Cylinder Porting vs Barrel Length

Chris Trivane at Replay Airsoft experiments with various combinations of barrel lengths and cylinder porting to find the best performance.
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[@anomalyp8584]

Waw....just....Waw. can't imagine the effort that has gone into this. This is solid research the community needs!!

[@Judiiine]

These tests were terrific, now we need a series that involves Springs up to m150 since you began these tests with an M100

[@alejandroarriagada3991]

Loved your style. Actually as an engineer I must add the porting, as well as in any 2 stroke engine is for venting air rapidly into a high velocity piston situation. If you compare the ports on the piston head traveling fast as hell backwards...is not much air that can get into the cylinder. Same applies for the cylinder head inner barrel. So porting has the mission to let air to be squeezed into the cylinder, dragged by the void pressure generated by the expanding volume of the cylinder versus the piston travel, minus the little air that can fit through the aforementioned vents and the compressible nature of air.

[@warrenwilson6345]

Can you do the same but also testing out different weights of BBs? I keep hearing that with non ported cylinders or those that are ported for longer barrels than what you have, that there will be joule creep. It would be interesting to see the results of doing the same in this video but with all the available BB weights.

[@kord2003]

Fantastic study! I will recommend this video for my airsoft buddies.

[@justintcov2402]

Thanks this video is great. I have a QD barrel with 3 different length options: 150mm, 190mm, and 260mm. This video helped me determine about how much porting I’ll need for all 3 lengths. If you do enough testing we could extrapolate a correct barrel to cylinder ratio. I wonder if barrel width makes a difference though.

[@Solidsnake0208]

Great bit of testing here, that not many of us can do without spending a small fortune on parts, but for a store this is much easier. There is and has been a lot of info on this for many years online, however much of the info surrounds ideal volume ratios for 0.2g BBS, there’s a a great thread on an airsoft sniper forum where a guy posted the ideal barrel lengths for each BB weight. I’d suggest you go over your testing again, but try new BB weights and see what happens. You should see that heavier BBS favour higher cylinder to barrel volume ratios, meaning for the same cylinder volume they prefer a shorter barrel than a lighter BB. OR for the same length of barrel, a heavier BB prefers a larger cylinder volume.

[@grussmisk]

Thx... love your videos 👍

[@rcrobturbo9433]

love the channel ! awesome job , I love your tests

[@alexandrubogdan917]

As for the longer barrels it's logic that a cylinder with bigger porting is worse because you also have to push the air infront of the BB out of the barrel = smaller velocity

[@airsoftfantom]

great test, thank You

[@JeremyStretz2146]

Please so more test videos with more parts please like different pistons and piston heads these videos are vary informative thank you

[@gabrielbarile73]

Amazing thanks!

[@abc121xyz]

Can you test the larger than 200mm with a stronger spring? I think that you lost power on the last cylinder because the piston didn't had the momentum due to a maxed out spring, so if you put a stronger spring you might not see a drop in fps. What I think it is happening is just like with HPA ,that you have a high pressure flow of little air volume in a short amount of time

[@friton6969]

Yheah

[@giuroy]

interesting video but there are some issues: 1) as others mentioned you are not considering the BB weight and that will affect the best cylinder:barrel ratio; 2) your displacement calculation is considering the cylinder volume and not the actual piston displacement during the stroke. this is an issue when calculating the best volume ratio based on bb weights. would be interesting also to consider piston assembly weight variation and spring strength if you can rectify the above then it'll be the ultimate volume guide.

[@Chretze]

Testing each barrel with different BB weights would be extremely interesting. I'm assuming you've used a fairly light BB weight, possibly 0.2g for all these tests, which would explain the result that at long barrel lengths there'd be almost no fps variation as long as there was more than a given threshold of cylinder volume available. My theory is that the BBs will have left the barrel before the cylinder hit the cylinder head, meaning that only a portion of the cylinder volume could actually be used to accelerate the BB. My bet is that this would change with heavier BBs as they take more time to accelerate, will stay in the barrel long enough for the pistonhead to reach the cylinder head so the full volume of the cylinder is used to accelerate the BB. This will result in more Joules, this is known as Joule creep.

[@snugglezbrah5558]

Can you do tests with the different cylinders, barrels and spring weights?

