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General control line discussion => Open Forum => Topic started by: Bootlegger on September 11, 2007, 11:16:19 AM
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:! Guy's Yesterday I was runnin' my RO Jett 40 rear exhaust with a 11.5x4 APC prop on 10% 11&11 oil and started with 5 oz of fuel. Timed it at better than 9 minutes, cut to 4 1/2 oz same fuel got over 8 min then 4 1/4 ox got over 7 min.
Is this normal ? The engine is broken, or has about 1 hr to 1.5 hr on the bench.
I am not complaining, but I sure am curious.???
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Thats not far off my own experience with the BSE 40 on a header muffler in my old Vector40. I ran with a filter on mine also. It would burn more if the venturi was opened up.
I ran my mostly 4 stroking along and breaking nicely into a two stroke up high. 10% was used when it got hot only--most of the time it was 5%.
For high density altitute days, try an apc 11 x 5. It seems to give alot of bite in the hot humid days. (Thanks to Dave Hemstraught)
Curt
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Kurt,
Thanks for the response. I failed to say that I'm running a muffler instead of a pipe,and that the tach was showing in the range of 9300--9550 rpm.
It still has the break in plug so that will be changed to a T bolt lont w/idle bar when it goes in the model.
I also don't run with muffler pressure instead open to the atmosphere on the vent.
I'm looking forward to getting it installed in the new model.
Again thanks for the info #^
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Wish my Ton Lay OS46VF had that kind of gas milage. I had to put a "wart" on the front of the tank to extend the capacity to a bit over 7oz to have enough fuel to finish the pattern. This with a .270 venturi. Man, what does Tommy do to these things? Sure has plenty of power. That's certain. I can tell you I was pretty shocked when I filled the tank (6.5oz capacity) and ran out of fuel in the overheads. Yeow!
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What about restricting the venturi by about .010 and see what it does for power and milage ?? Might help both ... H^^
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With the four pitch prop, you might need to run it a bit faster RPM in a plane so that will get you down a little on fuel.
Mine was the small insert muffler put into the end of the header--simple and effective.
And the engine will continue to get better as it fully seats in--perhaps over a couple of hundred flights.
Randy: Wow! 7 oz!! Well, around here we say that fuel burned is horsepower made. One of our group just put a 9 oz tank into his PA75 setup.
Curt