Brocock/BRK BRK Ghost Wheel only lowering FPS by 10

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msg1979 said:
So is mine faulty?
I have no change in fps from min to max on powerwheel. I only feel the pull of lever is getting harder when moving wheel to max
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I was replying to JoeDirt's comment, I have no clue if the BRK Ghost utilizes a balanced/assisted valve, but if it does, it would apply to your case, yes.

If changes in hammer spring preload do not effect the muzzle velocity of a gun with a balanced valve, the balance chamber volume is too great, or the vent/jet feeding that chamber is too small, essentially creating a Cothran valve effect.

-Matt
 
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Stubbers said:
I was replying to JoeDirt's comment, I have no clue if the BRK Ghost utilizes a balanced/assisted valve, but if it does, it would apply to your case, yes.

If changes in hammer spring preload do not effect the muzzle velocity of a gun with a balanced valve, the balance chamber volume is too great, or the vent/jet feeding that chamber is too small, essentially creating a Cothran valve effect.

-Matt
Click to expand...
Ok. Thx
Well then BRK messed something up. It came like this from the factory. Powerwheel doesnt do anything to the speed no matter what regulator pressure I use.
 
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msg1979 said:
Ok. Thx
Well then BRK messed something up. It came like this from the factory. Powerwheel doesnt do anything to the speed no matter what regulator pressure I use.
Click to expand...

Yea, based on some googling I believe the Ghost does use a balanced valve, to which I would say, yes, it is buggered somehow...because it should respond to pre-load changes on the hammer spring from the factory, especially given that there is an adjustment for it lol.

Either your vent is under-sized/clogged, or the volumes chamber setting is incorrect. If you're not super DIY friendly, you're going to have to warranty it.

-Matt
 
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msg1979 said:
Ok. Thx
Well then BRK messed something up. It came like this from the factory. Powerwheel doesnt do anything to the speed no matter what regulator pressure I use.
Click to expand...
msg1979 said:
Ok. Thx
Well then BRK messed something up. It came like this from the factory. Powerwheel doesnt do anything to the speed no matter what regulator pressure I use.
Click to expand...

Nah, it sounds like it's acting the same way mine does with the .177 and .20 barrels.

It sounds counterintuitive but with a .177 Ghost there's a point where increasing the reg pressure starts to decrease the power output. Somewhere between 120-140 bar is where you'll see the most power output with a .177 Ghost. And you should also see the largest swing between MIN and MAX on the wheel in that window of reg pressure.

In the larger calibers the Ghost will put out more energy with reg pressures around 150-160bar, but not in .177 and .20. I'm not sure why, but that's how the Ghosts I've played with have behaved.

WAG would be the transfer port has something to do with it. On a .177 barrel it's only 0.125." I can logic my way through a 160 bar blast getting choked at the transfer report and shutting the valve more quickly, but I don't know for s fact that that's the "why" behind reg pressures too high for .177 Ghost limiting the power output.

Summary: your reg pressure is too high. Put it at 130 bar and tell us what you get with MIN and with MAX. If yours behave like mine, you'll probably see more fpe than at 160bar, and be more happy with the effects of changing the power wheel.
 
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Franklink said:
Nah, it sounds like it's acting the same way mine does with the .177 and .20 barrels.

It sounds counterintuitive but with a .177 Ghost there's a point where increasing the reg pressure starts to decrease the power output. Somewhere between 120-140 bar is where you'll see the most power output with a .177 Ghost. And you should also see the largest swing between MIN and MAX on the wheel in that window of reg pressure.

In the larger calibers the Ghost will put out more energy with reg pressures around 150-160bar, but not in .177 and .20. I'm not sure why, but that's how the Ghosts I've played with have behaved.

WAG would be the transfer port has something to do with it. On a .177 barrel it's only 0.125." I can logic my way through a 160 bar blast getting choked at the transfer report and shutting the valve more quickly, but I don't know for s fact that that's the "why" behind reg pressures too high for .177 Ghost limiting the power output.

Summary: your reg pressure is too high. Put it at 130 bar and tell us what you get with MIN and with MAX. If yours behave like mine, you'll probably see more fpe than at 160bar, and be more happy with the effects of changing the power wheel.
Click to expand...
Thx for the good explanation.
I've been shooting the Ghost for a year. Maybe 2000 pellets
I've tried with pellets from 8,44-16g --> reg from 60-130bar. Everytime I have tuned in for a new pellet I've tried the powerwheel to see what happened. I've never seen a change in fps no matter how the powerwheel was set on x reg setting. I always try min and max when I have reached the desired speed with the regulator and with the powerwheel on 10. So far I've seen no change in fps.

