bore-up kit & barrel length

[tax]

hey guys, a few quick questions. Hopefully someone here can answer me!!

I have a version 6 gearbox and would like to mate a psg-1 650mm barrel to it. Now the questions are:

1. Does anyone know who would make a bore-up kit for this gearbox?
2. If someone does make a bore-up kit, will it be enough to push a 6.03 tight bore (650mm)?
3. I can't seem to find systema super torque up gears for this gear box neither.

Any help would be apprieciated. Thanks for taking the time to read this post..

tax

[ILLusion]

ONLY the CYLINDER will fit. Version 2/3 cylinder heads & nozzles will NOT fit v6.

any gear set for version 2/3 WILL fit v6.

some experimentation will be required, as I do not believe any conclusive evidence is availble of 650mm inner barrels properly working full auto in version 6 gearboxes since no bore-up v6 cylinder heads/nozzles are available.

Makes sure you test full auto vs semi-auto performance with that setup.

Herm, If you need, you can use my chrono for the tests.

[BiffTheAncient]

Tax, you're sick man, you need to attend AA (Airsoft Anonymous).

Hmmmmm...... PSG90?

Added:

If memory serves, I read that the optimum barrel volume to Cylinder volume was somewhere in the 75 to 80 percent range.... (I read this a long time ago from an article, I can't remember where, about upgrading barrel lengths and how too long of a barrel would hinder performance or not work at all.)

So the best bet would be to measure the volume of the P90 Cylinder and then we can figure out how much barrel it will support.

Added:

Check uot this thread on airsoftplayers.com

[tax]

Adding for reserch and reference for later on [taken from airsoftplayers.com]

P90 cylinder's useable volume is actually about 11cc. Cylinder specs: diameter 23.84mm; useable length 24.81mm (31.04mm - 6.23mm cylinder head thickness). So with this information, the optimal barrel volume should be about 7.3cc (2/3 of 11cc). Using the stock bore (6.08mm), the optimal barrel length should be 251mm. So P90's stock barrel (247mm) is already optimal.

If you want to use a tightbore (6.04mm) 455mm long barrel (~13cc), the optimal cylinder volume should be about 19.5cc (13cc * 1.5) or 26cc (13cc * 2). By taping the cylinder air bleed hole, you end up with a type-0 cylinder (~27cc) with slightly less useable volume due to the bleed hole gap. It should work provided that air loss is not too great.

Another method you can try to bring out more performance (muzzle velocity) is changing the weight of the piston/piston head assembly. Short barrel AEGs perform better with lighter weight piston assembly; whereas long barrel AEGs perform better with heavier weight piston assembly.

[tax]

Another post for reference and research [taken from airsoftplayers.com]

was thinking of replacing my 247mm P90 barrel with a 455mm AK tightbore and wondered whether I should replace the cylinder or not to minimize barrel suck.

So I did some math: A cylinder is 72mm long and 12mm in internal radius. The P90 cylinder has a 6mm wide, 14mm long hole that's 44mm from the front of the cylinder(useful volume) and 14mm from the end of it. The barrel has an internal radius of 3mm. Cylinder volume=h(Pi)r^2, so:

P90 Cylinder: 20,000mm^3
P90 Barrel: 7,000mm^3
AK Cylinder: 32,000mm^3
AK Barrel: 13,000mm^3

Why does the barrel have only 35%-40% of the cylinder's voulme? Does most of the air leave through leaks in the nozzle and cylinder?

I was also thinking of taping over the P90 cylinder's hole with some heavy aluminum tape to make it into an Ak cylinder. (I'll be sure to make sure no sticky surfaces face inside the cylinder; I don't want the piston head to be catching the tape.)

The area the piston shoots through is 455mm^2. Because I can't make the tape flush with the inside of the cylinder, I'll have a 0.75mm(cylinder thickness) x 6mm (hole height) or 4.5mm^2 gap. That's only 1% of the the total area. I was afraid that when the cylinder shoots forward, air will be forced through that little 4.5mm^2 gap instead of the 28.5mm^2 barrel since it is the path of least resistance. It shouldn't affect it much at all, should it?

[ILLusion]

Don't tape the hole to gain a full cylinder. It creates a lot of seal issues that lead to lower performance. Yes, it's a cheap partial solution, but you also get performance issues out of it. Adding tape to the inside will create gaps in the o-ring/cylinder wall seal at the edges of the tape. Adding tape to the outside will still leave a huge seal gap where the port is.

Rather than go through that mess, just buy a cylinder that's fit for your application. Manufacturers have already made and measured out optimal barrel lengths for their aftermarket cylinders. There's no need to re-calculate and re-invent wheels.
SystemA Type-0 cylinders go for around $20-$25.
More expensive KM (Head 1950) Titanium-Nitride (TN) coated cylinders for long barrels go for ~$40, but feature a smoother surface and better wear characteristics.

Although a bore-up kit would be optimal for a 650mm inner barrel, it may be possible to use a regular bore full cylinder with P90 cylinder head, piston head and nozzle to get it to work if you can find the right component combination to create an extremely efficient system with minimal to no air loss. Most air is lost at the cylinder head/air nozzle junction. Upgrading to aftermarket cylinders/cylinder heads will also minimize the loss of air at the cylinder head's o-ring area as well.

Also switching your piston head to a ventilated one will greatly reduce the effect of "suckback."

[tax]

I'm not one for math, im more of a trial and error type guy.... put everythingon shoot it, works well.. keep it.. LoL

Have to talk to you soon.. see what you have instock for this project =P