EVOL New Plenum Extensions - Increase Efficiency/Power Potential

[Pumacarl]

That is seriously awesome! I am shooting them around 850 and they fly well. I like the 860-875fps-890 zone for most pellet shooting if I can get the gun there without having to push it too hard. These plenums will provide endless hours of entertainment, that's for sure. That looks like a pretty stable shooting stick setup that you've got there too.
Edit: I just ran some numbers on Strelok and at 943fps the Zans are just about same (trajectory-wise) as the FX Hybrids at 905fps out to 190y. For a pellet to fly the same trajectory as a pellet, at any speed, is pretty good. Obviously, the B.C. of the pellet has to be increasing to .07 if it's matching the hybrid, very interesting!

 

[Pumacarl]

I can just picture myself falling down a parts rabbit hole, if this keeps up!

 

[American Air Arms]

Tom what kind of range are you guys seeing shooting the 56br out of the 18" evol? I heard when the tune is on point these pellets fly quite far.

Superb accuracy to 150 yards. BC measures at 0.078. I use 0.051 for a JSB 44. Also, they like to fly fast. Under 905 fps yield so so results.

This was 150 yard testing in average to poor conditions.

 

[Pumacarl]

Alrighty then! That is the highest B.C. that I have seen for a pellet, and beats the FX Hybrids too, at least what mine are doing. Just so-so under 905fps Tom? I have only been running at 800fps and 846fps, and they have been on the really great side of accuracy to me. I can't wait to say that I was actually shooting poorly up to now, when I try the bigger plenums!

 

[Dairyboy]

Superb accuracy to 150 yards. BC measures at 0.078. I use 0.051 for a JSB 44. Also, they like to fly fast. Under 905 fps yield so so results.

This was 150 yard testing in average to poor conditions.


View attachment 751

I might need a .30 in my life

 

[CTAirgunner]

I might need a .30 in my life

I already know a .30 paradigm is mine

Ugh man, when that happens you guys won't hear from me for a while! Too busy shootin!

 

[ctshooter]

Tom - current tune on my 15" .22 EVOL is 2200psi with the 25gr RDM @ 900fps and NSA 23gr @ 930fps. Do you think there is any benefit to be gained from a plenum extension to try and get the RDM up a bit higher in speed? Would like to hit 920-930 fps if possible.

If so, what size plenum would you recommend? If not, do you think I could get there with a little more reg?

 

[Pumacarl]

I might need a .30 in my life

You really don't, but they are just so fun to shoot at long range! It's the size, and how easy it is to see them fly, especially the shiny FX Hybrids. I had really liked my .25 shooting the 34gr MkII's before for this, but there is really no comparison, especially when you factor in the extra smack you get on target. Yeah, yeah, yeah, -it's more expensive, it uses more air, so what?, it's more fun too! You've got to pay to play.

 

[Dairyboy]

You really don't, but they are just so fun to shoot at long range! It's the size, and how easy it is to see them fly, especially the shiny FX Hybrids. I had really liked my .25 shooting the 34gr MkII's before for this, but there is really no comparison, especially when you factor in the extra smack you get on target. Yeah, yeah, yeah, -it's more expensive, it uses more air, so what?, it's more fun too! You've got to pay to play.

Lol oh I've had .30s in the past and I agree 100%. Honestly it's my favorite caliber to shoot. Just so fun when it smacks and silly big for a pellet. But practically I don't need anything more than a 30fpe .22. So that's all I shoot is .22. I havent owned a .30 in probably 2 years now but if I were to get one the Evol is the obvious choice lol. .25 I never got into either. Never stuck with me.

 

[Pumacarl]

Lol oh I've had .30s in the past and I agree 100%. Honestly it's my favorite caliber to shoot. Just so fun when it smacks and silly big for a pellet. But practically I don't need anything more than a 30fpe .22. So that's all I shoot is .22. I havent owned a .30 in probably 2 years now but if I were to get one the Evol is the obvious choice lol. .25 I never got into either. Never stuck with me.

I'll tell you what though, if I was forced to pick only one pellet for everything that I want to do with an airgun, it would be the .25 34gr JSB w/o a moments hesitation. I don't think I'll ever change my mind on that, but because I have choices I still shoot 5x as much JSB 18.13gr pellets as everything else combined. The .30 is on a whole different tier compared to the smaller calibers, it doesn't really feel like an airgun anymore. I am a lot more concerned about where I'm shooting it, but it can't quite compete with my rimfires. It is a blast, that's for sure.

 

[Pnwairgunner]

This is an internal plenum like huma air does with their xl plenum. The more plenum, the less tube left for air capacity. You would get diminishing returns after the initial install methinks. I’m sure Tom put a lot of research into size to make sure shot count didn’t suffer.

I looked again at the extensions and can now see what you are describing.
Initially I thought these were more of an extension to the reservoir, just on the other side of the reg. But these are basically moving the regulator back into the reservoir to accomplish more plenum. Thanks Madeintheuk!

