Wren Turbines MW54 Mk2 User manual

Wren Turbines Ltd. MW54 Mk2 & Mk3 Turbo-Jet, kit assembly instructions, Jun 2004
Page 2
John Roger Terry Mike
Important Copyright Notice
Copying of this manual by whatever means is prohibited. This manual gives the purchaser the right to assemble one or more MW54 kit engines solely for their own use and
enjoyment.
Any individual, group or consortium wishing to make parts or complete engines to this design, for sale or exchange must obtain permission in advance from Wren Turbines Ltd.
The design has been registered and any person or organisation that undertakes the manufacture of this or similar design for sale, anywhere in world, without express permission
from Wren Turbines Ltd, will be prosecuted. Manufacturers wishing to produce the design or parts for this or any Wren product, should contact Wren Turbines to arrange licence
approval at the registered office:
Wren Turbines Ltd
5 Stoneham Street
Coggleshall
Colchester
Essex
C06 1TT
Wren Turbines Ltd is a company formed by Roger Parish, John Wright, Mike Murphy and
Terry Lee.
Wren Turbines Ltd was formed initially to launch the MW54 gas turbine design and to
manage the design and production of cast turbine wheels and ngv’s for the engine.
This brief has now been very much widened to incorporate the production and supply of a
wide range of parts and accessories for the turbine enthusiast. The company has also
designed and developed turbo-shaft applications for the MW54 engine for turbo-prop and
helicopter applications.
Wren Turbines have also developed a smaller engine called the MW44, an 8lbs thrust engine
for the smaller aircraft. See the web site for details or call the Wren office for more
information and pricing on this and other products for the jet enthusiast.
Grateful thanks to Leonie Henson for supplying the “fingers” in the assembly pic’s, Sara Parish
for looking after the office, sales and Wren helpline, Steve Ebbage, Charles Abson and
Richard Green –the “backroom boys” at Wren and Roger, Terry and John for helping to
make Wren the first choice for many in jet turbines.
Mike Murphy, June 2004.
Copyright (c) 2002, Wren Turbines Ltd. All Rights
Reserved

Wren Turbines Ltd. MW54 Mk2 & Mk3 Turbo-Jet, kit assembly instructions, Jun 2004
Page 3
F
F
1
2
3
4
567
8
10 11 12 13
920 25
21 22
26
27
28
32
33
41 35
47
40
34 42 4844 43
45
12
41
6
6
88
38
49
7
4
42
51
52
Note: 'O' ring
not used
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Wren Turbines Ltd. MW54 Mk2 & Mk3 Turbo-Jet, kit assembly instructions, Jun 2004
Page 4
Item numbers - refer to general arrangement picture on previous page for location:
1
Compressor nut
20
Fuel Distribution Ring
40
Front and Rear Bearing
2
Front Spacer
21
Case Outer
41
M2.5 x 5mm Case Front and Rear screws (12 off)
3
Compressor
22
Case Rear
4
Intake Cone
43
M3 x 4mm NGV screws (8 off)
5
Shaft Seal
25
Turbine Wheel
44
M3 x 10mm Shaft Tunnel screws (6 off)
6
Case Front
26
Rear Spacer
45
Bearing O-ring (1 off –compressor end only)
7
Diffuser
27
Turbine Nut
46
M2.5x6 Intake Cone securing screws (6 off)
28
Exhaust Cone
49
M2.5 x 8 Case Front securing screws (7 off)
10
Pre-load spring
32
Quick-release Service Connector
11
Shaft Tunnel
34
Gas Injector Pipe
51
Bearing Circlip
12
Shaft
35
Nozzle Guide Vane (NGV)
52
Circlip Shim
13
Combustion Chamber assembly
38
Pre-load Tube
Additional items required for completion of this kit.
We have tried hard to ensure the highest state of preparation for this kit, enabling it to be quickly built up and run. We have assumed certain basic
tools are available to the constructor as would be found in a standard toolkit, to which we have added certain items we feel are appropriate and
useful.
The following items are required to complete the kit:
Metric spanners –5.5mm (Quick-release fittings), 8mm (Glowplugs), 10mm (Turbine Nut), 13mm (Compressor Nut).
Thread-locking compound –“Nutlock”, “Loctite 242” or similar.
High temperature sealing compound - “Holts Gun-Gum”, “Red Hermatite” high temperature silicon sealer, or similar (Mk2 engines only).
(Fuel pump, controller and other running accessories, can be ordered separately from Wren Turbines).

