NARB Build Question - T-Burner vs Choke

[Flynn]

Howdy folks...  I've been noodling on my new forge design, and I read through Frosty's T-Burner naturally aspirated ribbon burner build thread.  Brilliant work, Frosty, thanks!

In my own design I was thinking about building it with a washer/choke design similar to the Devils' Forge burners. I would think that adding in the choke to the design would allow it to be adjusted based on atmospheric conditions, eliminating the trial and error in designing one to your particular local.  Is my logic sound in this, or am I missing something and there is a reason no choke was added in the original design?

Thanks for the help!

[Buzzkill]

Generally speaking, a choke on a T burner is a step backwards.  When properly tuned a T burner pulls in the right amount of air for the volume of fuel being injected across the operating pressure range of the burner.  So, if you have to choke the burner then it wasn't tuned properly to begin with, and most likely is not burning as hot and as efficiently as it should be.

My personal experience with a NARB powered by a T burner is that it tended to run richer than it had as a single port burner.  I had to make some modifications to allow more air to be induced, which is the opposite of what you're suggesting.  However, with all these DIY projects no two are identical, so you can't assume you will get the specific results as me or anyone else.

[Frosty]

Well said Buzz, I only have a little to add. 

Flynn: Local conditions: elevation, humidity, etc. don't enter into burner operation unless you travel with it. Normally you tune your burners where you're going to use them so they're tuned PERIOD. Would you pull a couple spark plug wires on your daily commuter? Think it would get better mileage because it's not BURNING as much fuel? 

However if YOU wish to slop together a sub par something that requires a choke, you most certainly may just don't associate my name with it, Please. And for the sake of the blacksmithing world please don't make and upload pictures or videos of it. I have to spend way too much time helping people fix the problems caused by ideas like this as it is.

Frosty The Lucky.

 

[Flynn]

Wow, I feel like I just got slapped with an education.   My thought was only that adding the choke could give you a very easy way to tune your burner instead of trimming the MIG tip.  I stand corrected and we can remove this post if you'd like, in order to not confuse others.

[JHCC]

We generally don't remove posts, for the simple reason that they can act as warning signs for others who might want to consider such a course of action in future.

[Frosty]

I didn't mean to harsh on you Flynn. Weren't you following the thread over the last couple days where someone was trying REALLY hard to justify choking a T burner? He was skating with arguing about it, at which point I say why and stop responding at all. In his defense he'd spent good money buying them and was hoping to salvage a bad design. He's not a bad guy anymore than I think you are. 

I'd just finished virtually the same conversation and it makes me grouchy to see a replay so soon.

Please, experiment and feel free to bounce ideas but maybe wait till you've proven your improvements work before suggesting them publicly? I do, I don't present ideas without saying they're just ideas up front. Nor do I publish "improvements" before I've tried them first, often several times. Using a "floor flange" to jig a T to a drill press table and improve precision building a T burner saw 6 burners built before I  mentioned it anywhere, let alone on a world wide public forum.

Again, neither Buzz nor I were slapping you around. We thought you ad the other 56,000 forum members, deserved an explanation as to what made it a negative on a T burner or heck any jet ejector type burner. 

You wouldn't really rather have me or someone else just say, "NO, IT WON"T WORK!" would you? 

Frosty The Lucky.

[Flynn]

Don't worry, I'm not upset at all.  I'm not able to follow all the conversations that go on here and had just read through the Tburner and ribbon burner instructions.  I was specifically asking for advice from the experts with my post, not suggesting anything to anyone.  

Thanks again for the explanations. :)

[ThomasPowers]

TLDR: T burners start rich and you trim them to neutral/slightly rich.  A choke makes a burner burn richer so adding one to something already burning rich won't lean it out.

Funny thing; when I was at the scrapyard Saturday I found a set of tip cleaners in the detritus.  I'll be passing them on to a local person starting burner builds as I already have a short set and a long set.

[hornguy]

Good information here regarding chokes.

I have just finished my new ribbon burner build also using one of Frosty’s T burner inducers.

I panicked when trying to light it before putting it in my forge, because I just couldn’t make it fire unless I choked the air intakes dramatically.

I made up some intake chokes in order to test fire it before securing it to the forge.

 I needn’t have bothered.

Once it was in the forge it lit up like a Christmas tree and is burning nicely.

Today was only my second time firing it and it actually seemed to perform even better now that the burner block is properly cured and I have sealed around it properly.

Once the forge gets up to temp, it really seems to settle into an even better flame.

Another bonus is just how quiet it is compared to the two gas hog Venturi burners I used to have in there.

 

[ThomasPowers]

Back pressure in a forge will slow down the fuel/air flow; much like choking it in open air.  Why testing a burner in the forge it will go in  is suggested.