 

[Dairyboy]

I'll tell you what though, if I was forced to pick only one pellet for everything that I want to do with an airgun, it would be the .25 34gr JSB w/o a moments hesitation. I don't think I'll ever change my mind on that, but because I have choices I still shoot 5x as much JSB 18.13gr pellets as everything else combined. The .30 is on a whole different tier compared to the smaller calibers, it doesn't really feel like an airgun anymore. I am a lot more concerned about where I'm shooting it, but it can't quite compete with my rimfires. It is a blast, that's for sure.

With how well there BC is I definitely have thought about a .25 shooting those. Around 820fps would give me the same trajectory I've been used to for years of around 890fps with 16gr pellets, yet wind deflection would be way better. But yeah .30 is no game. Mainly why I stopped shooting them. Too dangerous around all our cows. Honestly what I would absolutely love if I could get a .20 for the heavy .20 15.89gr pellets. They have a really good BC and tend fly very very well. But no high end guns have the option gotta do it yourself.

 

[American Air Arms]

Tom - current tune on my 15" .22 EVOL is 2200psi with the 25gr RDM @ 900fps and NSA 23gr @ 930fps. Do you think there is any benefit to be gained from a plenum extension to try and get the RDM up a bit higher in speed? Would like to hit 920-930 fps if possible.

If so, what size plenum would you recommend? If not, do you think I could get there with a little more reg?

I have not tested very many combinations and honestly a lot of this work will be left to those who wish to tinker. I would say as you approach 50 fpe there may some gains from an increase average plenum pressure during the shot cycle.

4 or 5 years ago I had a conversation with Lloyd Sikes (credited for the first direct action electronic valve in the Rouge) about what he called the magic plenum volume. A volume where the efficiency jumps way up - like 50%. Not too small and not too large. We spent a long time postulating why and I sure I'm no smarter on this subject today. The point is massive plenums have little to offer unless massive power is being attained. Tuning is matching the plenum volume to your mass flow through the system.

 

[American Air Arms]

I looked again at the extensions and can now see what you are describing.
Initially I thought these were more of an extension to the reservoir, just on the other side of the reg. But these are basically moving the regulator back into the reservoir to accomplish more plenum. Thanks Madeintheuk!

Yes. I'm sure most are aware that the plenum only releases a portion of is charge during the shot cycle. So increased charge air in plenum that is taken from the now smaller HP reservoir is not lost, it is partially residing in the unspent charge in the plenum after the shot cycle. This is why we can increase the plenum without negatively affect shot count if we think it through. As I stated before, an overly large plenum compared to the mass flow of the system offers no advantages.

 

[CTAirgunner]

I'll tell you what though, if I was forced to pick only one pellet for everything that I want to do with an airgun, it would be the .25 34gr JSB w/o a moments hesitation. I don't think I'll ever change my mind on that, but because I have choices I still shoot 5x as much JSB 18.13gr pellets as everything else combined. The .30 is on a whole different tier compared to the smaller calibers, it doesn't really feel like an airgun anymore. I am a lot more concerned about where I'm shooting it, but it can't quite compete with my rimfires. It is a blast, that's for sure.

Recently learned to love the 18.13 lol the 33.95 .25 is by far the most underrated pellet out there, it is my FAVORITE round.

 

[AtlasAirguns]

There many are tuning accessories coming for existing EVOLs, these plenum extenders are just the start! If you are operating at the top of power range, these extenders will offer some pleasant performance advantages when used correctly. For example: adding the 27 Cc extender to a 30 cal will yield ~15fps with no loss of shot count.

These will be available to purchase from your favorite dealer or on our website in about two weeks.

View attachment 637

Wow that is amazing Tom!

 

[Pumacarl]

I spent some time today reading a lot of Bob Sterne's old threads on plenum size and efficiency and yeah, I am definately getting a 42cc plenum extension the moment I can. I'm not going to wait. I will make my own observations conclusions and let you all know how it works out. It would be great if the dealers getting these in, that are active here, would post to the thread when they get them, to give us a chance to pounce on them right away... hint, hint Thanks!

UPDATE EDIT: [I did do my testing: EVOL - Evol .30 18" shot count] TL/DR: Std Evol .30 not ported or sprung enough to make even the 27cc worth it to me, these extensions are for the HPS, just like Tom said.

 

[bobgm3]

I checked with Atlas Airguns yesterday to see if he had received any plenums. He contacted his distributor and they have not received them yet. I'm not a patient person, lol, and I'm really anxious to get my hands on the 42mm for my .30!!

 

[Pumacarl]

I checked with Atlas Airguns yesterday to see if he had received any plenums. He contacted his distributor and they have not received them yet. I'm not a patient person, lol, and I'm really anxious to get my hands on the 42mm for my .30!!

Get in line, I think I called him first! ha ha

 

[Madeintheuk]

I just got a 30! I’m third!!