Petersen build just started...any advice?

So I am very mechanical, live in Australia, on a property with lots of gadgets. I am a bit in awe of whats ahead of me so Im just going to follow the book step by step. already hit a couple of snags, I cut the tank 7 inches below the top seam and can see it is a very different tank to the book, I just guessed where the bottom hole goes…and Im about to guess where the 6 inch square gets cut. The small cylinder; it says to cut the top and bottom “ensuring the bottom opening is at least 10.5 inches” …what about the top hole size??? Anyway, Maybe there is some others who know where I am at and can offer some advice. Its always the same that you need to jump in and learn along the way. But advice is always gold! So much of what I have read is about charcoal systems and it gets really hard to find posts that help with what and where I am currently at. Many thanks!!!


Welcome to the DOW NeilW.
There has been three Ben Peterson book builder systems that I can recall done out to engines running here on the DOW.
Two Canadian. One east coast USA. All in bed asleep now. So’s you’ll have to wait at least 12 hours to a day or two for them to read this and respond.
In the meantime view these from one of them:

So as you can see you can fab, make up a system using general dimensions. Nothing is precise critical except gas tight welds where book called for.

Then read here . . . it’s long with lots of detailed construction pictures and some operational videos:

I started you off at his first construction pictures. Shows one of the two holes you are asking about. Once in-topic you can use the thin blue line righthand scroll bar and skip down to post #53 for more detailed pictures of the side holes. And their purposes. Again, nothing is precisely critical as long as the functions do perform.

Steve Unruh


Welcome to dow neil
I’m also a newbie so I probably cant give advice about gasifiers, but nevertheless, welcome


Hi back NeilW,
And another one with pictures showing your side holes locations:

View his pictures for references to the jacket holes.
You should go back up and read though too. And read down to the end. He machined up some beautiful jets
Odd he never showed engine running it though.


G’day everyone. Thanks for the comments so far! Thanks Steve for the photos! It really is a massive project, glad to be going already, once started I wont stop…just do what I can when I can.


my gasifier designed by ben engine works fine


Excellent Mr Andrzej
It that a VW/Audi engine or a Volvo red-block?

With the way you have this all on wheels compact it would be easy to plywood walls shield this directing all warmed air out the opposite of operator side to heats dry down wood fuel chunks or chips.
Best Regards; welcome to the DOW
Steve Unruh


Hi’ya NeilW,
by now hopefully you’ve had a chance to scroll thru the many. many pictures on DeanL’s Newbie from Canada topic.
As you will notice he has varied much BenP’s simplified cooler tubes. Ben recommends this change for larger loading engines.
Post #67 you will see TomH on his BensBook system also went with a larger area vertical tubes system too.
And way down on that topic you will see that DeanL even added a gas-cooler wood drying section too.
Please do note the wide variations fellows are using for the starting up/flaring blowers. Whatever you have locally regionally that can be made to work. It’s O.K.
Ha! just be sure they have NO internal combustible filters, and on suction usages the gas has been cooled enough for any internal plastics! When in doubt blow the system versus suck the system . . . or you’ll have an Opps too!

Wife rushed in to vacuum up some of my woodstove ashes clean-out spillage off of her carpet. Now her old plastic Panasonic is mine now. Along with her old all-metal Filter Queen. Too heavy she says. Just right says I.
My preference anymore is not Chinese made blowers; but old all metals vacuums.

Yeah. Six Kerby types now collected; average of $20 usd each.

I guess I got a little obsessive.
These all need throttling down. Too strong. Much better to strong throttle-able down, than too woosie weak.

Indeed the Ben’sBook system is not the simplest to fabricate. It was evolved for enhanced performance on raw wood fuels.
Steve Unruh


Welcome to the site Andrzej. Where have you been hiding? Your work is very impressive.


Wow Andrzej! That looks great. I’m just a novice and just starting out, but I will get it done. It makes sense to me to insulate, to allow the use of wood without charcoalising required. I guess I will learn about making charcoal, but not at this stage. I think the insulation is arriving today. I need to talk to the laser cutter guy and organise my first batch of cut shapes. He can cut stainless to.
Many thanks for the picture, think I saw a propane mixer pulled aside? I have played with propane quite a lot. Neil


Making your own charcoal can be helpful, even with raw wood gasifiers. Best to pre-fill the gasifier with charcoal, and some wood on top when you do your first run. Also good to have on hand for refilling the system if you run it empty and deplete the char bed below the nozzles, top it off with charcoal to a fair bit above the nozzles and then follow it with raw wood over it to the brim, and you don’t have to wait too long to re-establish the char bed. Otherwise you’ll just be using raw wood chunks if everything’s running good for a regular refill.

I think with longer distance trips in my truck I’ll keep a bag full of charcoal incase I deplete my char bed.


Thanks Cody, I dont mind using charcoal. Its a good tip to use a fair bit at the start! and when first lighting it each time. It will be exciting. If only life would stop so we can do these things without interruption. I basically find that when I want something I just need to work late for a few nights and things get rolling along, its not bad when its something interesting to.


Thanks Steve, its very interesting all the different mods people are doing. I don’t feel ready to make any changes until I understand the system better. Although I do want to make it so I can remove parts without cutting everything up again! As I get to these bits I will decide how I will go about that…high temp flexible pipe I guess.


HI neil-wiese.welcome to DOW drive on wood web site-I built 2 gasifiers that way, the only way i could replace or inspect the burn tube is to cut it out at the top plate that it is no rope seal connections there. Though the WK design uses removable burn tube with rope seal connection at burn tube housing… I am blabing to much allready- enjoy your new wood gas power project. AS Steve Uric would say- be careful , making engine grade fuel can be addictive.


