Engine Cooling Requirements; Propeller Selection; Fuel Selection; Engine Break-In Process - Zenoah ZENEP20 Mode D'emploi

ENGINE COOLING rEqUIrEMENTS

It is very important to consider adequate cooling inside the airplane cowl. Engines require a cooling airflow
exhaust:intake ratio of 3:1 to 5:1. A large open cowl may lead you to believe there is adequate cooling;
however, you must make sure air is flowing through the cowl and the cylinder head fins. Achieving the
proper ratio typically requires either enlarging the air exit or cowl and/or engine baffles to reduce the open
intake area.
1. Ensure there is adequate cooling air moving through the cylinder head cooling fins. The intake air tends to
move through the path of least resistance instead of through the cylinder cooling fins.
2. If necessary, add baffles to the engine to direct air flow through the cylinder head fins. Engine baffles force
cool air through the cooling fins and greatly reduce the intake area in the front of the cowl.
3. Add cooling baffles to the engine cowl between the top of the cylinder heads and the inside of the cowl.

PrOPELLEr SELECTION

Propeller selection is critical for proper engine operation. You can find recommended propellers and operating
RPM ranges in the specification chart. To get the most usuable power for normal everyday operations out
of your engine, you should select a propeller that achieves an rpm on the ground, which is just before the
rpm where the peak torque occurs for the engine (refer to the torque chart for each engine to determine this
value).
To increase climbing and acceleration: Increase propeller diameter and decrease blade pitch.
To increase top speed: Decrease propeller diameter and increase blade pitch.
Make sure the propeller is securely mounted to the crankshaft before attempting to start the engine.
1. Remove the propeller washer, nut or bolt(s) from the propeller hub.
2. For best results, when using the ZP 38/82/80T engines, use the propeller drill guide available from ZP
engines to drill the propeller mounting holes. Accuracy cannot be assured if you only use just the propeller
washer. We suggest the use of a drill press instead of a handheld drill motor for this process.
3. Install the propeller on the crankshaft.
4. Install the propeller washer, nut or bolt(s). We recommend using threadlock on the propeller screws to
prevent them from vibrating loose.
WARNING: NEVER start the engine without securely fastening the propeller nut or bolts. Doing so
may result in serious injury, as the propeller may become loose once the engine is started.

fUEL SELECTION

gasoline:2-stroke oil

ENGINE brEAk-IN PrOCESS

A good break-in process is essential to the longevity and performance of your ZP gasoline engine. You can
complete the break-in process by either mounting the engine on a test stand or on an airframe. If you choose
to mount the engine on an airframe, remove the cowl during break-in to ensure adequate cooling.
Specific fuel is required for the break-in process. Please refer to the chart above for the proper fuel. Break-in
fuel contains additional oil compared to fuel you will use for everyday flying. The additional oil is critical for
cooling and removing break-in debris from the engine.
Run the engine through four tanks of fuel (32 oz/1000mL) for 3–4 minutes at a time, allowing the engine to
cool between runs. Vary the throttle between idle and ¾ throttle for the first 30 minutes of engine run time.
Do not exceed ¾ throttle during the break-in. The engine break-in process is complete after the first four
tanks of fuel and you can begin tuning the engine for normal flying.
Break-in Fuel
25:1
5
Normal Flying Fuel
32–40:1
EN