Canister style expansion chamber

[Deleted member 12676]

frankenpipe

I'm calculating the dimensions of a torque pipe for use with a 48cc with standard port timing for you to test HS.
It has a 375mm header, 180mm diffuser, 60mm belly, and 180mm baffle.
In contrast, your compact version of an expansion chamber has a 370mm header, 70mm diffuser, no belly, and 56mm baffle.
Don't fool yourself into thinking this is anything as good as a true tuned pipe. It is a muffler with a mini cone section. My calculator figures your diffuser is tuned for 8500 rpm and your baffle is tuned for 10,500 rpm.
What you are doing is commonly called an "exercise in frustration" because you are trying to bend the laws of physics to meet the impossible demands of a customer.

 

[Fabian]

Awesome research Headsmess. I am thrilled to bits at the unique "look" of the stacked pipe arrangement, and at less than 400mm long and a shade over 3 inches wide, it perfectly fits the bill for a stealthy pipe design.

To say that i am excited over this concept is an understatement.

 

[Fabian]

you are trying to bend the laws of physics to meet the impossible demands of a customer.

Those were in an around about way the words of some of the scientists when President Kennedy made a bold statement to go to the moon in under a 10 year time frame.
As always, there was resistance by the educated types within the organisation who said it couldn't be done and if it could be done, that it was not an attainable goal within a 10 year time frame.

We all know that they were proven wrong.

Jaguar, i have removed posts from your thread because they did not contribute anything to your thread.
Would you please kindly remove your comments that do not support the concepts and goals of this thread.

Fabian

 

[Fabian]

http://www.falstad.com/ripple/index.html

What an awesome program.
Just wait till you select the 3D view - mesmerising to watch

 

[Fabian]

Just worked out that you can look look underneath the 3D view and move the image around to view it at different vantage points.

The sonic boom looks interesting in 3D

 

[KCvale]

the curtis pipe just looks like a standard expansion chamber, fed in at right angles. an expansion chamber, not a tuned pipe. big difference. an expansion chamber is exactly that, a chamber for expansion. its more of a silencer than anything.

I have to argue with you there, a properly designed and tuned X-chamber does indeed sent a shock wave back through the exhaust post shoving the otherwise wasted fresh gas mix back into the calendar resulting in a sort of 'reverse turbo charger' effect, as much as 1/2 a HP you can really feel.

I don't see how you could cram that specific wave tuned chamber that makes the magic into a smaller space, and the length of the pipe between the chamber and intake is how you tune it.

.

 

[HeadSmess]

its not to any particular scale, its just a diagram, the measurements are a byproduct. surprisingly good though maybe just try it out as is!

once again, i repeat, it is merely a diagram and i have not calculated anything or done it to any particular scale. i didnt even know what the dimensions were until i put those marks in there.

i feel those marks may define the critical dimensions in this design worth experimenting with.

i also repeat that i also dont believe this is a true pipe, and wont have the same effect as a true pipe.

playing around with that ripple tank link does give some idea of how the waves travel. in fact, its fascinating. i played around for 3 hours before passing out! resonances, reflections, reversion waves...

its majow drawback is it wont load an image. pixel by pixel with no zoom feature. tricky

which, once again, leads me to thinking the header join/connection is basically the downfall. in 2d, it definitely is, but in 3d...somehow that wave has to go from emerging from a square port, turn a right angle, and then travel in an annular cavity. here in lies the killer.


its much akin to a mismatched port, where the change in section simply reflects any returning waves away from the port.

 

[HeadSmess]

I have to argue with you there, a properly designed and tuned X-chamber does indeed sent a shock wave back through the exhaust post shoving the otherwise wasted fresh gas mix back into the calendar resulting in a sort of 'reverse turbo charger' effect, as much as 1/2 a HP you can really feel.

I don't see how you could cram that specific wave tuned chamber that makes the magic into a smaller space, and the length of the pipe between the chamber and intake is how you tune it.

.

and ill turn around and say...

"an expansion chamber is a change of section in a pipe, invariably larger than the original diameter(otherwise it would be a compression chamber, duh). pressure waves are affected by changes in diameter. when a pressure wave enters an expansion chamber, the positive pressure continues forward, whilst a negative pressure pulse is sent back up the pipe"

a tuned pipe is tuned so these diameters or changes in section affect the pressure waves at THE CORRECT TIMES.

a simple expansion chamber, does not. it may produce negative waves and reflected positive waves, but they have no "synchronisation" with a specific RPM.

a 4stroke uses an expansion chamber as a silencer. the ends are usually abrupt, going from one diameter to a larger one without a taper. these chambers are usually more designed to be resonant and produce a wave equal to the incoming wave, but in opposite phase. these interfere and cancel out, making for reduced noise at the outlet. that frequency has been eliminated.

they also benefit from negative waves drawing exhaust gasses out. tuned header pipes, extractors... they all use the same ideas of waves and inertia of gas flow to do what the do.

so yes, an expansion chamber does produce a power gain of sorts, when fitted in the right place.


completely correct

 

[Deleted member 12676]

I'm glad to see that HS is not just telling the customer what he wants to hear.
The first expansion chambers were just headers with diffusers. Loud as hell and for racing only but they did give the engine more power by the return suction wave helping the engine suck up more air/fuel through the transfers. This canister is a mini version of that and so will be of limited benefit. I once tried a trumpet pipe on my ride and it did help. But the noise is more than you would think humanly possible.

 

[HeadSmess]

http://www.falstad.com/ripple/index.html

What an awesome program.
Just wait till you select the 3D view - mesmerising to watch

im just going to run it permanently as a screensaver or summink

try the "ellipse" but putting the source central and down a bit... high brightness... hope you arent epileptic!


anyone who wants to understand wave propagation should check it out