Wren Turbines Ltd. MW54 Mk2 & Mk3 Turbo-Jet, kit assembly instructions, Jun 2004
Page 5
SAFETY NOTES
We make no apologies for positioning these notes early in the manual. Please read the following for your own safety and those around you -
thank-you.
The engine must be operated only in accordance with the Gas Turbine Builders Association code of practice and the accompanying appendix –
obtainable from the GTBA web site http://www.gtba.co.uk. New turbine users are recommended to read the information contained therein and to
familiarise themselves with turbine operation and special precautions needed. The rotor in the engine is running at very high speed and if there
were a failure of the rotor assembly it could inflict serious injury.
This engine is not a toy and can cause bodily harm to you or others if misused. Be especially on your guard toward the inquisitive spectator who
may not realise the dangers of gas turbine operation. It is your responsibility as owner, to ensure safe, careful and considerate operation of your
engine at all times, and in accordance with the manufacturers instructions. If you sell or give away this engine, please pass these instructions to the new
owner.
All spectators should be briefed before the run on how to behave, always have a safety person with you when engine running/flying.
Always have a fire extinguisher to hand when running/flying, CO2 or BCF is ideal –dry powder, foam or water is not recommended. This engine
must not be used near flammable gases, liquid or materials.
In the UK it is suggested that you join the BMFA to take advantage of their insurance cover, even if you do not wish to fly the engine.
Wear ear defenders when standing in close proximity of a running engine. This engine must only be run firmly attached to a secure and sturdy
engine test stand or model installation. The thrust is considerable for such a small size and mountings must be sufficient to withstand such forces. Use
appropriate screws and lock-nuts. The engine must never be run held in the hand or clamped in a vice.
During operation and for a time afterwards there are parts of the engine which are hot enough to cause serious burns –do not touch any part of the engine until it
has cooled to room temperature. This engine generates large quantities of heat –ensure the mountings and installation are appropriate for operation at these
elevated temperatures. The exhaust gases are very hot (over 450’C) on leaving the engine and can cause burns to skin or damage to objects close to it –keep
exhausts clear of anything which is affected by such heat.
Always operate your engine in open air away from confined spaces as the engine exhaust contains gases which can cause asphyxiation and nuisance from smells.
Turbine fuel is poisonous to living beings. Keep away from mouth and eyes and contact with skin. Always store in a marked container out of reach to children.

Wren Turbines Ltd. MW54 Mk2 & Mk3 Turbo-Jet, kit assembly instructions, Jun 2004
Page 6
Turbine fuel has a relatively high flash-point but in certain circumstances can be highly flammable. Keep it away from heat and sources of combustion.
The starting gas is highly flammable and must be used with extreme care. Maintain canister and fittings in good leak-proof condition. Protect from sunlight and
prevent exposure to temperatures exceeding 50’C. Keep out of reach of children. Discard used canisters in a safe place and do not puncture or incinerate, even
when empty. Avoid deliberate inhalation.
Ensure gas only is supplied the engine, liquid gas must not be allowed to pass into the system. Gas supply must be disconnected until ready for immediate use. Gas is
heavier than air and can fill a model if allowed to leak unchecked, and become a potential explosion hazard.
Turbine oil can be are hazardous to health and must not be allowed to come into contact with skin, mouth, eyes or through ingestion,
accidental or otherwise. Take care when decanting and ensure any spillage is wiped away immediately and clean any affected area with
warm soapy water.. Wash hands and any affected part immediately after any contact. Turbine oil can discolour or affect certain paint
finishes as may be used. Take precautions to prevent spillage . Do not discard or allow any spillage to run into drains.
If checking glow-plug operation, keep fingers or bare skin away from possible burn from the glowing element –use a metal tool or
appropriate insulation.
As operator, it is your responsibility to ensure any spectators (especially small children) or helpers are kept well away from the engine
whilst it is operating. The safest position to operate the engine is directly in front. The area inline and to the rear of the turbine is the most
dangerous area and you must keep well clear of this.
Keep all spectators away from the side and rear of the engine to a distance of at least 10mtrs (30ft) radius, as shown. If operating from a
pit area take special care as safety distances are often difficult to maintain.
Keep all helpers close by and brief them fully on their duties before starting the engine. One helper should carry out the role of fireman. Ensure they are aware of what
to do in event of emergency and where to position the extinguisher if required.
Do not attempt to alter the starting characteristics of the engine by spraying ignition agents into the intake, as might be used for gasoline and diesel engines. A
dangerous fire and flashback may result.
Finally please note, the exhaust of a gas turbine has a pleasing smell to enthusiasts of gas turbines but others may find it offensive. Please have consideration for others
when running your engine in their proximity.
Wren Turbines welcome feedback on this or other of their products, email on [email protected].co.uk or write to:
Wren Turbines Ltd, Unit 13, Century Business Centre, Manvers Way, Manvers, Rotherham, S63 5DA, England
Tel [phone], Fax +(0) 1709 300291

