parabens SniperPT!!! teu thread e um sticky agora!! ahahaha

wow...thanks guys it means alot to me!

Always working in your behalf

Best Regards
SniperPT

Yeah right... working...

Hi guys...

Today I used again a couple of coke can's (and with all "rigorous" procedures) my Vsr10 was able to do the following, with a PDI 200% spring and the modiffications present on this topic:

-Penetrate successfully the bottom of both cans (385fps needed)

-Top Near breaktrough in the 1st can and successefull penetration in the 2nd

Aprox. 59 fps increase!!!

Acording to PDI:
"What's the 200% ?
It means 200% than normal spring power(0.7J).

So it would be 1.4J arround (use 0.2gBB) when with PDI precision cylinder Set HD..
In that case,output level is here:

396 ft/sec , 120 m/ sec ,1.4J"


Best Regards
SniperPT

NOTE: It's the same spring in the previous tests, can't figure out the reason for the sudden increase...maybe my Vsr10 is like Porto's Wine xD

This post has been edited by SniperPT: Dec 1 2007, 03:15 PM

I'm sorry, but I was planning on doing this to a BAR-10 I might be getting in the near future, and seeing as how it is alread at 400FPS, I can't go any higher (the place I go has rules). before you said that this increased accuracy and range, but not as much FPS. Do yo mean that you increased FPS by 59 using the cylinder head mod?
by the way, thanks a ton

Read the post. His VSR is like Port Wine! The BAR-10 is not!

As I said, in previous tests (when I assembled the weapon) it didn't had enough "punch" do penetrate the bottom of a coke can... I might had been due to the fact that I was compressing and decompressing the spring a lot of times in just a couples of days.
A Few days ago, seeing it rest for almost a month I took the tests again and the gun was actually able not only to penetrate the bottom but also the top of a can.

Don't intend to be rude but, do I mean that the mod increased 59 fps? Hell Yeah!!! I'm only running a equivalent to a 120 spring xD

Accuracy and range remained pretty much the same!

If you're not alowed to go any higher than 400fps and if you say BAR-10 already has 400fps...why having trouble modifiyng the "thing"?


Best Regards

This post has been edited by SniperPT: Dec 6 2007, 06:41 AM

OK thanks... Guess I can't do this mod ... I freaking hate 400 FPS limit

And I freaking Hate the 375fps limit around here

Hey, sorry to necropost but I'm really curious as to whether or not this has turned out to be a valid modification. I'm a little doubtful of the theoretical approach behind it.

See, in pump up pneumatic airgun designs like the Crosman 13xx series, modders strive to achieve a flathead piston setup in order to reduce "dead space" in the cylinder. To achieve maximum effective use of the pumping action, you have to reduce the amount of space left when the piston is at full extension. These airsoft spring cylinders are essentially the same thing, albeit instead of forcing air into a check valve area, they send it right down the barrel.

When you open up the cylinder head like this, you're both increasing dead space and smoothing the exit of the air. What I'm curious about is how much the dead space reduces the cylinder efficiency, and how much the reduced turbulence helps. Has anyone combined the negative conical cylinder head with a positive conical piston face?

Also, how have your cylinder pistons held up? By increasing dead space, you also eliminate any airbraking, and I'd assume that would increase vibration and impact on your parts.

This post has been edited by russc: Mar 7 2008, 07:11 AM

Hi

Regarding vibrations, you'll obtain a smaller impact area,yes it reduces any air-braking effect, but in practcal results, it got really more accurate, fps's increaseg and I noticed a smoother action and impact. And I'm using a "conical negative" piston head and positive cylinder head, both are in excelent conditions, and the performance is really good.

And it's a homemade copy of a upgraded cylinder head of both Laylax and PDI. Both of wich sell well and with good results. In airsoft you don't need air-pressure like you do with a pump, you just need speed and a smooth exit, disregarding far more the overall durability of the components and think a bit,the last bit of air that remains in the cylinder isn't used at all, since the bb may have already left the barrel

Sorry for the bad english I'm in a hurry...

SniperPT

Thank you for the reply. Anyone else done this mod? I might give it a try on my extra HFC head.

I did after reading most of this thread.

Alittle background, few days ago I picked up a VSR Clone (JG Bar-10 G-Spec)
Out of the box, it shot 355 fps.

Did the following :
-Added DBC 490mm barrel
-Cut Airbrake
-Made a stainless ring to tighten up Hopup sleeve (like on some AEGs)
-Misc polishing here & there.

It shot consistently between 449-451 fps (1500 or so shots later it remains consistent)

I ported the Cylinder head although not as dramatically as the example on this thread,
But sufficiently enough so that water from the sink would flow fully through,
And a solid stream of water (no bubbles or splashing) came out the tip.
I figured that would be a good test for flow, as in stock form the cylinder head
placed under a faucet would just splash water all over the place, and the occasional
broken stream of water would flow through.

The gun now registers (on F-1 Chrony) a high of 459.8 fps
Thats only the results of 25 shots, but a noteworthy gain of ~9 fps.

