Welcome to the book owners area! – Parts, Tutorials, Specs & more

Here we have answered your most common questions and made updates to the book to make it even more clear. Enjoy!

Still need the basics?

Wood Gas Crash Course Series

Be patient with your gasifier… It has an operator-in-training using it.


Attention! Please use WOOD CHUNKS or really thick chips!


This machine does NOT run on tires, coal, pellets of any kind, arborist chips, grass or MSW. Period! Please follow the directions. Thanks!

Start it with natural lump charcoal NOT commercial briquettes

Download This Quick Overview of Gasification

Schematic, Flow Chart, Terms, Start-up Sequence + More


A Primer on Wood Gasification

Tools, Parts & Testing Equipment

These links are examples only. Buy wherever you like, but this is stuff I have used or recommend.

5" (125 mm) Grinder


5" (125 mm) Cut off disc


Mig Welder Miller 210 or larger


Tig Welder Miller 180 Diversion


Plasma Torch- Hypertherm Powermax 30


Air Compressor- Dewalt


Metal Roller- Grizzly Slip Roll


Note: This machine is described as a 16 ga. capacity unit, but that is at 50". If you go shorter you can go thicker. I use mine on 14 gauge stainless at 40-40" and 1/8" I can roll 24" wide. 1/4" flat bar I can roll at 2-3" wide.

There are two knobs to raise and lower the roller on the back (determines diameter size). I cut off the plastic knobs (they hurt your wrist after a while) and welded on short tubes that I can run a 16" bar through, so I have more cranking power.

That's it. It's cheap and mine has served me well for 6 + years.

Metal Bender - Grizzley Brake Press


Note: This may be bigger than what you need for this project, but this is a tool that can make you money and bend up to 12 ga. I have one and it's paid for itself 20 times over.

CNC Torch Table


Note: I haven't used this cutting table, but it will be my next purchase for my micro fab shop. It is only $3000 and it can be expanded.

These are the more specialized parts you will need to order.

Here are website domains or more precise part numbers to help you. Buy wherever you like, these are examples.

Blower motor- SOHON FL130021D-02 12VDC 5600 rpm-


Page 12

Line 6- Ceramic Insulation


Line 25- Lid Spring


Line 26- Lid Seal


Page 13

Line 4- Bronze Bushings


Line 8- Shaft Collar


Line 10- Ball Joint to Connect Grate Motor to Shaft Linkage


Line 21- Fire Rope


Line 23, 24- Filter Foam


Line 29- 12 volt gear motor, no switch 50 - 60 rpm


Page 14

Line 3- Aluminum Enclosure Box


Line 5- Din Rail


Line 6- Fuse Block


Line 10- Sight Glass


The best piece of testing equipment is you! Trust your 5 senses.

The next best piece of testing equipment is the sight glass described in the book. The color of the reaction can tell you alot about the flow and temperature inside the machine.

Gasifier Testing

Wood Moisture Meter

Test the moisture content of the wood to be sure it is dry enough to use.



Test the temperature at various points inside the gasifier system.


Omega Engineering has all the best testing probes, but they are more expensive.



Test power usage and diagnose wiring problems.



Test the pressure drop in the machine to find restrictions in flow. Measured in inches of water column. (How many inches the vacuum can pull water up a tube)



Measure the weight of the wood going into the machine and the weight of the water coming out as condensate. Anything will work.

Generator Testing

Digital Hand Held Tachometer

This will test your engine speed. Engine speed (rpm) affects power quality in AC machines and noise in every engine.


Power Quality Tester- Kill-a-Watt

Test the quality of the power coming from your generator.



Top 3 problems:
1- Weak suction
2- Wood too small or wrong feedstock
3- Leaks in seals


  • Green wood needs to be seasoned, it’s too wet.
  • Test moisture content. Start with 20% and move up when you install a monorator hopper as you gain experience. If it’s too wet you will quench your char and the oils passing through won’t be fully broken down. The result: creosote, commonly called tar.
  • Species: Avoid cotton wood (high ash/ low weight). Cedar can be oily.
  • Sizing: Is the sizing too large for the air inlet flow, leaving big gaps between charcoal chunks below the jets? Use smaller chunks or soft wood in place of hard wood. Chunked is better, chips may stick together.
  • Sizing: Is the sizing too small, limiting air flow penetration? Are the wood particles sticking together in a clump above the jets. This is called bridging. Use larger chunks.
  • Charcoal: Charcoal dust can plug up the hearth area. It’s important to only fill with chunky char. Fill 8″ above jets.