Wren Turbines Ltd. MW54 Mk2 & Mk3 Turbo-Jet, kit assembly instructions, Jun 2004
Page 7
The MW54 Mk2 and Mk3 Gas Turbine Kit - Introduction.
This kit is a development of our very popular MW54 Mk1 kit introduced in Dec 2001, of which over 200 have been sold. This earlier version required some
metalworking to complete and customer feedback had indicated it would benefit from a more complete level of fabrication. The Mk2 version was in response to
this and as a result there is no metalworking or soldering/brazing required for it’s completion. The Mk3 version is exactly the same engine but includes a deluxe
one piece machined stainless case and exhaust nozzle and the turbine comes pre-balanced on the shaft for convenience. The extras are available to Mk2 owners
for upgrade at any time to suit their budget and timescale.
The concept of the kit gas turbine engine is to bring to the modeller the latest in miniature turbo-jet technology but at an affordable price, and in the process
help the modeller to gain familiarity with this new breed of internal combustion engine. The kit is for the thrust engine in its simple but fully functional form, to
which the builder can add their choice of accessories such as a stylish anodized green front cover, pod-style on-board starter and clutch system, single-piece
stainless case, tuned twin piece exhaust, thrust tube, FOD screen etc, all available from Wren Turbines. This approach allows the builder to stage their
construction to suit their time-scale and budget and chosen application. Additionally, the engine can be fitted with alternative versions of the popular FADEC
ECU such as the Manual ECO or Auto-start version, (for which the green cover and pod starter are required). To this can be added a simple external gas start
system or a full on-board gas start system and as these are all standard accessories for the Wren range of MW54 engine turbines, you can be sure of plenty of
choices when building up your turbine installation.
Builders who have purchased the MW54 plan-set (available from Wren Turbines) which covered the in-depth construction from an engineering viewpoint, will
note several changes have been made to facilitate ease of assembly over the original design, although the basic design remains the same. It is not intended to
change the plan for the foreseeable future. The extras listed above and the balancing options following also apply to the “homebuilt” version of the engine. All
components of the engine are available separately as spares enabling you to structure your project to suit your chosen timescale and budget.
Balancing.
We are regularly asked about balancing and we have accumulated a lot of experience as to what is acceptable and what is not, and what forms of in-balance
correction are realistic. To achieve satisfactory smooth running of our engine we need a good standard of dynamic balance and how this is achieved is the focus
of this section. We have tried to keep the description of this complex process as straight-forward as possible and we apologize in advance if the reader finds the
section overly simplistic.
The two main forms of balance we are concerned with are static and dynamic . The simple way to appreciate the difference is to turn a bicycle over, remove the
chain and observe the pedals remain somewhat at rest, ie in static balance. However if we spin the pedals quickly the bicycle will wriggle about from side to side,
ie not in dynamic balance. On our engine the two components which are individually out of balance are fairly narrow discs so we can easily distribute the out-
of-balance correction without generating what is called a couple – effectively a wobble . The shaft can be regarded as not requiring balancing as it is highly
precision ground and concentricity run-out is unlikely or of small consequence here.
To achieve a pseudo dynamic balance of our engine we do the equivalent of balancing just one pedal without the other attached, ie we first balance the
turbine mounted on the shaft (with its bearing, spacer and nut) and then replace the other pedal , ie the compressor, and balance this to achieve an overall
balanced rotor. The turbine has considerable mass and will always require correction before use due to the casting process. It is supplied ready mounted to the
shaft and should not be removed except to replace the turbine bearing. Being narrow, it can be successfully “dynamically” balanced as it is quite easy to show

