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whats the different between tune muffler and tune pipe?

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whats the different between tune muffler and tune pipe?

Old 08-25-2011, 03:37 AM
  #51  
pe reivers
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Default RE: whats the different between tune muffler and tune pipe?

Stories are just that, each person intensifying his own role, sometimes at the cost of truth.
MVVS was erected to study the technical progress in the Western countries, especially in competition engines. I am quite sure that all competition fliers were aware of that fact. It was no secret. " Adopt, Adapt, Improve" is the motto all technology progress is based upon, even without the former iron curtain. If you study patents, in which technology progress is documented, you invariable see previous art as base for new "inventions", many of which are just "discoveries" and applications thereof.
I take it, that is the way the MVVS black muffler evolved into what it is today, and has been for at least 20 years.
Old 08-25-2011, 02:35 PM
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Default RE: whats the different between tune muffler and tune pipe?

Iagree Pe´.

Its just that I was looking long and hard as to how the MVVS black pipes work and wished that 'one' of the originators had stepped forward with more details.

Its interesting to note that these pipes vary the length of the tube inside of the can, the tube or the header outside of the can and the outside tube or the can itself but the rear angle is always a constant.
(Other brands of course vary this angle but once their variation is chosen its a constant in their designs also.)

And it was noted that if the angle is changed it dramatically changed how the pipe worked, and this alone tells me that are some reflective duties are going on.

Also note that the original 'Magic Muffler' by Ranjit had a far, far longer tail pipe, but again the angle of the rear cone never altered.

Ihave found that MVVS pipes on control line engines that probably only ever hit about 10 000rpm have a unique sound to them, its louder than expected for the volume and this indicates (to me at least ) that there is the opposite going on as inside of the classic Helmholtz resonator. Sound is not attentuated but instead amplified, but only on certain frequencies and my best guess is the external resonator enhances the internal quarter wave pipe. But even at modest control line stunt revolutions, these pipes work well.

Cheers.
Old 08-25-2011, 03:13 PM
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pe reivers
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Default RE: whats the different between tune muffler and tune pipe?

The MVVS mufflers all have their tune above 14,000 rpm? The CL engines run much lower, and thus run off tune. This was confirmed by the MVVS chief engineer when asked about the suitability for CL work.
In RCcombat I added an extra low pass muffler to the side branch resonator, and gained 200 rpm whilst getting rid of the annoying high pitched note in the MVVS system (and gained -2dB(a)). Other competitors using my system added a few holes to the reflector cone, and gained even more power. The MVVS muffler is not just a side resonator/attenuator, but also uses pure volume with pipe length (helmholtz) and wave reflection. Each and every type is well tuned, and can hardly be improved, but experimenting with them pays off.
In a 3.5cc engine, the original 3.5cc device (3243) worked from 14,000 to 17,000 rpm. Using a 2.5cc muffler(3241) raised the resonant region from 16,500 to 19,000.
The small side dump mufflerof the 3.5cc engine came into resonating at about 17,000 rpm, and in that region provided the same power as the 3243 device, albeit at higher noise levels.

Old 08-25-2011, 07:41 PM
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Default RE: whats the different between tune muffler and tune pipe?

Hi Pe,
       the MVVS 51 or 8,0cc GRR-ABC-Acrobat that comes with a lovely black tuned pipe/ muffler or whatever we can name it does indeed improve its performance over the standard muffler and I suspect over many standard mufflers also, and yes I know about the 13 000 to 14 000 rpm cut in point of the pipes so I am surprised also.

(The MVVS engineer, do you mean Josef Svajda by any chance? I have spoken to him concerning diesel conversions before - nice chap.)
Old 08-25-2011, 09:23 PM
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Default RE: whats the different between tune muffler and tune pipe?

OK,
It looks like you guys need perspective here. The sound of a stock muffler is like standing in Ghiradelli Square in San Fran on a hot humid day listening to a street band while aimlessly jingling the change in your pocket wondering if you should flip a coin into the hat. On the other hand, the rich acoustic cadence resonating from a finely tuned expansion chamber is like savoring a toast on a cool evening at the Hollywood Bowl.
Old 08-25-2011, 09:57 PM
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Default RE: whats the different between tune muffler and tune pipe?


