Fuel Size

First of all, thank-you Wayne for finally getting your information out there. The way things are looking it appears to be right on time. A lot of us are working on our own systems for either stationary or vehicle use, but yours is the only fully proven truly workable design for us “poor people with poor ways”.
My question is that in your book you state that fuel size should be about 2 to 3 inches by an inch or so (I don’t have the book in front of me), the videos of your chunker seem to put out bigger pieces, the photos of your sacked fuel in the book seem to be bigger and finally, I remember on the woodgas group “someone” saying that you burn “foot” size fuel. How big of pieces do you actually burn?

Hi Terry,

you might want to check out this thread on wood, i.e. fuel supply:

Best regards,


Terry, Are you still in your same house by the slough and RR tracks ? That was the last time I saw you and I stayed at Wayne’s house. I drove to St. Louis after your place and spent the night at my brother’s and then drove to Wayne’s the next day and got to his place just after dark and in the middle of severe thunderstorms. I was glad I had been there before and had the 4WD truck or I would have been way way lost. I got to run his chunker a bit just for fun. I made a couple of sacks for my return trip. I made my chunks way smaller than he does. He does 3" and 4" type stuff out of his slab wood for general driving. He likes to drive fast but he has a unique system that sucks that stuff down in an orderly fashion. He did a lot of experimenting years ago with larger pieces to get it figured out. We swapped a lot of pictures. He saves sacks of 2" hardwood pieces for racing and the such. I still run 2" type chunks but I have a 9" nozzle circle on my trailer. I can go to 3" or the such but my restriction is 3.5" so I try not to go bigger than the restriction. Depends on the wood and burn rate as well. I hope you are doing OK. We haven’t talked in a while. I am usually at 608-623-3000 during the days when I am not working in the field and at 608-623-2172 in the evenings but usually hit the hay before 9 PM … Drop me a line some time. I plan to drive to Argos via Warren and Freeport and then Rockford and south and then east to avoid Chicago with the trailer and slow speeds. I don’t plan to fill the passenger seat at the moment and there would not be room for the 4 legged one as this is a small truck. I hope she is doing OK … Sorry I forgot her name. It was 3 years ago … Mike

Hello Terry and welcome aboard,

I have in the past experimented with long wood strips 16-20 inches long. The gasifier would do OK with them if lined up vertically and inserted in the fire tube and sure they would drop on down. The problem is if any were put in radome they get horizontal and cause bridging.

I learned from the above if there were some means to line up and make sure the long strips would fed into the burn tube it would work OK . There is no easy way to achieve this so it is much easier to cut a long piece into several short pieces and have no problem with bridging .

If I had to chose just one size of fuel it would be blocks 2x2x2 blocks but when chunking the wood one will come up with various size pieces . Some near the size of a grapefruit or coffee cups size and small pieces down to saw dust .

As Mike has mention, I think the harder you plan on working the gasifier and for performance the smaller the fuel should be .

I think my rule of thumbs for general use of the trucks would be chucking the wood as big as I could and it still flow freely through the gasifier. ( less time and labor preparing fuel)

Pictures of the wood piles shows the size that works well for me.


Hello “someone”, hahaha. 3 years ago? Man, where does the time go? No, I had to move last year, the railroad bought my house. Seems like I can’t stay put, first ADM then the RR. I’m thinking that I’ll get settled in here and they’ll open the prison in Thompson,IL, then want to expand 84 with all the new jobs and people and buy me out again. I managed to stay in IL one lot away from the river. I bought an acre-and-a-half zoned agricultural and put a 6 foot high chain link around it with no trespassing signs all the way around. I’m still in the hundred year flood plain so I couldn’t build a pole barn over 600 square feet without raising the grade 2 feet so I put up a 20x30. I’m done with houses, keeping everything on wheels to avoid taxes, got another semi-trailer and a 32-foot camper. My girls’ name is Dudette and wherever and however I live is fine with her. I’m totally off the grid now. I made it through the winter so I’m confident that if the bottom fell out tomorrow I wouldn’t really notice. I have a lot of work to do this summer to try and get set up a little better. I’m really hoping that my job and the economy hold together for another couple years. I want to get some chickens and a couple goats. I saw the flock of chickens in the background in one of Waynes’ videos. Kudos to you Wayne, you’ve got it going on. It seems that no matter how much I do there’s always so much more to do, no matter how much I learn there’s so much more to learn. No surrender, no retreat. My # is 815-535-6989. We’ll get together again at some point. Later.