Wren Turbines Ltd. MW54 Mk2 & Mk3 Turbo-Jet, kit assembly instructions, Jun 2004
Page 8
the point of in-balance and minimize it using simple procedures as outlined in our “Balancing Instructions” leaflet. By sharing out the correction to each side of
the turbine we achieve a reasonable dynamic balance condition.
The compressor is supplied pre-balanced and the only source of in-balance here is due to the fit of the compressor to the shaft. In order that it is able to slide onto
the shaft it must be bored fractionally larger than the shaft and this looseness is where a potential in-balance at the compressor end occurs. The state of dynamic
balance can be checked for by spinning the rotor assembly (whilst assembled into the engine) to around 15,000rpm and feeling for vibration through the case as
it runs down. Although no figures can be attached to this test it is possible to get a good measure of the state of in-balance. Often, just loosening the compressor
nut and turning the compressor slightly results in a significantly improved balance condition. Conversely, simply loosening the compressor nut on a previously
balanced engine can often throw it out of balance. If an engine is run in a poor state of balance it can ruin both bearings in a matter of minutes.
As balancing is a labour intensive process (and therefore expensive) we have made it possible for you to save money by doing some of the balancing yourself.
To help you choose and to limit the confusion we offer three options in ascending order of cost and descending order of effort for you:
1) You balance the engine at home during assembly, (takes about 3 hours average for good results), no need to return the engine.
2) We balance the turbine wheel on the shaft, at the factory before dispatch of your kit, no need to return the engine, (standard on Mk3 engines).
3) Engine is fully dynamic balanced on compressor and turbine. Engine requires return to factory after test running.
To help you with option 1 we include step-by-step instructions for achieving a good standard of balance sufficient for normal running of the engine that can be
performed at home. This procedure has enabled countless other builders to build and run good engines which run smoothly and quietly. All that is required is a
short length of tube and a hand-held grinder such as the “Dremel” and a 30mm (1-1/4”) grinding disc.
With option 2, for which there is an additional charge for Mk2 kit builders, the turbine is factory balanced on the shaft to a high degree (below 50mg/mm at
balance ring). Due to the need to have the compressor a sliding fit on the shaft there is likely to be a small degree of residual in-balance but in most cases this is
minor. In all cases, balancing will require removal of a small amount of material from the balance rings on the turbine and the front face of the compressor.
With option 3, to which there is an additional charge, you get the best guarantee of perfect balance although is the most inconvenient from the users point of
view as it requires return of the engine to the factory, postage and packaging etc. This option of factory balancing on the complete engine ( full dynamic
balance ) is performed with the engine in assembled and tested form on a special balancing assembly called a dynamic table . This results in the rotor assembly
exhibiting lower than 50mg/mm in-balance on compressor and turbine. Before return for dynamic balancing, the engine should be run at least a couple of times
at moderate speeds to allow components to settle and stresses to be relieved and to ensure correct operation. Note; if subsequent running shows a problem you
may need to strip the engine for investigation and this will affect quality of balance, so you should ensure satisfactory operation before sending the engine for
dynamic balancing. Marking the position of the compressor to the nut may be only partially successful at retaining rotor balance on strip-down.
To review - the quality of balance will be affected if the rotor is disturbed –loosening the compressor nut is sufficient to alter the balance
condition. Therefore do not take apart unless the engine has a mechanical problem or you are replacing the bearings due to normal wear.
Please note that the balancing operation is just that, Wren Turbines cannot perform test running or fault finding on an engine as part of the balancing
operation. Additionally, if bearings have been damaged through excessive running in an out of balance condition then we (Wren Turbines) may be unable to

