3W 157xi B2 Manual de usuario
ENGINE MANUAL
3W 157xi B2 / TS / CS
www.3w-modellmotoren.com
3W 157xi B2 / TS / CS Engine Manual
more infos: www.3w-modellmotoren.de
Dear customer,
Thank you for placing your confidence in 3W. Our long experience (since 1985) in designing and
producing model airplane engines, ranging from single up to six cylinder, has been utilized to
provide you with the best engine possible. Our in-house engineer has been designing two and
four stroke engines for gasoline and diesel for 38 years. We are continually looking at new
technologies and working on new designs. Please be assured that we at 3W always strive to
provide you with engines that are state of the art.
You can count on your 3W engine to have:
• a high level of precision
• high torque in the low rpm range
• excellent running characteristics
•a long life
• lots of power
•And a 36 month conditional warranty.
We wish you plenty of fun and success with your new 3W engine.
Sincerely,
The 3W Team
Limited Warranty
We grant a 36 month warranty from the date of purchase.This warranty is limited to the replacement
of defective parts that are a direct result of faulty material or manufacturing. No claim concerning
a defect caused by non-compliance with installation or operation instructions, mishandling,
unsuitable spare parts nor unskilled repairs will be acknowledged. Please ask your dealer to fill
out a warranty certificate for you at the time of purchase. Important: Keep this certificate in a safe
place as this warranty will not be honored without it. The original receipt is also required.
The safe operation of the engine is our primary concern. Therefore any alteration, modification
or addition to the engine is not recommended and will void your warranty immediately.
In case of defect during the period of garantee, return this product to your nearest 3W-Dealer or to 3W -Germany
direct, at your costs. The garantee is limited to the value of the product. The guarantee does not cover any damage
caused by misuse or neglect, accidents, abrasion, exposure to extreme temperatures, solvents, acids, water, normal
wear and tear or damage by common carrier. Warning!
This engine is not a toy! Serious injury and /or death can occur from its misuse! READ and
become familiar with this entire instruction manual. LEARN the engine's applications,
limitations, and possible hazards.
When working on the engine(s) it is strictly prohibited to block the piston respectivly
crankshaft from moving by using a tool touching / hitting the piston crown / top.
Reason:
Distortion of the crown / top where the tool touches / hits the piston, material structure will be
changed as well as the outside diameter / conture of the piston.
What could happen:
Hole in the piston and / or piston will size after a running time which cannot be determind.
To block the crankshaft and / or piston from moving a tool has to be used clamping the propeller
hub only.
3W 157xi B2 / TS / CS Engine Manual
more infos: www.3w-modellmotoren.de
3W 157xi B2 / TS / CS Engine Manual
more infos: www.3w-modellmotoren.de
Important!
For your safety and for the safety of those around you -- also to learn what is required to maintain your warranty -
we strongly advise you to read this entire manual carefully BEFORE you start using the engine.
Safe Operation and 3W's Conditional Warranty
For safe operation and to maintain your warranty you must:
•Have a properly designed engine box on your model
•Mount the engine correctly
•Provide adequate air flow and cooling for the engine
•Provide adequate air flow and cooling for the exhaust
•Use an approved propeller and spinner
•Drill the propeller correctly
•Balance the propeller correctly
•Tighten the propeller bolts correctly and check them regularly
•Properly mount your ignition to avoid overheating
•Use the correct battery and regulator (if applicable) for your ignition
•Use the correct switch for your ignition
•Use an appropriate fuel tank, plumbing lines, and installation
•Use the appropriate fuel for break in and after break in (gas and oil)
•Insure adequate filtering of your fuel
•Maintain your engine properly, keeping it clean, etc.
•Use a pre-flight check list before flying your model
•Secure your model properly when starting
• Not use your fingers or hand to start your model
•Adjust your carburetor correctly
•Not adjust your carburetor while the engine is running
•Insure that your spark plug is in good condition and is secured correctly
•Insure that your ignition wires are not frayed and are protected
•Insure that your ignition cap is securely mounted
• Keep all people behind the line of the prop
•Do not put anything (i.e., fingers, body parts, objects, et al) into the rotating propeller
•Keep children away. All spectators should be kept a safe distance away from the running engine.
•Wear proper apparel. Do not wear loose clothing, gloves, neckties, jewelry, or neck straps for your radio
which may get caught in the moving propeller.
•Always wear eye protection when starting the engine.
•Do not operate this engine if you are under the influence of any drugs, alcohol or medication that could affect
your ability to use the engine properly.
