Let me start with saying what I'm going to disclose myself and Travis Whitney of JSAR had discussed Many times in the past 6+ months or so as the R&D behind the scenes was happening. We had the conversation that at some time these tuning traits should be brought to light and shared. In the past 6+ months further testing and tuning with an Actual Raptor valve ( SS-2 in function ) retrofitted into my WarP , have got to get some really good data and more importantly some Cause & Effect when changes are made in TRANSFER PORT SIZE ... which for now will be the focus of this thread.
To recap on how these valves work ... simply put is by having a DUAL use poppet head, one larger diameter side sealing the valve throat as is typical, Other end being reduced in diameter and extended into a sealed tube / chamber and sealed via an o-ring. * What has happened is the pressure within the valve internal space bearing down on the closed poppet has had PART OF IT'S TOTAL AREA isolated by having the opposing end up in the o-ring sealed chamber. THUS the pressure exerted on the poppet seat is greatly reduced and the valve will break free and open far easier with not only LESS hammer weight, but less strike energy as well ( Softer hammer spring, less hammer stroke etc .. )
While this sounds all good & fine we all like easy cocking fast cyclic actions
there is now the issue of getting the valve poppet to close quickly and this by design utilizes a partially hollow valve stem that goes from just under the poppet head within valves throat up into the end of the poppet within the chamber. * So at any time when valves pressurized the chamber at the upper end of poppet is at atmospheric pressure being vented via the poppet stem into throat, then out the barrel. Yet there is pressure surrounding the poppet that is kept from escaping via the o-ring mentioned earlier sealing it.
Here is where we're going .... WHEN THE GUN IS FIRED there is a spike in pressure filling the valves throat and ultimately launching the pellet or slug. In that very short time span that released pressure travels up threw the partially hollow valve stem and INTO the chamber pressurizing that space. In this instance the poppet which has traveled inward within the chamber via the seat side being lifted is now acted on by the pressure filling chamber and is quickly pushed back down the chamber violently closing the seat. Crazy stuff !! and now with this base knowledge to chew on we will address the purpose of this thread
Understanding the hammer that opened the valve, it's weight mass etc is also holding the poppet from closing very fast being reliant on the Balance chamber to push back so hard the hammers lift on poppet can be stopped with hammer forced to then go back the direction from which it came and allow poppet to close again. This is the tuning trick that for those incline will find HUGE efficiency gains, lower muzzle report and less air used in general at any given power level.
Because these valves have such generous port values, huge throat and transfer path they BREATH SUPER WELL releasing mass volumes of air that produce Really big power !!
Controlling there DWELL ( How long the air is flowing is dwell ) and this is controlled by HOW EFFECTIVE THE BALANCE CHAMBER is to sense the mass flow and SHUT IT DOWN !!!
For once the pellet or slug is underway and moving 1/2 the barrel length or less, releasing more air IS NOT DOING A THING or very little and somewhat caliber & projectile weight dependent.
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
AS WE CONSTRICT THE OUTFLOW or air leaving valves throat we are INCREASING the amount and strength of the air that makes it into the balance chamber / tube and gets the valve to close.
Valve opens EASY and breathes volumes, but control of getting it shut down is paramount to Efficiency & a Low muzzle report.
Below is a test recently done while shooting NSA .22 caliber slugs. hammer weight, stroke, spring tension never changed ONLY TRANSFER PORT SIZE. * Barrel is @24" with an elongated transfer port offering FULL caliber port specs so it to breaths to the bores caliber 100%. Pressure regulated at 2200 psi.
BIG transfer port at .250" being slightly greater than caliber @ 935/940 fps
>Caliber spec transfer port at @ .210" @ 980 fps
Smaller yet transfer port at .175" @ 980 fps
Smaller yet transfer port at .160" @ 960 fps
Smallest transfer port tried at .140" @ 915 fps
Whats really interesting is listening to the gun fire with the top 4 tests especially ( All Shots are exceeding 50 ft lbs ! ) in .22 caliber too. NOISE, that of the residual after the shot released air that is the heard muzzle report.
The largest port arguably having excessive volume poppet to slug and the least efficient with a good WOOOSH sound upon firing. * Still making great power !!
With the .210 transfer the report was notably quieter and as a tuner you know the dwell was reduced. YET it making MORE power ... kewl !
With the .175 transfer the report becomes a muffled SNAP and is quieter yet again. Whoa same power too ! Now I know we're wasting less air and dwell has really been cut back.
With the .160 transfer the report sounds like a 12fpe pcp with LDC ... Sounds like a cricket farting being weirdly concerning the guns power had tanked, yet we only lost 20 fps.
Finally the .140 transfer ... about like the above just less power tho still FLINGING these 24.8 slugs with authority !
