Dear Joni,
thanks for sharing your ideas and the cross cut!
Looking at your 8.0 and 9.0 version I wonder that your reduction zone between restriction ring and grate is very small. Especially the measure of H1 is very low (20 - 30 mm on version 8.0)
In older books it seems like oxidation and reduction zone are same size (book from Sweden, around 1970)
Kristijan and Jan have tried the other way round: No grate and big reduction zone.
Well, your system works fine for you and theirs for them. But have you ever tried a larger reduction zone? What are your thoughts about the size of the reduction zone?
One question about your filter: You use 10 cm sawdust and then fabric filter of old jeans? And no soot in the engine?
How often do you need to clean or replace the sawdust and fabric filter?