Disclaimer
We cannot control how safely our products will be used. And, therefore we do not accept any responsibility for
damage, or injury from their usage.
3W 157xi B2 / TS / CS Engine Manual
more infos: www.3w-modellmotoren.de
Engine Installation
The engine should be mounted on a motor box that will in turn mount to the fuselage.Aquadrilateral
shape (gradually increasing in size as it goes away from the motor) provides the best circulation
of air. The reason for using a motor box rather than mounting the engine directly to the fuselage
is that the cylinder(s) need enough room around them to provide proper airflow over and away
from them
The motor box should be stiff enough to prevent engine vibration and it should also have a solid
firewall. The firewall of the motor box should be made from 1/4" aircraft plywood for engines up
to 106cc, or 3/8" aircraft plywood for engines in the 150cc class. For builders experienced with
making composite motor boxes; a comparable strength should be attained.
It is absolutely vital to ensure a tension free mounting of the engine. The surface that the engine
is mounted on must be on an even plane (i.e., a flat and level surface) so that there is no strain
on the engine itself.Again, this is a vital and critical requirement to avoid distorting the crank case,
ruining the engine, and voiding your warranty.
Mount the engine to the motor box with high tensile bolts. Once mounted you now have a sub-
assembly that you can mount to your fuselage. Spacers can be made from hardwood dowels (3/4"
to 1") or machined aluminum bar stock to adjust your down and side thrust. These spacers should
go between the motor box and fuselage and not the motor box and engine.
3W 157xi B2 / TS / CS Engine Manual
more infos: www.3w-modellmotoren.de
It is strictly prohibited:
To mount the engine directly onto spacers for the following reasons:
a. If the spacers are too long and/or not stiff enough the engine could vibrate leading
to the crankshaft starting to twist, further leading to the crank case being destroyed.
b. If spacers are used to adjust the side and/or down thrust and this spacing no longer
provides an even plane (i.e., a flat and level surface) the crank case will be distorted,
leading to the crankshaft starting to twist, further leading to the crank case being
destroyed.
To mount the engine directly onto a large (wide) former or firewall for the following reason:
a. If the cylinder(s) is/are too close to this wide former or firewall, the floating air cannot
pass freely over and then away from the cylinder(s). Cavitating hot air can/will overheat
the engine.
Engine Cooling
A proper cooling system is vital for any engine. An air cooled engine requires an appropriately
sized air intake.Also to keep this air cooling process working the incoming air must be exhausted.
Further, the exhaust air outlet should be four times (4X) the size of the cool air intake.
Example:
•10 square inches of air intake area would require
•40 square inches of exhaust air outlet area
It is up to you to insure that the air flows freely to, over, and away from, the hot cylinder(s) and
muffler(s). Please refer to Engine Installation for motor box considerations, and to the following
tips on baffling.
Baffling
Deflecting of the air (baffling) to and over the cylinder(s) is highly recommended for engine cooling.
The idea is to get all of the cool air that is coming through the air intake opening(s) to hit the middle
of the cylinder(s) directly, and then be forced over the cylinder(s), creating turbulent air moving
3W 157xi B2 / TS / CS Engine Manual
more infos: www.3w-modellmotoren.de
through the cylinder(s) fins. The freely flowing, but directed and turbulent air between the fins
provides the maximum cooling for an air cooled engine. Without baffling (meaning wood or
composite dampers that direct the airflow) the air will take the path of least resistance. Some
incoming air will bounce off the cylinder(s) and the rest will escape around the cylinder(s) without
coming into contact with the cylinder(s).
Engine in pusher operation:
Important note! When engines are used operating in pusher configuration cooling gets critical and
special attention has to be given to an effective cooling method. A good cooling system layout
depends on the actual location (position) of the engine in the fuselage.
Operating temperature
The normal operating temperature range for your engine is 176-212 Fahrenheit (80-100 Celsius).
If the temperature of the engine rises above 230 degrees Fahrenheit the engine is in an overheated
condition where sealed ball bearings and needle bearings could be damaged. Further, you risk
an elongation of the heated engine parts, and / or having an oil film build up, which could lead to
a seized piston or pistons. Following the instructions and recommendations in this manual will
keep the engine operating comfortably within the normal temperature range.
Rear induction
Carburetors, whether front or rear, require a steady supply of fresh air. The best way to supply
air to a rear carburetor is by installing an air scoop. Some have thought to drill holes into the
fuselage near the carburetor area rather than creating an air scoop for the carburetor. This does
not work, it fact it will create a vacuum effect that will draw the air away from the carburetor!Again,
you should install an air scoop into the front of the plane which will supply air into the fuselage.