Wren Turbines Ltd. MW54 Mk2 & Mk3 Turbo-Jet, kit assembly instructions, Jun 2004
Page 9
balance the rotor satisfactorily due to bearing noise. Repair work for bearing replacement and subsequent balancing is charged at our standard rate as shown
on our price listing.
Spares and servicing.
By purchasing a high cost product like a gas turbine in kit form you are able to make a considerable cost saving over a ready-built and tested version, which
reflects the labour expended and warranty issues. Assembling the engine yourself also equips you to tackle servicing or rectification due to crash damage or
similar incident. To help, spare parts for servicing or repairs on your engine such as bearings, exhaust components, pipe-work, cases etc are all readily available at
modest cost and mostly ex-stock, from Wren Turbines. Please note that this saving also recognises that servicing and any fault finding required for your engine is
your responsibility although Wren Turbines can offer verbal assistance where practicable. It is not possible for Wren staff to perform fault-finding and/or test
running of a kit engine unless agreed in advance, where a charge will be made. Please note that if you decide to incorporate your own modifications or
“improvements” to your engine Wren Turbines cannot assume responsibly if it fails to perform as expected or develops faults that may be attributed to such
changes. Wren Turbines cannot accept responsibility for damage or incorrect operation where it is found that non-genuine Wren Turbines parts have been fitted.
Set-up for testing.
Once you have built up your engine we strongly advise that you do not install it straight into a plane or similar
installation without bench testing and confirming the start sequence and normal mode of operation. For such
testing it is useful to assemble the parts you intend to use in your installation, tank, filter system, pump, ECU etc and
connect them all up on the bench.
The engine can be mounted using a suitable mounting system such as the Wren two part mount and secured firmly
into place. All pipe work must be suitable for kerosene and we recommend “Tygon” type soft tubing for tank feed
to pump and 3mm “Festo” type fittings for the pressure side of the pump to the engine. We suggest you use a good
quality felt filter clunk for your pick-up in the tank. Use 4mm pipe work (solid or flexible) to feed from the tank to
your fuel pump. Do not use any other filters or valves in the input side of the pump as we have found they are the
major cause of engine problems with air ingress. It is advised you fit an in-line pressure filter in the line just before
the engine as a “ last chance ”filter. If a fuel shut-off valve is required then install this in the pressure side of the
pump. A version is available from Wren.
Fuel for the engine is clean and filtered Kerosene or Jet A, with a 2.5% (40:1) mix of non-synthetic outboard motor oil to TCW3 spec’, or standard turbine oil such
as Exxon 2380, Aeroshell 500, Mobil JetOil or similar. Starter gas should be propane/butane gas only mix (no dip or slop tube), supplied through an adjustable
control valve and pipe-work able to handle 2Bar (30psi). If you wish to read pressure, then use a “Tee” off the gas line and a gauge reading 2Bar (30psi)
minimum, and pipe-work to match. Please ensure the engine intake is kept well clear of any loose objects. Glow-plug leads, pipe-work, rags, sleeve cuffs and
unfortunately - fingers have all been known to be “hoovered” into the engine so please be especially careful. See the sections at the back of this instruction
booklet for running instructions – and take care!
Layout of instructions.
The order of assembly for this Mk2 kit as shown in the following pages, is the suggested sequence to follow and has been tested for logical flow and ease of
understanding, we would be pleased to receive your comments on this!
IMPORTANT –do the balancing of the rotor FIRST if you have taken this option, as you need to use the bearings. After this the bearings are
not accessible.

Wren Turbines Ltd. MW54 Mk2 & Mk3 Turbo-Jet, kit assembly instructions, Jun 2004
Page 10
MW54 Mk2 Gas Turbine Specifications (no accessories).
Length 136mm o/a (bare engine), 179mm o/a inc’ exhaust cone.
Diameter 89mm
Weight 780gms (1Lb 11-1/2oz)*
Pressure ratio 2.65
Mass flow 0.18kg/sec (23-3/4Lbs/min)
Thrust –55-60N, 12-13Lbs (Mk2) 62-67N, 13.5-15lbs (Mk3)*
Max rpm - 160,000
Idle rpm –40,000
Self sustain rpm - 28,000 *
Max case pressure - 1.65 Bar (24.5psi)*
Idle case pressure - 0.07 Bar (1psi)*
Fuel consumption:*
200ml/min (Mk2) 210ml/min (Mk3) approx @ max thrust
50ml/min @ idle thrust
Fuel - Kerosene or Jet A1 with 2.5% oil (40:1 mix)
Fuel pressure @ max thrust –2.6 Bar (38psi)
Fuel required for average 6-min flight –1200ml (40oz)
Oil mix required - 25ml per 1Ltr fuel, (1oz per 40oz fuel)
Oil - Turbine oil such as “Exxon 2380”, “Aeroshell 500 or 510”, “Mobil JetOil”.
Alternative - TCW3 specification, non-synthetic, outboard motor oil
Average aircraft flying weight –3 - 9kg (7 –20Lbs)
*= Typical engine.

