MSI Motor Service International GmbH
is the sales organisation for the worldwide aftermarket
activities of Kolbenschmidt Pierburg AG. MSI is a leading
supplier of engine componentsfor the independent after-market,
featuring premium brands KOLBENSCHMIDT and PIERBURG.
As a result of taking over the distribution of replacement
valves made by TRW Engine Components Group on 1st October
2005, the TRW brand has become a new addition to the
range.
Valve
Construction
Intake Valve
- Mono-metallic Valve
- Mono-metallic Valve with Hardened Valve Seat
- Mono-metallic Valve with Stellite Facing
- Bi-metallic Valve
- Mono-metallic Valve with Stellite Facing
Exhaust Valve
- Mono-metallic Valve
- Mono-metallic Valve with Stellite Facing
- Bi-metallic Valve
- Mono-metallic Valve with Stellite Facing
Mono-Metallic Valve
Mono-metallic valves are made of one material. The selection
of a material for this purpose is based on two requirements,
i.e. high heat resistance and good anti-friction properties.
Bimetallic Valve
A bimetallic valve allows material with a highly heat
resistant active ingredient (head) to be combined with
a stem material that can be tempered on the one hand
(stem end) and still posess good sliding characteristics
for valve guidance. The materials are combined by friction
welding.
Hollow Valves
Hollow exhaust valves are used primarily to
lower te temperature in especially vulnerable recess
areas, and are filled with sodium for this purpose.
A desirable positive side effect of this
is a reduction in the weight. For this reason alone,
to reduce mass, hollow, empty intake valves are used.
To achieve a reduction in the temperature
of valves, about 60% of the volume of the hollowed out
stem is filled with sodium and enclosed in a friction
welding process. Sodium melts at a temperature of 97.5°C,
has a density of 0.97g/cm³, and is an excellent
heat conductor.
During engine operation the Sodium becomes
liquid and is moved back and forth in the stem by inertia
forces. This is what is referred to as, "the Shaker
Effect". In the process the sodium transfers part
of the heat produced by the combustion from the valve
plate to the stem area.
There the heat is dissipated through the
valve guide. This way the temperatures in the valve
plate can be reduced by 80°C - 150°C.
Handling Sodium Filled Hollow
Valves
The machining and cutting open of sodium filled hollow
valves requires the appropriate caution. Special attention
must be given to ensure that the cavity is not openend
inadvertently, as sodium reacts violently to water or
drilling and grinding emulsions. When sodium reacts
to water, oxygen and sodium hydroxide are produced.
Examination and Disposal
Hollow valves in small quantities can be scrapped
in the normal manner. There are no special instructions
to folow.
If sodium filled valves have to be examined
or disposed of in larger quanitites, the cavities should
be opened, either by drilling holes in two places without
using coolant, or by splitting the valve open in the
middle.
Valves prepared in this manner are to
be placed in a bucket filled with water to neutralise
the noxious effect of the sodium. After the chemical
reaction has run its course, the valve can be scrapped
in the customary manner.
The sodium hydroxide is to be disposed
of pursuant to the respective local regulations.
Safety Instructions
Becuase of the violent chemical reaction and the release
of hydrogen when sodium reacts with water, the valves
should be neutralised only in well ventilated rooms
or out of doors.
Contact with the skin and eyes is to be
avoided in a y case. Sodium should therefore be handled
only by properly trained staff wearing the apprpriate
protective clothing (gloves, goggles, etc.). The customary
safety regulations governing the handling of abbrasive
and caustic material and explosive gases are to be observed.
Stellite Faced & Hardened
Seats
A great deal of thermal stress is placed upon
exhaust valves in particular, which wears them down.
It is therefore essential to strngthen or harden the
valve seat. Intake valves in high performance engines
are usually induction hardened. Pounding and wear of
the valve seat is thus avoided.
The Valve Stem End
The valve actuation (rocker arm, camplate, tappets)
places a great deal of stress on the end of the valve
stem. To avoid wear, the valve stem ends are hardened
where possible. If the valve stem steel cannot be hardened,
it is either strengthened with stellite or a hardened
pad will be welded to the end. |