Try lighting the gasifier high in the hopper (in raw wood) until you see thick smoke coming outof the fan. Close the lid and put slightly positive pressure on the system.
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Hmm, I tried lighting hopper this morning and doing so. When I closed the lid, it exploded in the hopper so wood and coal flew around my ears.
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Haha! Thatās why they say gasifiers are female. They can strike at any moment for no reason at all 
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Took a long time to find this skech and its without measurments but from the top of my head l remember my measurments being about the same, if not bigger thain yours. For a 1.6l engine!
I strongly belive your gasifier is too small. It is too restrictive but most importantly it can not produce enaugh small enaugh charcoal in time at right places for the gasifier to work good.
I am afraid to say there might not be much choice but make a new gasifier, if you want this to work good.
But for the mean time, make 120% sure you have NO hot leaks ANYWHERE! Ash doors, fittingsā¦
Can you take the restriction out?
If you can, try puting in a temporairly bigger one. 15cm without a problem. Then, take your small and dry wood chunks and mix with some walnut and hazelnut size charcoal, about third or a half by volume. Try runing a hopper or two of that. Do this allso if you cant change out the restriction.
This fuel is what Bob calls ārocket fuelā. It is a abuse resistant fuel. Resistant to overdrawing, moist wood, makes good quality gas over a small reaction area and a lot of it! It will make tar free gas even without much of a restriction.
What this will show you is what your engine is capable of on woodgas. You then have a comparrison point when you experiment with pure wood again.
BUT! your gasifier is not built for this fuel and it will melt down fast if you use it long term. Imagine feeding Nitros to engine. Not gonna hurt it at a few bursts but if you feed it non stopā¦
A hopper or two will not hurt anything.
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Oh, and you allso can ditch the grate all together. It will still work, but have more room to expand the reaction zone, if neaded. Its kinda how my later Mercedes grateless gasifier looked like. I think it was on the Mercedes anyways, l dont know for sure anymore the other day l counted 11 gasifiers on 3 cars. Too much to remember all
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OK Iām confused. Post 266; Jan says Drawing of a variety of imbert +skizz
Then post 267 Kristijan says, "Took a long time to find this skech and its without measurements; no sketch or is that the one in 266???
Kristijan just said take the grate out. Hmmmm. He would have to explain that. I think in order to run without a grate you have to have a very shallow ash pit. That way the bottom of the gasifier or ash pit works as a grate.
Kristian also said you need to make smaller char. I agree and recommended two things that will help that. Make the grate with narrower openings so the char doesnāt fall through when it is still big. The other thing was move the grate up to the bottom of the fire tube. The ring you put on your grate helped a little. The grate and ring act like a bucket and holds the hot char up higher in the reduction zone. Moving the grate up will do the same thing only holding the hot char even higher up in the reduction zone. The higher you hold the red hot char in the reduction zone the more the CO2 will react with the carbon and take part of the carbon away, leaving smaller char. TomC
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Tom, l was reffering to my old Chevy gasifier. I culd not find dimensions on my own topic.
Well not nesseserly. Imagine a lmbert oxidation zone and restriction. Put this in a bucket filled with charcoal. The gas will follow the path of least resistence. At low power the restriction will blow gases down in the char just a litle. When you step on it, the reduction can spread down and to the side in the char bucket (aka charcoal filled ashpit) and then up. That up going motion sifts the char bits, like a fluidised bed. Taking ash and fines with the gas stream and leaveing the good stuff behind.
You can never constipate your charbed, unless you make slag.
The gasifier doesent know how much char is around the reduction. For all it knows there culd be 50gal of char around it, the live reduction zone will form naturaly depending on the draw, the rest of the char/ash is just insulation. Like a self repairing ashcone in a lmbert oxidation zone.
The reason l made it small on my build is for space limitation. Bigger is better!
Imagine this kind of a gasifier as a updraft/downdraft hybrid. Oxidation zone is downdraft but a reduction zone works like a updraft charcoal gasifier.