Last week I tried the jsb KO 13g - to get max fps (930) fps the reg had to be 160 - I increased from 130bar in 5bar steps with wheel in 10 Thats was my first time at that reg setting - so when I reached the 930fps with the regulator I tried the powerwheel on min and max - no change in fps. Ill try again at 130-140bar with wheel on min and max since I did the 5bar increase with wheel on 10.

The reason im asking is that I looked into some Ghost tuning videos on youtube. All I see is fps change when the turners turn their wheel - so I dont get why my wheel isnt responding. But it makes a bit sense now - the tuning videos are on bigger calibers = bigger port as you described
 
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msg1979 said:
Thx for the good explanation.
I've been shooting the Ghost for a year. Maybe 2000 pellets
I've tried with pellets from 8,44-16g --> reg from 60-130bar. Everytime I have tuned in for a new pellet I've tried the powerwheel to see what happened. I've never seen a change in fps no matter how the powerwheel was set on x reg setting. I try min and max - no change - and then set it on 10, I can only use my reg to get the desired speed.

Last week I tried the jsb KO 13g - to get max fps (930) fps the reg had to be 160 - I increased from 130bar in 5bar steps. Thats was my first time at that reg setting - so when j reached the 930fps with the regulator I tried the powerwheel on min and max - no change in fps. Ill try again at 130-140bar with wheel on min and max since I did the 5bar increase with wheel on 10. Only tried min and max at 160bar

The reason im asking is that I looked into some Ghost tuning videos on youtube. All I see is fps change when the turners turn their wheel - so I dont get why my wheel isnt responding. But it makes a bit sense now - the tuning videos are on bigger calibers = bigger port as you described
Click to expand...

Very interesting.

My .177 with the short barrel is currently set up for the 10.34gr pellets. At MIN it's 890, and MAX is 910-912. Reg pressure is 105-110bar. So about 20fps spread from the power wheel, mostly b/c the reg is the limiting factor there. With the Ghost, a reg pressure just barely high enough for desired fpe gives the tightest ES, but also minimizes the changes to fps from the power wheel.

So if your wheel never does much, makes me wonder if you've got too much spring in the gun. Was it a .177 HP to begin with? Do you know what spring you have? And what exactly is the goal you're working towards?
 
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Shouldn't have anything to do with ports,...however it could be that the hammer spring is rated too high in lbf/in for your caliber and no matter what you do, from setting 1 to 10 it is reaching the plateau...which would be lack of foresight from BRK with that arrangement of caliber and spring.

I personally cannot say which is most likely, but can conclude it is not ideal to be in either condition (over sprung hammer, or poorly vented balanced valve)

The only porting that would effect hammer strike is the throat/valve seat diameter which, with larger seat diameters, you require more force to crack the valve from that seat, which again, would be corrected with a hammer spring with a lower lbf/in rating.

And if going upwards of 160 bar doesn't begin to have any effects, then that spring is WAY too strong, or as I originally stated, the balance valve's vent is too small for this arrangement, where bigger calibers require more dwell and this effect would potentially go away in either scenario (vent or spring issue).

-Matt
 
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Franklink said:
Very interesting.

My .177 with the short barrel is currently set up for the 10.34gr pellets. At MIN it's 890, and MAX is 910-912. Reg pressure is 105-110bar. So about 20fps spread from the power wheel, mostly b/c the reg is the limiting factor there. With the Ghost, a reg pressure just barely high enough for desired fpe gives the tightest ES, but also minimizes the changes to fps from the power wheel.

So if your wheel never does much, makes me wonder if you've got too much spring in the gun. Was it a .177 HP to begin with? Do you know what spring you have? And what exactly is the goal you're working towards?
Click to expand...
Its a HP model. Bought it from Krale. I dunno if they messed with the spring.
I dont know which spring is inside. But I can check tomorrow.

I did write to BRK yesterday with the serial and question about why my powerwheel has no effect. Might they can give me an answer.
Problem is that there is no dealers with springs in eu. If I buy from UK tax will top a 50% on price + a 30euro fee = very expensive spring

Goal is to get powerwheel working so I can fine tune with powerwheel and not the "bulkier" regulator wheel
 
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Stubbers said:
Shouldn't have anything to do with ports,...however it could be that the hammer spring is rated too high in lbf/in for your caliber and no matter what you do, from setting 1 to 10 it is reaching the plateau...which would be lack of foresight from BRK with that arrangement of caliber and spring.

I personally cannot say which is most likely, but can conclude it is not ideal to be in either condition (over sprung hammer, or poorly vented balanced valve)

The only porting that would effect hammer strike is the throat/valve seat diameter which, with larger seat diameters, you require more force to crack the valve from that seat, which again, would be corrected with a hammer spring with a lower lbf/in rating.

