Cooling System

Cooling System
Cooling System Schematic
Overflow Tank
Surge Tank
Steam from Cylinder Head
Thermostat
Water Pump
Radiator
Fan
Engine Block
Radiator
in2
Rule of thumb: 1.1
radiator surface
area needed per hp produced
Modify for
bleed line to
Surge Tank
Therefore need approx. 66 in2
Inlet from Engine
Radiator from YFZ450R Yamaha ATV
7.5” H x 11.5” W x 7/8” D
Surface Area 86.25 in2
Inlet and Outlet ¾” ID tubing to connect to
water pump
Outlet to Water
Pump
Radiator Cap
Coolant naturally builds to approximately 16-18 psi
Normal production cars run 16-18 psi, high performance cars run 2224 psi , and racing systems run 29-31 psi
Pressurizing the water allows for the water to reach a higher
temperature before boiling (therefore vaporizing)
Part# T30R Radiator Cap 29-31 PSI
Pressure (PSI)
Boiling Point (° F)
0 PSI
212° F
10 PSI
239° F
20 PSI
259° F
30 PSI
273° F
40 PSI
286° F
50 PSI
297° F
Surge Tank
30 PSI
Pressurized
Radiator Cap
Typically a 1 quart container
Need to modify the part of the
Radiator that currently has the cap
and overflow line to run a ¼”- 3/8”
bleed line from radiator to top of surge
tank
Bleed line
inlet from
radiator
and
cylinder
head
Outlet to
overflow
tank
½” – ¾” Refill line from bottom of
surge tank to inlet of water pump
Benefits – de-aeration
2% air in the system leads to an 8%
decrease in cooling efficiency
4% air in the system leads to a 38%
decrease in cooling efficiency!
Refill line back
to water pump
Water Pump
Comes stock on engine
Need to test flow rate once we
have the cylinder head again
No internal bypass system.
Thermostat will have to regulate
continual water flow through engine
¾” ID inlet and outlet tubing to
connect to radiator
Flow Rate vs. RPM from R6 water pump
Thermostat
Placed at the outlet of the engine, a thermostat allows water to circulate
through the block, but doesn’t allow this water to circulate through the
radiator until it has reached proper operating temperature
This temperature (195°F) melts the “wax motor”, which forces the
thermostat piston to open and allows the water to flow through.
If the engine’s temperature is lowered too much, the piston closes until it
has reached proper operating temperature once again
Stewart/Robert Shaw Thermostats – 302
Augments bypass system
$14.95
Cooling System Data
Reviewed three sets
of autocross runs
with different drivers
Fan
Verify radiator is receiving adequate
airflow at low speeds
SPAL Axial Fan
11” Dia.
755.0 CFM
Based on predicted power require
minimum 450 CFM
Based on airflow at speed available
require minimum 500 CFM
Maximum 7” Dia. to fit radiator
Yamaha R6 Fan
5.5” Dia.
Est. >500 CFM
F19
ft^3/m
mph
0
5
10
15
20
25
30
35
40
0
213
426
639
853
1066
1279
1492
1705
F20
ft^3/m5
0
130
260
391
521
651
781
912
1042