I don't get it, why don't these muffler makers make a tuned muffler for our gassers ??

it seams they make mufflers and then they make tuned pipes but nothing in-between,, I have found on my MVVS 35cc that just a difference of 2 or 3 hundred RPMs makes a noticeable difference in performance,,

I don't need a 26 inch long tuned pipe hanging off the side of my plane, but a different muffler that would give me a simple 300 RPM increase would make me very happy..

Jim

I absolutely agree,all they really need to do is do some computer calculations based on inlet size and carb sizing,exhaust volume.....I am sure a simple twist of the exhaust flow will make a difference.When I was younger I worked for a motorcycle dealer and they gave me a Kawasaki KX 125 they got in trade for next to nothing and handed me a factory race prep manual and said"have at it!" I was instructed to cut and re weld the factory exhaust and exspansion chamber(the front bulge of the exhaust header) a certain way , rerouting the exhaust flow and man let me tell you that thing ran meen as hell!!! I could not believe it,but it did also give carb jet sizes to use.Our walbro have that built in simple needle settings do make a difference...............just a thought.

You can't reinvent tuned resonance -
there are a million tuned gadgets for two strokes but to get smooth throttable POWER you need some volume
My ZDZ40 uses a carbon fibre pipe with the baffle at 28" from piston face
Makes no sense ,right?
Actually i does if you do some hands on comparisons
this pipe lets the engine start run extremely smoothly ,yet puts out a lot more torque (it's all about torque) I designed smaller setups year back also great power but more noise and not as smooth in entire band.

Dick,, I really don't know what your trying to tell us here,,

first you say,, ""You can't reinvent tuned resonance""

well that may true but there is Exhaust Technology today that is NOT being used on today's RC gasser plane engines, ever cut in-half a Weston Heli Mini Pipe, or a Youngblood Heli Muscle Pipe (see link),,

inside the Youngblood heli pipe,,
http://runryder.com/fastphoto/38148/MP_1-3606.jpg


Dick,, so I know from my dirt bike days of the 70s and 80s and my RC racing boat days of the 80s and 90s and the last 8 years of flying RC helis that a 2 stroke is a 2 stroke is a 2 stroke, meaning there are many different types of exhaust that will pull power out of a 2 stroke, and what will work on a 8cc engine will "in larger form" work on a 40cc or 100cc,,

for the last few years Century has made different "heli" Tuned Mufflers for the Zenoah 23cc/26cc (see link). I'm sure these Century Zenoah heli mufflers are smoother and more powerful than a 26cc Inverted Side Muffler would be, yet these mufflers are not 26 inches long and not that loud at all,,,

Century's Tuned 23cc/26cc Zenoah Heli Muffler,,
http://www.centuryheli.com/products/...?currentid=210

I'm not asking anyone to reinvent a muffler for me, I just would like a slightly more powerful muffler that is not 26 inches long, after all those tuned heli mufflers prove the technology has already been used !!!

Jim

There are other setups and they all work-within their limits
I designed a few myself but Ialways gave up sound or top end or sensitivity to prop load. The in cowl setups for gassers ALL reduce power -every last one of em. The best ones -very slight power reduction but also very low sound reduction.
the pipes which do the best job -have the most volume.
If you are into wide open running - then - yeh some small setups will tune to this type application. Helis are a good example. but I use the throtle as much as the ailerons or rudder when I fly a model. The pics are of a few examples I have used. The largish carbon fiber are the best but they require proper use and installation.
I have seen some which the users have promptly destroyed . but then some guys can wreck an anvil with a rubber mallet.

Dick is right.
The examples you use are for heli engines. Helis are not rpm controlled, they are throttle controlled whilst rpm stay at, or very near peak performance rpm. These engines need a High Q-factor resonance muffler. (high-Q means narrow power band)
Plane props are rpm controlled, and need a much larger power band, thus they need low-Q mufflers, which add less to peak power, but make the engine very tractable. Low-Q goes hand in hand with larger volume.

I asked this very question of Bob Brassell from Jett Engineering. I was looking for a 26cc tuned muffler at the time. He said that they had looked at it, but ruled it out because a tuned muffler that worked on a 26cc gasser will be nearly as big as a canister muffler and that in the gasser market, most users were more concerned with finding an in-cowl setup than max power. A tuned muffler would never fit in a cowl and would be cosmetically unacceptable to many gas fliers.

I think what you want is a good canister setup, it is much shorter than a pipe, can be very quiet and makes way better power than any in-cowl muffler setup. Done properly, a canister system will equal or even exceed open exhaust power levels.

Mark

IF the plane designer has thought about that wee requirement, and provided a muffler tunnel in his plane.

the reason I brought-up those heli tuned mufflers is, they are made/tuned to work at a given band and RPM,, enhance the word "tuned",, if they can be made/tuned to work at a high RPM for a heli then they can be made/tuned to work with a wider band for planes,,

now, if one was made to work on a plane I can understand how they may be too large to fit under some cowls..

In my assortment of pictures -note the ZDZ40 with the paint can behind it It WAS a tuned setup but quite fussy
My PIP muffer (shown)was also tuned and worked extremely well but operated in 8000-11000 rpm range.I abondened the whole project when the potential supplier lost interest in the low sales volume project.
Most flyers do not care to learn to match engine prop/exhaust .
It's a buy n fly world .

""I abondened the whole project when the potential supplier lost interest in the low sales volume project.
Most flyers do not care to learn to match engine prop/exhaust .
It's a buy n fly world""

I hear that !!

Jim

Dick,

I've been reading most of the zdz 80cc forums and I was trying to find an answer to my Q'S without asking, but its still a little unclear to me whats best. You'r the one who probabaly knows the most about the exhaust and prop setup on the zdz 80cc. So I would like to ask you a couple of Q's. First my zdz 80RVJ is an older version from 2000 (has good compression and is in really good shape) and the plane is the lanier 94'' edge 540 the zdz 80 is the reccomended engine, but has no cannister tunnel.

lanier says it should come in at 21-22 lbs, so would the zdz with a wrap around pitts muffler give me enough power to hover and do 3d? I'm not into imac and never will be, 3d only. The plane has 1680 inches of wing area and will have 9 servos three batteries all nickle metal (2000mah) and AR9100 receiver. What wrap around pitts muffler is best to get the most power from this engine, bisson or jtec? And what size prop and brand? Or will I have to modify the fuse for a tunnel if so then what should I use for cannister/tuned pipe and prop size and brand?

It doesnt have to be insane power but enough to do 3d and not feel underpowered. I'm still learning and this size plane is my next step as I started with the funtana x100 then went to a hanger 9 27% 260 then 30% lanier yak 54. Any suggestions would be a great help cause I've been putting off building this plane for some time now and would like to move on as I also have a 36% PAU edge that I want to get going too.

Thank you so much-mark

i have the same comb and with a vess 26a hovers 1/2 throttle and rockets out of hover like a missile im using lg volume pitts noisy though tach at 7300+ in air via reading peak rpm from zdz ignition upon landing. going to try a PT 27 x 10 carbon next. shooting for about 6700 in the air.

-


And this "problem", as described by several posters (in cowl muffler deficiencies with two-stroke gassers), is what is going to bring four-strokes to the fore in gassers after a time. The Saito FG-36 is just the beginning.


Ed Cregger

axxis,

Are you using the super 80 in your edge and what brand pitts?