[@fubene5495]

Generally speaking, you have to match your cylinder volume with your barrel volume, if you have a barrel with a 15cc volume you need a cylinder with an usuable 15cc capacity (the cylinder head reduces the volume, aswell as pads or sorbopads, so you have to bear that in mind). Thats why 400mm is the longer recomended lenght, because its easy to match the volume, if you have a longer barrel like a 509 or even a 610 you need a god damn perfect seal between your piston head and cylinder just from the start of the piston travel or you will be outvolumed (if this word exists XD) Maybe you didnt notice such a variation in FPS when overvolume short barrels, but the accuracy will be affected as there is still air pushing the bb when its going out of the barrel, if you correctly match the volumens the bb will fly free just as it leaves the barrel.

[@alejandroarriagada3991]

Actually the volume ratio from cylinder versus barrel should go around 1.5:1. Bigger ratio for heavier bb, never surpassing 0.3g bbs.

[@BTMonarch]

...not exactly. The useful work of energy to accelerate the ball may differ. For example, when using 0.32 balls I had 1.56 joules (this is the maximum allowed value during the game), but with 0.2 balls this value was higher (outside the allowed limit). And what’s even worse, the sound of the gearbox itself at 0.2 balls was very bad and was accompanied by very strong beatings (causing damage to the gearbox). Arcturus AR15 280mm internal barrel.

[@alexandrubogdan917]

Also if you have a gun with a longer barrel and big port cylinder you can improve the velocity by cutting you barrel shorter

[@TheSLFloW]

Very nice and detailed comparison, i am happy that you continue with this and make video Nr. 2 🙂 We see from this video that useful and peak for top lenght of barell is between 300-400mm so ideal 350 for max reachable FPS - of coarse for defined spring force. Thats why we have longer barells :D But i am very curious whatr about differences between 200-300mm, because there is some "knee" in graph between cylinder port nr. 4 and nr. 5 (blue vs purple) - you see it :) one mistake at begin in cubic cm on graph between 3 and 4 cylinder right? :-) because hole is more away from cylinder head on 3 than 4, so logically can not have less air volume. And I hope you know that it doesn't matter how big the port is, it only matters where it is located. Also cylinder head is important, because there are many types 1-o-ring / 2-o-ring / plasti/ metal and so on, so they differs with volume which take from cylinder itself. but i appreciate that you compare identical things and only one variable differs :) cylinder or barell 👍 What bore is used in new black barells? old were all 6,08?

[@captain_pies235]

Hey, great Work! Can you provide the the inner diameter of the barrels as well ? This way one could calculate the cylinder to barrel volume ratio which is probably a better measurement to compare. None the less, I love the scientific approach to the topic! That's quite rare in Airsoft.

[@Timon.Landewe]

Can you please make a video of different barrel matterials and see if there is a different

[@samwang7788]

Hello, your video is awesome! I recently bought a g&g predator do you think the stock gearbox can handle the m130 spring?

[@ElChiva762]

no.

[@GameSquirt]

Any chance you got around to testing the Prometheus cylinders?

[@alexandrubogdan917]

It's simple. You squeeze the air very fast into a smaller volume cylinder=a bigger ,,bang".

[@HHuseyinBilgen-kh6ek]

is black barrels are 6.08 ?

[@fnbcapone]

0:05

[@anomalyp8584]

Let's see now what the BB weight does!!

[@GalihAnggaPutra]

For bareel 200mm with cylinder porting 3/4 , is it good to use ?

[@bobbobb7244]

I did my test with most popular barrel lenght 340mm and 400 fps spring. Non ported cylinder, no hopup. Joules increases with bb weight to 28. Weight 28 most efficient. 20 400 1.5J 28 350 1.6J🙂 40 290 1.55J Ported cylinder 55mm from the edge, no hopup. Joules decreases with bb weight over 28. Weight 20 most efficient. 20 400 1.5J🙂 28 335 1.45J 40 265 1.3J No reason to install any ported cylinder.

[@FaraWitana-i7v]

what if i use 140 spring? i have 363 barrel

[@גלעוקשי-ר9פ]

Hey man I really need your advice with something. I use a cyma polymer gearbox and I now upgraded to an M110 spring with 13:1 gears. Will it stand the pressure of the spring? I used an m100 till now and everything was fine, I just read many bad things about non metal gearboxes

[@le_toys9442]

Just simply. Non Metal are less durable.

[@DgR1716]

Noice 👌👍

[@MrElios300]

As your tests had a significant impact on shorter barrels I'd love to see the same on AEPs 🤞🏽

[@herryswastika3708]

auto subss. mannn this is a what i ve been looking for. thank you

[@davidstancomb5380]

Wow.... you need to match the volume of your barrel bore against the effective swept volume and mean effective spring pressure to get best efficiency. Who would have guessed!!!?