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bob27s -> RE: Q-500 Engine (3/1/2005 2:41:40 PM)
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Get me a picture of it if you can. I will ask Dub about the combination since you got it from him.
If you bought it with the sidewinder, Dub likely sold it to you with a Sport Jett 50 or SS 40 engine. Since it does not have a Nelson plug, it is not a 428 or 422 racing engine. So its a bit different that what I described previously.
Does the engine have the red carb and throttle ? Does it have the RED muffler on it or a black muffler ?? If it is red, does the muffler have a hump in the middle of it or is the red part straight ?
Chances are the engine is a standard SJ-46 or SJ-50. In which case, that 18K rpm you saw was correct. The sport engines have a longer muffler tuned for the 15,500 to 18,500 range , which tends to peak tune between 17,500 and 18,000 rpm on the ground. The muffler not only boost performance, but it can also work as an RPM governer.
For a SJ-50 engine, you want to prop it to run just over 17.5K rpm on the ground, and launch it around 17K even. Typically, the engine will turn welll up into the 18K range in the air when it unloads. Props to get you here are the 8.8x8.75, 8.75x9W, and you can also try the heavier 8.8x9.25. Another prop to try on a QM application is the APC D-1 series 8.5x7.25 and 8.5x7.5 props. These will turn up well over 19K, closer to 20K on that same engine/muffler. Kinda hits a second note on the muffler. Find peak, back off 500-600 rpm, fly it.
Let me know on the engine configuration
Bob
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