Pipe/manifold length on the West Eurotech 50 V1
Hi!
I have been sneak peeked ("tjyvkollat" in Swedish) on this forum for a long time now but this will be my first topic.
I purchased a MagnumR with the West 50 V1 engine about one and a half year ago now, but I flew it myself for the first time in the late winter this year (I think it was mars) when it still was a little snow on the ground to land in. I am a member in a club that have access for a real airport (a small one) with a runway made of asphalt. That´s why I have put a carbon fiber landing gear with F3D wheels on my Magnum.
Anyway, I have been used a balanced APC 9x7 so far and I think I will be using a APC 8x10 for the comming flights now. I have read a lot about the Magnum and the engine on this forum but there is one thing I can´t understand, they say that if you use a 8x8 propeller you have to cut off 1/2" the mainfold and similar on the pipe because the engine will not get used of the pipe to 100% if it´s in the original length. But if you use a 8x10 propeller you don´t have to do anything. When i run the engine with the 9x7 propeller the engine has no problem at all to "go on" the pipe and with the 8x10 comes into the pipe already with a litte more then half throttle and the plane is still on the ground!? With full throttle the engine will not go very well, the rpm just goes up and down even how much I open/close the needle.
Should I short the pipe (how much?) or should I use a larger propeller? (9x9)
With a balanced APC 9x7 the engine will run up to somewhere between 17 and 19000 rpm depending how much I lean/rich the engine, with the 8x10 I don´t know yet because there was not enough sunlight and my rpm checker needs to operate in direct sunlight to work well.
I use my own home mixed fuel with 10% nitromethane and 18% syntetic oil, and yes the engine runs cool enough with that syntetic oil I use, castor oil is not needed.
/Eric P