ORIGINAL: the Wasp

if you really want to understand how a Peaky Tuned Pipe works and feel go find yourself a 1973 Suzuki TM 125 and ride it,, at one moment you will feel as if the engine has no power like a heavy truck in to high a gear, then in the next moment the tire is spinning the engine is screaming rocks are flying and you here yourself saying wow
Wow, My first dirt bike was a 75 TM125. Had a Air Cone down pipe on it. I had a LOT of miles on that bike!
Old 08-26-2011, 01:05 AM
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Default RE: whats the different between tune muffler and tune pipe?

Scooter, Roary,


This is a forum that discusses glow engines used in models...

Although tuned exhausts work basically the same for motorcycle engines, let's keep the discussion on-subject and only refer to other fields, when examples are needed that leave us no choice.



Chris,


MVVS' head engineer (for fuel engines) is indeed Josef *vajda.
Old 08-26-2011, 04:09 AM
  #58  
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Default RE: whats the different between tune muffler and tune pipe?

Da and Pe, I have never heard of a Helmholtz resonance chamber on a two stroke motorcycle in regards to what we are discussing here, so although convergent and divergent cones are a common science, I don't see the parallel with any form of purely resonant chamber with a power gain on any form of engine.
Helmholtz chambers are commonly associated with with noise suppression, not power gain so lets see how this pans out!
The ' fly in the ointment' here is that with control line flying and the lower rev range used is that full length tuned pipesundoubtedlywork , and if this is the case then why not a resonant chamber as described by Helmholtz? (Although I am at a loss to see how it works.)
Obviously there is some gain with the MVVS black pipes or the factory would not endorse them for the Akrobatrangeof engines that operate at less RPM. Resonance chambers, reflective cones and fixed volumes are a science not well defined outside of racing or full RPM conditions, so lets take a step back and look at what we have here for all conditions.
Old 08-26-2011, 12:07 PM
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Default RE: whats the different between tune muffler and tune pipe?

If you are at loss about a helmholtz resonator, just blow on the neck of an empty beer bottle. That's the Helmholtz resonator in purest form for you. (chamber and wall thickness AKA entry header). You can feel the pressure waves. An occarino clay flute comes to my mind as well, being a tunable resonator. This power can be uses for attenuation as well as amplification. Take your pick.

added:
see how the intensity and tone changes if you alter the volume of the bottle airspace. Intensity is Q-factor, tone is resonant frequency.
Old 08-26-2011, 12:10 PM
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Default RE: whats the different between tune muffler and tune pipe?


ORIGINAL: Roary m

OK,
It looks like you guys need perspective here. The sound of a stock muffler is like standing in Ghiradelli Square in San Fran on a hot humid day listening to a street band while aimlessly jingling the change in your pocket wondering if you should flip a coin into the hat. On the other hand, the rich acoustic cadence resonating from a finely tuned expansion chamber is like savoring a toast on a cool evening at the Hollywood Bowl.
Nice of you to bring the whole picture in perspective. Now I know the taste of a low-Q tuned muffler, and a high-Q tuned pipe

Old 08-26-2011, 12:49 PM
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Default RE: whats the different between tune muffler and tune pipe?


ORIGINAL: Diesel Fan

Da and Pe, I have never heard of a Helmholtz resonance chamber on a two stroke motorcycle in regards to what we are discussing here, so although convergent and divergent cones are a common science, I don't see the parallel with any form of purely resonant chamber with a power gain on any form of engine.
Helmholtz chambers are commonly associated with with noise suppression, not power gain so lets see how this pans out!
The ' fly in the ointment' here is that with control line flying and the lower rev range used is that full length tuned pipesundoubtedlywork , and if this is the case then why not a resonant chamber as described by Helmholtz? (Although I am at a loss to see how it works.)
Obviously there is some gain with the MVVS black pipes or the factory would not endorse them for the Akrobatrangeof engines that operate at less RPM. Resonance chambers, reflective cones and fixed volumes are a science not well defined outside of racing or full RPM conditions, so lets take a step back and look at what we have here for all conditions.
helmholtz principles can be used to amplify waves, but also to suppress waves. Amplification is used in the simple one chamber mufflers AKA mousse can muffler. It also is used in 4-stroke plenum intake chambers to get a power boost. Wave suppression is used in pumps to silence the pressure pulses. It also is used in two stroke exhaust systems, where a small side chamber limits the engine rpm quite effectively. The applications of the Helmholtz principles are countless.

If you want to study all the principles used in the MVVS muffler, I wish you good luck. It is a convenience that the muffler does not suppress power below it's effective range, a thing that other muflers tend to do.

Old 08-26-2011, 11:10 PM
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Default RE: whats the different between tune muffler and tune pipe?



