vented or non vented cylinder ca sa58

[screwdriver]

doing a tune up on the above but noticed the guns got a unvented cylinder ,thought short barrel guns should be vented . does it make any difference to power output, not interested in rate of fire ,barrel is just over 300mm long

[The Keeper of Secrets]

Re: vented or non vented cylinder ca sa58

Tech section.

Yes, I would recomend a vented cylinder. You could probably get away with an unvented one though.

The vented one wil cause a drop in fps.

[cyberi4n]

Re: vented or non vented cylinder ca sa58

Out of curiosity what's the theory behind this?

[The Keeper of Secrets]

Re: vented or non vented cylinder ca sa58

I like this one,

If the cylinder is too short, the bb will still be in the barrel and will experience negative pressure behind it as the piston is drawn back. The vented cylinder prevents this.

[screwdriver]

Re: vented or non vented cylinder ca sa58

thanks for your reply i know this should really be in the tech section, but ive got the gun apart and was worried it had the wrong cylinder fitted so was hoping for a quick answer before i put it back together as the tech section doesnt seem to move along as quick as this one.

[cyberi4n]

Re: vented or non vented cylinder ca sa58

but isn't the cylinder the same size regardless of barrel length? My old M4 with a 363mm barrel had a vented cylinder, the M15 with a 510mm barrel did not, yet both pistons were exactly the same length and diameter and sat in identical V2 GBXs?!? :s

[The Keeper of Secrets]

Re: vented or non vented cylinder ca sa58

Yeah, but the vent stops the pullback creating suction. the air pressure is removed by the vent.

Also, with short barrels, it means that the first part of the air is unused, so all the air coming out of the cylinder is used to power the bb. If the cylinder is unported, all the air is used to push the bb out, and when it exits (with the piston only halfway down), the resistance it provided against the piston is removed, so it slams into the cylinder head, causing damage.

[Barny Hamon]

Re: vented or non vented cylinder ca sa58

I seem to agree with this theory,

The piston compresses air and forces the bb out of the barrel, if the cylinder is not vented with a short barrel, the bb will exit the barrel before the piston has compressed all the way, thus not allowing full potential from the spring (reduced FPS).

With a vented cylinder the piston does not start compressing air until it is passed the vent in the cylinder, thus making sure that the piston finishes the compressing cycle as the bb exits the barrel.


and also what TKOS said as well.

[screwdriver]

Re: vented or non vented cylinder ca sa58

so what barrel lengths for ported /un ported cylinders

[The Keeper of Secrets]

Re: vented or non vented cylinder ca sa58

I don't know. Google, they'll be a guide. Some cylinders are ported designed for specific gun barrel lengths, which will be in the product description.

[MajorLandmark]

Re: vented or non vented cylinder ca sa58

Thats not an easy question to answer, because its also a question of rof... A high rate of fire will cause suckback sooner... So a long barrel with a high rof will cause issues... A short barrel with a low rof will have almost no issues.

Generally speaking, a ported cylinder is always a better idea in any upgraded gun. Anything thats running a stock TM spring at about 8.4V will be fine with an unported one taking an M4 barrel length or shorter. Anything with a longer barrel/faster rof than that, and a ported one is a much better idea.

Thats a rough guide... its not actually a massive factor for most guns... it only matters when suckback is an issue causing drastically lower fps as a result.

[cyberi4n]

Re: vented or non vented cylinder ca sa58

gotcha - cheers