To begin with, I am in no way to be confused with an engine guru, expert or otherwise well above the rank and file of model engine users. I have however built and flown lots of control line models over the years.
I purchased the J'en from Just engines because I always wanted to have an engine box with my last name so properly exposed. (My real last name is Just)

I am impressed with he quality of the engine, the colour and the finish. I mounted a control line venturi and needle valve assembly that I have been promoting here in the US, fitted one extra shim (JE provide 2 extra shims with stunt engine), mounted the engine in a solid test stand and filled the tank with a popular 10% fuel with 22% oil, half and half castor / synthetic.

My experience and thoughts

I mounted a 10 x 4 Zinger prop, primed the engine and then proceeded to use my regular
2 minute run, cool down time, 2 minute run. I ran the engine at a high rpm, about 12k on my tack until about 20 minutes of running had taken place. I then removed the engine and took it apart and found absolutely no wear. Reassembling the engine i then mounted an APC 11 x 4 and using the same fuel ran another 24 oz of fuel through it, maintaining a steady 10,300 rpm. Each time i was able to start the engine with just a flick or two, with the engine being either hot or cool.

I mounted the engine in a modified Twister, it's fittings for a Leo .37 I previously used with the model. I use a 4 0z Sullivan tank with muffler pressure, removing the fuel line at the
engine to fill the tank.

It exceeds my needs very well! Powerful when needed as in the overhead manoeuvres, yet docile in level flight. I had set the engine on the ground at 10,300. I have only flown
the combination twice but am very pleased.

My only negative report is that I think one needs to use a lighter muffler (silencer) than the one I received with the engine. (JE note - now supplied to Joe and with engine to future customers)
I plan on using one from another engine, and while it may be louder it will be a bit
lighter and thus closer to the balance point I prefer.

I also believe the Jen .37 could be an excellent profile carrier engine and may set one up as such in the near future. That portion of the control line hobby is in dire need of an introductory engine.

Joe Just
June 2005

Pictured are Joe (1st picture) and his grandson Logan (2nd picture).

Just Engines Online | Engine Reviews & Comments | J'EN Reviews | JEN .37 A Stunt Version Report