ATI Libert/Freedom Custom valve

[darkcharisma]

so, i have been playing with making and prototyping the best valve for power on my Liberty. these valves when installed can push the 14.3 CPHP closer to 1000fps even without boring the transfer port. if when the transfer port is bored out to 3/16, it still would not go past 1025fps due to lack of volume behind the pellet since the plenum is maxed at 11cc.  that and the valve stem length when pushed at these velocities, it wastes a lot of air.

Mind you, the stem is made of 2mm hss hardened rod. and it is almost twice as long as the OEM stem. what i have found for maximizing FPE is to add hammer weight. inside the spring and hammer, you can add a maximum 1/4 length worth of metal as heavy as you can machine a rod that goes down inside the spring, i recommend 1/2 length long.

So what is the maximum FPE can be attained with this valve? a lot of variables here. Stephens mods can shoot 50fpe with 25 grain pellets by upping regulator pressure, add shims behind hammer spring and porting work.

I have yet to test my new design, which is basically the OEM design but bored out exhaust and larger throat and counter sunk poppet seat with peek poppet and lighter spring. i have hit 45-47fpe maximum before the hammer weight was added. testing time was none existent due to full time work that pushed my lathe time into the early AMs.

So what is this post about? show and tell, and possibly give some details about the new design. so here are the specs

throat: .255
exhaust: .217
stem : 2mm
stem length: 1.35 and .425 from rear of valve

As far as I know. Ray, Matt and Gary will have the new design which has an oem trench cut in the valve. for those who has the old design and wish to upgrade to the new design. send me the valve, i can mill for the trench just as easily. just cover shipping charge which should not exceed $5.

here it is

[wll2506]

so, i have been playing with making and prototyping the best valve for power on my Liberty. these valves when installed can push the 14.3 CPHP closer to 1000fps even without boring the transfer port. if when the transfer port is bored out to 3/16, it still would not go past 1025fps due to lack of volume behind the pellet since the plenum is maxed at 11cc.  that and the valve stem length when pushed at these velocities, it wastes a lot of air.

Mind you, the stem is made of 2mm hss hardened rod. and it is almost twice as long as the OEM stem. what i have found for maximizing FPE is to add hammer weight. inside the spring and hammer, you can add a maximum 1/4 length worth of metal as heavy as you can machine a rod that goes down inside the spring, i recommend 1/2 length long.

So what is the maximum FPE can be attained with this valve? a lot of variables here. Stephens mods can shoot 50fpe with 25 grain pellets by upping regulator pressure, add shims behind hammer spring and porting work.

I have yet to test my new design, which is basically the OEM design but bored out exhaust and larger throat and counter sunk poppet seat with peek poppet and lighter spring. i have hit 45-47fpe maximum before the hammer weight was added. testing time was none existent due to full time work that pushed my lathe time into the early AMs.

So what is this post about? show and tell, and possibly give some details about the new design. so here are the specs

throat: .255
exhaust: .217
stem : 2mm
stem length: 1.35 and .425 from rear of valve

As far as I know. Ray, Matt and Gary will have the new design which has an oem trench cut in the valve. for those who has the old design and wish to upgrade to the new design. send me the valve, i can mill for the trench just as easily. just cover shipping charge which should not exceed $5.

here it is

So do you think by adding a small weight in the hammer area to a pretty much stock gun causing more hammer spring tension and adding weight to slam the poppet open (more momentum), I could gain some fpe ?

wll

[darkcharisma]

I know for sure you will gain some fpe. try finding a hex bolt 1/2 or 3/4 long that fits inside the spring, with the bolt head no more than 1/4 in thickness. 1/4 will max out the spring compression. round the hex sides to fit inside the hammer.

i have tested this and increased 75-100 FPS in the .177 with my valve. my weight is machined from o1 though, so i had to lube to prevent rust.

[Madd Hatter]

Does the trench cut make that much difference?

