electric fans. . |
|
When
using a mechanical fan always use a shroud. . |
|
Bottom
feeder air intake works well with pump driven fans. . |
|
Production
fans should not be used. . |
|
Use
electric fans during caution laps. . |
|
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