View Full Version : LP with HPA - much higher psi than with Co2

12-15-2006, 11:32 PM
What is the lowest psi anyone has been able to run at using HPA, cause I am running my Xtra at sub 200 psi with CO2, but when I use HPA, the lowest I can get without jackhammering is 350 psi.

But I have always had trouble with my Tornado valve and recocking at LP...

So, I'm looking for psi people have been able to run with HPA, and what valve they use. Thanks in advance...

12-16-2006, 12:53 AM
i can get mine down to 200 on hpa, and 200 on co2. I use a rocketvalve and a dh titanium hammer with a heavy spring (but the spring doesn't matter for my gun as far as lowest psi)
have you tried plugging the exhaust port? i know it works for the rocketvalve, but i have no idea how it would effect the tornado

12-16-2006, 12:59 PM
I have actually researched that quite a bit, plugging the exhaust port, and I deemed, along with help from people like sundragonops and otter, that the way the tornado is built, it wouldn't exhaust efficiently and possibly cause greater problems.

As you probably know, the rocket valve not having that rear oring allows the gas to escape easily, the tornado has the rear oring and very small holes in the valve body that the gas would have to escape from. I did actually reduce the diameter of the exhaust port, but I have not been able to conclude whether or not that really helped...

I should experiment with different spring combos probably, but am wanting to see what other people got just so i can compare.

12-16-2006, 03:16 PM
hmmmm i wonder what would happen if you were to remove the rear oring on it. i doubt it would work though. But yeah, the fact the rocket valve only has 1 oring is why you can plug up that port. i don't have it plugged right now, because i have no reason to. i think i might leave my gun alone and finish milling it. it's getting close to the same efficiency as a stock ion right now

12-16-2006, 04:40 PM
are you shooting 290fps with 200 psi, or thats your lowest recocking pressure?

Hob Hayward
12-16-2006, 04:42 PM
If your bolt seals well you can't plug the exhaust.

I have had the same problem Jobberwocky, My recocking pressure is much lower on co2 than on HPA. Its because Co2 is heavier than air and thus has more force to pus ht bolt back.

12-16-2006, 04:43 PM
The reason for this is because your C02 tank will normally have a higher output pressure than the N2 tank does so it's only natural that your marker will be able to run at a lower pressure-

Hob Hayward
12-16-2006, 04:46 PM
Dragon, that made no sense at all. If its regged, input pressure doesn't matter...

12-16-2006, 04:49 PM
Its because Co2 is heavier than air and thus has more force to pus ht bolt back.

Yea, I've heard that before, but Nenkitsune says he gets about the same. Thats weird though for you Hob cause you have a Rocket valve as well....

What psi you running at normally?

12-16-2006, 04:50 PM
Dragon, that made no sense at all. If its regged, input pressure doesn't matter...

It makes plenty of sense......a tank w/a higher output pressure will recharge the reg faster than one of a lower output pressure. You can also factor in the fact that C02 expands in your marker after it leaves the tank. HPA keeps a constant pressure -

C02 it heavier is what makes no sense to me lol. You mean like it's heavier like the heavy weight of the gas has more atmospheric pressure or something? Huh? -

12-16-2006, 04:54 PM
Yea, but if you have a gauge and it reads the same for hpa and co2 post-regulation, then it shouldn't be that different...

Well, to address recharge, I'm sure the tank regs are made to recharge fast enough, aren't they? How else could people use them to shoot 25+bps...

Also, co2 tanks have about 800-850 psi output, and hp hpa tanks are about 800 psi, not much of a difference.

12-16-2006, 04:56 PM
Put a gauge on both in normal weather and the output of the C02 will be higher. Hey, that's my take 'on why' anyway's......take it or leave it lol - ;)

12-16-2006, 05:00 PM
Hows about I incorporate it with everything else...

But thank you for your input!

I hope others add to this, cause I really wanna see what people are gettin concerning this...

12-16-2006, 05:14 PM
the regulator doesnt stop teh CO2 from expanding, after the regulator, it only keeps the pressure from the tank constant, so after the regulator, it will still expand after it leaves teh regulator, and will, up until it leaves the gun, that is why your gauge shows that it is at say 200, but after that, it can still expand, also, what causes the marker to shoot is the expanding of the CO2 gas, so when teh trigger is pulled, the bolt is released, and the co2 escapes, expanding, so the pressure goes up even more

12-16-2006, 06:08 PM
my lowest recocking is 200 for who asked. I have no idea why my hpa and co2 recocking pressures are around 200. there must be some bottleneck in my setup that makes it so it doesn't matter which one it is, it'll only go down to 200. of course, that's not my operating pressure. i still haven't sorted out what my guns optimal operating pressure is. all i know is, with my soft and medium springs (haven't tried heavy yet) the lowest i could get it recocking was 200psi. then again, my gun's been an anomoly ever since i put it together. I will say this though. For a while (while i was putting my gun together) there was a difference of around 50-75psi in lowest recocking pressure between the hpa and co2. i can't remember what the setup was though. Another thing that might be causing the weird pressure is my dwell setting on my rocketvalve. i think i have2-2 1/2 turns on it. (i kind of want to buy a rebuild kit XP)
oh, and why would a good sealing bolt prevent you from plugging the exhaust? my lightning bolt seals up really well (actually, i can't really feel any blowback through the feed at all)
also, does anyone know how i would be able to get a hold of a vs series valve and pin?

