Subtank RBA vs OCC Air Flow

[m00shie]

Hey all...first of all...I like to apologize if there's a similar posting around. I did search the forum and have gone thru quite a number of threads on Subtank but did not find a suitable answer.

Basically, I just did my first build on my Subtank RBA and was shock to find how constricted the air flow and juice flow (as mentioned in other threads) was compared to the OCC coil heads as I had difficulty sucking the air and get dry hits using the vaping method I used on the OCC. I look thru tons of threads in ECF (the pics on subtank builds was very helpful ) and elsewhere and came to a conclusion that my wick (cotton that came with the subtank) may be too thick and too cluttered (followed PBusardo's vid).

Today, I rebuild the RBA head with Fiber Freaks (rayon) and this time, with less density (just slight friction going thru the coil) and make sure the wick is touching the bottom and did my best not to block the juice hole. Tested the build and I still, the airflow was a wee bit better but still isn't what it felt on the OCC coil heads. It feels very restrictive and not smooth at all. This time, I got more dry hits and I think the density of the wick is not thick enough to hold more juice or the juice is not flowing fast enough.

So I'm now back to the OCC coil head (Ihank god it's still usable) for now to enjoy some hours of vaping before I go back to experimenting (I have a rebuild OCC coilhead on standby for testing).

Basically, what I like to know is if the ariflow on the RBA isn't as smooth as the airflow in the OCC head or if the mistake is on my poor skills at rebuilding the RBA...haha. From what I have read in various threads, the wicking on the RBA head is very sensitive. Appreciate any further tips if any to get the airflow as good as the OCC head (aside from rebuilding the OCC head ). Thanks!

Edit: Note...I'm using the coil that is already on the RBA.

 

[Aptivus]

While I can't answer as to why your airflow is restricted with the rba, I can tell you that a lot of people just rebuild the OCC coil itself. It's actually pretty easy and there are a handful of video tutorials on YouTube of the process.

 

[edyle]

Hey all...first of all...I like to apologize if there's a similar posting around. I did search the forum and have gone thru quite a number of threads on Subtank but did not find a suitable answer.

Basically, I just did my first build on my Subtank RBA and was shock to find how constricted the air flow and juice flow (as mentioned in other threads) was compared to the OCC coil heads as I had difficulty sucking the air and get dry hits using the vaping method I used on the OCC. I look thru tons of threads in ECF (the pics on subtank builds was very helpful ) and elsewhere and came to a conclusion that my wick (cotton that came with the subtank) may be too thick and too cluttered (followed PBusardo's vid).

Today, I rebuild the RBA head with Fiber Freaks (rayon) and this time, with less density (just slight friction going thru the coil) and make sure the wick is touching the bottom and did my best not to block the juice hole. Tested the build and I still, the airflow was a wee bit better but still isn't what it felt on the OCC coil heads. It feels very restrictive and not smooth at all. This time, I got more dry hits and I think the density of the wick is not thick enough to hold more juice or the juice is not flowing fast enough.

So I'm now back to the OCC coil head (Ihank god it's still usable) for now to enjoy some hours of vaping before I go back to experimenting (I have a rebuild OCC coilhead on standby for testing).

Basically, what I like to know is if the ariflow on the RBA isn't as smooth as the airflow in the OCC head or if the mistake is on my poor skills at rebuilding the RBA...haha. From what I have read in various threads, the wicking on the RBA head is very sensitive. Appreciate any further tips if any to get the airflow as good as the OCC head (aside from rebuilding the OCC head ). Thanks!

Edit: Note...I'm using the coil that is already on the RBA.

What is the internal diameter on the coil that is already on the RBA?

If the diameter of the coil is large it could be the main contributor to restricted airflow; compare the diameter of the coil in the RBA to the coil in the other head.

 

[m00shie]

It's the stock coil that comes with the RBA. Will need to measure it tomorrow. I think it's 3 mm or 3.5 mm. What you said may be correct. I think I'll make a micro coil and test. Thanks!

 

[jefx]

Its not anything you've done wrong. The airflow holes at the base pin on the RBA are smaller in comparison to the OCC heads. It's just the way it was designed. The stock RBA is going to be more restrictive than the OCC because thats the way it was designed.

I've considered dremeling out the airholes a little to see if it makes any difference.

However, your build can also add to the air restriction.

 

[m00shie]

Thanks for the info! I will either research into modifying the air holes or mellow down my inhalation method. .heh

 

[jefx]

Here's a pic of the airflow on the coil head vs. the airhole on the RBA post.



