FX Dreamline - max number of plenums?

[cowabunka]

Complete tuning noob here. From the look of things, it would appear that we can fit multiple dreamline plenums in series to form a huge plenum

I wonder what then will be the bottle neck in achieving higher speed / more efficient use of air. Transfer port?

 

[ImpactX]

Yeah good luck putting 10 plenum on there. If bigger plenum is the key. Wouldnt fx just make a 12 inch long plenum? There is a limit on how much plenum or required. Too little, not enough power. Too much, you just wasting length and consistency with shots.

 

[NickT]

One big one is going to do you more good than multiple small ones. If you are honestly considering doing something like running 3 plenums in parallel to really amp up your power, it’s probably time to start thinking about moving to a larger caliber...

 

[Centercut]

Once you get past a certain point the valve and port sizes become the limiting factor. I ran into this with my .30 Vulcan2 Tactic. Installed one power plenum plus the larger plenum that comes with the Huma reg. Got to lower reg pressure about 15 bar, and shot count at same FPE went from 18 to 30. So I thought, if big is good, then bigger is better, right?

Wrong. I added another plenum and saw no benefit other than it made my air tube longer. My thoughts are the valve, valve house port, breech port and barrel port became the limiting factor... Unlike Godzilla, size doesn’t always matter past a certain point. It’s hard to overcome the physics of dynamic high pressure air flow...

 

[Glem.Chally]

Only so much air can push before the projectile has left the building.

 

[DanielL]

It is all about the pressure drop as you deplete the plenum air. Over a certain volume the pressure drop becomes insignificant and more plenum is just wasted cost, weight and length.

 

[Mrshosted]

The diminished return start's at 1cc per lbs of power muzzle energy. For example, if your dream line was a .22 shooting a 18gr jsb at 880fps building 31lbs of energy. The maximum size of plenum you could optimally use would be 31cc. But on the other hand a smaller plenum will work just fine. At the same energy level of 31 lbs using a 16cc plenum you'll expect to have to raise your regulator set point about 300psi higher when having half of plenum size. Now I'm only stating this for you to use this as a guide not a rule. Please fill free to do you own testing. Just as Centercut has said there are other things that play important roll in the tunning of your airgun. Just as much as the plenum size can play a factor in shot count so can other things like a longer barrel.

 

[cowabunka]

The diminished return start's at 1cc per lbs of power muzzle energy. For example, if your dream line was a .22 shooting a 18gr jsb at 880fps building 31lbs of energy. The maximum size of plenum you could optimally use would be 31cc. But on the other hand a smaller plenum will work just fine. At the same energy level of 31 lbs using a 16cc plenum you'll expect to have to raise your regulator set point about 300psi higher when having half of plenum size. Now I'm only stating this for you to use this as a guide not a rule. Please fill free to do you own testing. Just as Centercut has said there are other things that play important roll in the tunning of your airgun. Just as much as the plenum size can play a factor in shot count so can other things like a longer barrel.

thanks, this is a very interesting topic.

Just out of curiosity, where does that 1cc / fpe come from? Your personal experience? or is there some dark magic formula that I'm not aware of?

I'm fascinated by this simple addon claiming to add 100fps+