Wren Turbines Ltd. MW54 Mk2 & Mk3 Turbo-Jet, kit assembly instructions, Jun 2004
Page 11
Building the engine –start here :
Step 1. Parts set.
Familiarise yourself with engine parts,
read all steps carefully before starting.
Proceed directly to balancing
booklet if yours is an unbalanced
rotor.
Step 2. Lubrication pipe.
Insert pre-formed lubrication pipe
through the 1.5mm slot.
Step 3. Lubrication pipe.
Insert lube’ pipe connection into
correct hole in Diffuser, and position
feed end at cut-out.
Step 4. Shaft Tunnel.
Insert front bearing this way round
(printed arrow points out).
Step 5. Shaft Tunnel.
Check thick side of inner ring faces out
(other side is thin).
Step 6 Shaft Tunnel.
Fit Shaft Tunnel into rear of Diffuser
and align fixing holes. Note Tunnel is
supplied as a complete assembly.
Step 7. Shaft Seal/Shaft Tunnel.
Align Shaft Seal with groove over
lube’ pipe and place into position.
Secure loosely with six M3 x 10 cap
screws.
Step 8. Shaft Seal/Tunnel.
Loosen each screw in turn by 3 turns,
apply drop of locking compound, and
tighten firmly and evenly.

Wren Turbines Ltd. MW54 Mk2 & Mk3 Turbo-Jet, kit assembly instructions, Jun 2004
Page 12
Step 9. Case Front.
Align Case Front over Diffuser –use
the three large holes to position.
Step 10. Case Front.
Secure with 7 M2.5 x 8mm screws, but
do not tighten up as yet, as we need
to centre the Case Front later.
Step 11. Aligning Case Front.
Insert (balanced) Shaft assembly into
Shaft Tunnel –be extra careful when
easing through front bearing.
Step 12. Aligning Case Front.
Holding the shaft in against the pre-load
spring, insert the front spacer –small
diameter downwards. Do not press hard
as you might “pop” the bearing apart.
Step 13. Aligning Case Front.
Slide on Compressor and secure with
Compressor Nut –note it has a left-
hand thread.
Step 14. .Aligning Case Front.
Fit the Intake Cone onto Case Front,
be careful to align the service cut-outs
correctly.
Step 15. Aligning Case Front.
Secure Intake Cone with the M2.5 x
6mm screws, temporarily.
Step 16. Aligning Case Front.
Place NGV with turbine shroud up,
and gently lower assembly into it –
turbine will rest on rim, not the blades.

Wren Turbines Ltd. MW54 Mk2 & Mk3 Turbo-Jet, kit assembly instructions, Jun 2004
Page 13
Building the engine.
Step 17. Aligning Case Front.
Spin Shaft Tunnel and view gap between
Compressor and Intake –adjust by easing
Case Front across until it is perfectly even,
& tighten the eight M2.5x8 fixing screws.
Check, then remove Intake Cone, Nut,
Compressor, & Spacer, and set aside.
Step 18. Fitting Combustion
Chamber.
Chamber is supplied with fuel and gas
manifolds ready fitted.
Insert one of the 3 off M3x14mm cap
screws through the chamber front, from
the inside.
Step 19. Fitting Chamber stand-offs.
Slip one of the short metal tubes onto
the screw, holding the screw in place
with the hex key.
Step 20. Fitting Chamber stand-offs.
Using a pair of side cutter pliers, crimp
the tube onto the screw to retain it.
Step 21. Fitting Chamber stand-offs.
Crimped tube shown here. Repeat for
remaining two tubes.
Step 22. Fitting Combustion Chamber.
Align and insert fuel and gas fittings to
the holes in rear of diffuser.
Step 23. Fitting Combustion Chamber.
Align the 3 stand-offs to the mounting
holes (bend fuel/gas pipes if needed).
Step 24. Fitting Combustion Chamber.
Screw in and tighten the three stand-
off screws, ensuring the fuel/gas fittings
are pressed fully home.
Do This
Carefully

