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Power
is created by combining fuel and oxygen, then igniting this mixture.
This
ignition leads to a rapid rise in temperature as the mixture burns,
pressure increases rapidly and forces the piston down the bore. Hence
power is produced.
However,
much of the heat generated ends up in areas which don’t contribute to
power output. In fact it has been estimated that 70% of the potential
energy in the fuel ends up wasted out of the exhaust pipe or fed into
the cooling system. Anything that can reduce this heat loss will result
in an increase in power output.
This
is where a thermal barrier coating, relatively new to the automotive
industry, is beginning to make it’s mark.
A
thermal barrier coating applied to the piston crown, valves and
combustion chamber will increase combustion temperature whilst reducing
heat loss into the piston (therefore into the engine oil), cylinder head
water jackets and incoming charge.
Boyles
law tells us that the volume or pressure of the gas must increase if the
temperature goes up.
By
keeping a larger portion of the heat within the combustion space
pressure on the piston is increased, flame propagation and travel is
enhanced. Test engines have recorded up to eight percent increases in
horsepower from this treatment alone.
Less
heat into the piston rings also means that radial ring tension has an
increased life expectancy.
Piston
designers and engine builders will also be pleased with the
opportunities presented to improve the basic design of the piston by
virtue of the thermal barrier.
The
reduced heating effect on the piston can also allow piston-to-bore
clearances to be reduced in some instances. This can lead to more
effective compression rings and more effective oil control rings, simply
because the rings are more accurately located in relation to the bore.
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Aluminium
loses its strength very rapidly as temperature rises. Pistons are made
thick in certain areas to give sufficient strength at the elevated
temperatures normally encountered. It may now be possible to run lighter
pistons due to the thermal barrier.
70%
.....ends up wasted out of the exhaust pipe or fed into the cooling
system.
The
closer the top ring land is to the piston crown , the better the
combustion process is. In the past the major restriction has been that
placing the top ring too close to the top of the piston causes the ring
land to collapse because the intense heat cannot be dissipated.
Coating
the piston crown means the top ring land will operate at a far cooler
temperature.
The JET-HOT
Thermal Barrier Coating has the same coefficient of expansion as
aluminium. Particles are bonded with an inorganic binder which is
unaffected by petroleum products. With a bond strength of 10,000 psi., this coating’s non-porous ceramic matrix improves
flame travel, reduces oil temperature, increases radial tension life of
rings and prevents carbon build-up.
Arguably
no part of an engine undergoes greater thermal shock than pistons and
valves. Yet this has no effect on the bonding properties of the JET-HOT
Thermal Barrier Coating.
Caution:
Piston damage - detonation
One of the major causes of piston failure is detonation. When a ceramic
coating is applied to a piston top and a combustion chamber, it will
increase the heat retained by combustion and this in turn may cause bad
detonation. There should be an adjustment made to engine tune to
compensate.**
What
makes JET-HOT so superior to
traditional high temperature coatings is its metallic-ceramic structure.
Combining
the benefits of aluminium and ceramics in a single coating. (more)......
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