Question:  Hello, I recently purchased at Hangar 9 Jackal.  This is a prop driven jet airplane.  I'm going looking at getting the Novarossi R91CF motor to power the plane and wondering if you feel this is a good choice in motors.  Can you also give me some information on the break-in procedure for these engines?  What glow plug would I need for the motor? Also, what propeller would you recommend for this setup to get top speed out of the plane?  I can only fit an 11 inch prop on the jet due to ground clearance.  What size 11 inch prop would be best for top speed?  Is an 11 prop too small for this engine?  Thank you for the help.  

Answer:  Thank you for writing to us.  Let me see if I can answer all of your questions about the Novarossi motors, plugs, prop's and fuel needs to get the best performance out of your model and engine.

On the glow plug, Planethobby.com has all the Novarossi glowplugs in stock.  The C6S is the standard replacement plug.  However we stock many other heat range plugs that are useful for matching plug to nitro content and weather conditions for your given area of the country and altitude.  

On breaking in the motor. The first tank of gas should be run with the engine rich and at slow idle to break in all the moving parts. After that, the engine should run at faster speeds to finalize the piston and sleeve fit. 

 We like to run the engine at top speed for a few minutes and then reduce the speed to a midrange setting for a few minutes and repeat the process perhaps with several tanks of gas. During this process the engine is slightly rich to insure adequate lubrication. Props that don't overload are good because the engine needs to run at higher RPM's for the break in process to be completed. 

This process varies the heat range that the piston and sleeve see and helps finish the final piston and sleeve fit. There are lots of methods on breaking in engines. These are a few of the principles that can be applied in a number of ways and achieve similar results. 

On fuel, any brand works as long as it is fresh and kept tightly sealed to prevent moisture in the fuel.

18-20% oil with a half synthetic and half castor blend

10% nitro is a good choice

Methanol balance

Sometimes fuel additives are added

Any quality brand with these specs should work well. 

Keep the fuel tightly sealed and in a low moisture environment. Use a good after run oil to keep the engine from rusting. Fuel components attract water from the air. 

On the prop sizing questions.  Since you are limited to 11 diameter we suggest a pitch of 10 inch or greater. APC makes props up to 14" pitch.   The more pitch the greater the potential for more speed.  Recommend pitch sizes that do not overload the engine and create too much heat, especially through the break in process.  The 11 inch is not too small for the motor to handle, however it possibly would effect flight characteristics.

These are strong and powerful engines. You won't have problems with just a few precautions.