ADVANCED TUNING for those with JSAR Raptors or the SS-2 Balanced Valves

[Motorhead]

Due to repeat PM's on the subject of Tuning ... here a post from a few months ago that gets into the subject having pictures and early conversations on the use of Choking the transfer size.  Which in this threads converted WAR valve is REALLY really important to get the output stable.

See: https://www.gatewaytoairguns.org/GTA/index.php?topic=160999.msg155792422#msg155792422

Scott S

[shorty]

Interesting read on the valve Scott.

I don't understand the loss of power with an over bore size TP though. I would be curious if you took the .172" TP and manually pushed the projectile 1/16" to 1/4" further past the barrel port.  You know pressure delta across the TP with adequate volume.

Based on some data Bob generated years back your 22 should hit over 100 fpe at 3000psi with .2" porting and it looks like according to the graph your on par with .172" porting. Any chance of you trying this out ?

https://www.gatewaytoairguns.org/GTA/index.php?topic=46011.0

[rsterne]

your 22 should hit over 100 fpe at 3000psi with .2" porting and it looks like according to the graph your on par with .172" porting.

You lost me on the relevance of this Tim.... He is getting just over 50 FPE at 2200 psi.... What point are you trying to make?....

I think Scott's point is that with this particular balanced valve design using a slightly smaller port is not costing performance.... I don't know if he is using a retractable bolt probe or not, and if not, what diameter it is.... If he has a conventional bolt probe that is, say, 0.094" diameter, then any port larger than 0.196" would not gain power anyways.... It is not surprising that there is no gain in going larger than bore size porting, as the bore itself (or the chamber area minus the probe) becomes the limiting factor on power.... If there is any surprise here, it is that the power is significantly less with an overbore port.... rather than just marginally so because of the pressure drop it causes....

Bob   

[Motorhead]

Interesting read on the valve Scott.

I don't understand the loss of power with an over bore size TP though. I would be curious if you took the .172" TP and manually pushed the projectile 1/16" to 1/4" further past the barrel port.  You know pressure delta across the TP with adequate volume.

Based on some data Bob generated years back your 22 should hit over 100 fpe at 3000psi with .2" porting and it looks like according to the graph your on par with .172" porting. Any chance of you trying this out ?

https://www.gatewaytoairguns.org/GTA/index.php?topic=46011.0

Tim, Currently with the gun set up and running so well ( regulated ) I don't see in the foreseeable future undoing it by removing REG, Put in a heavy hammer, change ssg spring etc just for a test.
Tho said, when first screwing around with the FIRST GENERATION SS valve did do some unregulated tests which can be found here: https://www.gatewaytoairguns.org/GTA/index.php?topic=143027.msg1448481#msg1448481

Test was inconclusive being we could not get a full hammer stroke using an SSG, and Never did try it with a real heavy hammer and heavy spring.

In my testing similar to current set up ... INDEED increases in pressure raise the velocity and pretty substantially too.  But come days end only have a 3K bottle and need to get some shot before pressure falls to set point ... Thus we stopped at 2200 psi where I've got plenty of power and 40 or so premium shots.
100 FPE I seriously DOUBT ... but then again

[shorty]

Scott,
It would be just so cool breaking the 100fpe mark with a 22. You got to do it man. So cool....

Bob,
I wasn't making a point, I am just trying to understand if there is some kind of limiting factor in the valve design that is preventing the mathematical reasoning.
The power and efficiency doesn't add up when comparing to a conventional valve with a .25" throat, .2"exit port, .17" TP, barrel port .17" and thin bolt probe (non regged).
I know because my .22synrod can generate 50FPE at those pressures with that efficiency and with a barrel length of 19.5".

I don't want to ruin Scott's post. It's just questions and envy of the cool stuff and the TP change from .17" to .25" was really weird in regards to power levels.

[oldpro]

Scott,
It would be just so cool breaking the 100fpe mark with a 22. You got to do it man. So cool....

Bob,
I wasn't making a point, I am just trying to understand if there is some kind of limiting factor in the valve design that is preventing the mathematical reasoning.
The power and efficiency doesn't add up when comparing to a conventional valve with a .25" throat, .2"exit port, .17" TP, barrel port .17" and thin bolt probe (non regged).
I know because my .22synrod can generate 50FPE at those pressures with that efficiency and with a barrel length of 19.5".

I don't want to ruin Scott's post. It's just questions and envy of the cool stuff and the TP change from .17" to .25" was really weird in regards to power levels.

Im not sure why you think a balanced valve makes less power in fact they usually make more power. Given the same exact set-ups with same pressures and plenum sizes a balanced valve typically will majke more power. Scotts set up is not for raw power if he wanted to do that he would pull the reg and have full length plenum and put in a heavier hammer and drive the valve dwell higher its all in the set-up that determines the out come.

[Motorhead]

Tim,
I think your missing a POINT MADE going back a few years ago when forum conversations started happening about such valves, be them Cothrin, SS or any prototypes & various individuals one offs.

THAT BEING the primary reason to go with a balance / reduced opening type valve was that of EASIER COCKING when compared side by side to a conventional valve at equal power. So yes, it is very doable with like size ports in a conventional valve your going to make equal power. This has NEVER been in dispute IMO.
Another advantage to a "per-Say" balanced valve configuration is LESS CYCLIC VIBRATION being your no longer required to propels a massively heavy hammer with equally strong spring to fire the gun.  End result being in most applications in sporter weight guns ... Better accuracy !  Lets not forget the trigger mechanics as well are effected and generally for the better with less load applied to them.

