Mercedes-Benz E230 vol. 2, charcoal powered

In the first picture ( drawing ) this appears to be an “up” draft mixer. Then the picture of it on an engine it looks like a “down” draft and everything is upside down and backwards to the first drawing. TomC

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Huge thanks for this link for gas mixers. But I think we the automixer is VERY simple as Max conceived it and Chris S built it, and now Kristijan has made it even simpler by having it control a gate valve.

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Ha, l remember seeing those woodgas throtle bodys, never knew the reason why there are 2 flaps. Now it makes sence!

Well thats a ideal maridge of automatism and simplicity. I think l will go in that direction, thank you!

Oh, l found the reason behind bad performance with the automixer. A leak between the housing and membrane. Now the question is, fix the membrane and try again, or make a manual valve system with a “low throtle enrichment mechanism” as Til showed. Sugestions?


Kristijan, maybe a small (auxilliary or bypass) pipe with a solenoid valve that you could cut in or out with a switch, or even by a control that sensed RPM?. Kind of like Bob M. has done?


Hm…I’ve found very little reason to adjust air-mix depending on throttle position. Most of the time not needed at all.
However, differences in charbed restriction need to be compensated for. Starting off with a cold gasifier, ash and fines restricts the flow path and the air needs to be tightened. When the gasifier is warmed up the char clears up and the air valve can be opened up some.
My guess is this invention was used mostly to pull as much as possible on the gasifier at idle, not to make tar. @Til , you know the history. Could that be it?


Fix the membrane first and see how that works has my vote.


I agree with Don.


Hi Kristijan,

now that you are that far I would try to finish the “real” automixer.

@JO_Olsson, I guess you are right. I once read some hints for gasifier drivers from the wartime, suggesting to close the air valve for long idle periods or long downhill sections to keep the gasifier temp high with an overly rich mixture and thus more suction on the gasifier.

If it is really necessary? Well, here I miss some practical experience. I just noted the problem with Krisitijan’s lean mixture due to the fixed air valve with less than full throttle. Here it could help.


Hi Kristijan
you have an afr display on your car is not it?
Is this the probe
, lambda of origin, connected to a voltmetre?

I would like to install an afr on my truck without ruining myself. (the “afr” displays that I saw online are quite expensive ) Do you have any advice to give me about this?

in advance thank you


JO, this makes sence.

Thierry, yes, l hooked a cheap 0-1000mv display on the original narrowband o2 sensor. Not ideal but it shows whats going on.


You all may be familiar with this, but I discovered it tonight while reading Small Scale Producer Engine Systems, and thought it might fit in with the discussion about auto-mixing valves a while back.


I book marked it to study on this some more. Looks promising.


Ok guys its been a while, time for a fast update. The MB had problems runing on petrol since winter. I culd not figure the cause. It started rough, if at all, run poorly, then just before US trip it died completely.

A couple of weeks after the trip l got back to it. I decided to check the whole fuel system and on emptying it, l found about half a galon of water in tank, pump and filter. Pump seized, but got it to run. I cleaned it all out, now it runs reasonably well, still not ideal. Water did damage standing in for a month.
How it got in, no idea. The fuel tank cap does not lock so an evil human being culd have something to do with it allso…

In order to pull out the fuel tank, l had to take out the gasifier and since out, l decided to do some minor modifications and today l was allmost done with them, when l noticed a design flaw burned a hole in the top part of te gasifier hearth. Its the only part not protected with cheramic wool and extreme heat got te best of it.

So after dealing with the fact l wasted half a day updating a broken gasifier, l decided to learn from the mistakes l made and make a new one. The hopper is still useable, and l am trying something l have been thinking for some time now, make the flute nozzle DOWNDRAFT gasifier. When l get the rigt pipe and some sheet steel, it shuld be a quick project.


Hi Kristijan,
Good to hear you’re back in business.

About water in the gastank…could be condensation. Up here with fluctuating temps during winter, one day -25C and the other thaw, most people are very careful to always have their gas tank filled. Just a WAG.

About the gasifier…sorry about your burn through but interesting you’re willing to, once again, push limits and try a different design.
What about the ability to mix in wood, with an upside down flute?


Wow Kristijan, I was just looking at @mggibb Michael Gibbs new water cooled flute design and was thinking that this could work in a down draft gasifier. And up pops your thread of making a new flute down draft gasifier. Take a look at what Michael has come up with.
I have not been happy with all the slag that my charcoal gasifier has produced in the short runs that I have made and was thinking of converting it to a down draft gasifier. Now I am thinking the water cooled flute down draft gasifier.
Great ideas are floating around on the DOW dark side site.


Glad to hear you are getting some time to come back and “play” with us. I hate the ethanol that they add to our gas in the states, but I think that it helps from getting condensation JO talks about.
Did that fellow that does the great drawings of gasifiers ever finish yours? If so where could I see it.
I hear talk about you using a “down draft” design. Does that mean you have the holes in the flute pointing down and the gas still goes up and out, Or, does the air come out of the flute and the gas go down through a grate and out. TomC ( still amazed at how you folks make hay on the mountain side.)


JO, condensation is likely. But l dont quite get it, its a sealed fuel tank system???

Well l was wery pleased with performance, the mistake was all mine. Fixing it wuld only be temporairy, modifying wuld require more time thain building a new one.

Well l plan on retaining the shape of the hearth more of less, with restriction and all. Will see…

Bob, l have. I have no dubt his system will work and only tears shed will be those of joy. But l am personaly not a fan of cooling the nozzles. By coolng them you are stealig heat from the gasifier and even if the heat is used to make steam, there are heat sorces that provide actualy free energy.

The flute works flawlessly as a updraft, but l have no idea how it will s a downdraft. This system will probably have less air preheat, l want to keep nozzles cool.

This projectis kind of a experiment to see how fast and simple can a useable downdraft be made.

Tom, Eddy tryed but gave up :smile: the hearth looks kinda like a hybrid between a lmbert and a WK, quite simple. But the way gas and air ways are interacted is way too complicated for us to be able to draw accuretly jast by description and sceches. If you like l can video it thugh.

There will be two oposite flutes about 6" apart faceing each other.


Please do. Or at least some pictures.


Hi Kristijan, if you want to keep the nozzles cool it would make sense to use some of the heat that is of excessive in the gasifier and that causes problems of slag. Then add the exhaust preheated air back in to the gasifier. It is like the saying goes, robbing Peter to pay Paul. You get free hot steam out of the trade off and your nozzles are protected.
Of course if using the tungsten nozzles, which seem to be a durable material when it comes to high heat or mass of steel nozzles seem to be working well also. The balancing act of heat in the gasifier is the key.


This probably didn’t happen over night. The empty space in the fueltank is always replaced with air no matter how sealed it is. Normally small amounts of condensation is mixed with the ethanol part of the fuel and doesn’t cause a problem. However running wood/char in a cold conditions and not consuming much liquid fuel, condensation could add up (speculating again).

My head is spinning of flute theories :smile:
Thinking about what flute and WK have in common:
MASS around the blowholes. CONDUCTIVITY.
Just saying, not to lock our minds into a corner of what a flute looks like :thinking: