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Old 11-03-2012, 07:11 PM #1
Vask
 
 
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Air efficiency pre-2k cockers; what is proper?

I am currently running an 13 cubic inch 3000 PSI Ninja HPA tank.
obv the last 500 psi is unusable so:

I get about: 150 rounds per 2500 PSI

so
16.7 psi per shot
and
.086 cubic inches per shot

This seems extremely high to me; none of my other markers are over 5psi a shot... and .053 cu inch

I have "sweetspotted" the reg at about 80% open,
running 285 fps,
LPR is at factory setting,
no leaks anywhere

Any ideas what could be wrong?
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Last edited by Vask : 11-03-2012 at 07:35 PM.
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Old 11-03-2012, 07:43 PM #2
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Most autocockers in general are airhogs. I'm lucky to get a bag off of my entire 68, 4500 tank using my sniper. I do have a slight leak in my valve I'm too lazy to fix though.

Maybe try a Maddman spring kit to change the spring strengths. Having a heavier valve spring and lighter hammer spring should help reduce the air being used per shot. At least that's what I think.
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Old 11-03-2012, 07:55 PM #3
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Cockers are known for being efficient. A good tune can yield over a case of paint on a single 68/45 fill.

Buut, it takes a lot of time and tuning. Do some research on which valve you want (AKA is great), and their tornado bolt can help too. You'll also want an expansion chamber, or a reg extension, preferably both. The larger the valve chamber, the valve chamber will experience less turbulence while it's charging/discharging. This helps with consistency most of all, but efficiency is in there too.

Once you've got the parts you want to use, get a spring kit and get to testing. A heavy hammer helps, but you want the main spring/hammer to exert as little force as possible, and the valve to release as little air as possible, all while maintaining a consistent FPS.

A sweetspot at 295 FPS will be less efficient than one at say, 285fps. Also worth noting that your tank is tiny.

Last edited by Dk-79 : 11-03-2012 at 07:59 PM.
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Old 11-03-2012, 11:56 PM #4
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Small 3k tank = not good measuring device.
Ive never measured my air usage, but I also fill up after every other game reguardless if I need to or not.
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Old 11-03-2012, 11:59 PM #5
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Quote:
Originally Posted by Darkapollo View Post
Small 3k tank = not good measuring device.
How would you suggest the experiment be conducted?
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Old 11-04-2012, 12:02 AM #6
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Quote:
Originally Posted by Dk-79 View Post
Buut, it takes a lot of time and tuning.
could you elaborate on what sort of tuning you are referring to?

Im looking to get an additional 50 shots out of the small tank. (30% increase in efficiency)


Valve spring too stiff: Another possibility when you’re having a hard time getting sufficient velocity is that your valve spring is too stiff. Installing a softer spring allows the valve to stay open longer and allows lower pressure operation and higher velocities. Conversely, if your efficiency is terrible your valve may be staying open way too long and might be improved with a slightly stiffer valve spring. Changing this spring requires taking the valve out, and thus requires a special tool, a lot of work, and retiming the ‘gun. I only recommend this for those experienced with the inner workings of the Autococker.

^^would the valve also stay open longer if the mainspring was stiffer? I believe the nelson hammer kit has a stiffer mainspring right?
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Last edited by Vask : 11-04-2012 at 12:29 AM.
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Old 11-04-2012, 08:04 AM #7
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Quote:
Originally Posted by Vask View Post
How would you suggest the experiment be conducted?
Use a common 68/45.
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Old 11-04-2012, 09:46 AM #8
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Quote:
Originally Posted by Darkapollo View Post
Use a common 68/45.
With a 68/45 it would get
780 shots
at 5 psi/shot
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Old 11-04-2012, 10:27 AM #9
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That's bad, efficiency wise, though not unheard of.

What pressure are you running now, what position is your IVG in, and what internals are you using?

Pre2k cockers have smaller valve chambers, which is a bad deal all around. An expansion chamber and an inline reg extender go a long way.

When you say sweetspotted at "80%" open, what does that mean?

What pressure are you currently operating at?
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Old 11-04-2012, 11:03 AM #10
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220psi
10% in on the ivg
nelson hammer kit

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Old 11-04-2012, 11:24 AM #11
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Your pressure is way too low.

Your operating pressure should be sitting around 285-325psi. I would back out your IVG a turn or two (one or two turns from flush) and sweetspot again with a goal sweetspot of 290FPS @ the same 280-325psi
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Old 11-04-2012, 12:04 PM #12
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^ i was at 300 psi with the ivg flush originally

this resulted in huge velocity spikes over 330fps.

per this LP explination it seems that the nelson kit mainspring is in-fact too stiff to run at higher pressure.

http://cockertech.net/basictech/52-aclowpressure
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Last edited by Vask : 11-04-2012 at 12:09 PM.
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Old 11-04-2012, 12:14 PM #13
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When the pressure is too low, the hammer has to hold the valve open longer to get the FPS up, and running that beast of a main spring at high pressures doesn't help in any which way.

Get a maddman spring kit and try the medium (blue) spring with your current setup and your IVG close to flush. You'll still want to stay above 250 psi, if you're after good efficiency.
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Old 11-04-2012, 12:38 PM #14
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^ ill look into that, thansk
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