If one would to put in summery what your argument / question is in rebuttal, it would be that a balanced type valve makes getting big power output far easier, requires less mechanical heft in the parts and pieces to fire the AG.

No argument that the system has more parts, likely less reliable than a conventional valve system.  The gains however outweigh the negatives IMO.   Misapplication where & when such valves are utilized is an entirely different conversation.

My take on it & nothing more ...

Scott S

[darkcharisma]

i think he's only referring to this chart Bob made. hes just being hopeful. but i dont think 100fpe can be achieved in .217 caliber at 3000psi.

[rsterne]

Well, it certainly can be in .224 cal.... My Hayabusa shoots 47.6 gr. bullets at 1035 fps (113 FPE) using 3000 psi in a 29" barrel.... and detuned to 100 FPE the efficiency is 1.19 FPE/CI....

but that has nothing to do with this thread, so my apologies....

Bob

[shorty]

What I thought this post was about.
Quote:
"more importantly some Cause & Effect when changes are made in TRANSFER PORT SIZE ... which for now will be the focus of this thread.
and
TRANSFER PORT SIZE MATTERS and is a MAJOR major tuning parameter with these valves and Bigger IS NOT better in many instances belief it or not"

My comments and questions have absolutely nothing to with me thinking that a balanced valve makes less power than a conventional valve. In fact, I am currently trying to make a decision on what valve I want to replace my 25 with and thought asking questions may help my decision.

Great information and thanks for sharing.

[Motorhead]

Yesterdays shooting with the WarP and SS-2 / RAPTOR valve with the .160" transfer port.

42 shots at @ 975 fps ( 500cc bottle, 3K fill, 2.2K set point, 24.8 slug ) results in an efficiency of 1.31 

I'll take that to the bank any day !!

When I get a few extra dollars I see a 4500 psi Carbon bottle in this guns future ( Either a 480 or 580 cc ) 

* Given gun is producing 42 @52+ ft-lbs shots on just 800 psi, going to a 4350# fill bottle would give it @ 2150 psi to use and if math's correct would yield @ 103 shots on a 480cc and @ 124 shots on 580cc

This is crazy !! for such a high power .22 ... IMO

[rsterne]

You won't get quite the increase in shot count you will expect going to 4350, compared to a 3000 psi tank.... Air doesn't act as an ideal gas (with a linear pressure/density ratio) at over 3000 psi.... In other words, the pressure will drop more each shot from 4350 psi than it will from 3000 psi.... Still, you will end up with a wonderful shot count.... 

Bob

 

[bear air]

That's an awesome shot count as is let alone adding the bigger better bottle. Scott do you think the 2nd gen SS valve would work well in 357 cal?

[Motorhead]

That's an awesome shot count as is let alone adding the bigger better bottle. Scott do you think the 2nd gen SS valve would work well in 357 cal?

Unless somethings changed ... valve having @.280 throat, .125 poppet stem is going to have an exit area equal to @ .250"
So in a .357 your likely going to have modest power being the Bore / Transfer area is only going to be @ 50%  ( If I crunched numbers correctly ) being not ideal IMO.

For a .357 and HEAVY slugs would be looking at getting the Transfer / Bore ratio at 80% or better.

But this said as a guy WHO DOES NOT SHOOT BIG BORE stuff ... so don't take my word on it.

[rsterne]

1/4" porting is a bit small for a .357.... Having said that, my first edition of my .357 Hayabusa, with a 28" barrel on 3000 psi, peaked out at 225 FPE, and could be tuned for a decent string at 200 FPE with a 1/4" port.... The same gun with 0.281" porting peaked at 257 FPE and could be tuned for a short string at 230 FPE.... Increasing to 0.328" ports with my balanced valve only resulted in another 10 FPE peak, but gave the ability to get an efficient tune at 250 FPE at 3000 psi....

Most guys tuning a .357 / 9mm use either a 9/32" or 7 mm transfer port (0.281 - 0.285")…. Going larger really requires a retracting bolt to take full advantage of the larger porting.... The same goes in .22 cal.... If you aren't retracting the bolt there is no point in using bore-size porting....

Bob

[bear air]

Sounds like a .250 port will do the trick with what I'm wanting. 150 fpe is about all I expect out of it. Now I need to figure which valve to go with. Thinking a Don Cothran valve.

[rsterne]

Here is what I got with a Cothran Powerhouse valve in a 28" barrel at 2900 psi.... 127 gr. bullet @ 850 fps = 204 FPE....



Be advised, however, that you cannot get a bell-curve with a Cothran valve.... as the pressure drops, so does the velocity.... Also note that as you reduce the hammer strike the efficiency increases until the valve "falls over the cliff" and fails to fire properly....

Sorry, Scott, I guess we sidetracked your thread.... again.... 

Bob

[Motorhead]

Such is the sharing of relative information ... forever sifting to find years later what you wish to read & be enlightened with .

[bear air]

Yes, sorry Scott. I have been watching how very successful you have been with this valve in 22 caliber and I had to inquire about the 357 application. It goes to show that where something works outstanding in one application, not so much for another. You have had such good results that I found myself going through a mental price tag to turn my one 22 into a bottle gun and install the 2nd gen valve yesterday lol.

[OCPgunner95]

I’ve been following this for a little while now and was able to get some sound advice as well. My .357 is one low power shot after a long sit, but then is fine until, of course, I let it sit for a long time…it’s a killer though, and the accuracy is out of this world!