Author Topic: I'm NOT crazy ... am I ? beat my best ever for efficiency (Read 2501 times))

Motorhead · « **on:** September 25, 2018, 07:02:21 PM »

Short recap ... been playing with my long time and heavily modified .177 m-rod getting it ready to convert over to a high power slug shooter. Just fit a new 20" no choke barrel to test and have a modified stock valve in the gun for now. Porting of the valve to barrel tho is FULL BORE SPEC at .175" with the barrel port being oblong in shape. Bolt probe thinned too. Running regulated at @ 1600 psi, a light 14 gram hammer with a SSG devise snaps the valve open super quick. valve is set up with a cobra chamber on poppet so it closes lightning quick too, poppet is PEEK.

Anywho ... was shooting the gun sunday after our FT match and put 120 shots threw it w/o a fill and gun was still on the regulator ... wow thats pretty good i thought

Today decided to test out just how efficient it was shooting ?
Hooked up my test gear to the guns tank and filled it to 2000 psi and then shut all the valves from fill bottle so the only additional air in the system was the 2' of microbore hose and the test gauge ( 10 cc tops )

Took 20 shots over the chrony
Average speed 920 fps
pellet weight 10.5 grains
Guns tank size 250cc * JSAR aluminum w/ extra length * measured HP storage ahead of regulator.
** ending pressure after 20 shots 1850 psi

AVE FPE / Cu In 2.51

using just 8 psi per shot

The gun while you do hear it fire, sounds like a small twig snapping with nearly no muzzle report.

I'm going to do a longer string to double confirm the data ... but feeling and seeing first hand how the guns shoots in count, noise etc it is just sipping air while making some pretty serious power for a 10.5 grain pellet.

If this data is sound .... I am thinking this maybe the first to break that elusive 2.0 AVE FPE / Cu In while operating at a somewhat higher output power. ( not a low power target gun )

Tinker tinker tinker ... its a sickness !!

Scott

PS. A recap of where we've been to this point: https://www.gatewaytoairguns.org/GTA/index.php?topic=140404.0

Hobbyman2007 · « **Reply #1 on:** September 25, 2018, 07:11:54 PM »

Now that is awesome . Your light weight hammer and ssg will no doubt make a difference but I think the SS valve might be the trick for such high numbers .

oldpro · « **Reply #2 on:** September 25, 2018, 07:18:52 PM »

Quote from: Hobbyman2007 on September 25, 2018, 07:11:54 PM

Now that is awesome . Your light weight hammer and ssg will no doubt make a difference but I think the SS valve might be the trick for such high numbers .

The cobra valve is much better suited for what hes doing we have plenty of data to support that I am working on a NEW Cobra valve more on that later but for now congratz but Im not surprised by your efforts your darn good at what you do!

Motorhead · « **Reply #3 on:** September 25, 2018, 07:34:24 PM »

Quote from: Hobbyman2007 on September 25, 2018, 07:11:54 PM

Now that is awesome . Your light weight hammer and ssg will no doubt make a difference but I think the SS valve might be the trick for such high numbers .

No ... the SS valve breaths to heavy and dwells to long for such a small caliber. While it does make some STUPID POWER in .177 ..... efficient is not its strong suit.
Had the SS valve in the .177 last week and it was producing nearly 33 ft lbs of power in a .177 shooting pellets !!
See it Here: https://www.gatewaytoairguns.org/GTA/index.php?topic=148177.msg1511737#msg1511737

Hobbyman2007 · « **Reply #4 on:** September 25, 2018, 07:43:27 PM »

Scott ,

What your saying is you’re not using an SS valve but only the rear section of the cobra valve ? I somehow got the two mixed up .

Motorhead · « **Reply #5 on:** September 25, 2018, 07:52:47 PM »

Quote from: Hobbyman2007 on September 25, 2018, 07:43:27 PM

Scott ,

What your saying is you’re not using an SS valve but only the rear section of the cobra valve ? I somehow got the two mixed up .

The "Cobra Tech" predates the SS valve and was some early R&D that I helped Travis refine and better understand.
See:https://www.gatewaytoairguns.org/GTA/index.php?topic=139401.msg1402661#msg1402661

oldpro · « **Reply #6 on:** September 25, 2018, 07:53:29 PM »

Quote from: Hobbyman2007 on September 25, 2018, 07:43:27 PM

Scott ,

What your saying is you’re not using an SS valve but only the rear section of the cobra valve ? I somehow got the two mixed up .

He made his own Cobra valve.