[darkcharisma]

not by much without mods. the OEM valve can make 50 fpe with oem plenum, port and shims. which i haven't reached yet with my modded oem valve testing. i blew the power wheel after valve mod and testing went on halt fast.

in theory, the trench holds another 1/2 to 1 cc worth of space after the valve shuts. but does that help push pellets faster when that extra cc expands? i have yet to test it but if the oem valve with the same design can do 50fpe, i am betting my valve can match it or beat it with other mods. i have to be careful NOT to port too much since 11cc will expand and probably loose pressure in the larger ports before reaching the pellet.

extensive testing is due when i am back from vacay

[BigBird]

Nice work.  Couple questions, does this fit a freedom? Does the trench cause an area of more volume before the TP?  I dont know how this fits in the gun.

So your poppet is not convex on the front and is epoxied?  Is the peak poppet tapped?  I am just trying to get ideas about how your valve works for research.

[Madd Hatter]

Is it really a vacy if you miss home? What size bolt do you use to weight the hammer and what size do you do you grind the head down to? 3/8 on the head? Do you sell a replacement for the power wheel? Don't want it to be a restriction from the valve to the tp. I'm not looking to drill out the port in the receiver just want a smooth port heading up from the valve to the tp. I use to do all of my own cylinder head (4) and cylinder (2) porting myself and didn't really hog out the ports but just removed any abrupt changes in the ports flow. Here's the one off of my 1995 KTM 550 that because it ONLY? had 61 HP to the rear wheel and just had to port the cylinder. lol By the way that's a 92.25 mm bore.

[cosmic]

I believe the Liberty and the Freedom valves are the same part number..

[cosmic]

Nice massage Bob...

[rsterne]

I don't see the reason for cutting the "trench" around the exhaust port.... Since it is downstream of the poppet, it adds (wasted) volume between the poppet and pellet.... That decreases the pressure available to accelerate the pellet throughout the shot.... If you are gaining performance with JUST the trench, compared to an identical valve with the round exhaust port.... and the diameter of the exhaust port matches the port leading to the barrel.... it must be because of less resistance to flow when the air it turning the corner from the valve throat to the exhaust port.... Normally I would expect a decrease in performance by adding volume between the poppet (valve seat) and the pellet....

What does the porting look like between the trench and the pellet?....

Bob

[Madd Hatter]

Nice massage Bob...

Just one of many!

[AVS Stephen]

Hey Duy that is very impressive. I have one suggestion. I have been thinking that one way to increase flow would be to have a ramp at the base of the valve so that air could flow more smoothly from the Airguns tube/plenum through the valve and up the transfer port. Sort like a bent piece of pipe at a 90 degree angle.

To my way of thinking, the air leaves the plenum throught valve and slams into a wall at the back of the valve then rushes upwards toward the barrel. What kind of efficiency can be had by making the 90 degree turn smooth?

I hope that makes sense. If not I can make a drawing that might explain it better.

[darkcharisma]

Dan, more areas before TP, 2mm reamed and epoxied in poppet, as straight as possible. same part number so it should fit. but if someone post a picture of the Freedom i can verify.

Robert, missed home because total change of scenery, and was not impressed with Garden Groove area and their food. we traveling with another family and been tagging along, but we finally went hiking and sight seeing i stead of indoor activities like museums, and theaters.

Bob, glad to have your opinions here. quick question. is .217 appropriate with .255 throat and 2mm stem?

so i made a previous one hole exhaust .217 and .255 throat with a 15 degree bevel and longer stem, but no counter sunk seat. that valve did not push to 50 fpe compared to Stephen's simple mods like hammer shims, 3/16 TP port, upping reg pressure with his oem valve. things could be different between us are shimming and reg pressure since we have no gauge read and i was double feeing pellets instead of shooting the same pellets for comparison.

The current trench port looks .217 or .255 rounded squared, no bevels. i would think without the straight shot it would loose pressure and speed when filling in "wasted" area due to turbulence and all that jazz. but having more area between the pellet and poppet, wouldn't that give it more air to expand also?

i don't understand it fully but this OEM style trench was probably cut for easy assembling and aligning of the ports. i doubt its a design to maximize fpe. but it seems to do better than my bored out design with the above comparison. i havent tested my new trench valve myself but will make another pair of old and nee design to test later on and compared results to the first pair sent out to Matt.

