Tippmann 98 low pressure kit questions

[Cunha]

Looking for some feedback from people who use them.

1. How does it feel versus a normal tippmann?

2. Has anyone used one without the volumizer? A lot of paintball volumizers are snake oil so I was wondering if the volumizer on the LPK is necessary or just a way to make the kit look more high impact than "Lightened hammer, and volumized power tube"

3. What is actually different on the LP kit, guts wise? I know it comes with the vertical air adapter, the volumizer that screws into the valve, but what is different than stock?

Thanks.

[EvilCreature]

I have used one or two kits, here are my thoughts:

1. There is less kick due to less mass in the hammer and less force required to open the valve and also less force to recock the hammer. Back in the day people would use different springs to "dial in" their preferred feel with varied results but the "stock" setup is fine.

2. The volumizer is actually pretty critical for consistency and shooting a rate greater than one or two balls a second. The reason is that at the pressures used and given the somewhat long, narrow passages the air needs to travel through, recharge can become a problem. The volumizer gives the gun a pressure-steadying reserve to draw from if higher rates of fire occur. I believe some have tried running the regulator straight into the valve with no front grip. That could work if you have a really good regulator but I wouldn't do it. Given the marker was originally designed to run on between 700-800 psi (co2), I am impressed that a little volume chamber can make up for everything that is designed wrong for operating at lower PSI HPA.

3. People actually had pretty good guides for modifying the stock parts to make their own kits without spending a ton of money. Basically, the hammer is lighter (don't remember the recommended weight but the mod was easy), valve channels that direct the air towards the ball are increased in size. I believe they are a little deeper/wider and modders would either deepen, try to add a channel, or both. The valve stem might have been slightly bigger as well to allow more flow. I believe modders were more inclined to run their air directly from the reg to the valve rather than mod a regular gas-through-the-handle kit but some modified their kits just fine. Be careful if you want to mod the valve body! I am not sure if the spring was lighter or the same... people may have modified the stock spring slightly to lighten it.

[Toestr]

Before the crash, there I had a pretty long thread chronicling making a homebrew LP kit. I never actually tried doing all mods other than the volumizer, but I am 90% sure that it would be necessary. It should be noted that I have yet to get my homebrew going.

The differences in the valve are:
Wider channels
Valve seat has a wider opening
Valve stem is thicker
Lightened valve spring



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[Cunha]

Thanks for the responses.

[apamburn]

In prep for the '21 paintball season I had my franken-98 out for cleaning and chrono this morning. It came in at 270-280 FPS with about 400 PSI input pressure on HPA and the lightest (blue) spring turned all the way in.



I posted about the build on the old site, but just a reminder of mods / features:

1. Palmer's reg (HP springs)
2. RVA
3. Spring kit
4. polished shells
5. DIY lightened hammer
6. TechT light valve spring (actually cut a few coils off)
7. DIY volumizer (gutted and jb welded LPR)
8. TechT Trigger Pin Kit

Don't think I'm missing anything there. I don't believe I have opened up the valve flutes, though I do remember toying with a valve...maybe in my other 98? I know I messed one up and had to chuck it.

Anyways, keeping in mind that this is a DIY LP 98 (if 400 PSI is considered LP for this marker) my take on your questions:

1. How does it feel versus a normal tippmann?

>> I guess the additional stuff adds some weight, but nothing significant. The biggest difference in my case is in feel when firing, and that is primarily due to the weak mainspring. Mainspring strength seems to impact trigger weight substantially, which makes sense - stronger springs mean the hammer pushes on the sear more, which means pulling the trigger will require greater force.

I don't particularly like the trigger with the weak mainspring; it's almost spongy.

The gun also sounds softer - not sure it's quieter. Hard to describe, probably have to see / feel yourself.

I may change to a slightly stronger mainspring, which might drop operating pressure even lower, primarily to make trigger feel better. If you go LP you might keep that in mind.