The inner diameter of the RBA post is larger than my 3.0 mm screwdriver, so I'm guessing it's probably about 3.5 mm. So in my mind, the most restrictive part is the 4 tiny holes at the bottom of the post.

So I dremeled those 4 holes into 2 slots, so it's no longer the point of restriction.



So after some test vapes, if feels less restrictive. But I have no way to quantify the amount. It's still not as airy as the heads, but better than it was. I'm gonna try a vertical coil next and see if that changes anything, because the coil placement is now the only restriction.

 

[m00shie]

Yeah. ..i see your point. Let me know how the vertical build goes and how you are planning to wick it as I believe vertical should improve it drastically. Thanks!

 

[Dioxyde]

The original subtank RBA is designed that way unfortunately, as an advantage though it does make for incredible flavor.

 

[m00shie]

The original subtank RBA is designed that way unfortunately, as an advantage though it does make for incredible flavor.

Ya...I'm currently vaping on the RBA as I'm typing and it does enhance the flavor somewhat. I just hope a vertical build will improve the smoothness of the air flow.

 

[jefx]

The vertical build... I tried it. At this point I can no longer tell a difference between the draw on the heads and the draw on my RBA!!! It's just as airy! This was my first vertical build attempt, and I made the coil's inner diameter ever so slightly larger than the inner diameter of deck post (where the air comes in), so that way, there is nothing obstructing the airway.

Remember however, that I also dremeled out the intake holes to make 2 large slots instead of 4 tiny holes.

At this point, I can draw my full lung capacity through the RBA, in under 7 seconds if I want.

Also, with this much wick in the deck, I'm not getting any dry hits even with these full lung hits.

Here's a pic:

 

[jefx]

I just pulled my full lung capacity through the RBA in 4 seconds flat....(but I didn't get much vapor). So my RBA deck is flowing air at maximum potential. Now I can actually turn the AFC down if I want.

 

[m00shie]

Man. ..that's awesome! Thank you so much!

 

[m00shie]

My first attempt at vertical coil using 1 ohm using 28awg kanthal at 2mm. The pic shows my first build which I placed too much cotton. The juice was spitting thru and started to leak thru the AFC. After 2 more attempts on the cotton, I manage to get the density somewhat correct..no more spitting, no more leaks. The air flow is way better than the horizontal coil...vaping is much smoother but as I have not modify the airflow yet, it's still not up to par with the OCC yet.

I will try to increase the coil inner diameter to possibly 2.5mm or 3mm and compare the differences with the airflow before moving forward to modify the AFC.

 

[dleister1981]

the wicking is real easy with Ko Gin doh cotton http://youtu.be/d24KY-uw7dM thats a link to .... kickers, he does an amazing job showing the ins and outs of what to do

 

[dleister1981]

My first attempt at vertical coil using 1 ohm using 28awg kanthal at 2mm. The pic shows my first build which I placed too much cotton. The juice was spitting thru and started to leak thru the AFC. After 2 more attempts on the cotton, I manage to get the density somewhat correct..no more spitting, no more leaks. The air flow is way better than the horizontal coil...vaping is much smoother but as I have not modify the airflow yet, it's still not up to par with the OCC yet.

I will try to increase the coil inner diameter to possibly 2.5mm or 3mm and compare the differences with the airflow before moving forward to modify the AFC.

View attachment 418340

yeah, way too much cotton, this is where your dry hits are coming from, less is more in the case of the subtank rba, and there should be no reason to mod the airflow, it should be real open stock

 

[FOG clouds]

Haven't tried a vertical coil yet. However, i found that the cotton amount and placement has A LOT to do with air flow. should be fairly snug in the coil but not too tight. cut it so it reaches just to the juice flow opening. fluff it and use a piece of wire to move the cotton away from the holes on each side. Have you had any issues with juice coming up through the mouthpiece?

 

[m00shie]

Haven't tried a vertical coil yet. However, i found that the cotton amount and placement has A LOT to do with air flow. should be fairly snug in the coil but not too tight. cut it so it reaches just to the juice flow opening. fluff it and use a piece of wire to move the cotton away from the holes on each side. Have you had any issues with juice coming up through the mouthpiece?

Initially yes. Then I was advise by my friend to move the cotton away from the juice holes. After that, I have no issues on the horzontal build aside from the air flow. The vertical build is awesome in regards to the airflow but I'm having trouble getting the right amount of cotton..haha

 

[jefx]

there should be no reason to mod the airflow, it should be real open stock

Maybe compared to other RBAs, but compared to the OCC heads, it's pretty restrictive.

 

[dleister1981]

Maybe compared to other RBAs, but compared to the OCC heads, it's pretty restrictive.

mine is as open as the occ head