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bob27s -> sport jett? (2/3/2003 10:15:56 PM)
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Hi,
Thank you for writing.
Sport Jett engines are some of the most user-friendly engines you will find anywhere. They are indeed based on our expereince with racing engines, but designed purposely for sport use, featuring our famous Red-Jett carburator. They run no differnt than what you are currently use, and are used in many sport and scale applications around the world. Each engine is test run before shipment, and the low speed needle is pre-set at that time. After user break-in, the engine will scream on top end, and reliably tick over at idle.
The Q-500 and QM engines are actually no different to operate. They simply require the correct prop selection to allow then to run at their designed RPM, then a careful operator to set the top end mixture slightly rich.
The only difference between what you may be use to, is that you must prop the engine to run within the rpm range the engine/muffler are design for. This is quite easy to do, and we specify our 'baseline' prop and rpm along with the engine description on the web site. For the SJ-50, for example, any prop that will allow the engine to turn between 16,000 and 18,000 rpm on the ground will work well. As with the racing engines, your best bet it to briefly find peak RPM with your desired prop, then set the ground RPM down from that about 500 rpm. It will unload pleanty in the air. Don't get it lean, and it will serve you well for a very long time.
When combined with the Turbo-Jett in-cowl muffler, the SJ-50 rpm range is a bit broader, as is the chocie of prop for the application.
For reference, I fly a SJ-46 and turbo-jett combination in my P-51 mustang. I have it set up with a remote needle, and running a 12x4 prop. It turns the 12x4 prop just a tad over 15K rpm. Excellent performance at any throttle setting (infact, I rarely fly this thing full throttle... other than in vertical)
Having said that, let me make the following recommendation. I'm a bit behind on getting the website info up to date, so this is will likely be new information for you.
Jett now offers two new engines developed especially for the "40" size fun-fly and 3D application. The .60L or the .65L are both in a .40 size case. Available in either the cast case or the BSE case.
You use a non tuned muffler, but get the advantage of haveing all that displacement crammed into the small package. Jett offers a new muffler too, currently called the Lite-Jett that weights only 1.3OZ, making the total package weight a mere 15 oz for the .65L BSE and a little lighter for the .65L cast case.
Price of the engines are $275 for the .60L and $295 for the .65L. BSE is 40.00 more.
If you have an in-cowl application, you can use the Turbo-Jett muffler for compact installation, and superior operation.
The engines have full-linear throttle response, and no "on-the-pipe" transition. They are designed from the ground up as 3D and fun-fly type engines.
You can contact Dub directly at [email]jett@jettengineering.com[/email] if you wish some more performance data on the new engines.
I hope this is helpful.
Bob Brassell
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