Tuned Pipe Discussion... what exactly makes it "tuned"?

[WA2FAST]

Okay, I completely understand exhaust, how it works, how different characteristics effect performance and so on. When I see adds for "tuned pipes" for R/C, it makes me wonder. What exactly are they tuning with them? I know that there are baffles inside and different size chambers and so on, but what exactly is it "tuned" for? I would think that an engineer would have to sit down with a given motor and work with it to find out what actually does make more power design wise for the exhaust. I can't imagine that there is any real 1-pipe that is better than all else out there. I see pipes all of the time that are super expensive mainly for craftsmanship, build quality, and look (polished)... but how can one tell what pipe really IS better for THEIR particular motor? I just don't personally see how you could... not like we have little dyno's for our R/C

Someone please enlighten me on this subject if you can... just curious as to what exactly one pipe would have over another for a certain motor... and if a different motor, how the two pipes would work with that one. Just seems like there are too many variables to be able to market a pipe as a best for all applications. Just how "tuned" are they really... when I think of something being tuned... it is specifically for that one application in that one environment. Nothing over the counter unless specifically designed for a certain counterpart in my mind can be tuned... but I could be wrong?...onder:

 

[Nitro_Freak]

i think it basically means the pipe is specifically tuned for the engine it comes with. if it's an aftermarket exhaust...some mfgs say what engine the pipe is for, some don't.

at least i think lol

 

[WA2FAST]

Yeah... just saying... that word gets thrown around a lot when in all reality, if something is tuned, what exactly is it tuned for?... you know? How are you supposed to really know outside of how it "looks" how good it is anyway, you are simply taking a company that is trying to make money's word for it.

 

[WsW-WYATT-EARP]

this is from venemous rc

"The reasons behind changing length and or thickness is due to the rebound of the exhaust gasses. When you have a pipe that is long and thin. the gas travels down and rebounds off the end, then comes back and that is what gives us the little bit of back pressure that we need to run these engines. If you have a pipe that is short and fat, the gas does not rebound as well. The reason is that it has to fill such a large cavity. I know that you said you would keep the same volume, but I due believe that that will not matter. I am going to research this alot and I will post anything else that I find"

a tuned pipe is giving you the ability to get more top end or low end out of your mill ...different pipes will do different things .. alot of them say a low end pipe .. or high end pipe .. or mid / high ... you can also "tune" it by sliding it in or out of the silicon coupler ... longer gives a bit more low end .. and shorter gives a bit more top end ...

 

[Digital Liquid]

Here is a good article which breaks down the basics of the Tune Pipe:

http://www.rcnitro.com/rn/articles/tuned.asp

Later.....

 

[niggle]

Re: Tuned Pipe Discussion... what exactly makes it "tuned"?

There are plenty of resources on the internet that will explain 2-stroke tuning theory far better than I can, and I would urge you to Google for them, but here goes anyway...

Tuned pipes are tuned to provide peak power over a specific engine speed range.

High performance 2-strokes have aggressive port timing and as such they are prone to the fresh fuel/air inlet charge disappearing straight out of the exhaust port on overlap before ignition occurs, this robs power from the engine.

The exhaust gases form a pressure wave as they leave the exhaust port and travel down the exhaust pipe.
By carefully choosing the size and shape of the tuned pipe it is possible to reflect the pressure wave back such that it reaches the exhaust port at exactly the same moment that the fresh fuel/air charge is trying to escape.
This forces the fuel/air back into the combustion chamber and effectively supercharges the engine.

The engine speed at which supercharging occurs is directly related to the shape and size of the tuned pipe and is referred to as being "on the pipe".

By changing the shape/width of the pipe you can control whether you have of a large boost over a very narrow RPM range or a smaller boost over a wider RPM range.
The length of the tuned pipe determines the centre of the boosted RPM range.

Resonance also plays a part and therefore choice of materials is important. RB Concepts pipes tend to be made of thinner material as they claim that this improves the resonant properties of their pipe.

 

[WA2FAST]

Digital Liquid... VERY good article.

You guys are all on the money. I completely understand how exhaust works and what the different waves, backpresure, and so on work... just like I said before. I was refering to some of the adds I see that call themselves a tuned pipe that will add power to any motor. I understand how it works, just some of the adds I see make pretty big claims. I guess it all comes down to what engine you have, what it's characteristics are, and what you are trying to get out of the motor vs. gearing, application, etc. You guys are all very knowledgable and have put some VERY good info down on this thread. Thank you guys.