MSS999

I am thinking of getting an MVVS 26 pipe (#3266) to try out on a Raplh Cunningham converted Zenoah 26 and a Brillelli 25GT. This is purely to educate myself on the tuning and use of pipes.

Does anyone have experience of either of these engines on a pipe?

My driver is to quieten the engines and to achieve the "tuned pipe sound" rather than any significant power gains. Any power gain would just be a welcome bonus.

I will probably try the pipe on the Brillelli initially.

The brillelli gives maximum thrust on an APC 18x8 and 17x6 props. What size of prop would you suggest as a starting point on the pipe?

Also, does anyone know the distance between the mounting holes on the MVVS 3265 header? The distances on the Zenoah and Brillelli are 34mm and 32mm respectively.

Thanks in advance.

MSS.

pe reivers

The MVVS pipe works excellent on all 25-30cc engines. If your engine does not make 7500 rpm with a 18x8 prop, the header needs to be 1" longer
Header diameter/length is 20/150 mm, flange bolt spacing is M4x36.5mm.
The 3266 pipe has quite a long straight entry pipe of 50mm, which can be shortened should you need a longer header, dictated by the engine mounting.

MSS999

Thanks Pe, thats most helpful. The flange bolt spacing is close enough for some improvising.

I didn't understand "If your engine does not make 7500 rpm with a 18x8 prop, the header needs to be 1" longer". Are you saying that the header may need to be longer than the as-supplied MVVS 3265?


My intention was to follow the tuning guidelines at the following sites:

http://www.macspro.com/tuning.asp

http://tech.flygsw.org/tuned_pipe.htm

Are there any other guides available on the internet that one could follow?

Thanks again.

MSS.

pe reivers

The header as supplied is for the MVVS26cc. (item 3265). Other engines have different timing and compression ratio, so may not react the same. It is wise to add header length first before you try to tune it. If it brings better rpm, then you are done.
A long header will give good power on large props, but hit an rpm limit on small props. A (too) short header will give you all kinds of problems with your engine.