ORIGINAL: jrjohn
ORIGINAL: turbo4
Stock muffler cut off to 1.5": 6700 rpm @ 98db
Stock muffler uncut: 6720 @ 97-98 (it jumped between the two a little but stayed mostly on 97)
Supersonic inverted pitts wraparound (pipe exits are straight, no swages): 6510 rpm @ 95 db
Bisson inverted pitts wraparound (swaged pipe exits): 6250 rpm @ 94 db
Chip Hyde Quiet Pipe: 6780rpm @ 93 db
According to Maudib's tests as shown above how does 500+/- rpm(diff.between the highest and lowest) translate in how the plane feels. Big diff., some diff., cant tell?? Im really struggling on muffler selection. I like the pitts look /touch quiter but dont want to sacrafice any power or add weight unless it gets made up on power. I wish he would have included the slimline in the test[&o].....is the stock DA muff loud enough you wish it were quieter? Annoying? Help[sm=bananahead.gif]
Turbo, if noise isn't an issue then as far as i'm concerned there is only one choice. The stock muffler.
1 Great power
2 very lite (less than 1/2 the weight of the others
3.Easy install
4. low cost
As for your question about rpm's 500 rpms is a lot
John
And to further answer your question, 500 rpm on this engine is at least 3 pounds of thrust, so it is a noticeable difference. Also, the bisson muffle is not only restricting, but a TANK!
I went the middle route...chip hyde pipe-a half pound heavier but 12 more ounces of thrust. I still plan/hope to be under or right at 15.5 lbs. I figured that if Wayne's plane is 15lb,7oz. with nimh batteries, a tru-turn spinner, wheelpants, and the dubro tires, it shouldn't be a problem, since I am running Li-ions, a CF spinner, Dave brown wheels, no pants, a mini throttle servo, and smaller tank. Off the top of my head, that's over 10 ounces savings right there...