With all my testing coming to light in this shared manor, I not going to get into efficiency number beyond a recent check I just did a few days ago. That being when the .210 port was fitted and thought I was done and giggle happy. Efficiency numbers crunched at 1.29 fpe/cu in shooting the NSA 24.8 at the above speed which was Awesome. Having just run these smaller transfer port tests just hours ago ... IT'S EVEN BETTER and going to keep the .160" transfer in place for now and see just what the efficiency does. * Have a fun shoot next weekend and will be shooting the gun quite a bit and able to really gain some extensive real world numbers.
Hope this all makes some sense, was not overly long winded and you gain some knowledge from it
Scott S
To recap on how these valves work ... simply put is by having a DUAL use poppet head, one larger diameter side sealing the valve throat as is typical, Other end being reduced in diameter and extended into a sealed tube / chamber and sealed via an o-ring. * What has happened is the pressure within the valve internal space bearing down on the closed poppet has had PART OF IT'S TOTAL AREA isolated by having the opposing end up in the o-ring sealed chamber. THUS the pressure exerted on the poppet seat is greatly reduced and the valve will break free and open far easier with not only LESS hammer weight, but less strike energy as well ( Softer hammer spring, less hammer stroke etc .. )
While this sounds all good & fine we all like easy cocking fast cyclic actions
Here is where we're going .... WHEN THE GUN IS FIRED there is a spike in pressure filling the valves throat and ultimately launching the pellet or slug. In that very short time span that released pressure travels up threw the partially hollow valve stem and INTO the chamber pressurizing that space. In this instance the poppet which has traveled inward within the chamber via the seat side being lifted is now acted on by the pressure filling chamber and is quickly pushed back down the chamber violently closing the seat. Crazy stuff !! and now with this base knowledge to chew on we will address the purpose of this thread
Understanding the hammer that opened the valve, it's weight mass etc is also holding the poppet from closing very fast being reliant on the Balance chamber to push back so hard the hammers lift on poppet can be stopped with hammer forced to then go back the direction from which it came and allow poppet to close again. This is the tuning trick that for those incline will find HUGE efficiency gains, lower muzzle report and less air used in general at any given power level.
Because these valves have such generous port values, huge throat and transfer path they BREATH SUPER WELL releasing mass volumes of air that produce Really big power !!
Controlling there DWELL ( How long the air is flowing is dwell ) and this is controlled by HOW EFFECTIVE THE BALANCE CHAMBER is to sense the mass flow and SHUT IT DOWN !!!
For once the pellet or slug is underway and moving 1/2 the barrel length or less, releasing more air IS NOT DOING A THING or very little and somewhat caliber & projectile weight dependent.
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
AS WE CONSTRICT THE OUTFLOW or air leaving valves throat we are INCREASING the amount and strength of the air that makes it into the balance chamber / tube and gets the valve to close.
Valve opens EASY and breathes volumes, but control of getting it shut down is paramount to Efficiency & a Low muzzle report.
Below is a test recently done while shooting NSA .22 caliber slugs. hammer weight, stroke, spring tension never changed ONLY TRANSFER PORT SIZE. * Barrel is @24" with an elongated transfer port offering FULL caliber port specs so it to breaths to the bores caliber 100%. Pressure regulated at 2200 psi.
BIG transfer port at .250" being slightly greater than caliber @ 935/940 fps
>Caliber spec transfer port at @ .210" @ 980 fps
Smaller yet transfer port at .175" @ 980 fps
Smaller yet transfer port at .160" @ 960 fps
Smallest transfer port tried at .140" @ 915 fps
Whats really interesting is listening to the gun fire with the top 4 tests especially ( All Shots are exceeding 50 ft lbs ! ) in .22 caliber too. NOISE, that of the residual after the shot released air that is the heard muzzle report.
The largest port arguably having excessive volume poppet to slug and the least efficient with a good WOOOSH sound upon firing. * Still making great power !!
With the .210 transfer the report was notably quieter and as a tuner you know the dwell was reduced. YET it making MORE power ... kewl !
With the .175 transfer the report becomes a muffled SNAP and is quieter yet again. Whoa same power too ! Now I know we're wasting less air and dwell has really been cut back.
With the .160 transfer the report sounds like a 12fpe pcp with LDC ... Sounds like a cricket farting being weirdly concerning the guns power had tanked, yet we only lost 20 fps.
Finally the .140 transfer ... about like the above just less power tho still FLINGING these 24.8 slugs with authority !
With all my testing coming to light in this shared manor, I not going to get into efficiency number beyond a recent check I just did a few days ago. That being when the .210 port was fitted and thought I was done and giggle happy. Efficiency numbers crunched at 1.29 fpe/cu in shooting the NSA 24.8 at the above speed which was Awesome. Having just run these smaller transfer port tests just hours ago ... IT'S EVEN BETTER and going to keep the .160" transfer in place for now and see just what the efficiency does. * Have a fun shoot next weekend and will be shooting the gun quite a bit and able to really gain some extensive real world numbers.
Hope this all makes some sense, was not overly long winded and you gain some knowledge from it
Scott S