And if going upwards of 160 bar doesn't begin to have any effects, then that spring is WAY too strong, or as I originally stated, the balance valve's vent is too small for this arrangement, where bigger calibers require more dwell and this effect would potentially go away in either scenario (vent or spring issue).

-Matt
Click to expand...
I start to believe I need a "smaller" spring since the powerwheel/valve is working on other Ghosts. It makes sense if the spring is too heavy. It doesn't make sense if BRK fitted a oversized spring though.
 
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msg1979 said:
I start to believe I need a "smaller" spring. It makes sense if the spring is too heavy.
Click to expand...

This would be a great place to start, however if a spring with reduced rating does not have an effect, or the effect is only valve lock, then either that spring is too low in rating, or its the balance venting/chamber volume out of 'balance'.


This is how you can determine your current springs rating if you have a set of calipers, which would make it easy to source a lighter one of equal length and similar dimensions, albeit reduced wire diameter.

Compression Spring Calculator

compression spring calculator, compression spring design, compression spring calculation, compression spring calculations, calculate spring constant, spring design, calculating spring constant
www.planetspring.com

-Matt
 
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Now, why I think its BV vent/chamber versus spring...

In theory, you should notice a change in the muzzle report, and possibly even a decline in velocity at higher settings/preload of spring as you'll only be wasting more air while producing no more energy, or bouncing the hammer off the rear of the valve, or bouncing the poppet off the inside of the balance chamber.

However, your valve is behaving exactly like a Cothran valve where, muzzle velocity only changes when pressure changes. BUT, it could still be too much hammer spring...

If the vent that feeds the balance chamber volume is too small, it cannot create enough closing force thus, you experience 'blow open' valve behavior, likewise if the chamber volume is too great, the vent cannot fill it fast enough to reverse the balance valve effects to create proper closing force, which also creates a blow open effect.

-Matt
 
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Stubbers said:
This would be a great place to start, however if a spring with reduced rating does not have an effect, or the effect is only valve lock, then either that spring is too low in rating, or its the balance venting/chamber volume out of 'balance'.


This is how you can determine your current springs rating if you have a set of calipers, which would make it easy to source a lighter one of equal length and similar dimensions, albeit reduced wire diameter.

Compression Spring Calculator

compression spring calculator, compression spring design, compression spring calculation, compression spring calculations, calculate spring constant, spring design, calculating spring constant
www.planetspring.com

-Matt
Click to expand...
BRK make a set of springs to the Ghost
It contains 5 springs with 5 different ratings. I will check which I have in my Ghost and then buy the two springs "below" mine.
 
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msg1979 said:
My .177 fac
At 160bar and shooting KO 13.43 I get 930 fps no matter if wheel is on minimum or max.
I can only adjust speed with regulator 🤨🙄
Click to expand...
Barrel length?
You will need to reduce reg pressure back to around 115/120 as for that weight pellet using the white FAC spring your PWR wheel won’t do much better for your speed.
To increase efficiency and effectiveness of power wheel you need to decrease or increase spring type but which spring is installed?
Also your hammer may have slipped a bit and require adjustment / retightening.
 
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cavedweller said:
Barrel length?
You will need to reduce reg pressure back to around 115/120 as for that weight pellet using the white FAC spring your PWR wheel won’t do much better for your speed.
To increase efficiency and effectiveness of power wheel you need to increase spring type to the next level up.
Also your hammer may have slipped and require adjustment.
Click to expand...

He said he tried reg from 60-130 bar with no change in velocity from the PWR wheel adjustment (altering spring preload)...therefore he is not under-sprung, he should be over-sprung...

If his spring were too light, he would be able to experience either reduced velocities or valve lock at higher reg pressures, while having the PWR wheel be effective at lower pressures, however I don't think this is the case...


-Matt
 
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Stubbers said:
He said he tried reg from 60-130 bar with no change in velocity from the PWR wheel adjustment (altering spring preload)...therefore he is not under-sprung, he should be over-sprung...

If his spring were too light, he would be able to experience either reduced velocities or valve lock at higher reg pressures, while having the PWR wheel be effective at lower pressures, however I don't think this is the case...


-Matt
Click to expand...
My experience in both the 17” and 23” barrel in .177, using the lowest power spring, regardless of pellet weight, is using more than 115/120 reg pressure will net negligible difference utilizing the power wheel and may actually result in some slower speeds. Don’t know why but it is a thing. Remembering that we don’t really want or need Diablo pellets moving faster than 915/920 fps. But I’d definitely check the hammer spring shoe as it may be loose.
 
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