John Lucas 4 Posted May 18, 2019 Share Posted May 18, 2019 I have a OS Max 61 RF ABC -P which I am installing in a DSM Excelsior. I have had a new header pipe made but I don't know what length the header as to be. The tuned pipe is blue in colour, Code 72101110. Thanks John Quote Link to comment Share on other sites More sharing options...
Denis Watkins Posted May 18, 2019 Share Posted May 18, 2019 You have to make that choice John, with your installation The tuned pipe runs centrally as you know within the wing chord Your motor is fixed on the forward mount So the usual solution is the header running aft, to be joined by flexipipe to the muffler Quote Link to comment Share on other sites More sharing options...
Lindsay Todd Posted May 18, 2019 Share Posted May 18, 2019 Hi John, from memory I have a figure of about 14 inches from the piston centreline to the cone on the pipe however this will depend on individual motor, prop and fuel being used so some experimentation will be required by starting with a longer section of connecting silicon tube and reducing the length say 1/4 inch at a time whilst checking for peak rpm and throttle response. hope that helps. Lindsay Quote Link to comment Share on other sites More sharing options...
Nigel R Posted May 18, 2019 Share Posted May 18, 2019 You'll have to discover the best length for your own installation by fine tuning. If you state your prop size then perhaps a starting point can be suggested? Quote Link to comment Share on other sites More sharing options...
John Lucas 4 Posted May 19, 2019 Author Share Posted May 19, 2019 Nigel Prop size will be 12.5x11.5 or 12x12. These sizes is what I run my hanno on. John Quote Link to comment Share on other sites More sharing options...
Nigel R Posted May 20, 2019 Share Posted May 20, 2019 Hi John Might be a bit much for the standard RFP. 12x10 is about their maximum useful prop I think? It'll barely get 10k on a 12x10. Quote Link to comment Share on other sites More sharing options...
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