Hi guy's i have searched but cannot find an answer to the question i have. I am trying to find out if my tm l96 pdi palsonite cylinder has to much or to little volume for the pdi 6.01 tbb i have. I havnt got a clue how to calculate the volumes myself and vindi is on holiday so i wonder if someone can help. If the cylinder is under volume i'd like to shorten the inner barrel to match the volume to where it's eifficient to use .3g bb. And if their is to much cylinder to barrel volume then match the cylinder volume to the barrel. Or possably do both as i want to shorten the length of the outer barrel. Thanks in advance and sorry if the way i've worded this topic is confusing.
bigguns
To find the volume, take the area of the bore and multiply by the height of the compression area.
If you have a 6.01 and the barrel length is what, 500mm?
Area=pi*radius^2, so 3.005^2=9.03 Area is 9.03mm cubed.
multiply by the barrel length of 500
Barrel volume = 4,515mm cubed.
I would guess that if you are using .3's that you would want a cylinder - barrel volume of 1.85 or something similar, MAYBE 1.9
Which means the rough volume of your cylinder should be 8,352mm cubed.
If it's not enough, you can shorten your barrel to match it.
If it's too much, you could just calculate the volume of your new barrel and then work from there.
We would just need your cylinder diameter to work from there.
If you have a 6.01 and the barrel length is what, 500mm?
Area=pi*radius^2, so 3.005^2=9.03 Area is 9.03mm cubed.
multiply by the barrel length of 500
Barrel volume = 4,515mm cubed.
I would guess that if you are using .3's that you would want a cylinder - barrel volume of 1.85 or something similar, MAYBE 1.9
Which means the rough volume of your cylinder should be 8,352mm cubed.
If it's not enough, you can shorten your barrel to match it.
If it's too much, you could just calculate the volume of your new barrel and then work from there.
We would just need your cylinder diameter to work from there.
I'll do better than that. Wanted to match mine much better than just theoretical. To start with, my setup for the testing:
TM L96 AWS
PDI HD piston with airbreak
PDI HD spring-guide
PDI 130 or 140 spring(don't remember)
PDI W-hold or original bucking(don't remember)
Tapered cylinder-head
Original barrel in different length
Chronoed three times for every different bb-weight. Marked average and maximum velocity. Then cut the barrel approximately 2 cm. Repeated. Results in the graph attached.
Do note that it'll most likely be different for your setup. Unsure if the air-brake actually steal any air-volume in the configuration I have now, but if it does, it could be very inaccurate for other people. Use with common sense. The tighter barrel will probably cause it to be a bit more air-efficient as well. Personally I'll get the PDI tapered fluted short barrel for the TM, and cut my PDI 6.01 to match it's length, which will be 380 mm. Probably as good as it gets without cutting the outerbarrel.
Left graph is made with average and the right one with maximum value. Left column marks velocity in m/s. Bottom marks (inner)barrel-length in mm.
TM L96 AWS
PDI HD piston with airbreak
PDI HD spring-guide
PDI 130 or 140 spring(don't remember)
PDI W-hold or original bucking(don't remember)
Tapered cylinder-head
Original barrel in different length
Chronoed three times for every different bb-weight. Marked average and maximum velocity. Then cut the barrel approximately 2 cm. Repeated. Results in the graph attached.
Do note that it'll most likely be different for your setup. Unsure if the air-brake actually steal any air-volume in the configuration I have now, but if it does, it could be very inaccurate for other people. Use with common sense. The tighter barrel will probably cause it to be a bit more air-efficient as well. Personally I'll get the PDI tapered fluted short barrel for the TM, and cut my PDI 6.01 to match it's length, which will be 380 mm. Probably as good as it gets without cutting the outerbarrel.
Left graph is made with average and the right one with maximum value. Left column marks velocity in m/s. Bottom marks (inner)barrel-length in mm.
Attachments
I think you will find that if you cut the airbreak off the ratio is about right. So the current barrel is fine.
@Rubik: Sorry about that, got cut off. At 380 mm the ratio would be approximately 1,9(1.88).
@1tonne: Possible, but the cylinder is much shorter than on the Type96, so I wouldn't be too sure about that.
Ratio at the spikes:
1,97 @ 362 mm
2,08 @ 343 mm
2,22 @ 322 mm
I've read that the cylinder to barrel ratio should be from 1,2 to 2,4, depending on who you ask. However 1,7-2,0 is probably the range I've read the most. So I find my results quite reasonable.
@1tonne: Possible, but the cylinder is much shorter than on the Type96, so I wouldn't be too sure about that.
Ratio at the spikes:
1,97 @ 362 mm
2,08 @ 343 mm
2,22 @ 322 mm
I've read that the cylinder to barrel ratio should be from 1,2 to 2,4, depending on who you ask. However 1,7-2,0 is probably the range I've read the most. So I find my results quite reasonable.
Hey, at least I was close.
Thank you for the data! I hadn't suspected that the TM had such a low cylinder volume (when compared to other cylinders, at least)
Thank you for the data! I hadn't suspected that the TM had such a low cylinder volume (when compared to other cylinders, at least)
Thanks for your help guy's.
@miqafox the chart is very helpful thanks for taking the time to do it yourself must have been time consuming
@miqafox the chart is very helpful thanks for taking the time to do it yourself must have been time consuming
Yes, it was time consuming. However if you want the best performance, it's the only way. I recommend everyone to do the same for their setup, as they're never the same. Sacrificing the original barrel is't that big deal.
@miqafox i may be missing something but what are the variables between the to graphs regarding the power efficientcy. both seem that a .3g bb is at optimum with a 322mm barrel ?
Perhaps I didn't describe it enough. For every bb-weight I fired 3 rounds. The left graph shows the average velocity of the three, while the right one simply shows the maximum velocity for one of the three. Don't really know why I added it here, but I suppose there is some relevance in it. Since I only fired three for every value, looking at specific values probably is't the best idea, you see how uneven the right one is.
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