Tuning Should FX recommand not to install the Slug Power Kit on the Impact M3?

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Here is a crude illustration of the three scenarios I was talking about. I think I poorly described "valve opens/closes faster". I am working off the assumption that the total time the valve is open is constant across all scenarios (ex: Keith and Norm both have 700mm barrels with max power tunes). In the end I think these three scenarios are all tied together. If we are getting the same power from 30 bar less pressure, the curve w/spacers has to be bigger, we just don't know the shape of that curve.

  1. valve opens/closes faster while opening travel distance/depth remains the same
  2. valve opens/closes at same speed, but opens more/deeper
  3. valve opens/closes faster AND valve opens more/deeper
    [/LIST=1]



    M3_valve_spacers.1642029042.jpg
 
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TDK, I think it boils down to what hypothesis we use for the curves. Here is what I suggest:

- the valve travel will depend about the initial speed of the valve. The valve will be subject to the force resulting from plenum pressure only. It means it speed will decrease until it reaches its maximum travel, and from here the valve will immediately move in the opposite direction untill the port is closed.

- I believe the force applied on the valve is constant since it is just the plenum pressure times the valve surface. And both are quite constant. According to Isaac Newton constant force means constant second derivative means the curves will be parabolas. My triangles above are just a very gross approximation but you get the idea.
 
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Now a question I have is.Does the depth of the valve opening,contribute to a higher rate of air moving through the valve.. basically like a faucet. Or is it just a open close scenario.? So does a valve open all way for a certain duration flow more cfm than a valve opened Less deep for a longer duration.. if that makes sense..lol seems like it's self explanitory

So I guess the ? Is the does the cfm change with the depth of the valve being opened.




 
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On the X-axis (time) on your graphs you have the valve open for different length of time. I am assuming open time is the same in both cases, hence why they touch the X-axis at exactly the same points on my graphs. I'm was also considering 'OPEN' to start as soon as the valve started moving, rather than when it reached the apex of travel. Same thing for CLOSE. Do you think this is the wrong way to look at it? Air is going to be moving the second that valves comes off the seat after all.

I really want your take on my original assumption. Considering the following:

  • both barrels are 700mm
  • both projectiles leave at the save velocity
  • both tunes are near max

With the above, is it a good assumption that the valve open time will be nearly identical in both cases?
 
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Yes TDK, I agree with the 3 assumption you mentionned above for Keith and Norm rifle, but you are also assuming the open time is the same for both rifle, this may not be true since Keith have less reg pressure than Norm if the open time are the same the slug will get less energy and its speed will be different isn't it?

I'm trying not to make any assumption for the open time and just model the valve opening time for different valve initial speed due to the higher mass of the spacers. In my model the open time is different. I think the model with the parable above can explain different speed and open time at the same reg pressure. According to my calculation we should get about +2.5 % speed increase with the 2 spacers for the same reg pressure. That's about 25 fps.

Does it alows such a massive 30 bar reg pressure reduction for Keith rifle with the same speed as Norm? Certainly not.

Just like you I'm still banging my head on the walls to understand why the power slug kit can give such a massive impact on Keith's rifle: 30 bar reg reduction! Hard to believe. The more I think about it the more I think it cannot be true unless the barrel lenght is different (but both seem to be 700mm on the video) or Keith manometer is damaged or Keith is shooting lighter slugs.

I have the slug power kit, I removed it since I didn't installed it properly and my rifle lost all its power, Now that I understand what I did wrong I will give it another try if I I have time today and post the results for 34 gr .22 patriot slugs.
 
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I spent the whole day testing disassembling and reassembling the rifle and shooting 100 slugs in my bullet trap. Here are the results and my key learning.

Note1: I define the maximum spring preload as the preload you can achieve just one micro click before you can’t anymore cock the rifle.