Wren Turbines Ltd. MW54 Mk2 & Mk3 Turbo-Jet, kit assembly instructions, Jun 2004
Page 14
Step 25. Connecting services.
Fit fibre washers to each of the three
service fittings.
Step 26. Connecting services.
Screw on the three brass service
adapters and tighten gently. Do not fit
the push-on fittings yet.
Step 27. Sealing ring.
Fit the O-ring to the Front Cover, be
careful not to damage the section on
the sharp groove edges.
Step 28. Fitting Nozzle Guide Vane.
The NGV can now be eased onto the
end of the Shaft Tunnel and
Combustion Chamber.
Step 29. Preparing to fit case.
Apply a small smear of silicon grease
or petroleum jelly to the O-ring to
help it slide into the Outer Case.
Step 30. Making up Mk2 Outer
Case.
Find the “WREN” mark on the case –
this indicates front-end, top . Now
rotate it 180’ and locate the hole at
the bottom of the rear-end (the hole
by the seam).
Step 31. Making up Mk2 Case.
Insert the Case Rear at a slight
inward angle. Align at the point
where case and NGV holes come
together.
Step 32. Making up Mk2 Case.
Screw in about four turns, one M2.5 x
5mm screw into this hole to act as a
peg (locate in centre, as hole is oval).

Wren Turbines Ltd. MW54 Mk2 & Mk3 Turbo-Jet, kit assembly instructions, Jun 2004
Page 15
Step 33. Assembling Mk2 case
Rest assembly on flat surface and
using a block of wood or metal drift,
tap Case Rear into place, level with
end of case.
Step 34. Assembling Mk2 case.
Check the Case Rear is exactly flush
with the end of the case, using a
metal rule or straight edge.
Step 35. Assembling Mk2 case.
Fit the remaining 5 screws, thread-
locking them all into place by
loosening each in turn, as before.
Step 36. Sealing Mk2 Case Rear.
Seal in place with a small fillet of high
temperature sealing compound (Holts
“Firegum” shown here).
Step 37. Sealing Mk2 case seam.
Finally, finish off with a light smear
along the welded seam inside the
case.
Step 38.Fitting Mk2 case.
Align the two glowplug holes with
those on the Combustion Chamber
and gently slide case on.
Step 39. Fitting Outer Case.
Holding the engine as above, gently
ease the case into position, being
carefully not to nip fingers or O-ring.
Step 40. Fitting Outer Case.
Gently pull the NGV outwards and
press/turn it to align with the eight
screw holes.

Wren Turbines Ltd. MW54 Mk2 & Mk3 Turbo-Jet, kit assembly instructions, Jun 2004
Page 16
Step 41. Fitting Outer Case Mk2.
After aligning the NGV, fit the eight
M3x4 screws and tighten evenly.
Step 42. Fitting Outer Case Mk2.
Confirm the glow plug holes are
correctly positioned. Make small
adjustments as required.
Step 43. Fitting Outer Case Mk2.
The six M2.5 x 5 screws can now be
fitted to secure the front of the case.
Step 44. Fitting Outer Case –Mk3.
The Mk3 case is installed in the same
way, after carefully pressing on, pull
NGV into position and secure with
eight M3 x 4 screws, as before.
Step 45. Fitting Outer Case Mk3.
Fit the six Outer Case securing screws
once NGV has been secured.
Step 46.Preparing the glow
element.
Prepare the glow plug by carefully teasing
out plug element with a pin. Make the
bend gently to not break the fine wire.
Step 47. Fitting Glow Plug.
Fit the glow plug(s) and tighten
firmly. The copper washer is not
required and can be left out.
Step 48.Fitting Service Connections.
The main assembly is complete, we
can fit the quick release fittings and
tighten gently –note placing.

