Sorry was think of powdery ash not hard slag. You must be running pretty hot for that but should be making good gas, no tar.
You are right on both. But allso, l suspect we have lots of silica in the wood (it grows from quarz sand). Silica rich ash gets wery sticky when hot.
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Will have to watch for that. Much of the soil here has a base of weathered down sandstone. Also high silica.
Thank you Kristijan, Iāve been waiting for this one. I really enjoy your videos.
Iām sorry the washing mashine part didnāt work. Maybe the holes were a bit too small?
Does your restriction sit loose, full diameter, on that ledge?
Is see your nozzles are different length. Is that something left from running sec nozzles or is there another reason?
I like your thinking of an extra char reserve. The hard part is to maintain good breathing. I think the solution with our kind of setup is to use the grate as is and keep a good pile of char below to absorbe any overpulling. I havenāt emptied my dump for well over 2000 km now. It seems when the path gets narrow down there, all the ash and small char will end up in the cyclone. I know from previous dumps that pea size char is what stay put.
Stay warm - chop chunks 
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Thank you
Well, it was a far shot to try the washing machine grate, didnt take 5 minutes to make, but l learned something new (so a partial win l wuld say).
I followed the advice of less is more when it comes to grate area, so thats why l didnt make holes bigger. But it might help.
The restriction sits on 3 weld marks, and the loose space between the restriction plane and firetube is sealed with ash(l put in the sifted ash at cleanouts).
The nozzles were first 7". Then Max advised on smaller circle, l screwed them out to 6", thain l found some bridgeing happend with bigger fuel, so l screwed some back to 7".
Exactly! l think the future of wood gas improovements are in the turndown ratio. Were getting there slowly.
Now that l learned to poke more in the charbed to break the ash, l can idle for a long time, drive in the city, but allso drive on the highway at 110kmh for short time, then power is back to 80-90kmh. If l know 110 can be reached, l want to be able to use that ability always and for as long as l want. Thats whats eating my nerves for the past few weeks now 
A post grate reduction is one solution, but agenn, when we run out of the secondayry char, party over. We need to find a way to make the charbed adjustible.
One thod is the KƤle charcoal gasifier nozzle princip. It used a diafragm to push the airnozzle in and out of the oxy zone, dictated by the engines wacuum.
Or perhaps a moveing grate?
Perhaps Max is right. Perhaps there realy isnt anything new under the sun. But hey, the solar system is a big place 
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Hi Kristijan, I like the the design you did there. How about putting the grate back in with it being lower by cutting the support legs shorter. Also make the holes a little bigger in your washing machine ring. This will allow the holes to clear of build up and still have gas pass through the bottom grate and still have a charcoal bed below the grate. This will create more gas passage area for the gas to flow thought. Just my two cents of in put. Keep up the good work.
Bob
Hi Bob
This culd work. The ash falling trugh the grate shuld be able to be drawn trugh the second grate.
I did lower the grate about half a inch.
I have fownd l get best power when l emty the gasifier and refill back some more more engine grade charcoal thain l emptyed out.
I am thinking to try woodchips in the gasifier. I know pellets run great but are pricey. Woodchips are cheap (or free sometimes) but are more bulky.
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Iāve given this some thought. That is - why I have pea size char in my dump and youāre consuming yours leaving mostly ash. Hearts are after all about identical. I think it has to do with preheat.
I know weāve been touching this subject before but I just canāt let it go.
When I run short trips, less than 20 min, my gasifier is not yet fully warmed up and the air entering the nozzle manifold is rather denst, the char shrinks fast and Iām running borderline constipated. When on a longer trip the preheat is at its maximum. The same volume of air enters the nozzles but itās less denst. Less oxygene means I canāt make char fast enough. Big lumps of char are probably getting way down the reduction and the charbed is getting loser than I like.
I still canāt fully wrap my head around this, but I know you run a little lower on preheat than I do. Could this be the difference?
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I think the anwser layes in your thread. The charcoal being consumed at cooldowns.
I think since l dont close the air intake at shutdowns, l burn so much charcoal l am left with too litle of it to operate well at the next startup. It takes some time for the charcoal to be made, but at that point l usualy shut it down again. Longer runs work well.
Like l sayd, if l empty the wood out of the hopper after a cooldown, l can see charcoal about an inch LOWER of the restriction.
This allso explains why l concume the char post the grate. There are still hot unreacted gases passing trugh the reduction char.
But on preventing this, eaven if l close theair intake, l will suck air trugh the gas hose back. Yours is a bit better as you have a whole hayfilter of gas to be drawn in first, l have not.
Edit: or! The gasifier works like a chimney! Drawing air back in trugh the gas suply hose and out trugh the gasifier air intake! This allso explains burned up sliped char! What do you think?
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Maybe a combination of both. I shut down fairly tight on both ends but I still find a nearly empty oxidation zone with a glued bridge above at next lightup.
Michael Gibb resently presented a third factor. Maybe oxi zone is more lose than we think while running.
