I vote SniperPT for being shot!

I'm glad that my team is rich on creative minds hehe...

This post has been edited by DeviantDragon: Oct 1 2007, 05:44 PM

yea, a medal that is in the shape of a vsr cylinder head that its tapered

j/k. but really good job there PT

parabens pra vc pela imaginaçao!!

how the second mod works? more vibration?

Thanks guys

Well the second mod did'nt give me anything new... I also would say it lost a tiny bit of range...
(the weather conditions today aren't the ideal, but even with more tests I think the second mod isn't worth adding and it also makes the Vsr10 a lot more noisy)

It's an Honor to help you guys improve

Obrigado

Best Regards
SniperPT

I have a bore-up nozzle and I seem to have lost some fps, boring up the nozzle may not be the good thing. But still, your first mod is an excellent idea.

Bore-up nozzle? never saw that... apart from the other cylinder heads the only one I know is the laylax one, with interchangeable nozzle (that differs in lenght, not sure that they may vary in bore size...)

Results:
As I was suposing my gun is shooting a bit faster, from the shooters view (I do not own a chronograph),
Range increased a little..
As said before, since there is less air resistance on the piston, it's movement is quite faster (in both ways, cocking and chambering the bb), but of course the piston, because of that, is hitting a lot harder, thus making the shots little less consistent... And MUCH more sound is produced!!!

I'm now able to hit a Man-sized target up to 70 meters, with a top range of aprox. 80 meters
Using:
PDI SPR 200% 13mm spring (should give 396fps with HD set)
PDI 9mm spring guide
PDI Hard Piston
DeepFire Sears
Tapered Stock cylinder head (with 5mm nozzle bore)

FPS should be aprox. 365/370 (can't penetrate the bottom center of a Coca-Cola can, 385fps) not even near :p


EDIT: I was finally able to reduce a great amount of noise from the impact, by refiting the frontal o-ring (that was torn apart when I still used the stock flat cylinder head.
It seems that the smaller o-ring does not serve as a shock absorver (it doen'st even touch the tapered cylinder head,silly me), what it does is divide and trap the air, forcing a small amount of air in the piston head holes, spreading the piston o-ring and to form a kind of "ring-cusion" in front of those holes, absorving a fair amount of impact, thus reducing the noise, with 0% air loss!
So forget noise issues with new mod :D
here is the o-ring, for those who aren't familiar with:


Hope I'm not boring you...

Best Regards
SniperPT

This post has been edited by SniperPT: Oct 7 2007, 02:04 PM

Can this modification be done to all sniper rifles that have a cylinder head? ...say the maruzen L96...?

This post has been edited by deadeyesniper: Oct 8 2007, 11:48 PM

Well...I believe so..but I can't asure you that it will be as easy neither that the material in witch the L96 cylinder head will stand the "operation"...
If it's a soft metal (brass in the case of the Vsr10) go for it...

Good Luck

Best Regards
SniperPT

Ya, it looks like the cylinders are the same shape and same with the cylinder heads.

I don't know anything about metals and such but the stock cylinder head I think is brass while the cylinder head I upgraded to is stainless steel.

Is brass easy to work with?

Yeah brass is very soft and smooth to work with...
(If it was stainless steel you would take at least 3 days to do the same )

Good Luck

SniperPT

This post has been edited by SniperPT: Oct 10 2007, 07:32 AM

in the begining I started with a tool, a conehead-shape of some sort of material

This head spining CW and the cilinder head in other drill spining CCW...

So my time was drastically reduced to get the shape, in brass of course. You can try the same on steel

sorry for my english if you don't understand what I wrote

Muy bien pensado amigo!
That's a very clever way to accelerate the "operation"

I don't if steel is so easy to polish (is this expression correct?), in my case I used the steel bit of a similar drill against the cylinder head to give it a really shiny and smooth surface, again it was steel against brass, not steel against steel, it's better to use something harder to get the job done (in steel I'd use tungsten carbide hehehehe )

Best Regards
Saludos
SniperPT

Those are not steel drill bits. Those are conglomerate drill bits used for the Dremel. If you tried that on a brass head, because it's much softer, it would melt and break the drill bit. I've had such problems while using my dremel on a computer case.

