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Engine basics => Engine set up tips => Topic started by: John Leidle on November 21, 2011, 04:58:28 PM
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I have an ongoing situation with my PA .65 RE I realease it & the thing takes maybe 3 laps & it has increased engine speed a lot I have a .192 venturi in it the head is pinched down a bit , the pipe is a Randy pipe .65 Ultra Torqure from 2000 13-4.25 Eather Wide blade .Any ideas how much pulling the pipe out will make or not? The pipe is set a 17.6".
John
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I have an ongoing situation with my PA .65 RE I realease it & the thing takes maybe 3 laps & it has increased engine speed a lot I have a .192 venturi in it the head is pinched down a bit , the pipe is a Randy pipe .65 Ultra Torqure from 2000 13-4.25 Eather Wide blade .Any ideas how much pulling the pipe out will make or not? The pipe is set a 17.6".
John
What RPMs , fuel, etc?
Randy
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hi Randy,
I normally set it for a ground release in the lower to mid 9s 9200 to 9700 ground release it does it with the thinner props at a higher rpm also say 10,100 the fuels are Sig Champion fuel 10% , GMA 10/22 , ROjett 10% all synthetic, Byrons 10% all synthetic I add Areo 1 & 2 ounces of castor in the all syn fuels. I thought I read sopmeplace if you shorten the pipe & pull the pipe out you get a certain effect to prevent speeding up oe slowing down during the flight.
John
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Hi John
With the wide blade E prop I would use more the 18 to 18.5 inch pipe lenghts, I think you will find that to needle better and run more consistant,
Also if you are having to lean the engine out more on the ground and get a lot of richness after you launch, then I would suggest reducing load from the prop ie trim some diameter or thin the aspect ratio of the blade
Let me know how this works when you move the pipe
Randy
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Thanks Randy, I looked into my box of PA papers & it said " Engine speeds up during flight? Pull pipe out.
Thank you, John
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Randy,
I had decreased the venturi a bit & it behaved better but still sped up from laps of 5.2 to 4.9 or even faster I guess the increased speed is ok because the vertical manuvers are in the latter part of the list , but I like consistancy & control. I did what you said & pulled the pipe out an inch or better to 18.5"
now it holds a needle at 5.3 to 5.25 or so pretty good .It feels like it's down a shade on power but,,,,,
Thanks Randy, John
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I had a similar problem with a Ro-Jett 50. Increased pipe length helped but what cured it was going to a smaller diameter prop as Randy suggested. I'd give that a try especially if you are running an undercambered prop. They can really put a load on an engine. 8)
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I'm running a big boy prop its an Eather 14-4.5 cut to 13" but the plane is big too its a Magnum plus at 75 ounces. I will spend time fiddleing with it .
Thanks, John