Small expansion chamber for 4 stroke

[ATC185R]

-I read a thread on hydroforming and am kicking around the idea of making an exhaust with a small expansion chamber (kind of like FMF powerbomb) here's link http://i.timeinc.net/mx/content/imag...rotopipesm.jpg this is an FMF prototype for 4stroke mx bikes (sorry I checked the link and it is disabled but I attached the pics and also a couple on the hydroforming method (this is very interesting)

The idea is to use the expansion chamber to take advantage of the small overlap between strokes. I know how 2 and 4 strokes work and I know thumpers don't need expansion chambers but I think this is possible and was wondering if anyone had any formulas for figuring the placement of the chamber. This could be the next new thing....

ENJOY

[300rman]

interesting. it just might work!

[ATC185R]

C'mon guys give me some ideas and resources. What do ya think?

[NOS_350X]

the powerbomb headders from FMF is a gimick They dont do a thing. Just an item to get you to buy the new product.

[boonis]

will the power bombs work and they give more low end but worth 400 idk i think its cool that *Edited**Edited* thinking of doing it tho the page aint working

[Tri-ZNate]

I dont think it would achieve the same affect as a 2 stroke by any means. Isnt the point of the expansion chamber on a 2 stroke to recirculate the unused fuel back into the chamber for more combustion? Bigger the diameter better it circulates back in

[ATC185R]

No, I think the main thing an expansion chamber on a 2 stroke accomplishes is drawing more air into the cylinder. As the exhaust is pushed out at a faster rate (less restriction rite away because of expansion chamber) more fresh fuel/air mixed is sucked in on the intake.

[NOS_350X]

On the fmf powerbomb the larger part is just like a pre sclincer, It has a core running through the center with exhaust packing on the outside. Like i said its for looks. With the 2 stroke deal, you guys need to see one of the cartoon type things of a 2 stroke engine working and maby you would understand it better.

[Bryan Raffa]

now that you say that look at joe byrds pipe!! this is this years pipe, Like a boost bottle comeing out of the bomb part

[Tri-Z Pilot]

I dont think it would achieve the same affect as a 2 stroke by any means. Isnt the point of the expansion chamber on a 2 stroke to recirculate the unused fuel back into the chamber for more combustion? Bigger the diameter better it circulates back in

Yep sxwheelie. Your on the right track. I dont think an expansion chamber can apply to four stroke being as the intake charge is valved, and not ran through tranfer ports. This helps http://www.quadracerhq.com/tech_tips.htm

[Billy Golightly]

I suppose, that theoreticly, with enough math, and pulse wave measuring/calculating you COULD make an functional expansion chamber for a 4 stroke that would work in sync with the exhaust valves but there would be very little for it to actually do.

Megaphones are very popular on 4 strokes, and those do work.

[madmanwithmouse]

On a 2stroke its the sound waves that bounce back to the cylinder to keep the fresh fuel/air mix in the combustion chamber wile the exaust port is open. Ive got somewhat of an expansion chamber on my diesel truck and it seems to keep the egts down, it comes out of the turbo4'' then to 5'' for about 5foot then 4'' out to the end. I think the strech of 5'' gives the gases time to cool abit so that they shrink down and go through the 4'' better, but thats just my theroy.