First time build questions?

Hi all, im a first time builder from Aus seeking some advice. After a spur of the moment start following some advice on you tube :grin:i built the reactor, i have since built more peices and am ready to weld them together. My issue is i am now worried my design may not work and i cant really test it without welding it together. Any help would be greatly appreciated.

the dimensions of this are, fire tube is 5.5in wide,13in long. The reduction tube is 2in wide 4.25in long. The shaker grate sits an inch below this. I plan to have a.75in pipe running down the fire tube to 10cm above the reduction tube for air injection.20170812_221432|375x500i will have another smaller gas bottle mounted on this for a hopper along with a cyclone and media filter, i will install a gas cooler as well if i need to. I would like to run my 8hp water bore pump with it. Will the design of the reactor and reduction areas work can anybody tell me please. Cheers

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Welcome Jamie. Good start in the gasifying business. This might just work, at least for a while. Did you raise the reduction tube up a little into the fire tube to act as a stopper for the ash insulation “cone” at the bottom of the reduction tube? Ash insulation is important there to keep those metal melting temps from destroying the vessel. Will the 3/4" nozzle pipe be centered in the reduction tube 4 inches above the restriction? and will the hopper be air tight? I would say weld her up and try it out. That is the fun of this I think.
Edit. Fuel size experimenting will be an important thing to do. If one size gives trouble another size might be perfect.

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Hi Don, thanks for the reply. The nozzle pipe will be 4in above the reduction and the hopper will be airtight. Alas, i didnt raiss the reduction tube, it is flush with the bottom of the fire tube. I could cut it and lift it a little, how much of the reduction tube should protrude into the fire tube would you suggest? The fire tube is an extinguisher and the angle of the cone at the bottom is a little more severe than i would have liked, do you think this will affect its operation? I was planning on putting the ignition port (1in pipe)about the same height as the nozzle and 1.5in pipe for the gas outlet at the top, do you think this will work? Thanks mate 🖒

Welcome Jamie!
Before you do any cutting you may try put in a small slice from a pipe with a flange on it to support the ash cone. This will act as a restriction at the same time.
Hard to tell how this design will work. I guess not many people here have ever tried a wood gasifier this small. Very important though to try keep the reduction hot in some way or another. Ideally the whole reduction tube should protrude into the above ash cone for insulation.

Hi Jan-Ola, thankyou for the reply. How far should the reduction tube protrude into the ash cone? Do you think i should make the reactor bigger? I have a bigger extinguisher i think its 8inch diameter. If so how long and what diameter should the reduction tube be? I thought from the information i found on the internet that a reactor this size was right for an 8 or so horespower motor? Cheers!

Very hard to tell dimentions with this size and type of gasifer. I´m actually just guessing here.

Anyway, I would let all of the reduction tube protrude for insulation purpose and use at least a 3 in tube. Maybe make it a little shorter, 3-4 in, and then put a restriction, that can be changed out, on top. Start with a small one. No signs of tar and you can increase the diameter if needed.

Just for reference I use an 8 in firetube and a 6 in reduction about 4 in tall with a 3.5 restriction on top. I guess I culd satisfy engines in the 15-60 hp range. My 1.8L 95 hp engine runs ok too but the gasifier doesn´t like me going WOT for any longer period of time.


Welcome Jamie. I’ve been mowing the lawn which for me is a good time to ‘‘think’’. This a web site to supply videos to compliment their book ‘‘Have Wood Will Travel’’. The plans in in the book have been successfully followed by ‘‘many’’ group members. This design is mostly for engines in the 318 to 350cu. in. It has been proven to run a 5 hp engine, but who wants to build a 400 lb gasifire to run a 5hp engine?? A few of us members have built various versions of the Imbert… One of the members has built Imberts for a small walk behind mower to a 454 Chevy truck. He has stayed that the smaller the engine the harder to make a gasifier for. With this information I suggest build a ‘‘charcoal’’ gasifier. Look up the ‘‘Simplefire’’ . Go to the ‘‘small engine’’ section. Some will down play charcoal because ‘‘it wastes heat’’ or the ‘‘making of charcoal’’. Guess what. For the size gasifire you are building, you will have to buy pellets or figure how to make wood chunks the size of sugar cubes…I have not use charcoal, but from seeing what others have posted, I would say you are guaranteed success the first time, a d you will learn a lot…TomC


I would suggest charcoal for that small of an engine. Just because of the tar factor and low cost to get started. It should get you up and running with success faster.

I have seen people do it with wood. However one of the issues is there isn’t constant airflow with a single cylinder engine which can lead to tars. so it is a bit trickier to do.


Hi Jamie, I would have to agree about the charcoal generator. Much easier and lighter too. From my exp. dried wood chips make great fuel grade charcoal. No grinding needed, just screen at 1/8 inch. Nozzle size and position are important.
I mount the noz. pipe horizontal
but use a 3/4" elbow and point the noz. Up
Then I use a SS nat. gas flex line adaptor
Nipple set into the 3/4" elbow, tappered end up. Now take a small SS pet food dish make a hole in the center of the bottom for the SS nipple to just poke through. You may have to cut a slot for the noz. pipe
in the side of the food dish. I have been running this nozzle system for months
only had to change the heat sheild once
Still using the same nozzle for 6 moths at least 2-4 hours a day. 3-4 days a week. No melted nozzles no slag problems. Slag is always off to one side at clean out.