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Tom, moveing the grate higher will only make problems worse. Look at the skech, he allredy only has 2" of actual reduction zone under the restriction! Thats wery litle for a big engine like his!
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Kristijan; I bow to you superior knowledge and experience. Just a couple of things. You refer to this gasifier as being too small. His dimensions are very close to the ones I used in my 4.3L. I was always striving for āmoreā performance, but it was good enough to drive the interstates. My dimensions came right out of the tables for an Imbert gasifier. Another point, Iām not good with metrics but doesnāt he have 4" of reduction, plus 2" to the top of his ring and I donāt know how tall the ring is. TomC
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Good morning.
I have 4 ā, between the firetub and the roster, and the ring is 2ā, becomes 2" between the top edge of the ring and the firetube.
What I understand is the gas is too cold for there to be any reduction under the firetub? So what is there is only as a filter?
What have i to do bigger, Kristijan do you think and how big.
Tom, how big pipe do you have between radiator and engine?
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This is the main issue with vehicle gasification.
When you idle around gravel roads looking for moose the bottom char pile is nothing but drag and it acts pretty much as a filter, yes. Still the gasifier internals have to be kept hot, well insulated, tight and small enough not to make tary gasses.
At 100 km/h and WOT the entire char pile is glowing like crazy trying to keep up making the amount of woodgas you are asking for. Itās ok for a little while, but pretty soon you have consumed more small char than you have been able to replace. With only coarse char left, oxygene will finally find its way through the char pile and start burning your gas. At this point you wish your gasifier was a lot bigger.
I donāt know if our saying translates well to English, but something like this: āNo matter what direction you turn, your arse is still in the rear endā 
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Morning.
Tom no bowing neaded spare your back for welding and stuff 
My bad on the reduction height. Still, 4" is litleā¦
Jan, not at all. It is possible not all hot gases react with the char in time! Its what we call heater mode. The badly reduced gases exit the gasifier wery hot.
Or like JO butyfully described
As he pointed out you are not making enaugh small char in time when at full power. This is why l like to mix some charcoal in. You help your charbed with feeding it a bit of char allredy at full power and at idle the fire burns much hotter thain just on raw wood, wich means there is less of a possibility you make tar wich means your restriction can get bigger. Bigger restriction = less drag = more power.
Jan, its hard to say. I never gasifyed a engine that size. All l can tell you your gasifier has the dimensions of myne for a 1.6l engineā¦
Basicly l wuld go bigger on everytihg
That allmost sacret lmbert chart is a bit funny if you ask me. I am questioning its accuracy for real world applycations for a while nowā¦
I just thod of something you culd do to make this gasifier work but l need to skech it so l will post you the skeches in the evening
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Good morning Jan; I run 3" plastic pipe and fittings from the radiator to the engine.
Only picture I have of my plumbing/piping. You get the idea.
Could you please give us a dimension from the bottom of your fire tube or even from the bottom of your grate to the bottom of your gasifier ( ash pit ) TomC
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Hi Tom
Do you have an air filter on that truck? I am assuming that that valve I see on top of the tee is your air mix valve.
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Hi Tom.
I have 4" between the firetub and the grate and 6" between the grate and the bottom of the gasifier.
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Jakob; No air filter. TomC
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Thanks Jan: I ask for Kristijanās benefit.
Kristijan: Jan has 4" from the restriction to the bottom of the fire tube---- then 4" from the firetube to the grate---- and then 6" from the grate to the bottom of the gasifier. That makes 14" from the restriction to the bottom of the gasifier. Wouldnāt you say that is a little large for a reduction zone, if you donāt have a grate? TomC
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Tom,
Is there a filter in the red housing I see on top of your engine?
Rindert; There was but I think it caught fire and burned all but the wire cage. It also melted the wires to the selinoids on the tbi. Donāt know when or how this happened. TomC
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