Morning TerryH.
Glad to hear you are settled in as well as possible somewhere. Yep. Got three of those foot warmerers myself. Woolie Ausie “Ruby” velcro’ed to underfoot right now.
Nothing beats the ecomony of home chickens. Nothing. Bit of wild bird seed scattered and mine now scratching, dethatching and weeding under the blueberrys and raspberries right now.

Like Mr Wayne I’ve found it very advantageous to vary the size of the wood for heating or gasification to the actual demand. Even with boring same, same Douglas Fir I separate out into four different rates of reactive types and fine tune that further with sizing. Smaller sizing always produces more heat 'n power, quicker. Larger sizing with less reactive surface area and the grain dense limb wood is for the already up to heats low power needed idling along times.
This is where I do get critical on wood stoves, gasifiers and engines - I want them to be able to handle the widest ranges for power and fuel flexibilties. Want no picky specialized woosies in my life even at the expense of some on paper untimate fuel efficiency. The efficiency IS the flexibilty in real life useage.
This woodstove hearth will eat anything I’ve got from 20 incches by 18 inches, down to rake-up bucket pour in wood scraps. ~6000 BTU per hour up to 60,000 BTU’s per hour.
The tall SS hearth on the left has eaten and IC engine powered with woods from fine split 18 inch long stick form down to ~1 inch chunks all with the same 4 inch restrictor. Generator electrical power capable 1000 watts to 10,000 watts.
Power capabilities about 10 to 1 max to minimum in both cases. Hearths themselves only about half of this range. Operator fuel sizing and types selection the other half of this capability.
Best Regards
Steve Unruh

Hi TJ, That’s the third number I have had for you. I’m glad you and Dudette are doing OK. Very nice friend. I hope you finally got your chompers. You are welcome up here pretty much anytime with some advance notice and can stay up in the trailer house with your friend. It only has a cold shower right now and is full of wood chunks, gasifiers and other crap. I couldn’t get the heating element out of that heater, even with the huge wrench. I’m getting into my busy season here now but feel like just hangin out. I was sick much of the last 3 months and it took it’s toll on my ambition and lungs. Fell on the ice and had a concussion and possibly a couple of small strokes so have lost some brain mass. I have to write more things down now and then I lose the notes :o) … New truck is all hooked up and ready for it’s maiden voyage on 2" chunks getting back on topic. I usually wait for a visitor to show up before I do that. It’s way more fun that way. I don’t have much desire to drive anywhere. I just drive when I have to … ML

Hahahaha!!! Doesn’t sound like the conditions in your trailer have changed since you invited me up to stay in it 5 years ago. I’m excited about Waynes, gasifier, can’t wait to get started on it. I know it’s going to be a long process just hunting everything down though. Visited the scrap yard in Clinton Saturday and bought 10 55-gallon drums, 7 heavy duty grays and 3 regular blacks. I need to swap out some of my storage barrels too, they got rusty sitting out at the other place. I’ve got a few 30-gallon ones but 15 or 20 gallon will be hard to find. Stainless for the grate is no problem and I found a good length of 3" x 4" tubing. Saw blades are another matter, I’ll have to call the welding shop I used to work at and have them save their wide banding for me. Nope, no chompers yet, but I need to do something pretty soon, I can hardly chew peanut butter. I got Delta Dental at work, now I’m trying to get more money out of them so I can get it done. Maybe after I get the gasifier built, hehehe, guess it’s a matter of priorities. As usual, no way can I get away for more than a day at a time, winter will be here pretty soon and I’ve got to get better prepared. BTW, my phone will be off till Thursday or Friday. Take care.

Hello Steve, good to hear from you, it’s been a while. I don’t know if it’s chemtrails,flouride,age or all this damn moving but it seems to be getting harder to stay focused. It’s a good thing I keep notes and information gathered along the way to keep me going after periods of interruptions. I’m glad I asked that question, the replies I got sure cleared that up. So I’m guessing from what I read in Wayne’s book and Waynes’ reply that you set your restriction size and height according to a “standard” size, like say 3" chunks and you should be able to go down to 2" with no trouble and increase in size until you start producing tar, again, depending on the type of driving you’re doing.
I remember that SS gasifier. I don’t remember what size engine it’s sized for. I’d just put in mothballs, it may be a collectors item one day. Well buddy, 3:00 a.m. comes early and I know you understand, I’m not getting any younger. Take care.