Tuning Air Venturi Avenger upgrade/mod help

[heavy-impact]

Has anyone considered using a threaded disposable C02 cylinder as a plenum to save some time? You'd just need to make a bushing to fit.
Or you can use an inline filter housing and a close nipple. I believe I was first to do that on an impact before designing a larger one. You can put an air bleed in the bottom rather than a gauge. This one came from my first Yong Heng compressor.

 

[paul67]

That's good to know. I was hoping to get to 80+ft/lbs and now I know it's achievable. I don't know how big you went with the valve / poppet but I'll be going 7mm (5.9mm being the max with the OE poppet) with a new peek poppet to match. I'll also be using the 25cc plemum.

I did some 'out of the box' shots last night to see where my new .25 is at and also used the Seneca 43gr pellets. Averaged 53ft/lbs. I can understand slugs holding back as they have way more surface area engaging the rifling = more friction BUT they'll carry more of that energy down range.

Upping the muzzle fpe of slugs will probably require finding a smaller dia slug that engages the rifling less but you'll also have more pressure losses around the slug too.....

Glad you like the plemum

I Haven’t done the poppet yet. Sounds like that should be my next project. I’ll have to figure out exactly what needs to be done.

 

[Reidy]

Has anyone considered using a threaded disposable C02 cylinder as a plenum to save some time? You'd just need to make a bushing to fit.
Or you can use an inline filter housing and a close nipple. I believe I was first to do that on an impact before designing a larger one. You can put an air bleed in the bottom rather than a gauge. This one came from my first Yong Heng compressor.
View attachment 311209

An inline filter housing is a pretty good idea. The CO2 bulb though I don't think it's capable of taking 3000psi is it?

 

[heavy-impact]

An inline filter housing is a pretty good idea. The CO2 bulb though I don't think it's capable of taking 3000psi is it?

I doubt it's rated for it but they're seamless hydroformed steel and should be capable. Better safe than sorry though, I just remembered c02 is stored as liquid and the pressure is much lower. I can't find any test info.

 

[paul67]

I just measured it and it’s 33 cc

 

[MongooseV8]

80fpe is for the .25 you can get in the 50's with the .22. Not hears of anyone breaking the 60's yet but it wouldn't surprise me if someone has .

Yeah Numiza on youtube said he is getting ~58fpe from his 22 cal. I think he has done everything you guys have mentioned, but he is using the much smaller Doux 11.4cc plenum. So I think over 60fpe is possible but havent seen any reports either. But like I said, Im shooting for 30fpe and high shot count =)

 

[paul67]

I did the barrel port but not the transfer port yet.

 

[revenger]

I did the barrel port but not the transfer port yet.

Definitely worth while upgrade. Did mine at 7/32"

 

[paul67]

It looks good I like it.

 

[paul67]

Definitely worth while upgrade. Did mine at 7/32"

I just got my transfer port done I’ll test it tomorrow. Without any upgrades I was getting 913 fps with the 25.39 Jsb. With the 33 cc plenum it raised to 968 fps, tomorrow we will see what opening the transfer port to 7/32 gets me.

 

[MongooseV8]

Nice you guys are getting some great numbers out of the 25cal

 

[paul67]

At 2000 psi on the regulator and 2 turns in on the hammer spring I’m getting 980 fps. At 2200 on the regulator and 4 turns in on the hammer spring I was getting 913 fps before the modifications. It started to rain, so I never got a chance to really see what it’s capable of at the same settings, tomorrow’s supposed to be clear, so I’ll get a chance to really test things out. Right now the way it sits that’s 54FPE. This rifle was underpowered compared to what other people were getting with theirs So I’m happy with the results so far. I’d like to be able to get the FPS up to 900 or around there for the FX hybrid slugs my barrel likes them but I can’t push them Fast enough, same with the jsb 33.95 I can’t push them fast enough.

 

[revenger]

At 2000 psi on the regulator and 2 turns in on the hammer spring I’m getting 980 fps. At 2200 on the regulator and 4 turns in on the hammer spring I was getting 913 fps before the modifications. It started to rain, so I never got a chance to really see what it’s capable of at the same settings, tomorrow’s supposed to be clear, so I get a chance to really test things out. Right now the way it sits that’s 54FPE this rifle was underpowered compared to what other people were getting was theirs. So I’m happy what’s th Right now the way it sits that’s 54FPE this rifle was underpowered compared to what other people were getting was theirs. So I’m happy with the results so far. I’d like to be able to get the FPS up to 900 or around there for the FX hybrid slugs my barrel likes them but I can’t push them Fast enough, same with the jsb 33.95 I can’t push them fast enough.

If you haven't yet, you need to do the barrel port too. Drill to 7/32 but oval it out a bit lengthwise. Make sure to file all the sharp edges down. The biggest gain you will see is is porting the valve to 15/64 or 5.9mm along with installing a much lighter valve return spring. The spring is something metric, however just go to hardware store and get some 3/8" springs in varying wire diameter and length. When you find the right one it will do over 70 FPE with jsb 33.95's. will do over 80 FPE with Seneca 43.2 pellets.

 

[paul67]

If you haven't yet, you need to do the barrel port too. Drill to 7/32 but oval it out a bit lengthwise. Make sure to file all the sharp edges down. The biggest gain you will see is is porting the valve to 15/64 or 5.9mm along with installing a much lighter valve return spring. The spring is something metric, however just go to hardware store and get some 3/8" springs in varying wire diameter and length. When you find the right one it will do over 70 FPE with jsb 33.95's. will do over 80 FPE with Seneca 43.2 pellets.

Thanks revenger for the advice. I haven’t found much information what I take apart to get to the valve. Do you have any pointers I would like to take it apart tonight and do the modification.

 

[revenger]

Thanks revenger for the advice. I haven’t found much information what I take apart to get to the valve. Do you have any pointers I would like to take it apart tonight and do the modification.

AVS on YouTube has a good disassembly video of the avenger. I had mine apart like 10 times but couldn't give you perfect instructions.

 

[heavy-impact]

I'll start his very long video at the disassembly for you.

 

[revenger]

For reference you do not need to remove that black plastic cover from the main block.. plus it's near impossible to remove.

 

[paul67]

Maybe I will get a chance to do poppet seat part next weekend. Thanks for the info.
I’m really surprised at how powerful it has become and I’m not even pushing it. Today I shot the 25.39 and with the regulator set at only 2100 I got 1022. The mods have really increased the power and efficiency I got several duplicate velocities. At the same regulator settings the 33.95 got 917 FPS That’s 63.4 fpe ! This is what I was aiming for being able to push The pellets and slugs to the optimal fps and not having to max out the rifle to get there. The groups for the 33.95s really tightened up when I was able to push them to 900 FPS.

 

[revenger]

You will find that they group well even over 950. I shoot mine at around 975 fps and they are very accurate.

 

[paul67]

You will find that they group well even over 950. I shoot mine at around 975 fps and they are very accurate.

That’s great to know I’ll have to try them at higher speeds.