New Expansion Chamber Theory

[Deleted member 12676]

They've been around for at least half a century but no one has ever offered an explanation of exactly how they work. All explanations have countered laws of physics concerning the action of sound (pressure) waves. I have an explanation that may interest you, not just to tickle your intelligence center but because once you understand how they work then you can figure out a way to solve the long standing problem that pipe builders have always been faced with: build a pipe with a strong hit but a narrow powerband, OR build a pipe with a weak hit and a wider powerband. (Or settle for something in between which has no strong points at all)
Now that I've caught your attention you might as well follow through and read it all at http://www.dragonfly75.com/motorbike/pipes1.html

 

[speedster huffy]

If you post measurements in inches. Ill make you one!

 

[Deleted member 12676]

Already have one and it works great! Now I climb hills like they're nothing. And I've not lost any top speed. A two-in-one pipe!

 

[Creative Engineering]

The truth is...tuned pipes are "tuned" to the engine...the specific engine that they will be attached too. Naturally, anything is better than what is provided in the Chinese kit.

Jim

 

[Creative Engineering]

If you post measurements in inches. Ill make you one!

Divide millimeters by 25.4 and you will get the inch equivalent.

Jim

 

[Deleted member 12676]

thanks for the correction Jim. I changed "decade" to "century" in my fist message.
Concerning tuning, a pipes top rpm should match the top rpm of the engine. But this two-in-one pipe has a lower "low rpm", thus a wider powerband and a good hit although hard hitting pipes always have a narrow powerband. It has broken the "powerband" barrier so to speak. Email me if you want specific info on this magic pipe.

 

[Creative Engineering]

thanks for the correction Jim. I changed "decade" to "century" in my fist message.
Concerning tuning, a pipes top rpm should match the top rpm of the engine. But this two-in-one pipe has a lower "low rpm", thus a wider powerband and a good hit although hard hitting pipes always have a narrow powerband. It has broken the "powerband" barrier so to speak. Email me if you want specific info on this magic pipe.

Hi Jag,

You're right...hard hitting pipes do have a fairly narrow powerband. A pipe that offers good all-around performance is best for motorized bikes.

I built the pipe for the morini spoiler, shown on my website, based on the specs that Morini provided with the engine. The dimensions that they provide are for a good general purpose pipe for the Morini engine. The performance was excellent for this application!

Jim

 

[BoltsMissing]

While on the subject of Expansion Chambers.

The subject of "variable expansion pipes" has been noted before and trashed, .... use Google,variable expansion chamber lots of "debates" out there.

I think Lotus is still working on something.

Conclusion so far seems to show; cost, materials, engineering and heat issues in regards to, "Variable Expansion Chambers for 2-Stroke Engines"

However,
the standard BS*** exhaust on a HT kit by now needs a major overhaul. Seriously, enough is enough of this carpe.
At least, at the very least, where the pipe fits to the engine, hope they make it all matched some day soon, like yesterday, 18 months ago!

As for the maths behind the pipe in a kit in regards to expansion etc, that can be sorted by each to their own to purchase or make their own after-market parts.


HOW it works, the theory I think has to be understood, WHY the expansion chambers do what they do etc.
Here's more graphical stuff, while we are waiting for jaguars theory and conclusionz.

http://www.froggy.se/skalmanmc/rd350/tuning/expan1.htm

 

[Deleted member 12676]

Who said anything about variable pipes? My pipe has set dimensions.
My new pipe breaks the return wave up into 2 parts, one for high rpms and one for low rpms. So it works good both at high and low (relatively speaking) rpms which has been impossible to do until now because no one knew exactly how the return wave was formed. (hint: it's not bouncing off the baffle cone because even at a 10 degree angle the wave reflects off the wall and goes out the stinger.)

 

[BoltsMissing]

No one said anything about variables, just something I thought I throw in the ring while we waiting in anticipation.


But you have a interesting concept,<<breaks the return wave up into 2 parts,>>
anything that will supersede what we get in these kits will do.