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3,366 Posts
Discussion Starter · #1 ·
So back in 2018 or 2019 I made an HPA engine for my old Double Bell VSR-10 and quite liked it, but eventually I got a Wolverine BOLT in a separate gun and the homemade engine broke not long after.
The cause was I didn't use any glue to affix a gasket into a little piston and the gasket came out, and since I pressed and glued the engine together there was no fixing it.
The second failure was the trigger valve, I assume because I didn't know about oils back then and had used WD-40 on the O-rings.
Excuse the terrible camera quality, this was an extremely bad phone.

Fast forward to 2 weeks ago, where I made this here GEN2 engine
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So the major improvements
Not inside of a cylinder, replaces the cylinder
Better nozzle geometry
Better refresh rate
Lower volume (more controllable power)
Better trigger valve
More simple
Cooler looking

So this system is a QEV (Quick Exhaust Valve) with a 2/3 (2 position 3 way) normally open trigger and can output probably 4J with a good length barrel and heavy BBs, and will do so with good FPS consistency.
Not really much else to say except that I'll be putting it in my current ultra custom VSR-10 and selling it once I am pleased with how it shoots, so look forward to that upcoming post if you are interested.

Also, here's a blank firing demonstration

Another thing, you guys are completely allowed to make these if you so desire, but you need an understanding of airguns and air systems.
Still, 13-14 year old me was able to build my first one which lasted 30K shots or so, so it's not rocket science.
For better information on these, look of QEV airgun and QEV pen gun/flashlight gun and maybe try building one of those first as they aren't so hard.

3,366 Posts
Discussion Starter · #7 ·
That's so awesome. Gotta admit it makes a funny noise though
The noise is less noticable when it's in a gun, but it's certainly annoying lol.
It's kinda like hearing someone shooting a PTW and you're totally confused for a bit.
I bet that if I make another piston that's tighter or something then it won't make that noise, but it's not very urgent.
You can easily get 5 plus Joules with a piston valve setup like this if the piston is well made.
Downside is the exhausted air. But the valve is normally way more efficient than a simple solenoid and makes up for it.
My old engine once stuck a .36g BB into a piece of wood when my shitty Redline SFR pressure crept, and that's with a 313X6.01 barrel and a terrible air seal (an AEG bucking inside of an AA chamber because some dipshit said it's good) and I wasn't able to get even a .48g to stick into that piece of wood a few years later even with 3.6J, so that must have been some serious power.
That engine had an air volume that was extremely oversize, so I made this newer one smaller to make it more efficient.
Also seeing as this one is able to be disassembled, you can put plastic or metal discs on the small tube inside, taking up volume and reducing wasted air.
You only want to add spacers until you drop in FPS as you probably know, as then you'd just have to turn up the PSI and then you'd be slightly less efficient.

That's because the higher the PSI the more air comes out of the trigger valve to fire the piston, as the air is more compact.
But yeah, if you lower the PSI and maximize the volume then you will waste less air to fire the piston, and you can tune the volume that goes out the barrel with the before mentioned volume adjusters.

3,366 Posts
Discussion Starter · #9 ·
That's chill lol, I'm not too mad unless it's irrelevant or a bot.

The main valve is what is called a QEV valve.
The trigger valve is a Clippard MJV-O3. The O3 is important, as that means it's a 3 way valve that's normally open.
Any 2/3 valve(2 way 3 position) should work, but these vent air and therefore waste a surprising amount of air, probably enough to fire a BB at decent power.
As for QEV valves, I think that there are much better setups, especially hammer valves, as they have a shorter lifespan and seem less consistent. This engine was rather crude, and there are much better ones available like the electronic BOLT and Mancraft offerings. If you are looking at building a gun from bar stock or are looking to substantially rework an existing gun, building an engine may be good, but for a normal gun or some homemade guns a BOLT will be very good, as routing 2 wires and a switch is infinitely easier than making a decent mechanical trigger, especially in a bullpup or in tight spots.
You could also just get something like a Redline N7 or a Jack, and just shoot like you're a sniper, and you could even limit your semi ROF, but manually operated engines I think have the ability to be more accurate when everything is maxed out, as they have a solid rigid nozzle while semi auto engines have a relatively wobbly and less forceful nozzle.

I am not super big into DIY engines these days as I lack the tooling and CAD skills I would like to make them with, so I struggle on with my BOLT and F2, and have since reused the parts from this engine.
If you want to make an engine, I'd talk to @airsoftbuild or WYZ2285 on here, as they have the skills and tools I lack to make a decent engine, and both have more experience than I.

4 Posts
Thanks for the information! Im a machinist so I have the CAD and cnc skills to get it done. I'll definitely look into some other valves as well! I've already got a krytac lvoa that has a jack. More just moving into the sniper game. Wanting to design and potentially bring some cool stuff to the game.
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