RE: i want speed plane
Hi guys, I am trying to get a pipe set up on an engine and because I don't have alot of experience with tuned pipes I am looking for some help. here is what I have. Rossi .61 5 port long stroke with a Picco 80 DF carb ( 12mm) The exahust port has been raised .040. That gets the duraration up to 170-175 degrees. Running an Enya 3 plug and 15% nitro 18% oil ( partal castor ). Last time I raced the airplane was with the Rossi 10 mm carb and a different pipe. The pipe was a full length Macs header and Macs muffled pipe. prop was an APC 11X11. I did not tach the engine but was reasonably happy with the speed. Took a first place finish that day. To protect my points lead I went searching for some more speed. Got the bigger carb and set out to make a better pipe. The new header is 7/8" inside dia that matches the exahust port wheras the Mac's header was only 3/4". The new pipe's body ( area between the forward and aft taper ) is 2" longer then the other pipe. I set the header length so that the distance from plug to forward taper is the same on both pipes. Overall the new pipe is 2" longer then the old pipe.
Results. On the ground with an APC 11X11 I got an even 12K. I flew and saw no real speed increase. Bolted on a 11X12 and set the needle to what I thought would be really rich knowing it will unload and lean out in the air. It did and the speed went up a little. My concern is that the engine seems overly rich to keep it from running too hot. Not sure what adjustment to make from here. Thanks for ant help you can offer