Gas Quality

  • Intermittent flow: Bridging- feedstock is sticking together and not falling down in a uniform way, causing your charcoal to burn up before wood finally falls down and has to try to turn into charcoal again. Plugging at the grate or in the filter. Check the grate automation. Clean filter foam. Condensation may be forming and the gas has to pass through water, slowing it down. Drain condensate. Also service soot cleanouts.
  • Weak gas: Too much air is getting into the oxidation zone causing the gas to be burned and releasing CO2. Make jets holes smaller. An air leak, you may have left a cap off (most likely)
  • Tar: Valves are getting tar. Wood is too wet or gas flow isn’t sufficient. Wood chips may be too small. Choke plate diameter may be too big, reduce choke opening diameter.


  • Gas is has excess steam: Use dry wood. Also run the machine for 45 minutes in flare mode (first run only) to break in fresh charcoal and turn it into activated carbon which has much greater surface area and the ability to fracture more water vapor into hydrogen. Next check to see if the wood chunks are too big, leaving giant gaps in the charcoal bed.

Power Supply

  • Is the battery charged? Automation controls don’t work below 12 volts. Have a voltage tester handy. Connect to engine alternator or a plug-in charger. 2 marine cranking batteries are recommended for energy storage and engine starting.
  • Are the battery terminals wired correctly. Black is negative. Red is positive. Track the black wire to make sure it is grounded to a metal frame
  • Are the terminals corroded. It may not appear so, but oxidation can still have an effect. Wire brush the terminal ends. Spray with silicone spray.
  • Are you on rubber wheels? Run a wire to a ground spike.

Gas Grading

There are basically two grades of gas you can make with your gasifier depending on your feedstock type and preparation. This is similar to diesel oil which comes in fuel grade or heating grade.

Grade 1- Engine grade. This is a clean gas made from wood chunks and thick wood chips. Wood is ideal because of it’s low ash content. Wood breaks down from a solid, to oil vapors, to pure gas and small carbon molecules that are filtered before reaching the engine.

Grade 2- Heating grade. This is a more energy dense gas, but it has impurities that can foul an engine, like tar, a cooled oil vapor. Tar is no problem when you are just burning gas for heat. And you can use a wider range of feedstocks including chipped wood and some biomass. Chipped wood tends to stick together so be sure to have a stirring mechanism to keep it from clumping. Biomass is best gasified at lower temperatures to avoid fusing the silica into small stones called clinkers. To make this happen, you can use a slightly larger choke plate hole opening. Consider that tarry gas can foul your blower motor, so use a suction blower to start (10 min) and then switch to a push blower to maintain gas flow after start-up.

Wood Chunk Sizing to Engine Size

Your engine size will determine how much air passes over the charcoal in your gasifier. The more air there is, the faster it will eat up the charcoal, so with larger engines you can use larger wood chunks and with smaller engines you must use smaller wood chunks.

Wood sizing is also key in making the char reduce to a size that will pass through the opening in the choke plat in your hearth.

Rule of thumb for new users (newbies)

1″ sq. chunks for 2 cylinder engines, kohler type

2″ sq. chunks for 4 cylinder engines, generac type

2.5″ sq. chunks for 8 cylinder engines, ford industrial genset type

For hardwoods you can reduce the size 15% because of the higher density.

Gasifier Maintenance Video

Hearth Zone: Combustion/Reduction

Automation wiring diagram

This is the color wiring layout for the relay specified in the book from www.customrelays.com

Download pdf

Here is the updated part number for 3 seconds on/ 3 min off. Download quote sheet


Wood Gasifier automation module wiring diagram

Wood Gasifier automation module wiring diagram

[Clarified] Hearth sizing drawing from page 35 + charcoal fill side view

hearth sizing

High Performance Hearth

Finished v-hearth

Finished v-hearth

Hearth tuning- Now that we have enough people building I wanted to share a really cool design trick that I used on the Victory line of gasifiers called the Victory Hearth. It’s a favorite.

