Stuka Stunt Main Forum · 13 of 13 known posts recovered
I've been fiddlin' with my .25VF. and so far I got these results:
17- 1/4"pipe lenght, it breaks at 11,500 RPM
16-1/2" breaks at 12,100 RPM
After that, no use squeezing the needle, th won'tgo a single above that.
I wonder how mant degrees is it's eaxust timing.
That would give me more assurance on what I'n doming...
Randy?
Brett?
Ion
I'm thinking this might get real ugly, real fast.
If you want more motor, get something bigger. Rooting around with tools of destruction in a nice engine is to be avoided.
Or do you have a spare piston/cylinder set to plug in when your rework goes just a little bit too far? That's how a lot of us figured out engine mods, you know. Going too far with a good thing. Replacing with new parts cut to timing found in next-to-last experiment.
Dan
Personally I would love to come up and you could help me with the trimming of my Legacy <no smiley just for you>
Ion,
Why don't you measure it yourself, I am sure you can find instructions on the net someplace, all you need is a protractor, you can then make a degree wheel. Not that difficult....
If you are contemplating messing with the exhaust timing - dont! The pipe is being used as a governor, not a power enhancement device.
Cheers, Dave
If you want more motor, get something bigger. Rooting around with tools of destruction in a nice engine is to be avoided.
Or do you have a spare piston/cylinder set to plug in when your rework goes just a little bit too far? That's how a lot of us figured out engine mods, you know. Going too far with a good thing. Replacing with new parts cut to timing found in next-to-last experiment.
John Leidle
Reality is a place I visit, although not very often.
Sounds to me as if Ion is getting ready to make chips and/or grinding dust.
There is no serious difficulty in driving from Brazil to the U.S., it just takes a little time. You forget that I was the one who corrected Ion's spelling of his F1 hero's name, Ayrton Senna.
You helped John Thompson with his Oriental, I think it only fair he get your Legacy whipped into shape.
Dan
Like the guys said, you can find out for yourself with a degree wheel. I'm not sure knowing the exhaust timing will help you, I think you want to know the blowdown as well. Generally speaking somewhere between 6-8 degrees between exhaust opening and bypass opening, but not necessarily. That's not necessarily the magic trick either, there are many other things at play here. I am not familiar with this particular engine so I'll stop here. Check your Email.
Randy Ryan
AMA 8500
SAM 36
I fly 'em all and love it!
Knowing the exaust timing of my VF would give me an idea about how far should the baffle shoud be from the plug.
I guess I'm being lazy... I'm just gonna unscrew the head and meausure it myself.
I salute you with 1 John :2
Ion
Which pipe are you using, a 40 or 32?
I would suggest a starting point of 17 inches and go from there. You know what pushing out or shortening the pipe will do, so flight testing is going to be necessary.
I would also go with the 10-4 APC at 10,800, 10% nitro, hot plug.
Bill <><
P.S. I got one (25VF) myself, and we used an OS 32F on pipe for a while.
Just an Old Advanced flyer. 
Since it's a VF I make a <guess> that it's timed the same as the other VF's. My .46VF was 145 degrees. I suppose that you could just start with the pipe set for that length and adjust from whatever type or run you get.
Jim Pollock 
II'm using what I *think* is a Nering Carbonmaster pipe, it looks just like the one I saw at FM on an article about Mike Starret, his "Eliminator" and the OS.25VF.
Ion