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Call me chardad or call me asshole
I really don’t care just call me in time to cook supper can’t beat burnt chicken when it’s scorched over a roaring charcoal flare!!!
Hahahahaha!!! Been there man it tasted good!!!
Whether I am making wood chips, or making pizza. The chargas generator is the way to go. nozzles point up for long life heat sheids are cheap, dollar tree pet food dish

Hello and welcome Jamie Keatley.
A member here: Dutch John, did make up very small mobile wood gasifers IC engine fueling systems. One for his down to 2 hp lawn mower.
His documented information is here: Microgasifiers
Hard to exceed his proven results and experienced based learned wisdom.

Ha! My bbq’ing wife steals all actual wood charcoal I’ve ever made up. And only the limb-ring knot sections on 75 year+ conifer trees like my Doug Fir can make a hand-able/storable wood charcoal chunk!
Only wood chunks safe from her bbq-loving hands.
Chickens and garden get the 95% conifer wood char “dust-fines” with my ash clean-outs…
tree-farmer Steve Unruh

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Thanks for the replies people. Theres so much information here, im thinking i might go the charcoal route. Ive had a bit of a look through the small fire thread and would like to look further into the design of it but i cant find the files document under the forum tab as suggested by gary in the thread. Hey @Chardad58 your system sounds sweet, could you share a link, or post me some photos of your set up please? Cheers

Jamie, Gary Gilmore is the name to go to for the original ideas of running a (small) engine on charcoal —also he has some good basic info for making charcoal. He posted the information on a charcoal gasifire he named the ‘‘Simplefire’’. You can look him up on YT, but unfortunately some of his YTs are under another name of a person who videoed for Gary. I will try to get details for you and post later. TomC. :…Been trying to find some address for sites for you. The best I have for you is to type in the search area of this site,’’ Simple-fire’’. TomC

Not a problem, on my way outside to fire up want to flare with water Tonite then tear down tomorrow add one more five gallon pail for hopper capasity. I also wanted to add another nozzle, for more volume of gas my 4.5 hp. ice will run but won’t keep up with a load. So I’ll add more fuel to the mix and then we can hook up a bigger engine. For the time being I’ ll pipe
each nozzle separate untill I have enough gas to run V 6 then I’LL have a nozzle manafold made. And will progress to a much larger gasifier in the future

Welcome aboard Jamie plenty of small engine charcoal users here all willing to help out with idea’s ect if needed .

Chardad your system sounds great cant wait to see and hear more , vertical nozzles are the better way to go for extended life for sure


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Hi Jamey, Welcome to the best information center on woodgas on the web.
After you log onto the DOW page, click Forum. On the upper left side of that page you will see an All categories box. Click on that box and the All categories menu will show a bunch of colored squares. These are all the different categories. The first brown box is the Small engine category . You’ll probably find what you’re looking for there.
I think these boxes used to show the category title when you put the cursor on it. Now you have to open the box to see what the category is.
What happened , Chris?
Hope this helps.

A bug happened. Will look at it shortly. EDIT: fixed, sorta.


Thanks for the info guys, i am having a crack at the simple fire. I will post some pics and no doubt more questions as i go…Thanks again, cheers!


Hey fellow gassers
Well, I went out and did some cooking
on my over powered charcoal gas grill
(forgot to charge my battery pack so had to use my bucket vac on low.) After that I did flare for few minits with water. Hard to get the drip count low enough with a 3/8 ball valve, but after a little bit I think I have it figured out. My char gasser is two five gallon buckets stacked one on top of the other. I use black iron pipes so I don’t have to worry about the heat melting hoses. every so often I pressurise the system to check for air leaks. Alas my bottom bucket has a leak in the bottom.
So I guess it’s time to build a new one.
I have a big steel garbage can that I normally keep my dogs food in. That will be my new char gasser. I like my nozzle set up the way it is. So that won’t t change
The only change other the size, is I am going to the Fab shop on the hiway and have Van make a sheet metal cone that will be mounted inside the g can narrow end down about an inch above the nozzles
I think if the narrow opening is about 6 inches the small pieces of coal will still flow down around the bottom of my nozzles
to help insulate them,plus when I run the gasser right down to nothing. That’s about what will be left: nothing but about 4 inches of char above the nozzles.
I know every one says you shouldn’t run right down because it melts the nozzle. Catastroffic oxidation = melted nozzle
I have run right to the point where the gasser stops making gas several times
without damage to the nozzle.
My new cheap phone will not upload
to YouTube. No way. So I created a Facebook page chardad charges. All my pictures and vids will be there if you want to look. Please do not message me on Facebook messenger. I will not answer
This page is set up for veiwing only.
No friends accepted
Bye for now got to go drill some holes in the big can. The job that never gets started
is the job that never get finished.
Chardad out.

Look on FB chardad charges all my pics and vids will be uploaded there til I get a better phone