Longer burn tunnel

Hi. Been researching for a good.. 10 mins and can’t find an answer. I know I should just read that book, but don’t want to buy any more stuff till I start expiramenting.

If I wanted a longer burn tunnel (aesthetic, ease of use [if my barrel is set back somewhere harder to get to idk?], wanting to sit on burn tunnel). Whatever the reason. What would need to change? At inovators event dvd, Earnie talked about theoretically lengthening burn tunnel with “fins” and said something about shortning riser.

Ive read people saying a longer riser? Can burn chamber be too long? Can there be a bend in burn chamber? Would a longer tunnel burn hotter? Without getting into equations, does anyone have any thoughts on this, or has tried it.

I just haven’t seen many people changing that part of the design much.

Yes Ted ;  I tried it.... didn't work out well at all.  Seemed to work ok until mid winter when it just wasn't burning like it had been ... A quick check at the ash pit showed me the problem.....  My entire ash pit and over 1/2 of my horizontal pipe was full of ash!!! Yup , A mid winter rebuild of the core took place that year .... I think I went from a 16" burn tunnel back to a 12" .. MUCH better .....Bless COB ,  crumble it up, get it wet and reuse it !  

Thanks so much. So interesting. I’ll stick with the old standard then.