Originally Posted by okitoki
I have been informed in previous threads that dwell tuning doesnt really help much with efficientcy... bummer
Originally Posted by 96 Ls lnteg
remember lower dwell doesn't always equal efficency..
As 96 Ls lnteg stated, reducing dwell doesn't automatically mean an increase in efficiency. However, sometimes it does, so there is certainly no harm in dwell tuning and seeing what the result is.
For instance, maybe all the air in the firing chamber is released in less than 12.5ms anyway. Maybe when you are reducing the dwell, you are just cutting the dwell time down to the minimum time required to release all the air in the chamber. However, as all the air in the chamber is being released anyway, you aren't using any less air.
Maybe you have screwed the VVC in, so there is less air to be released. Maybe your dwell reduction is just the time that would have been used to release the extra air in the chamber had the VVC been all the way out. So, you have saved some air, but it is the VVC that has really made the difference, not the reduction in dwell.
Then again, maybe you don't need to use all the air stored in the chamber in order to get a ball up to speed, and maybe the VVC doesn't make a big enough difference in volume to prevent more air being used then required. In that case, shortening the dwell to prevent more air being used than necessary will save you some air.
Long story short, no, dwell tuning isn't necessarily going to save air, but under certain circumstances it will, so why not give it a go? If nothing else, reducing dwell will save battery life even if it doesn't save air. Just don't go so low as to compromise reliability or consistency, and it's all good.
Originally Posted by Noblesse_Oblige
I'm working on this too. I don't have the ST bolt yet, GR2 though. I'm currently running my dwell at about 9. Is there a reason for the GST bolts having such higher dwell settings? My Geo seems to shoot fine like this but am I just overcompensating with input pressure and reducing the efficiency more than I realize?
The general recommendation with dwell tuning is to set your velocity at the stock dwell setting of 12.5ms, and so get your base operating pressure. You shouldn't be changing your input pressure after that point, just changing the dwell. By setting your reg pressure up front, and then leaving it alone, you shouldn't be compensating for any velocity loss caused by reducing the dwell, by increasing the HPR pressure. If you are changing the HPR pressure during the tuning process, then you are defeating the object of dwell tuning, as you aren't just tuning the dwell.
The reason that the ST kit requires a higher dwell setting is because the bolt cycles more slowly with ST Kit that with the stock bolt and can. This is the reason why the ST Kit kicks less and makes for a smoother shot.
Let's say for sake of argument that the bolt takes 2.5ms to move forwards in the stock kit, leaving 10ms for air to flow out of the air chamber to propel the ball. Now let's say that the ST bolt takes 4.5ms to move forwards. If you still had a dwell of 12.5ms, that would only leave 8ms for air to be released to propel the ball. As such, with less air released, your velocity will drop. The ST kit requires a longer dwell to allow time for the bolt to open at it's lower cycle speed, and still have the same length of time to release air.
This goes back to the point about changes in dwell not necessarily leading to changes in the amount of air used. It's all circumstantial. In this instance, with the ST kit, a longer dwell does not mean more air being used, as the additional dwell time is not being used to release more air, but to compensate for the slower bolt speed.
As for improving efficiency, as has already been stated, a good bore to barrel fit will assist - get some more bore sizes when opportunity allows. Make sure that your bolt tip o-ring is in good condition to prevent blow back. Make sure that the pin hole behind the can o-rings is just that - a pinhole; too large a hole will lead to air loss as the bolt cycles. Make sure that the solenoid back check ball is 4.00mm or larger. Make sure that the ball is clean and undamaged.