Huh? Tuned Pipe 4 Stroke?

Yeah, I thought the heading might grab your attention.

Just caught this on the bay. (see link below) Is this old news? Where does/doesn't/could/couldn't it fit in for our use? Is this a hop up pipe, or a regulator? I wouldn't think it would need anymore regulating, so I'm guessing more of a hop up piece for the R/C pattern guys?

It appears to be original equipment built by O.S.

Just when you think you are up to speed on stuff, you see something like this, heh...

Eric Viglione

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3164403347&category=34055

Tuned pipes have been used by RC/pattern guys, I think.

Since the waves won't do anything on the admission stage (the valves are closed) they just hit the closed exaust.

On the exaust stage the combustion remnants will be sucked, giving the engine a better performance.

I don't know if it's good for stunt, since I don't care so much for them four bangers...

God bless you!

In Christ,

>Tuned pipes have been used by RC/pattern guys, I think.
>
>Since the waves won't do anything on the admission stage
>(the valves are closed) they just hit the closed exaust.
>
>On the exaust stage the combustion remnants will be sucked,
>giving the engine a better performance.
>
>I don't know if it's good for stunt, since I don't care so
>much for them four bangers...
>
>God bless you!
>
>In Christ,
>
>Ion

Ron B.
Ion:
It works exactly the same way as in a two stroke-cycle engine.The
valve overlap period in a four stroke is analogous to the blowdown period in a two stroke.Also like a two stroke,the effect of a pipe is very speed specific,and,again like a two stroke,can be broadened or narrowed by the configuration of the pipe.
As an experiment,I once set up a low speed (long) pipe on a Moki.61 I was developing for my Macchi 202.With a short header it would turn a 15-6 11,200;a 13-6 11200;an 11-6 you guessed it,11200.with a new(longer)header revs came down to 7800 on all the props.
The same sort of control is possible with a four stroke.The problem is that no one,to my knowlege,has done the necessary development work on four stroke pipes for P.A.,and I seriously doubt the existing pipes are going to be anywhere close to the requirement.As an extreme example of this,consider that some early four stroke engines used for driving pumps,and other similar equipment,had no speed control other than the length of the exhaust pipe.In dealing with engines we need to keep reminding ourselves that all the engines we use operate on the same cycle,the Otto cycle.the only real difference is the number of strokes of the piston needed to complete the cycle.

Looks heavy.

Personally, I'm with Da Dirt. I want a megaphone.

I had a YS 63 for a while. It was a real work of art. By it's self it was a real hoss. For giggles my wife bought me a tuned pipe from Central Hobbies that the pattern guys use on this motor. It went from strong like an OX to STRONG like a mid 70's Russian Olympic weight lifter. It was amamzing the power it added, but, it also added a tremendous amount of speed. At one point I had sub 4 second laptimes on 70' lines on a Time Machine. Still managed a pretty wild pattern. The pipe gives the pattern guys the AWESOME verticle performance they need on those long straight up legs. I dont really understand why it works like it does but it would seem to me that the backpressure from the pipe gives these motors more power. Sound Crazy? I thought so also. But then again this is a glow engine with no active ignition so the efficiency is probably in the toilet. The backpressure helps keep the cylinder pressurized??? I know when I put a tuned pipe on my OS 26-c it gained 4000 rpms. Yep 4000! Something is deffinently different than the normal 4s motors we think about. The tuned pipe also not only gives an RC app more power and top end rpm but the acceleration seems to go up also, and the plane stays very clean.

>Looks heavy.
>
>Personally, I'm with Da Dirt. I want a megaphone.
>
>

Randy Powell

Randy,

We must be very specific, as you and I have specific needs: We don't want a simple megaphone, that's much too easy. We want an open-end, reverse-cone megaphone. I think we're looking for something six to eight inches long, measured from exhaust port to end of exhaust pipe.

Ideally, we would also have a device for slamming the venturi closed on down lines, just to get that lovely rrrrapppp! sound, but this does not seem likely to appear.

Dan,

Hey, I'm waiting for you to design it. Cool: a carbon fiber, 8" long megaphone. Think we can get Saito to put the exhaust above the intake? Or will we need to use a "wraparound" header? We can run it down a pipe tunnel. Or is that megatunnel?