| KKK-K26
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Second hand Turbocharger from an Audi Quattro
bought cheap through Ebay. |
Compressor Map
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This turbocharger is theoretically capable of delivering
0.2kg (0.44lbs/sec) of air at 2.3bar ( 33psi ) boost pressure at a
maximum safe speed of 120,000 rpm. This should hopefully give me about
11kg ( 24lbs ) of thrust to play with. With an afterburner about 30%
increase in thrust can be achieved which would give about 31lbs ( 14kgs )
of thrust.
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Compressor
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Inlet ( Inducer ) about 44mm in diameter, major diameter
( exducer ) 66mm. The compressor nut will be
used to couple some sort of device to spin the shaft to +20,000rpm for
starting. The standard way of starting these engines is via a
powerful source of air for example from a leaf blower, that is forced
through the engine spinning the turbo to the required rpm in the process.
As I would like to have everything self contained this won't be an option
for me. I haven't developed this yet but ideas I have for this are either
a high speed electric motor, a small model 2-stroke engine or a high speed
air tool like a drill powered by compressed air from a small high pressure
cylinder. |
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Turbine Wheel
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In the process of being cleaned. Hard encrusted
deposits from combustion products from the original engine require
laborious scraping, as there is no known way of removing them chemically.
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Bell Mouth
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Bell mouths help smooth the passage of air to the inlet.
This one I made from a stainless steel travel mug..! |
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Turbine Scroll
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Removed for cleaning. Like the turbine wheel this
was encrusted with beige coloured deposits that had to be scraped out.
The internal surface was also smoothed off using various files and
emery paper to aid the passage of the hot high speed gases. The inlet
is of the undivided type, i.e. it does not have two seperate channels
which tends to reduce flowing efficiency of the hot gases. |
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Turbine Adaptor Cone
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Cone made from 4mm gauge steam pipe. Like the
pipe/combustor mating flange this was made by making Vee cuts in one
end of the pipe and brining the petals together. The radius of
curvature of the petals then needed to be reduced which was done using
a home made three-pronged device and a vice. A very laborious process
but the result was well worth it! |
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| Combustion Chamber
| Made from an old style
Thorn 9 Litre water fire extinguisher 7 inches in diameter with
1.75mm thick walls and of welded construction. Conveniently sized and
already designed to contain pressures in excess of 20bar although it
will only ever see less than 50psi in practice. The flame tube
will be made from a 5 inch diameter section of stainless 316 20swg
( 0.92mm ) flue pipe. |
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Large..!
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With a diameter of 7 inches and overall length of 14
inches the combustion chamber is probably larger than it needs to be
given the size of the turbo, but I wanted to be sure that it was going
to work first time. It is better to have it too large and working
rather than too small with combustion problems! Making it bigger also
means I can attach a larger turbo at a later stage without having to
make another combustor. |
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Fuel Delivery End
| Top of fire extinguisher
capped off with 5mm steel plate with 10mm hole for fuel nozzle.
The ring of bolts are for locating the flame tube. |
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Mating Flange
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Flange plates made from 5mm steel used for joining
two halves of chamber together. |
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| Cleaned
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Water fire extinguishers are internally coated with
plastic for corrosion protection which has to be removed. I did it
using a blow torch, a hot knife and a wire brush ( very smelly
process! ) |
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Assembled
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Combustion chamber temporarily assembled with 90
degree turbine inlet pipe. The pipe is heavy gauge steam pipe, a bit
heavy for the job but the only thing I could find other than making it
myself. A lucky find in the scrap bin of a local engineering firm!
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Pipe/Combustor Flange
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The flange was made from a single disk of 5mm steel
plate. Petals were cut into the edge and bent inwards to create a
conical effect to match as close as possible the curve of the
combustor. The mating surfaces will be sealed with a high temperature
gasket paste the kind used for repairing exhaust systems. |
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Exit Hole
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Other half of the combustion chamber. The individual
petals at the mouth of the exit hole are temporarily there to act as
shims for shaping the pipe flange and will be removed. The ring of
bolts holding the flange will act as locating pins for the other end
of the flame tube. |
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| Oil System
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An improved version over the Phase 1 effort.
Includes oil filter adaptor and oil cooler powered by a more powerful
12v car fan motor. |
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Drive belt
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Power steering pump driven by belt drive using
smaller pinion on motor to give a better 8:1 reduction ratio. |
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Oil Inlet & Drain
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The drain pipe is used to transfer the hot oil from
the outlet to the oil tank having passed through
the turbo shaft housing. The internal diameter is larger than the oil
outlet hole and drops vertically to the reservoir to ensure that the
oil does not back up into the housing and cause problems with the
bearing seals. The small attached pipe receives the excess bypass oil
via the pressure relief valve. |
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