Note2: in my rifle 1 macro click moves the ladder indicator just like 4 mico clicks, 5 macro click or 20 micro clicks moves the indicator by half a graduation. All this make the number on the macro wheel totally irrelevant to define and compare your setting what really matters is the graduation on the ladder.

Note 3: for all the tests below I kept the original valve spring and didn’ add the small rubber ball of the kit.

  1. Initial settings for maximum speed of my Impact M3 in .22 cal for Patriot 34 grains .217 cal. The rifle is only equipped of the pin probe from the Slug Power Kit: Preg2 = 170b, Spring Maximum Preload= 5.175 (ie one macro click and 3 micro clicks after 5th graduation), Valve =5 turns (ie one full turn after the 4th line). Average Velocity = 990 fps.
  2. One spacer is added. First learning: I could still get the maximum preload at 5,175. My understanding is that the first spacer don’t only add mass but also some spring tension. My hypothesis in the first messages of this thread was wrong. With all other settings being the same, I got an average velocity of 1024 fps . The fist spacer increased the velocity by 34 fps, this is not to be neglected.
  3. The 2 spacers are added: now I can’t get the initial maximum spring preload of 5.175 anymore. The maximum preload is 4.925 (ie 5 th graduation minus 1 macro click plus 1 micro click). My Key learning: the second spacer is not as useful as the first since the spring preload it add need to be decreased on the ladder. There is however some marginal velocity increase: now the average maximum velocity is 1029 fps. Only 5 fps above the velocity for 1 spacer. It is the same order of magnitude than the speedometer precision (I’m using the FX radar). Anyway it' 39 fps above initial settings.
  4. I decided to keep the 2 spacers and adjusted Preg2 in order to achieve the same maximum velocity than the initial settings as in bullet point 1 above. It was achieved for Preg2 = 150 b. Maximum velocity was 991 fps.
    [/LIST=1]

    Key learnings:
    1. Yes the Slug Power Kit adds value to the M3: you can either get an extra 39 fps or decrease your reg pressure by 20 bar while keeping the same slug velocity.
    2. The fist spacer adds much more value than the second. The second spacer may add more speed but that’s quite marginal.
      [/LIST=1]
 
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I guess you folks should convince me to uninstall the power kit. 

😂



It must be inhibiting the performance if I believe all I see here.



So I guess the opposite is required. Take your stock 22 M3 and convert it to 35 without the power kit and let me know if you can reach 150 ft lbs. 



It's a challenge and I'm not afraid to eat crow. I dont have the ego. Do it. 
 
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M0ist0ne said:
Yeah, pin probe is about it. The spacers make the hammer super twangy. You're right about the ball and valve spring. But if FX said all that and their paid shooters were specific that you're only buying the spk for a pin probe...who'd buy it then? 😁
Click to expand...
I’ve got the tungsten hammer weight and there’s just something I don’t like about it. I get a nasty twangy sound when I turn the valve adjuster all the way out also I noticed I lose power if the macro wheel is set to 16 and the micro I can really only go up to around 2.5 or else power lose twangy violent recoil. I’m trying to shoot zan 33 grain with my .25 cal in the 950 -1000 range I’ve got the regs set to 165 1st and 2nd set to 135

.25 cal
600mm heavy liner.
1st reg 165 2nd reg 135
Valve adjuster line 1.5-2
Macro 1 micro ranges between the beginning of the barrel roller to just before 3
Upgrades = heavy liner, huma v2 dual hole transfer port, huma tuning spring, huma pin probe, and tungsten hammer. I want to shoot 33 gr zan slugs.

If anyone would be kind enough to help me I would greatly appreciate it. Thanks for the help
 
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I will add the suggestion that if FX is encouraging you to change the probe, they should include a note with the slug kit stating that the original probe (and it’s holding block - in case you replace with the NSA adjustable) are attached with hex screws and “the worlds most intractable loctite”, such that you’ll end up tearing your hair out and having to drill out the screws or sending your gun in for repair.
 
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