This air will then need to flow out of the fuselage. Drill exit holes into the rear area of the fuselage
for this purpose. Important: The interior of the fuselage must be sealed to prevent damage from
gasoline that sprays from the carburetor. Use a thin epoxy or other appropriate fuel proofing
method. Do not overlook this step as gasoline will melt some materials like Styrofoam very quickly.
3W 157xi B2 / TS / CS Engine Manual
more infos: www.3w-modellmotoren.de
Ignition
Consideration needs to be given to the placement of the electronic ignition module. Avoid placing
the module in the path of hot air. Mount the ignition module using the four supplied rubber grommets
so as to create a 1/16" gap between the ignition module and the mounting surface. Without this
1/16" gap the ignition module can overheat. Important: If the electronic ignition overheats it will
malfunction (e.g., backfiring or shutting down).
Ignition details:
• The red cable is positive (+)
• The ignition timing has been set at our factory
• When fitting a new ignition it is important to achieve the correct coordination of the sensor(s)
to the magnets
Refer to our special ignition description for further information
Canister mufflers
To prevent damage to the header(s) a flexible support bracket is required to mount the canister(s).
The location for this bracket should be at the canister's center of gravity. 3W canisters have a
reinforcement ring at this location.
We suggest creating two compartments in the front section of the fuselage by installing a horizontal
3W 157xi B2 / TS / CS Engine Manual
more infos: www.3w-modellmotoren.de
tray. Fuel tanks, batteries, and other equipment can be mounted on top of this tray; the canister(s)
being installed below it. Close off the lower compartment at its rear with an angled former. Locate
this former 1" behind the back of the canister(s). Next cut a hole in the bottom of the fuselage just
under the rear of the canister(s). In this way the air coming from the front of the model can flow
over the canister(s) and then be deflected by the angled former so as to exit through the hole in
the fuselage. Do not forget to reinforce around this hole.
Important:
This exit area needs to be four times (4x) as large as the intake area.
Propellers
•Only use propeller brands and sizes that are approved for your engine
•The propeller blades must be of the same length
•The propeller must be flat (You can check for flatness by putting the propeller on a level
surface. The maximum difference of the blade heights should be no more than 1/64".)
•The propeller tips must have an identical shape. This is especially important when using
3 or 4 blade propellers.
•You must use a drill press to drill your propeller.
•You must drill the propeller from the rear.
•A drill guide is recommended, but the propeller washer can be used as a drill template. (Fix
the propeller washer onto the propeller in the center-bore using a bolt and nut. Drill one
hole; put one of the propeller bolts into the hole. Continue until the last bolt is used.)
•If you cannot hand tighten all of your prop bolts easily then you have not drilled the propeller
correctly. This can lead to sheared propeller bolts.
•Balancing your propeller is absolutely critical to the health of your engine. You must keep
your propeller balanced. (Propeller balancers are available from DUBRO, and others.)
•Always remember that when the engine is running every person must stay behind the line
of the rotating propeller; never to the side or the front!
Carburetor settings
Before each engine is shipped it has to pass QC and is then test run. We do a basic adjustment
of the carburetor needles at that point.
highspeed needle H: 3/4
3W 157xi B2 / TS / CS Engine Manual
more infos: www.3w-modellmotoren.de
low speed needle L: 1 3/4
Important: Do not remove the carburetor spring as the spring helps keep the carburetor butterfly
aligned properly. Merely release the ends of the spring so that it no longer holds the butterfly
closed.
Carburetor Linkage
Included with your engine is a metal bracket to extent your carburetor pushrod horn. Fix this
bracket onto the carburetor horn with a 2.6m machine screw and nut. Then solder the arm in place.
Refer to the attached illustration.
Note: The use of a soft pushrod for the throttle (plastic or nyrod) is not recommended. Use a metal
or carbon fiber pushrod with a plastic ball joint or plastic clevis at each end. This will keep your
RPM much more consistent and accurate around idle where it really counts.
Engine Break In
•Use a 2-stroke petroleum based oil (preferably ashless) as this type of oil has a good
honing effect which helps to break in the engine
•Use a mixture of 32-1 or even 30-1
•Use this fuel mixture for approximately 2-3 hours of run time
•Use a high Octane unleaded fuel (98 Octane is ideal)
Este manual sirve para los siguientes modelos
2
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