Thanks Kevin, I am glad to be here! Its funny! I always knew about historic use of wood gas, a friend of mine still has a relative still alive who used to dig pits and make charcoal for fuel. I still remember the guy who first suggested to me that it would be interesting to build one…i thought he was crazy and didn’t have anything going on in his life. Seeing the petersen design handling straight wood was a significant thing for me, also seeing the clean burning flares proving absence of tar and ash helped. The last thing was seeing the efficiency…i always thought it would take excessive amounts of wood to go anywhere. many mis-perceptions!! In summary, happy to be here!


I bought the ben patterson wood gasifier bible, it seems too have many of the features that are in the WK design- I think ben paterson uses a monerator hopper though i would have too go study the book blueprint form. Once you get a few builds in it all falls into place easy the next time- i am on my third wood gasifier- I gess i like building fabrications- and my last 2 gasifiers had NO-complete-monerator hoppers. THIS one i am building now will have all the features in the WK design- other than i am using water heater steel in place of all the barrels used- i might need air shock before its none built- hopefully it wont be too heavy. i must be a slow learner-though its sinking in how all the features help keep the tar at bay or AWAY. I see nothing wrong with the ben peterson gasifier design. I will be building one like bens design ASAP,for a generator fuel supply. lord willing and the train derailments don’t rise.


Hi Neil and welcome aboard , are you in Victoria ? good luck with the build hope to see plenty of photo’s or your build along the way .

Cheers Dave

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Once the char bed is established you won’t need to use more at light up unless it’s below the nozzle level, the gasifier when everything is working right makes its own charcoal layer.

But if you do empty it you’ll need to refill the bottom with charcoal.

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thank you for your good feedback about my work. the project is not finished yet, i’m in the testing phase. engine is vw. now working on an electronic carburetor. I greet everyone


No. No. No. NO Flexible couplings on a B.P. system design Neil Wiese.
The system is too compact to lose enough heat soon enough for even the H.T. silicone ones to survive for any length of time.
I have intentionally NOT linked you to those doing this dangerous modification.

But linked you to those who chose to modify this from an all weld up; to disassemble using high temperature capable couplings.
Cast/machined pipe fitting couplers. Inexpensive but heavy.
Automotive/truck cast exhaust manifolds to tubing pipe coupler systems. All metal ball and socket types. Eared flange types. V-band types.
And these are for burn-out carbon monoxide safety. Any gasifier at stop-usage shut-down will self-pressurize form the still internal heated charcoal mass still producing and spew out over 20% carbon monoxide gasses. That is multiples times human fatal doses.

And then I see guys building up BenP systems using black neoprene couplers downstream after the filter cans thinking they are temperature dropped safe then.
Well not if that neoprene rubber coupler is used to span a gap. Or do an “easy-made” 90 degree sweeping turn.
To be safe operating a gasifer system it is engine sucked to operate. THEN any leakages are sucking in air leaks. Not forced out explosive Hydrogen; toxic CO; asphyxiating carbon dioxides.
Under an engine loading-usages flows instead of weak blower flows, the gases will be just warm enough still to soften gap spanning neoprene that they will then be sucked flat blocking your gas flow.
They can be used way downstream alright. You see this a lot on WayneKieth type long-path truck system cooling rails. But those fellows have learned the hard ways to keep their gaps spanning close and tight.

So yes it is more than just as a cost saving that the Ben’s Book system is offered up as an all weld-up design.
It will be built and used by new, inexperienced users.
Other systems designs were/are as mostly all-weld ups too. The M.E.N.S.; Stigg-Eric Werners from tanks built systems. Same reasons. Safety. Cost to build.

All of BenP’s personally built systems 2008 to current were/are all very modular. Almost all are 100% stainless steel. The most durable, expensive way to build in materials, time, and welding requirements.
Vesa Mikkonen’s book offered up four different sized plans systems. All are modular. All SS building. Great book for the math’s, charts and pictures. And his decades of operating experiences wisdoms written out. But, be at least 4X, to 5X the costs and efforts to build versus a Ben’s Book system.
The Wayne Keith book system is great for bigger loaded vehicle applications. Semi-modular. But to make it truly sectional for use age wearing out (corrosions pin holing) replacements; and having it’s advanced able to use wettish woods takes at least 300 to 500 hours to build. Most guys taking a full year in life-squeezed out time to get it built to actually using.

Oh and my own current personal small engine wood gasifier? An all SS thicker plates unit. A Ben’sBuilt made from many boned-out shop experimental units. Was saved from the scrap. A very widely videoed 2009-12, much modified unit. The unit that proved many of the internal design details: the drop-in exchangeable choke/restriction plate; the insulated hearth cores; the gently action on-command shifting grate system; the between the jets flow shaping V-fins. And more changes were made from mine, to the actual sold for $$,$$$ production units. Ha! Move up the hearth top flange farther from the air nozzles to stop time-in-use burning out the inexpensive red silicon sealer. Requiring then he felt the use of a die cut high-tech rigid gasket sealer.
It was in 2012, moving on from this experimental unit that he’d felt that I’d earned it from my hundreds of hours in his shop doing engines testing and mixer; blowers designing works. Even careful. Open shop doors in the cold raining blowing winters I still sucked down too much carbon monoxide engine made puffs and systems changing over spews. Minor headache making exposures takes a week to recover from. Your body has to make new replacement red blood cells. Exposures to happy, I do not care . . . you do not recover from. The movies and old books, head-in-the-kitchen oven opt-out-of-life’s were from city gas plants supply CO fuel gas.
Don’t easy way make yourself, your family, your cat or your dog; your bestest drinking buddy Jake, one of these; Oppsie’s, “I did not know”.
Steve Unruh