Sorry I didn't express myself correctly, I held the drill bit in my hand, with the steel section that's suposed to attach to the dremmel touching the spinning cylinder head...
Just because it was the nearest steel tool I had :p

Best Regards
SniperPT

Hello all,

I've seen this weapon shooting before and after the cyllinder modification, and it's lot better. Like many at first I didn't think that a small change like the one SniperPT made would do anything to the gun, but after shooting it I saw the power of the thing.
It shoot's more accuratly and the it shoot's a greater distance, and in a much straighter line in the air. It's not that much louder I guess...

Best regards

MMelo

This post has been edited by mmelo: Oct 13 2007, 08:36 PM

Thank you very much for a second hand report mmelo

Chris

What do the piston heads look like that you are using with this modification, are they flat? Pointed?

I'm using the HD piston, that uses this cylinder head:

Ups...sorry for the double post, but need to correct for this:

Not cylinder head, PISTON head...

Is it what you were asking?


Best Regards
SniperPT

Thank you Sniper PT. this will be a mod I will do. I tried it with my L96 and it works. but I have other problems I need to work out of the system. I plan to do this next to my JG BAR-10

I have a small concern though.

The stock cylinder head is flat with a small taper towards the hole. And this new tapered head is of course tapered. similar to a velocity stack.

When the piston head hits the cylinder head, there is very little room. now there is a gap. a small volume of air is left. so in essence do you think less air is being used since some is still left?

here is a quick pic I drew up. to illustrate what I am talking about.

Your theory is correct, I think... it's possible that some air stays inside the cylinder...
But even if it stays, it will not have a significant effect on the flight path, because when the piston hits the cylinder head (and if there are no air leaks) the bb is already outside the barrel (and going really fast, factor that leaves a certain vaccum behind the bb, this makes more sense with really big barrels)

But of course you will always have PDI's vaccum piston

And also if the mod is correct, the piston will move faster, since there is less air resistence due to the fact the the air itself escapes much better, the bb will travel faster and maintain momentum for a longer distance, making that bit of air less usefull as it would be will a slower setup

Thanks m8

Best Regards
SniperPT

This post has been edited by SniperPT: Oct 26 2007, 05:07 PM

I'm sorry my friend but your assumptions are wrong. By modifying the Cylinder Head, you are increasing the useful volume inside the cylinder, so even though some air stays inside the cylinder, tha amount of expelled air stays the same. In practice, what this mod does is to force the airflow from the cylinder into a jet compression effect, rather than a vortex compression, thus reducing turbulency in the pellet, and improving the hop-up effect (the air applies pressure on the mass center of the pellet, rather than the whole surface).

This is a bit theoretical but I can draw a picture if you want :)

Yes! I've been looking for DIY mods for sniper rifles.

yes please with bright colors haha. yeah draw some pics. I would like to understand what you are saying. sounds interesting.

I don't get it. Whats hard to understand?

~I couldn't find any readable bright colors, but I hope these suit you



I'll try to explain: On the first example, the wind forces are aplied in different directions troughout the BB due to the cylinder head creating much more pressure inside, and thus expeling the air in an unstable form. When the BB is impelled, these forces from different directions counter the BB's rotation, while at the same time identical forces on the other side force the BB to rotate. Some of the air is, therefore, used on a null purpose, and it's energy wasted.

Now on the second example we have the "cone" shaped head, which reduces pressure inside the cylinder and stabilizes the way it is expelled, therefore when the wind applies force on the BB, it is applied on a much more uniform direction, not affecting the hop-up effect and propelling the BB further.


Understood now?

thank you. a picture is worth a 1000 words. that cleared it up so much quicker than me having to re-read your post.

I'm glad I was able to help

OMG!!

I gotta do this to my VSR this weekend!! Have been scratching my head on how to mod it with minimum expenses..

Brilliant idea, and thanks a lot !! You should be given an award for this !

I don't think that's quite right. I certainly haven't taken any courses regarding the behavior and air and such, so feel free to correct me if you have, but that doesn't seem quite right to me. Here's how I see it. In the first drawing, some of the air is moving into the cylinder head wall instead of through the gap, while in the second, some of the force from that air is directed into the gap instead. It would explain why there'd be an FPS increase.



Still, I have to admit, even my own idea doesn't really make sense to me because I don't 100% think that the piston so much pushes air forward as it pressures air inside the entire thing. To be honest, I have no idea how pressurized gas behaves in a container and the variation of it depending on the shape of the hole.