Ha, it seems we are back to one of WayneĀ“s earlier statements again: āThere are so many factors involvedā¦ā
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Hmm l buy all those theoryes. So much more to lernā¦ such fun! the important thing is we are all better and better! Keep up the good work guys!
I have sealed both ends of the gasifier today, we will see what happens.
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Hi,Kristijan!
16.1.2017
Is the Physisist forgetting what the Chemist knows?
Cold or hot, equally many atoms are needed to produce a certain gas flow, only the velocity varies in the same process flow areaā¦ extending accordingly.
The two older Imbert types have a āfull diameterā sieve-like grate a bit under their steel reduction cones.
This full diameter, just within the outer mantel has so big an area, that the collected ash at slow speed town driving and āfilteringā into the char has no significant gas resistance.
Still easier performance with horizontal outflow.
But, on road ārunningā a sieving filter movement or shake push may be more than enough at each tanking, or even less.
The small ātubelikeā reduction chamber with a small volume can be trimmed for excellent road performance with 1/2 matchbox size chips, and eaven cigarett pack sized chunks, but it is always more critical, as it needs velocity to keep blown open. Or more frequent shaking/sieving.
Do you have room for a full-diameter sieving angle-iron grate? The principal function becomes clear, looking at Chrisā animation from last autumn.
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Thank you Max, for correcting us (or me). Of course, the more preheat the higher nozzle velocity and volume (and drag), but still the same mass of oxygen, right?
So, in your opinion the only thing making my charbed tight when running cold, and loose when reaching full preheat, is the difference in velocitiy? Blowing clean from ash and fines when hot and high velocity?
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No. No.
Cold char bed flow restriction versus Hot char bed flow restriction is different in real life use.
Watch this through view ports, live.
Then think through the whys-must be different. (hints: char particle outgasing; gasses exchanging particle bouncing; heat expansion of the char particles; particles shrinking as carbons given up - lost to COās making)
Ha! Ha! Or . . . woo-woo energy magic if you please.
S.U.
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Hi Max, lond time no read
I am wery limited in height. There is only a 4 cm gap from the end of the reduction to the bottom of the ashbox. just barely enough for a free gas passage.
I remember about the anination well, but unfortunaly have no free room to install such a contraption.
Steve Unruh,
The symptomes of high activity, low density, high volume, high flow and hot enviroment show as well, as a slightly higher vacuum ratio in the short time frame when pulling hard. If I let go of the pedal for a little while Iām back to a lower ratio.
BUTā¦
ā¦what I described earlier is the other way around - a restrictive charbed when cold, which will loosen up after half an hours run time.
Iām beginning to think that it might be only due to fines and setteled ash that I donāt get rid of until the inferno reaches its highest level.
99 times outof 100 itās not a problem, because I get about the same power running 6:1 as 3:1, but itās still annoying not knowing. If I did, I might be able to fine tune for long/short trips.
On the other hand, when the whole puzzle is solved the fun is over
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Jan, I always seem to find a loose oxidation zone, but I also have plenty of charcoal to the side and below my grate even if I clean it out. It fills back in quickly. That first hopper load burns up very fast, it seems in 25 to 30 miles it time to refill, then it goes back to the normal 45 to 55 miles before refilling, depending on how heavy my foot is.
My grate is 3/4" to 1" gap below the oxidation zone. I slip char though that area, but I always have plenty of charcoal for the hot gas to go though. To me thatās what we want gas going though plenty of charcoal and a place for the ash to settle and not plug everything up.
The preheated air in cold weather really helps, in the hot summer time I think it is not as important, but you still need some for starting up and getting up to temperature and slow speeds and stops, and idling. The heat flywheel effects in the gasifier is a good thing to have working for you.
I think Kristijan and your Imbert gasifierās are work great for the conditions that you both are driving in. My hat is off to both of you. Good job and keep it up. Hopefully by Tuesday I will have my truck back out on the road driving on wood.
Bob
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Thanks Bob,
Crazy Europeans Driving around with only a couple of handfulls of char. I still canāt belive itās possible myself, but it is. No major hickups actually.
Iām looking forward reading about your comeback.
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Jan,
My thinking on your absorvation is about as you described and it most likely happens to me allso (but l dont have vacuum guages to proove it). In a shutdown, the charcoal gets consumed a bit, reducing its size and since there us no gas stream to blow off the ashes they get stuck in.
I found l must open the air a bit after some driveing to give me best power. This indicates the same problem.
Thanks Bob, were just haveing fun
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I was experimenting a bit over the last two days with different fuels. The new manual gasmixing alows for more experimenting.
I found motorways are too smooth for the fuel l use usualy. Blocks of wood about 3x4cm dimensions tend to bridge too much, same with smaller blocks.
Yesterday l tryed pellets again, great sucess, got a constant speed of 95kmh, but the pelets are pricey. Today l tryed small peaces of dry brunches, about 10mm dia x 20mm long, and the resaults were same, if not better. The system runs much, much cooler.
This is actualy a great thing. l have a unlimited supply a brunches we usualy burn or let in the forest to rot, by building a small caliber rebak l culd make a years suply of highway grade fuel in a day!
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