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GLOSSARY :
Pertaining to this Site
Ambient
-- The atmosphere outside of and effecting the cooling medium. Has an effect on
all facets of cooling, the higher the ambient temperature, the harder to cool to
the same level.
BTU
-- British thermal unit. Measurement unit of temperature.
Cavitation
-- Eddying of water off the edges of water pump impellor blades, generating
aerated bubbles in the water which can turn to steam and worsen hot spots.
Much more detrimental in turbo engines or ported heads. Also promotes corrosion
in all engine cooling systems.
Core
-- Centre part of radiator/intercooler/oil cooler etc, that consists of
tubes running between the two header plates carrying the hot medium, & fins
joined to these tubes to dissipate the heat to the ambient air flow.
Corrosion
-- Chemical or electrical removal of material from a metal, main problem
for us is the interior walls of the water jackets. Remember, not only can it
cause the very expensive replacement of blocks, heads, housings etc., but the
deposits have to go somewhere, and usually that's into the radiator tubes to
block them. A double needless expense!
Coolant
-- Usually misnamed inhibitor. A true coolant may have very little corrosion
inhibitors in it, but will raise the boiling point, carry heat away from hot
spots and exponentially lower the water temperature, ie:- the hotter the engine
runs the better the coolant keeps the temperature down, might lower it 2 deg. at
90 deg. but 6 deg at 120 deg.
Chemical Current
-- A small electrical current that is generated from mixing chemicals in the
cooling system. Can be detected for up to a day, after running a cleaner
through the system, flushing and then adding inhibiter.
Detonation
-- Aaaaaaaahhhhhhhhh !!! The Achilles heel of the force fed internal combustion
engine. When the flame front travel in the combustion chamber destabilizes and
causes preignition - the fuel mix explodes to early in the upward stroke of the
piston. Fixes are different piston dome &/or combustion chamber shape, higher
octane fuel, retard timing, enrichen mixture, lower compression, lower
boost, water injection and/or the only device which noticeably increases power,
fit an intercooler!
Dimple wall
-- A process that presses small square depressions into the wall of a water tube
to break up the capillary tension water has. Gives approximately 6 % more
cooling.
Dissipation
-- The transferral of heat from the hot medium through the tube wall into the
fin and then taken away by the cooling medium.
Efficiency
-- The percentage cooling offered by the cooling unit. The
equation is hot medium - cooled medium X
100
Note that this is for Intercoolers, Radiators,
oil coolers etc., not Turbos.
hot medium - ambient
Engine
-- at college I was taught an engine is an internal combustion power plant &
a motor an electrical power plant
Fins
-- A strip of aluminium that is folded to "zig zag" between the two flat
sides of the tubes. A fin in a 500mm long tube, can be 2400 mm long! It is these
joints that gives an aluminium core it's advantage over copper/brass, as solder
is a very poor conductor of heat compared to the all aluminium fused joint.
FPI. or fpi.
-- Fins per inch. The number of fins attached to the wall of the tube. The more
fpi., the better the heat dissipation up until the fpi ratio exceeds the core
thickness slowing down the ambient air passage through the core.
Header Plate
-- A plate with holes punched (rarely machined) in it to allow the tube (part of
core) to protrude through. Clearance of the slot is very important for proper
tube fit & sealing at manufacture, which then affects longetivity. Joins the hot
medium transporting (part of core) tube to the tank.
Intake Charge
-- The air that has been sucked/forced on it's way between the air filter & the
combustion chamber.
Intercooler
-- A heat exchanger used to cool the hot pressurized intake charge of a
turbocharged/ supercharged engine. The cooling gives a denser charge with more
oxygen for kw. gain and also less chance of detonation.
Motor
-- At college I was taught a motor is an electric power source & an engine is an
internal combustion power source
Oxidation
-- The breaking down of the alloy external surface. Turns to a powdered
insulating coating that for maximum cooling, needs to be cleaned off every few
years, acidic cleaning works best. A much slower process than the corrosion of
copper fins, at least 400% slower!
Pipe
-- Solid, usually round tube to transport a cooling medium.
Polished
-- Bloody hard messy work that we can't charge high enough hourly rate to make
it worthwhile. Looks Good!
Radiator
-- A heat exchanger used to cool the engines coolant. Needs air flow to
dissipate the heat out of the radiators core. Coolant heat is unwanted by
product of the engines power.
Step Back
-- Or overhang, where the header plate sits over one side of the core more than
the other, usually used to gain more volume.
Stray Current
-- A small electrical current in the cooling system, usually from a bad earth on
the vehicle. Measured with a special tester or analogue multi meter. Maximum
allowable in aluminium system is 0.05 volt. The silent killer of aluminium
radiators!
Supercharger
-- A mechanically (usually belt/s) driven compressor with rotors/vanes/turbines
that force large amounts of air into the combustion chamber. Usually will
not heat the intake charge as much as a turbocharger for the same pressure
boost. Uses allot more engine torque than a turbocharger.
Tank
-- Contains the hot medium between the inlet/outlet pipe and the header plate.
Usually a closed rounded rectangle shape. Also a vessel to hold liquids.
Thermostat
-- Controls the travel of fluid in relation to it's temperature. The opening of
the valve/flap/piston is controlled by a wax pellet, so replace after 4 or 5
years. A cold engine will wear out allot quicker than a hot engine.
Throttle Body
-- Housing containing the throttle butterfly/s which control the amount of air
entering the combustion chamber. Usually has a sensor to tell the computer the %
the throttle is open.
Torque
-- Imperial measurement of the twisting force generated to lift a set weight a
given distance. Used in formula with revs to give horsepower readings. Gives an
engine "grunt". Turbocharging a n/a engine can more than double the torque
output, interestingly, mostly less than halving the life expectancy.
TPI or tpi.
-- Tubes per inch. The number of tubes across the width of the header plate. The
more tpi. the larger volume of water that can be transported through the core
still in contact with the cooler tube wall.
Tube
-- The solid rounded rectangular section to transport the heated medium (water,
oil and intake charge) past the cooling medium -air or water. Needs a flat side
wall to give a sufficient surface area of contact with the fin fold.
Turbocharger
-- A compressor with two turbines on each end of a shaft. The driving turbine is
rotated by the exhaust gasses, twisting the other turbine, which in turn sucks
large volumes of air into the housing, compressing & heating the air in the
process and forcing it into the combustion chamber. Can supply higher boost than
supercharging. Negligible engine power drain.
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