It seems to me that besides what has been discussed, that the tapered cylinder head would provide much less resistance on the piston because of one simple variable. When the piston pushes the air to a regular cylinder head, the air impacts the flat sides of the cylinder head and is forced backwards into a compression cycle before it is forced out of the nozzle. When the air is pushed against the tapered cylinder head the airflow is not trapped and compressed because it is encouraged by the slope of the cylinder head to move into the nozzle freely, without resistance. Because of these this, in theory using a tapered cylinder head would allow the piston to move faster, allow for more consistent airflow, provide greater velocity and provide for quieter operation.

It is entirely possible that I may be wrong, however through my current knowledge this theory seems to be quite logical.

This post has been edited by Graham Abram: Oct 29 2007, 01:06 AM

My thoughts as well.

I started work on this mod however I'm going to perform it gradually beginning with the small amount that I've removed and polished already and see how it goes with each progression. It may just be me, just being attentive to the sound, but with the small amount that I've removed it seemed it became just a fraction louder.

Update: Just performed a quick coke can test: .2 fired at coke can top from 1-2 inches.

I compared the latest coke can results with a previous tested coke can and it seemed that the newer coke can was just a little bit deeper than the previous. Now this is just from me eyeballing it so take it with a grain of salt.

This post has been edited by The Mad Bomber: Oct 29 2007, 01:48 AM

Those other examples you provided are not correct. You are assuming the air behaves like a wave or light, and that is completely wrong. The air behaves like a fluid inside the cylinder. Are you familliar with the Bernoulli theory? (not the one which explains the hop-up effect, the one which is used to measure flows)

For you gear heads (aka car fans) you will know what a Velocity stack is. they are a fantastic improvement for air intake.

as I said before if you imagine the cylinder head like the opening of an air intake, then the tapered version is like a velocity stack. The similarities is not just in the shape. but the fact that air is rushing from the opened end to the narrow end, irregardless of the fact that with a cylinder the head is pushing the air, and in an engine, it is the stroke of the engne that is sucking the air in.

The characteristics of the movement of air is the same.

read this, it is an article on velocity stacks from wikipedia.
http://en.wikipedia.org/wiki/Velocity_stack

Frankly I don't see where there is a true disparity between anyone's (recent) examples. Perhaps the problem is one of semantics.

Stock head: The compressing air is deflected by the flat side of the cylinder head causing an effect (whatever you want to call it) that causes a loss of energy (to the BB) because the air hits the face of the BB in a nonuniform manner. Think of it like hitting a billiard ball with your stick on the sides of the ball rather than in the dead center (in the micro second before it empties and hits the cylinder head).

Tapered head: Being that air is a gas and a compressed gas will seek the path of least resistance to escape the tapered surface of the head allows the gas to escape easier and diminishes the vortex, turbulence, gremlin effect on the pulse of air. Thus allowing for more of a jet like stream of air on the BB. Also allowing the piston to impart more energy into the pellet because that air isn't being trapped in the cylinder by a vortex which would slow the piston down.

This post has been edited by The Mad Bomber: Oct 29 2007, 11:33 AM

Maybe it is. I'm not that good at english... Sorry

Well, I'm not saying that at all. (Your English is better than some posters whose first and only language is English.) I'm just saying that, as far as I can tell, everyone been saying the same thing...just in different ways. Semantics.

This post has been edited by The Mad Bomber: Oct 29 2007, 11:56 AM

I tried this with good results! :)

I had teflon cylinder, Red silent shaft piston (with AEG O-ring), 7mm old 300% spring and guide for it, Damper cylinder head with some extra silencing. It shot 2,7 joules.

Now I have same cylinder and same piston, but I made those holes on piston's head bit larger, now the holes are ~2mm, new 9mm CA 300% aps-2 spring and 9mm Type96 spring guide (yes, in vsr, and works fine!). But then to the cylinder head, I have 2 cylinder heads, so I toke the older one and made it taper, not as much as I have seen in your pics , and more rough(=uglier :E), but now it gives 4,21 joules. (140m/s @ 0.43g) :)
I have own chronograph.

I will soon test with damper cylinder head without any extra taper to see how much the effect is.

(And sorry my bad English again, don't even try to understand everything, just the point pls :)

Good g0d man, that is... quite impressive.

At the left, Damper head PRO with some extra damper. 124m/s with 0.43g, meaning 3-3,3 joules.
At the right, Damper head, and homecustom tapered. :) 140m/s with 0.43g, meaning +4joules



And as you can see, the Damper head Pro has more length, (and goes more inner to the cylinder) than Damper without pro :P



And more Air in the cylinder means more fps, but harder to cycle a bolt ;0

This post has been edited by Lippi: Nov 1 2007, 11:23 AM