After spending hours running gasifiers with glass over the top watching how the charcoal heats up in the air stream I began testing some ideas to even out the hearth temperatures and force any wood and water vapor through the hottest part of the combustion zone, giving it the longest residence time. This is the brute simple type of approach I am known for.

Steep v-angles channel the fuel and vapor into the the jet stream while also insulating a normally colder area, boosting performance. I don’t have any measurements for you, but you can eye ball it and start with a cardboard template. Steeper is better. Works like a gee-whiz.

Pre-welded parts

Pre-welded parts

Hopper Upgrade

60 gallon air compressor tank monorator hopper. For use after you have produced quality gas and desire extended run time.



gasifier-wheels-4You will be very wise to add a set of wheels to your machine so you can move it. Get something sturdy and bolt them on.

Blower Tutorial

Double blower configuration

Push blower

Push blower/ Pull blower

Blower- Using a blower in suction mode is an easy way to get your gasifier started, but sometimes it makes good sense to use a blower to push air into the gasifier. (if your seals are tight)

A gasifier needs alot of flow to attain and maintain it’s internal temperatures. If you have a tight filter, you might need a little push. Need more power out of your engine? Give it a little push. Keeping the blower on the front end means only clean air passes through it, so it will extend it’s life.


Dual blower T-bar

If you put it on the outside of your check valve as pictured, then you want to drill a small hole through the side of that check valve and attach a rod with a small cam to force the check valve open when its gets sticky from pyrolysis oils. Rotate the rod until the cam pushes the flap open.

You can put the valve on the intake side of the blower if you mount the blower rotated 90 degrees, but pyrolysis oil can accumulate on the internal blades and throw off the balance over an extended time.

Wood Chunker Design Elements

There is no one size fits all chunker design that is going to please everybody and every budget, so I wanted to point out the elements a good chunker usually has and several options for making it happen.


  1. Power- If you have a tractor I would start there. Next I would consider a dirty old used engine. Something that is cheap and ideal for practicing woodgas will be fine for chunking wood. 4 cylinder is probably ideal, but v-8’s work too.
  2. Gear reduction- This is just a means of slowing the shaft speed down to something usable like 60-100 rpm at the cut head. Ebay has lots of deals on gear boxes or you can use old wheels of differing sizes pressed together to reduce the speed.
  3. Energy storage- A smaller motor will be able to do more work with a flywheel because of duty cycle. When you aren’t chunking wood the energy is banked up in the wheels mass, just waiting to be harnessed.
  4. A cutting head should slice and pinch the wood so it comes apart in neat chunks. The screw head is complicated, so I would go with an old tire rim cut to a steep angle and sharpened.

Here is an idea…

No tools? Need Help Building? Here are some ideas:

1- High school or community college welding students.

2- Hire a metal sculptor when they are slow… artists work cheap.

3- Maker Spaces. A really cool thing is happening. After the death of manufacturing in the 90’s there is a rebirth of community fabrication shops called “Maker Spaces.” Tools, talent and low monthly fees make it much easier to get stuff made.

Check out this global directory:


maker space list

maker welding

Blower Motors

Sold OUT on our site- Contact Manufacturer (see below)

Try ordering a “sample” from Sohon direct. Talk to Ann. Use part number “FL130021D-02” for 12 volt blowers. Use this link below to contact her. If you are nice they might give you the wholesale rate, I’m not sure.


12 volt blower motor - $149

12 volt blower motor. Red + Blue –

Blower motor specs click here FL130021D-02(12V)

Machined Parts

Permanently SOLD OUT

No longer stocked

No longer stocked

Folks are making their own now so we stopped carrying these. Need help? Have them machined by a local high school machine shop or http://www.emachineshop.com/


Pipe plug

Pipe plug

READ THIS: Make your own jets by drilling holes in the center of 1/2″ stainless pipe plugs. OK:-)

Get straight cut threads if you can. They are better for the high temperature environment. If you use taper threads then don’t over tighten! Finger tight plus 15 degrees with a wrench. Use graphite lube on the threads.

Dimensions for machined jets. Click the image or link below.

gasifier jets
Click here for Jet Dimensions not found in the book

Download This!


Bonus Assembly.pdf

Bill of Materials

Bill of materials


These are the same parts in your book, just in excel format. This was done as a courtesy, if for some reason you can’t open it, then you are shit out of luck:-)

Electronic Carburetor Code



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