poly tube transfer port

[mackelby]

Just what is a poly tube transfer port?

[chongman]

Well... I will let the guys that have done this mod to chime in but I think it eliminates the steel transfer port 

[Brent]

I am also wondering this

[Crosshairs]

They just cut this tube to take the place of the stock TP it allows more air to pass through into the barrel giving a bit more fps.
                              Mike

[mackelby]

Seriously, Mike! We can add FPS this cheaply? WAY COOL!

[Crosshairs]

Seriously, Mike! We can add FPS this cheaply? WAY COOL!

well I can't let you off that easy, you will need to drill your valve out to a 1/4" so the tube will fit into it and not just sit on top of the TP hole.
Mike

[WyoMan]

Seriously, Mike! We can add FPS this cheaply? WAY COOL!

It kind of depends on a lot of things......
But mainly, if you have a build that benefits from higher air flow then it helps, thats the short answer
Some builds it will hurt like a 1377 with stock barrel and a reduced volume valve
It hurts low volume valves because enlarging the TP increases the parasitic transfer volume (dead space that has to be pressurized)
This TP mod started sometime around 2003 +/- and was done to a CO2 2240 I believe
http://www.network54.com/Realm/CFTech/BioTPort.htm
So the tranfer port size needs to be "balanced" with the volume available for discharge
CO2 needs more help flowing than regular air because its molecule is so large
Lots to research here....

[Brent]

It kind of depends on a lot of things......
But mainly, if you have a build that benefits from higher air flow then it helps, thats the short answer
Some builds it will hurt like a 1377 with stock barrel and a reduced volume valve
It hurts low volume valves because enlarging the TP increases the parasitic transfer volume (dead space that has to be pressurized)
This TP mod started sometime around 2003 +/- and was done to a CO2 2240 I believe
http://www.network54.com/Realm/CFTech/BioTPort.htm
So the tranfer port size needs to be "balanced" with the volume available for discharge
CO2 needs more help flowing than regular air because its molecule is so large
Lots to research here....

Good points Wyo! So if I am following this correctly... this would have an advantage on a stock 2240/ with the valve also opened up?

[quickster47 †]

Good points Wyo! So if I am following this correctly... this would have an advantage on a stock 2240/ with the valve also opened up?

If you are running a 'Boss' valve or have done your own valve work, like increasing the volume and opening/smoothing the exhaust port, then yes the poly tube mod can help.  Just remember this, it is not a panacea and can often lead to decreased performance.  There are lots difficulties installing poly tube with the biggest one being the ends need to be square and both the valve exhause port and barrel input need to be enlarged to accommodate the tube.

Carl

[Brent]

Good to know! How much FPS on average can you gain?

[Crosshairs]

Not much and maybe none, you might lose more then you gain if it's not done right. It's something i only did once and it's not really worth the trouble IMO.
                          Mike

[Brent]

was mostly curious is all. I actually did hear you on the other post, about it needing to be perfect in execution... and still no guarentee of the results. It so sounds like there must be a better way on this, and this is not a preferred method of the mod.  I was mostly curious, as there has been so much talk about this poly tube mod over the years, and I was trying to figure out what that was all about.

As I have read and learned more here on this subject... am I on the right track with my thinking here:

it is better to take one of the newer TPs, and then to drill it out - and then make sure it matches the hole in the valve perfectly, which might mean some working on the valve opening of the valve to match it well?

As you can tell, a newbie question... but I am trying to wrap my head around what this is all about, and what is recommended here now. THX

[quickster47 †]

Not much and maybe none, you might lose more then you gain if it's not done right. It's something i only did once and it's not really worth the trouble IMO.
                          Mike

I can also agree with Mike on this.  It seems like you can spend more time fussing and fidgeting with the poly tube to get it just right and then nothing happens.

Carl

[mackelby]

Sounds like a can of worms I am not willing to open up.

[Brent]

Sounds like a can of worms I am not willing to open up.

That is what I was thinking too.
So am I even a little bit on track, with my drilling the TP, valve comments/ thoughts above?