Hob Hayward
12-16-2006, 07:33 PM
Et Voila'

"Update - March '04: I have gotten several questions about the type of gas used. Some have expressed that when they were using CO2, they got a very nice low pressure. However, when they changed to HPA (same day without changing any settings), the marker fails to recock. Actually, they neede to increase the regulator for it to recock the marker. Some changes were significantly higher. I do not know for sure why. But, I do have a theory.

CO2 is a heavy gas. Probably why it is close to being a liquid. When you fire, the tank will cool and the gas will not evaporate from it's liquid state. HPA is air that we breathe. It takes a severe temperature change to cause it to be a different substance. In short, CO2 has a heavier mass than HPA. I do not know if this phenomina is true for N2."

Straight from the bible.

12-16-2006, 08:34 PM
Yea I've read otter like a bajillion times, but he didn't give any examples so thats what I am doing with this thread. But I must be one of those people with "significantly higher differences" because I can shoot 300 fps @ 200 psi with CO2, but it takes 350 psi to shoot 300 fps with HPA... I am also curious if people had come up with ways to bring their hpa psi down...

But the Tornado valves are known to be best for efficiency and rocket valves best for low operating pressures...so I don't want to get any lower necessarily (co2), just bring my HPA pressure down if thats at all possible..

12-16-2006, 09:13 PM
hmm i wonder if it has something to do with the fact that the rocket valve doesn't have a rear oring. that would allow a lot more air to be able to be used for recocking the gun, and sicne it's really high flow, a lot of air going to fire the gun. that, and i've got a weird hackjob VA that i modded. I will say this though. Right now, my gun is running about 280 at 400psi, and i'm getting pretty good efficiency (1000 shots with 2000psi left in a 71cu) the reason for the high pressure is because i haven't been able to tune my gun right, and i need to get a rebuild kit for my rocketvalve

12-16-2006, 09:49 PM
Nothing to quip about - thats in the LP range.

Yeah here are the specs for my xtra:

-Old spudnkl delrin bolt that was swollen so I turned (milled) it back down to dimensions (i got it free)
-Milled stock striker (cupped face and cut off some extra material) looks alot like the dragonfly striker
-Stock V/A: drilled for airflow, cut to increase air chamber, and tapped for gauge
-Shocktech LPC
-Tornado valve
-Spring kit - using medium valve, hard main to get 200 psi operation, if use light main, I can do 250 psi
-Palmer stabilizer

Tons of other stuff, but thats the performance items...

12-16-2006, 10:00 PM
true it's lp range, but it almost seems weird with the parts i have:
Rocket Valve
DH Titanium
Aka Lightning Bolt
BL Torp
Moddified Rebel VA (45*internal passages)
Heavy main
stock lpc

I should bring it to the feild and re-chrono it. I chronoed it bassed off my friends ion that's chrono'd at 280fps. We had a friend stand way far away and we shot towards him to get a distance reading. both our shots went the same distance, give or take a few feet. to make it fair we basically had them on stands to make sure the angle and such was the same. I really haven't tried using a diffrent main spring yet, but it'll recock down to 200psi on hpa. i need a new torp. mine is really beat up, and the adjusting screw is stuck, so i use pennies and dimes to shim it to get the psi right. i can go in 100 and 200 increments

12-16-2006, 10:03 PM
wow, thats a ghetto torp lol. yea use a real chrono, with those internals you should be much lower...

12-16-2006, 10:10 PM
i've actually had a lot of problems getting the psi lower. i remember last time at 600psi i could only get it to chrono 240 due to the crappy kingman va (and i couldn't use a heavy spring due to a bad battery) wtih the heavy spring it was 270 at 600 though. I have no idea why i can't get my psi down. maybe i should just rebuild my rocketvalve and get another torp. actually, i kind of want to buy two torps and a bushmaster VA (or maybe just 1 torp and use it on 2 guns) well, at least now i can hear the balls hissing through the air. oh wait...isn't that a sign of shooting hot?

12-16-2006, 10:27 PM
hehe, well yea, get a functional reg and rebuild the rocket if you suspect its messed up, my guess that would solve a bunch of problems for you....

12-16-2006, 10:46 PM
i just think maybe my rocketvalve's dwell is too low. then again, i wonder how it would do with my ndz valve...my reg works XP, it's just not as adjustable as it should be hahaha

12-18-2006, 11:32 PM
any other people with experiences?

01-29-2007, 12:48 AM
Just thought I'd bring this back up since its been awhile, I'm still stuck with the high hpa pressures. I just installed a timmy bolt, so I'll test it and if there is any diff...

01-29-2007, 01:44 AM
I hit around 225-250 psi with hpa but I have a Bandit valve and Bolt (with o-rings). I found CO2 harder to tune with than N2 even with a reg. The N2 was more consistant at the chrono and made using different springs and setting the velocity knob easier. Good luck anyway.