ORIGINAL: FlatSpin
ORIGINAL: Ernie Misner
>>> Which do you guys prefer, the stock muffler, a mac's muffler, or a pitts? I just recieved my engine today, and can't decide which muffler to use. I installed the engine on a H9 Pawnee >>>
Scott, read post #391 by flatspin. He lost a ton of rpm's by going to the mac's black one piece muffler. This baffles me since that muffler is the extra volume one made especially for the 60NX, 55AX, etc.
Flatspin, you are sure your mac's muffler is not the one for the .46, right? It will bolt right to these larger engines also but is too small.
I used the newer MACs muffler designed for the OS 55AX. On the glow engine, I did see a performance improvement over the stock muffler. On the Evolution, I saw about 1000 RPM decrease and then it dropped even more RPMs. As I said before, I tried the muffler 2-3 times to make sure I wasn’t doing something wrong. Same results... The engine wasn't fully broken in when I did this, so maybe that has something to do with it???
I did notice later that the MACs muffler had a lot of the "black goo" in it and I poured a fair amount of it out when I was cleaning it up. Maybe 1/2 oz. or so. With the muffler loaded up with oil residue, I can assume (hate to do that!) it affected the muffler performance. That might explain the additional RPM decrease as it collected oil residue in the chamber. Now that I have the engine more broken in, and the residue output has decreases a lot, I will try the MACs again.
Dave
<hr />I thinkin a cold climate the oil is collecting in the exhaust because the oil is condensing...kinda like smoke does in a chimney of a wood burning stove. For a experiment use heat tape and wrap the exhaust like on some motorcycles.
Capt,n