ORIGINAL: pe reivers
It is a convenience that the muffler does not suppress power below it's effective range, a thing that other muflers tend to do.
So why is it that the diesels in the MVVS range can use the same black tuned pipes as the glows and not suffer from overcompression since they will certainly operate well over the 13 to 14 000 rpm threshold?

Logically there must be no returning wave to supercharge the very end if the exhaust stroke. If there were, like the full length pipes, then you would have the Devil to pay trying to tune it.

'If' there is no returning wave or positive pulse then it could be a purely negative pulse system with the resonator simply assisting the central quarter wave core.

And quote that ubiquitous site Wikipedia -

The exhaust pipes in automobile exhaust systemsare designed as acoustic resonators that work with the mufflerto reduce noise, by making sound waves "cancel each other out".The "exhaust note" is an important feature for many vehicle owners, so both the original manufacturers and theafter market suppliersuse the resonator to enhance the sound. In 'tuned exhaust' systems designed for performance, the resonance of the exhaust pipes is also used to 'pull' the combustion products out of the combustion chamber quicker."

So a negative wave or pull seems likely.

Old 08-27-2011, 03:43 AM
  #63  
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Default RE: whats the different between tune muffler and tune pipe?

Don't jump to conclusions.It's a pull-push system or it will not work well.
Diesel ignition is not very depending on the amount of charge, but are depending on end of compression pressure. It works well.
Old 08-28-2011, 06:46 PM
  #64  
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Default RE: whats the different between tune muffler and tune pipe?

Pe´, you have got me thinking and that's dangerous!

Valveless pulse jets would appear to use a similar resonant chamber that both pushes and pulls and the affected chamber would equate to the rear expansion volume on the black MVVS pipes.

Can you see any parallels?
Old 08-29-2011, 04:44 AM
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Default RE: whats the different between tune muffler and tune pipe?

That's true. It is the resonant system in it's most simple form, though there is only pull action due to the negative value of the reflected wave off the open pipe end.
Two strokes have been shown to run without crankcase charging (porting in cylinder only) by using this system. (Gordon P Blair). It does not matter much if a tuned muffler, or tuned chamber, or tuned pipe is used. The reflected wave of the tuned pipe boost the pressure at compression start. Mufflers and tuned chambers have a bit of a problem doing this.
Old 08-29-2011, 06:59 AM
  #66  
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Default RE: whats the different between tune muffler and tune pipe?

Pé,


I cannot agree with you about the last statement.

The power addition from installing the MVVS tuned silencers on engines, is much too great to be only a result of suction (more complete exhaust scavenging and quicker induction).
The RPM difference on the same prop size, like an 11.5x6 Bolly on the .49/8.0 engine, is ~2,000 RPM, to 13,600; compared to the #3245 muffler.

This is an addition of no less than 61% in HP compared to the base number, which cannot be accredited solely to better scavenging.
There is definitely a positive pressure boost; supercharging, as compression begins and the exhaust port closes.


A very good muffled tuned-pipe installation, can only bring a gain of 300-400 RPM over that number.
Old 08-29-2011, 07:08 AM
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Default RE: whats the different between tune muffler and tune pipe?

Dar, did I say anything about suction only in the black muffler? My last post was about the pulse jet chamber.
The 3245 is very restrictive and is a power choker at lower rpm. You should compare rpm gain over open exhaust systems if doing gain or loss analisys.

Old 08-29-2011, 07:50 AM
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Default RE: whats the different between tune muffler and tune pipe?

Pé,


Maybe you did not, but please read Chris' post and your reply once again, to understand why I reacted with my statement.
It was not completely clear what you were responding to.

I agree that boost should be measured, comparing the power to the open exhaust condition.
But since hardly anyone runs a .15 or larger engine with an open exhaust, comparing power with a tuned system to that of a normal non-tuned system, is quite legitimate.
Old 08-29-2011, 01:29 PM
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Default RE: whats the different between tune muffler and tune pipe?

so there remains the legimate boost of about 400 rpm of a tuned pipe over the tuned muffler system. This was the OP original question. No tuned muffler will ever obtain full tuned pipe performance. They may get close, but that is as good as it will get.
Old 08-29-2011, 02:26 PM
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Default RE: whats the different between tune muffler and tune pipe?

This really has gone beyond the scope of the original question posed many years ago and perhaps it deserves a new thread?