Wren Turbines Ltd. MW54 Mk2 & Mk3 Turbo-Jet, kit assembly instructions, Jun 2004
Page 17
Assembling the engine.
Step 49. Re-fitting rotor assembly.
Carefully insert the turbine rotor into the
casing and fit Front Spacer, Compressor and
Compressor Nut and tighten firmly. Torque
setting for Compressor Nut is 6Nm or
54lb/ins if torque wrench available.
Step 50. Fitting Intake.
Position Intake over compressor and align
cut-outs for service connectors. Secure with
four M2.5 x 6 screws (see next step) –use
locking fluid to retain.
Step 51. Fitting Intake.
Leave the top two fixing holes vacant –
this is to allow fitting of the RPM pickup.
Pic’ shows earlier style of connectors.
Step 52. Prepping the RPM sensor.
Press the brass tube spaces into the
rubber grommets on the sensor. Wire
should protrude at r/h side.
Step 53. Fitting RPM sensor.
Fit the RPM sensor to the two vacant
holes above the Inlet using the two
M2.5 x 20mm cap screws.
Step 54. Fitting lube’ feed pipe.
The Lube’ feed pipe is connected between
the tee and angle fittings, above the
Intake. Ensure pipe is pushed fully home
to seal properly.
Step 55. Fitting Exhaust Cone, Mk2 & 3.
Remove four of the M3 x 4 NGV fixing
screws, as shown above.
Step 56. Fitting Exhaust Cone (Mk2).
Fit the Exhaust Cone, positioning the
temp’probe hole at 4 O’clock. Refit the
four M3 x 4mm screws.
(Not Used)

Wren Turbines Ltd. MW54 Mk2 & Mk3 Turbo-Jet, kit assembly instructions, Jun 2004
Page 18
Assembling the Engine
Step 57. Fitting Exhaust Cone (Mk3).
Fit the Exhaust Cone, positioning the
temp’ probe hole in the 4 O’clock position.
Refit the four M3 x 4mm screws.
The Mk3 engine complete ready for
mounting and test running. Additional
accessories can also be fitted -
Pod style on-board starter and cowl
for the MW54. Suits direct switching
(7.2V) or Autostart ECU operation.
Motor is 280BB with Wren miniature
clutch.
Step 58. Assembling pod starter.
Solder suppressor capacitors to the
motor brush terminals –one each 47nF
from brush to case and one 100nF brush
to brush.
Step 59. Wiring pod starter.
Thread starter wire through cap and
solder to terminals –check polarity is
correct using battery.
Step 60. Fit starter pod to cowl.
Align pod legs to cowl and insert 3 off
M2.5 x 5 screws, using locking fluid to
secure.
Step 61. Fitting cowling.
Fit grommet to hole and thread rpm
sensor cable, fuel and gas pipes (and
pressure pipe if fitted).
Step 62. Fitting cowling.
Remove the six Case fixing screws and
ease cowl into place. Refit the fixing
screws and tighten.

Wren Turbines Ltd. MW54 Mk2 & Mk3 Turbo-Jet, kit assembly instructions, Jun 2004
Page 19
Step 63. Fitting pod starter.
Slide motor into place fully and pull
back approx 1mm. Nip into place by
tightening M2.5 cap screw.
Step 64. Fitting pod starter.
Check operation be connecting switch
start lead and battery. Action should
be clean and “snappy”. Ease pod
position if clutch sticks at all.
Step 65. Completing pod starter.
Once correct operation is confirmed,
the black cap can be eased into place.
A filter screen cover can also be fitted to
engine. Provides mounting for on-board
starter. Suits direct switching (7.2V) or
Autostart ECU. Pipes exit at bottom. Fit
as for pod starter.
Not Used
Not Used
Not Used
Not Used

Wren Turbines Ltd. MW54 Mk2 & Mk3 Turbo-Jet, kit assembly instructions, Jun 2004
Page 20
Set-up for bench-test running
With Fadec ECO ECU and hand starter.
For engine bench-testing secure the engine to an
engine mount*screwed to a firm base.
Attach thermocouple probe to engine and insert end
4mm into exhaust. Secure body with clip provided.
Connect thermocouple and rpm sensor to the ECU.
Connect fuel pump and ecu battery (4-cells) and the
starter gas supply via a quick-acting valve*to the gas
supply port on the engine. Connect ECU signal lead to
receiver and set-up radio as described in next section.
Secure fuel tank and connect to fuel pump. A fuel
on/off valve may be connected in the fuel pressure
line.
The ECU readout should also be secured –sticky pads
are suitable for quick testing. Once secured it can be
plugged in and you are ready.
Connect a 6-cell charged nicad to the hand starter
and spin the engine and check the rpm reads on the
display.
Note, picture shows Mk2 version, Mk3 version uses
same setup and range of accessories.
NB. *Indicates accessories available from Wren Turbines Ltd.
Fuel Pump
ECU
Starter wand
Fuel in
from tank
Gas valve
ECU Display