Gassifier design

hi all,

i have a question on gassifier design it seems like most people are using a variation of an imbert design, is there any real reason those designs are better than the FEMA stratified downdraft gassifier. the reason i’m asking is it looks like my main source of fuel will be wood chips and most of the information i have read leads me to believe the imbert gassifier is unsuited to this type of fuel.

I was also wondering if Mr. Keith’s design overcomes the problems with fuel sizing or am i better off using the FEMA design

any thoughts or help is much appreciated

at this point i’m still making sure i can secure a fuel source before i start building but i have some materials already.

Hello Eric,

My experience with Imbert type gasifiers is that these do not very well on soft woods, because soft woods makes soft char, which crumbles easy to dust. High blast tends to blow soft char to dust. Imberts work with high blast speeds and mostly with full flow grates. Mr. Waynes design is based on slow gas speeds and a grate design that is less prone to plugging. A well trimmed Imbert on hard wood is however absolutely tar free.

The Swedish Imbert (FAO 72) can handle woodchips. But chips are a fuel that is prone to bridging. Small fuel makes also small char. You will need a very well tuned grate and dimensions. I would not start with a difficult fuel like chips. They bring along problems that only an experienced woodgasser can detect and deal with.

As for the original FEMA, well, it is an excellent methode to ruin good engines. Maybe less when in hands of a good operator and perfect wood.


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ok well that’s not what i was hoping to hear but what i suspected. i do think there are several small sawmills in my area that i may have to check out but with ruling out wood chips for right know i’m stuck with no fuel source


you can try truss companies also, they have tons of scrap and they don’t get much for it when they sell it. A lot of people go into the woods and cut wood with bow saws. I can cut a couple of hundred miles of wood in a very short time with a bow saw set up properly. Wood is everywhere. That is what is so great about this sport. Chips can be mixed in with wood blocks on a Kieth gasifier. I mix all kinds of stuff in and have never clogged it once I learned how to operate the thing.

thanks woody im not giving up but I have other options just less appealing.

is there enough info on the premium site to build a kieth style gassifier I want the book but I dont want to wait the engine in my truck is a 5liter I would guess the gassifier for the 318 would be sized correctly

Hi ErikS.
If the vehicle you intend to convert is the 92-96 ninth generation F series in your picture go for it.
I have a 94 F150 302. I have crawled all over mine and a friends F250 460. Great chassis with lots of under hood and under vehicle space to work with.
Yes there is enough info being live posted up in eh Premium section to do this NOW.
The gas demands of these Ford 5.0L will be much the same as the Dodge magnum 5.2L V-8’s.
And these EECIV Ford systems have much better aftermarket computer reprogram timing re-mapping available to boot.

Steve Unruh

I don’t have a wood truck YET but i have a jqx10 stratified 10kw unit It was a really good tar maker but not much else.
I have modified it into an imbert with adjustable stratified flow and a ceramic swirl burner it now seems to be tar free
It will burn pellets,chips, up to 3" chunks
I have a schetch but don’t know how to put it on here
Good luck

thanks steve
ya thats my 94 im planning on converting. its a 4x4 with the dual tanks which will be nice since I can just drop a tank and unwire the switch bam ready to roll fuel shut off

I think i figured out how to post pics

Looks great ThomasM
I have a couple of friends with these Chineese gasifiers unmodified and unran. They want to small generator run.
Could you cross post this info into the “Small Engine Users Corner” in the forum section here?

Yeah EricS my thought too. Dropping out the front gasoline tank gives lots more room to work.
Couple of problems with chipped fuel on a vehicle is the light weight density makes it hard to keep enough onboard fuel at 1.5-2.5 pounds of woodfuel per mile. And the small char from the thin aspect ratio chips likes to crumble and gasses flow pack tight with road vibration. Chips seem much more to be a stationary system fuel possibility.

Steve Unruh

nice thing is both tanks work and are in good shape so i can drop the side tank and use it for spare parts it the rear goes. not sure if there are any truss companies near by but like i said a few mills most of which is eastern cedar so no one really wants it for fire wood. i do have a place i can go and cut wood if the need so arises. also have some trees in my yard that need cutting. so i guess my next problem is i have to wait til next week so i can get payed up for the premium site.
Steve i was thinking since the wood chips would probably be free density would be an inconvenience but that’s what the rest of the truck bed is for. but the small char is defiantly a major problem.

thanks for putting up with me so far I’m still learning a lot wish i could make the wood gas meet but time and money are at a premium right now

hey steve
sure i’ll try to post this in the small engine section but i’m new here and not up to speed

Eric- I am new to woodgas but I was thinking you might use one of your trucks gas tanks for a condensate tank. Don’t know for shure if that would work, but I do know that you would need to fill it with water before cutting or welding on it. Just a thought

Duh! You are correct RichardC.
My Ford front saddle tank is metal (unlike a late Dodge plastic) long and skinny and already in place.
Idea award to you man.
Steve Unruh

Richard i had that same idea but i just don’t think its worth it. the fuel vapors might also cause a problem latter on in the system and it would require alot of cutting and welding to get something useable. the fuel pump hole would have to be blocked off and welded in as well as the fill tube. then inlet and drain tubes put in
think ill just stick with a water heater nice thing is the mounting straps will probably work for it.

haven’t driven the truck since i put a new battery and distributor module in it. so i drove it to work today. it has part throttle chug. think it might be plugs. when i lay into the throttle it runs fine, when i’m cruising along and climb a hill it starts chugging in lower gears its right after an up-shift, in 5th it does it about 65mph just maintaining speed