Hobbyman2007 · « **Reply #7 on:** September 25, 2018, 08:50:25 PM »

I think I’ve finnally understood what is happening inside this valve . Took me a while as I just wasn’t seeing the relationship between cylinder / plenum pressure and pressure inside the pilot cylinder/ cobra cylinder . Thanks for the redirection to the original post on cobra tech . I wouldn’t have understood otherwise . Just great now I’m gonna have to make one or ten . This might just be the cure for the hammer bounce I’m getting with my K550 .

shorty · « **Reply #8 on:** September 25, 2018, 08:56:28 PM »

Sure sounds legit and fairly easy to do with the porting you have along with a SSS or or SSG.

oldpro · « **Reply #9 on:** September 25, 2018, 08:59:28 PM »

Quote from: shorty on September 25, 2018, 08:56:28 PM

Sure sounds legit and fairly easy to do with the porting you have along with a SSS or or SSG.

Easy to do in a 177? I dont think so, Its quite the achievement and to hit 2.5 has never been done with and extended shot count only in short bursts with big bores shooting really slow speeds.

Hobbyman2007 · « **Reply #10 on:** September 25, 2018, 09:13:34 PM »

Shorty , you missed the part in your spreadsheet where Scott filled his gun to 2000 psi. Otherwise ya would be pretty easy.

rsterne · « **Reply #11 on:** September 25, 2018, 10:27:18 PM »

Great job, Scott.... I have been over 2.1 FPE/CI a few times, in lower powered applications.... so I know how difficult it is to get that kind of efficiency....

WELL DONE !!!!

Bob

oldpro · « **Reply #12 on:** September 25, 2018, 10:30:58 PM »

Quote from: rsterne on September 25, 2018, 10:27:18 PM

Great job, Scott.... I have been over 2.1 FPE/CI a few times, in lower powered applications.... so I know how difficult it is to get that kind of efficiency....

WELL DONE !!!!

Bob

Same here Bob I was shooting 357 slugs at 650 fps at high fill pressures not 2k with a small bore thats just Awesome.

rsterne · « **Reply #13 on:** September 25, 2018, 10:38:24 PM »

My best was regulated at 1600 psi, and .22 cal.... but at just under 12 FPE.... 2.12 FPE/CI.... It would be more difficult with a .177 at nearly 20 FPE....

Bob

Jr007 · « **Reply #14 on:** September 26, 2018, 04:22:34 AM »

Hey Scott, Keep up the great work that how you learn to make something better.

WOW
82.4%....efficiency
2.5.........avg FPE/cuin per shot
8............avg PSI used per shot

rsterne · « **Reply #15 on:** September 26, 2018, 01:55:05 PM »

Not wanting to derail the thread.... but perhaps, Jr., you could explain where you came up with that 82.4% efficiency?....

Bob

shorty · « **Reply #16 on:** September 26, 2018, 05:09:03 PM »

Don't mean to side track either. So I will start off with Awesome job Scott. It would be great to see a full string..... I have made the mistake of not using a full fill before when calculating efficiency to nearly .5

Hobbyman, I didn't miss it. Top left is reg setting (1600psi) and the right side is a calculator to estimate shot count based off of efficiency.

Same question about efficiency that Bob has. How did you come up with over 80% ? Since I just learned how Bob does "gun efficiency" I added that into my spreadsheet and it's an eye opener. Where the heck is that potential going ?

Hey Bob,
How about starting up "gun efficiency" post with your ideas of "lost potential" so that we all can get a better understanding of how to improve it.

rsterne · « **Reply #17 on:** September 26, 2018, 08:52:27 PM »

Shorty, it is well covered in my articles in Hard Air Magazine.... Parts 1 through 4 online now, lots more to come....

Bob

oldpro · « **Reply #18 on:** September 26, 2018, 09:07:55 PM »

Quote from: rsterne on September 26, 2018, 08:52:27 PM

Shorty, it is well covered in my articles in Hard Air Magazine.... Parts 1 through 4 online now, lots more to come....

Bob

Link here https://www.gatewaytoairguns.org/GTA/index.php?topic=144675.0

USAFANG6799 · « **Reply #19 on:** September 27, 2018, 12:06:03 AM »

Why not add more helium to air to reach the desired % of efficiency and be done with it?
There seems to be so much give and take when increasing port size and a host of other things. Sounds like this can only be taken so far.
Mixing more helium with air from my novice point of understanding sounds like the logical step.

Bob hope you don't mind I used your drawing for ref for helium vs air.

Chime in please

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I'm NOT crazy ... am I ? beat my best ever for efficiency

Author Topic: I'm NOT crazy ... am I ? beat my best ever for efficiency (Read 2501 times))