I admit that I am struggling to understand exactly what is going on with MVVS pipes or their 'Magic' cousins but if we accept that there is a push along with a pull and we can not scientifically seperate those wave forms and test for that then I would call upon a device that would indeed react to a returning wave - a diesel. (Just building upon what Diesel Fan has posed.)

Happily MVVS make a very similar range of diesels and glows with common pipes so its easy for some one like Pe´or perhaps Dar to test if the exact same tuned exhaust system works on an engine like the MVVS 2.5cc glow and a diesel (thats assuming of course that they have access to these engines and pipes still!)

A diesel when properly warmed and in tune will over compress with any form of returning or 'positive push' wave as that wave will force gases back into the open exhaust port at the last moment. This has been confirmed by fliers who have diesel speed models - no pipe other than a straight length that gained perhaps 200 rpm has any benefit on a diesel.

Yet here we are with MVVS 2.5cc diesels running with a known power boosting pipe, in the correct rev range and yet suffering nothing from over compression.

This seems to tell me that if the MVVS pipe has a 'positive' wave then its effect is not felt back at the exhaust port.

At the moment, my head hurts thinking about this!

Old 08-29-2011, 08:10 PM
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Default RE: whats the different between tune muffler and tune pipe?


ORIGINAL: Recycled Flyer

...A Diesel, when properly warmed and in tune will over compress with any form of returning or 'positive push' wave as that wave will force gases back into the open exhaust port at the last moment. This has been confirmed by fliers who have diesel speed models - no pipe other than a straight length that gained perhaps 200 rpm has any benefit on a diesel.

Yet here we are with MVVS 2.5cc diesels running with a known power boosting pipe, in the correct rev range and yet suffering nothing from over compression.

This seems to tell me that if the MVVS pipe has a 'positive' wave then its effect is not felt back at the exhaust port.

At the moment, my head hurts thinking about this!


Chris,


It is exactly for this reason that when selling an MVVS Diesel, I always emphasized buying a standard silencer with it was the proper thing to do.

It could be that the compression can be adjusted at top-RPM, with the tuned-silencer installed...
...But this modest compresion setting still allows the engine to idle and to transition from low RPM, without bogging...

Go figure...

It could be that 'the step' with the MVVS tuned silencers, is gradual and subtle; not sudden, as it is with a tuned-pipe (especially a dual-cone type)...
These exhausts; although MVVS do specify an effective RPM range for them, seem to positively affect the engine's operation wherever you take it.


EDIT: Addition of info.
Old 09-01-2011, 12:57 AM
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Default RE: whats the different between tune muffler and tune pipe?


ORIGINAL: pe reivers

The MVVS mufflers all have their tune above 14,000 rpm? The CL engines run much lower, and thus run off tune. This was confirmed by the MVVS chief engineer when asked about the suitability for CL work.
Pe,
I am confused here since I have seen documentation from an MVVS dealer that states that the 3248 and 3249 MVVS mufflers are intended for the range 10 000 to 15 000 rpm - and it is very possible to run a control engine in that range. Typically a piped engine may like to run at about 10 500 rpm and non piped anything from 7 000 upwards.

So possibly these pipes have a broader range than first expected. I remember Czech fliers(specificallyStanislav Cech's 'UNO')using MVVS 40's with rear intake and exhaust with a mini pipe with good success but I don't know what rev range they ran in but it must have matched the pipe surely. The only MVVS like that is the 'Quicky" I think?



Old 09-01-2011, 01:40 PM
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Default RE: whats the different between tune muffler and tune pipe?

CL has a wide range of application. An 8cc stunt engine will run nowhere near 10,000 rpm when in 4-2 rithm!
MVVS documentation on the mufflers has not changed, but the mufflers did. 5000 rpm power band is guilding the lily. More likely 3000 rpm.
Old 09-02-2011, 04:48 AM
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Default RE: whats the different between tune muffler and tune pipe?

If you like to read, here is everything you wanted to know about sex..... I mean two stroke engine tuning.

http://www.vintagesleds.com/library/manuals/misc/Two-stroke%20Tuner's%20Handbook.pdf
Old 09-02-2011, 12:19 PM
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Default RE: whats the different between tune muffler and tune pipe?

For gas engines that is. Jennings gathered all the information wandering about in the racing circles and put them in his book; a job well done. Gordon P Blair however is much more valuable reading.
Glow engines do behave a bit differently than gasoline or self ignition diesel engines due to the extreme internal cooling by the methanol fuel they burn. Take this into account when looking at flow efficiency and exhaust systems.

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