2. Has anyone used one without the volumizer? A lot of paintball volumizers are snake oil so I was wondering if the volumizer on the LPK is necessary or just a way to make the kit look more high impact than "Lightened hammer, and volumized power tube"

Yes. My initial build didn't include a volumizer. I had serious recharge issues. Turning in my FVA allowed successful recock (because it redirected all input air back to the hammer), as did cranking up input pressure (which obviously defies the point of my mods). Once I added a DIY volumizer I was able to achieve recock and playable velocities at lower pressure, even though the LPR doesn't exactly provide a lot of additional volume.

That calculus may be different with a genuine LPK valve - not sure if they hold greater volume of air than the stock valve.

3. What is actually different on the LP kit, guts wise? I know it comes with the vertical air adapter, the volumizer that screws into the valve, but what is different than stock?

The valve pin hole and the flutes on the valve of the LP valve are different. Here's a pic, I downloaded from here I believe, before the death of the old board:



To be honest, I don't remember which is which.

Anyways you can DIY this. Because this is a balanced valve, I'd highly recommend that you lighten the hammer, lighten the valve spring, install a reg, and install an RVA (and preferably spring kit) - or don't do anything at all. You need to lower the magnitude on both sides of the balanced valve equation to be able to lower pressure.

If you want to play around, I also noticed that the front cap of the 98 can be hollowed out more and, when installed, it blocks part of the 1/8 npt input hole. On one of my 98s (the other one, I think?) I drilled out the cap and cut it so that it doesn't partially block the hole - probably not a huge difference, but adds a tad bit of volume and might help air throughput a little. I'd have to go back through my notes, pictures, and messages to Magmoormaster to see which gun got that treatment.

[GreenMan]

I can chime in a bit as well. My old LP 98 has long since been sold off, but I remember it quite well.

-The main difference in feel was significantly reduced reciprocating mass. It was quite noticeable, and rather pleasant. The downside was that with the addition of a regulator and the volumizer/adapter, it felt significantly heavier to me. Its worth noting that the 98 already has a lot of mass in the forward part of the marker, and thats where much of the weight in the LP kit was added. That was the ultimate reason I sold it: the 98 is already the heaviest marker on the market, and the addition of more weight just seemed to be too much. I would also add that it didn't seem to lighten the trigger pull at all. I agree that the shot signature was different but not really quieter.

-I personally never used it without the volumizer. However, a reliable source once claimed to run a standard LP tank directly into the valve, no regulator, without any issues. I imagine with steel braided hose, a high flow ASA, and no restrictive regulator, there was plenty of air available.

-The differences have been covered, but it seems like a fatter valve stem and hole, wider channels, and a lighter valve spring are the real differences.

Additional notes: I can't help but wonder if the actual pressure difference at the bolt hitting the paint is minimal. Paint handling is probably improved because the bolt is moving forward with less force behind it.

[Toestr]

I think if you were to combine a lpk with an act bolt, it might actually work. A lower pressure is definitely half the formula when it comes to low force bolts. If you dry fire an act bolt on your finger, it feels lighter than an Emek's. But if you fire an act bolt at 800 psi on your finger, it will hurt like hell, but a bit less than without act. It might work for winter or very hard field grade paint, but that's a big might.

Beyond that, some people say that if you spring a Tippmann light enough it will pinch paint. Again, it might work for winter or field paint, but even when I tried it with the lightest spring in a kit and a lightened hammer, I'm doubtful.

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[Brokeass_baller]

The air pressure coming from the bolt will definitely not be 800psi. Tom Kaye back in the day did A LOT of research into this and explained it in one of his old Tom's Tech essays on AO. Basically there's a relatively small amount of air that is discharged at the time of firing, and between the turns out of the valve and into the breech, as well as the increasing amount of total volume accumulating as the ball is accelerating, the air pressure decreases significantly and rapidly.

He found that the paint is hit with somewhere between 80 and 120psi of air upon initial impact (or something like that, I can't remember exactly), but at 150psi, the paint will shatter under the force.

So, there's something.

[apamburn]

Yeah I haven't seen the act work even with my lp setup. I can't say I've seen any chops though I do get some barrel breaks.

Definitely never any "chuffing" typical of act doing it's thing..