[darkcharisma]

Hey Stephen

Yes please draw for visualizations.

i was also thinking of beveling the plenums threaded sections for better flow. the threaded section sticks into the main plenum a little bit so i do t think beveling will jeopardize its strength. please draw the ramp

also wanna add plenums, yes plurals on the 3 sides on the block... like this  , maybe not lol.

[Madd Hatter]

Think what Stephen is thinking is like the exhaust port of a 4 stroke engine . I don't believe it would result in much of a increase in power due to the pressures involved. The exhaust gasses from an engine don't come close to the lowest pressure we use in the Liberty. IMHO  The complex machining involved just wouldn't be worth the insignificant gains.

[darkcharisma]

i am game for new ideas. post a drawing or blue print and see if i can make it and test it. is it something like this?

[AVS Stephen]

i am game for new ideas. post a drawing or blue print and see if i can make it and test it. is it something like this?

Hey Duy, Yes. but In my head the most efficient is smooth. I understand there is no easy way to create a smooth turn as I have drawn without doing it by hand or creating a mold of  the valve.

It's just a theory and Im not sure if it will be worth the effort.

[darkcharisma]

i have thought of something like that also but all the way to the pellet. see drawing below.

i think your idea is more doable. i can mill that radius on the rotary table to a perfect round smooth radius with a ball mill. the only thing is the valve need be cut in half before milling. two problem arises.
 1) the counter sunk seat.
2) the sealing oring on the OD of valve.

remedy for problem 1 will be to epoxy the valve halves and machine a separate seat and epoxy that in so there wont be a leak through the cut surfaces. the cut lines in the oring groove can probably be epoxy too.

my idea can be used on a custom receiver it self with some extensive sealing technique of the halves.

this will challenge my zeroing and truing techniques on the mill and lathe...i wonder if it can be replicated to produce many more like it or just a one of a kind

[Madd Hatter]

Get to know your edge finder and dial indicator real well my friend! lol

You know, I always thought a pellet was suppose to shot out of a straight barrel? 

[Madd Hatter]

so, i have been playing with making and prototyping the best valve for power on my Liberty. these valves when installed can push the 14.3 CPHP closer to 1000fps even without boring the transfer port. if when the transfer port is bored out to 3/16, it still would not go past 1025fps due to lack of volume behind the pellet since the plenum is maxed at 11cc.  that and the valve stem length when pushed at these velocities, it wastes a lot of air.

Mind you, the stem is made of 2mm hss hardened rod. and it is almost twice as long as the OEM stem. what i have found for maximizing FPE is to add hammer weight. inside the spring and hammer, you can add a maximum 1/4 length worth of metal as heavy as you can machine a rod that goes down inside the spring, i recommend 1/2 length long.

So what is the maximum FPE can be attained with this valve? a lot of variables here. Stephens mods can shoot 50fpe with 25 grain pellets by upping regulator pressure, add shims behind hammer spring and porting work.

I have yet to test my new design, which is basically the OEM design but bored out exhaust and larger throat and counter sunk poppet seat with peek poppet and lighter spring. i have hit 45-47fpe maximum before the hammer weight was added. testing time was none existent due to full time work that pushed my lathe time into the early AMs.

So what is this post about? show and tell, and possibly give some details about the new design. so here are the specs

throat: .255
exhaust: .217
stem : 2mm
stem length: 1.35 and .425 from rear of valve

As far as I know. Ray, Matt and Gary will have the new design which has an oem trench cut in the valve. for those who has the old design and wish to upgrade to the new design. send me the valve, i can mill for the trench just as easily. just cover shipping charge which should not exceed $5.

here it is

You know, I'm looking at my valve and I think I'll radius the exhaust port some on the inside of the valve to make it a little more smooth transition. Mainly toward where the poppet seals. Instead of going crazy with making halves and then trying to seal them why not just do a angle exhaust port  and using a porting tool smooth the transition? It wouldn't be more than a 10 or 15 min. job. You'd just have to leave a little extra material so it can be smoothed.

Here's what your flow should look like. https://www.physicsforums.com/threads/air-flow-through-a-90-degree-bend.185436/