The only other changes I made at the same time, was adjust some barrel spacers,
and that would not have affected velocity. I made sure not to re-build the Hopup
so I could measure gains from this cylinder head port mod only.

A side note, on the how it was done..
-I ended up using a large drill bit (1/2in) at first to create a 1/4 deep cone in the
cylinder head surface. I actually had the head in the drill, and held the drill bit
with my hand like a chisel.

-Next, I used an actual chisel in a sort of lathe action while the head was spinning on
my drill to create a more gradual cone curve which a drill bit could not achieve.

-Finally, 400-1000 grit wet sanding to smooth it all out.

** Be sure to apply a layer of shrink tubing or some other type of sleeve
to the head tip before attaching to drill to prevent scratches **

I used 2 layers of shrink tubing for this purpose.

BIG Props to SNIPERPT for this mod, and a personal thanks for the 10 more fps.

do you think this is worth doing to a laylax cylinder head?

I think the Laylax cylinder heads have a built in rubber dampener.
To do this mod would involve cutting into the center of that.

If that were the case, it might get alittle messy.

I would say do it one your stock cylinder head first..
Then see for yourself if the benefit is worth messing with the
more expensive upgraded Laylax one.

Its always safer to experiment with stock parts first.

Also, it does not appear the Laylax one is made of brass..
If it is steel, then it will be alot more difficult to cut using
the methods described throughout this thread.

Again, Ive never seen a Laylax one in person, so im not 100% sure,
just looking at descriptions & pics of the part on Trinity's site.

well I did it any way, and I removed the built in damper, it took REALLY long, I started using drill bits to speed up the process, but it worked really well.

I have yet to test it out

I hope you took down some "Before mod" chrono readings.

I'd be interested in the results for comparison to mine.


Edit :

Threw the cylinder head back on the drill & re-shaped it a little bit more.
Leaving plenty of flat surface for the piston dampener to strike,
I merely made it more cone shaped.

Just prior to the second re-shaping of the cylinder head the gun was shooting 490-492 fps
** Added a spacer to the stock spring **

After the second re-shaping the gun shot its first 500.9 fps averaging around 496-497 fps
Another +5 fps gain

Again, great mod! Smoother airflow = higher velocity

This post has been edited by Noobie: Apr 10 2008, 12:14 AM

it improved alot more.

I can tell the accuracy improved.

not so much the power. but the accuracy did

its an overall good mod

Daniel or noobie, did either of you notice a significant change in noise? If the piston moves faster it must be lauder, plus it's striking at a higher velocity so would it reduce the lifespan of the piston? Im thinking about doing this to a stock bar-10

The part that stress is increased on is the head, or front area of the piston, which is pretty much indestructible due to it's design. The reason pistons break is they wear down in the area where the sear holds it.

So, no, it would not affect the life of the piston. This mod is very much worth it, and I recommend it.

Chris

I would say make the cone funnel no more than 1/2 inch in diameter so that you leave
a certain amount of flat area for the stock pistons rubber dampener to strike against.

As far as noise level :

If you increase the spring rate by replacing the spring, or using a spacer to preload the spring
as I have done that will increase the speed of the piston significantly enough for you to hear
and feel a difference with or without this mod.

If you are simply increasing the efficiency of the gun by perfecting the compression, then
there should be no significant change in sound.

Something to think about however, with extremely good compression, and absolutely
no leaks at the hopup & cylinder head tip or piston O-ring; the sound level drops & impact
is reduced simply due to the fact the BB in the barrel is acting as a dampener.

When you can hear a difference between dry firing & live firing you will have an indication
of how your compression measures up.

Now if you make the funnel into the cylinder head extremely large in diameter, and the
rubber dampener has no where to land flush, I would imagine the piston might be prone to
damage in terms of deformation at the front where its striking the cylinder head, or maybe
even cracking since there is no impact dampening.

I have no airbrake at all, since porting the cylinder head rendered the "Cut airbrake"
length useless. Since the diameter where the airbrake previously entered the cylinder head
tip is widened beyond the depth of the airbrake's length, it no longer functions as a brake.
Therefore, it has completely flattened & cupped slightly approximately 1/4 inch diamater
at the center.

don't know if that made any difference, but I figured it might help scoop air better in
a forward direction rather than force air around the edges of the piston as it moves forward.
Probably doesnt make a difference, since its not a very aggressively large scoop / cup.

But anyways, with a spring "pre-load" spacer on the [Stock] spring, compression mods, & this
cylinder head mod I've probably fired off several thousand shots with no abnormal wear.

I would focus more so on how this mod reduces the effectiveness of the airbrake and
reduces the amount of rubber dampening area, over how it increases the speed of the piston.
In terms of piston wear/damage. In other words, *IF* you are really concerned with piston
damage, then try leaving the airbrake un-cut or cut less. See how that works for you first,
then maybe cut more or all of it off later.

But certainly proceed with this mod, its well worth it.

wow, thanks a lot. Now I have another free mod to add to my bar-10 after my teflon and airbrake mods!