Hi RobinR
My spark ignition explanation is very much simplified down just like my how to make woodgas summery. Both of these aimed at getting you off and DOing. Takes twice as many words just to explain the very precise technical words needed to then explain these processes properly: capacitance, inductance, flux density, magnetic saturation, gasses ionization, etc. I am satisfied if my 101 level explanations help the majority non-Tech/mech/brainiac normal people understand enough to get them out and just do something, anything so we can go on to a more multi level dimension of understanding from a dirty real on hands approach. Read. Do. Think about it. Then either read some more, or do some more. Stop. Think again. Repeat. Repeat. Repeat again until sucess to making a shaft go round and round for a purpose.
Short complete Internal combustion engine spectrum answer is NO. The two used derived systems of calculating, one for closed top resticted hearth side jets, and the other for open top stratified downdrafts all fall short of usability on the the small engine sizes below ~20 hp (100mm/4" restiction opening) and above a certain point call it 50-100x that at ~1-2000 hp.(above a 200mm/8" restriction opening).
Read and re-read Dutch Johns www.woodgas.nl Microgasifiers for a glimpse at the limitations of this by his conclusions.
My real world experience with GEKs, Victory Hottwatts, and other constricted hearth variants say you do not want to go below a 3" restriction opening as TerryG has said he is using when chunked wood is your fuel. Their actual from accross the air nozzle ring and down to the to constirction volumns (closest equivalent to the fire tube space) is all over the board. Same with nozzle air % sizes - some “Impossible” (by calculations) too small to “Impossible” too big. Yet they still worked just fine for the users.
Change the fuel type: chunked, chipped, crushed/densified, its moisture content; or even just go from a low ash to high ash fuel base; add gobs of insulation; add gobs of preheating; add external heat as in engine exhaust; go above 1000 meters/3500 feet; 90F 10% humidity versus 40F 100% humidity, etc, etc and each one of these will demand changes. I have operated small engines gasified at these extremes. Why you will generally hear anyone with learned experience ask 20 questions before giving up squat for advice.
Now a fire tube design like Waynes is a different animal outside my range of experience.
Adapting his system down is being discussed by Wayne in the actual Builders Discussion Area in a Building Down for Small Engines topic. You are a Premium member. Please read there your specifc size guestimated fire tube to try with. Follow along. Do some building your self, contriibute and we will work it out and see what proves out to be workable. Always seems to take three tries to narrow down a range of possibilities.
Ha! Ha! Rule of life - more to be learned from working up and out from “failing” then a lucked out first time “calculated” success.
I built a truck mounted unit for transportation. Once it is warmed up it will run any small engine for hours without making tar. The key is the temperature at the hearth and keep that temperature in the zone where tar is destroyed. This can be done with a simple 12 volt bilge blower that pulls gas from the gasifier and pushes the gas to the generator, A few well placed thermocouples on the gasifier will keep you informed as to state of the unit. Wayne has several videos showing how he runs generators and other vehicle off his truck. I start my truck with one 12 volt bilge blower and it takes a little longer but I don’t care and it never shows tar. If you build one of Wayne’s gasifiers on a vehicle it will do the same. Buy the book and build it.
Maybe we need to start a new topic on “TAR” since it is such an issue. Thanks Woody for the insight. Can you give a temp. range that works?? Will it work on big and little rigs?
Terry, that before, and after photo needs to go in the “What not to do” section. I had to laugh, forgive me.
You need heat in the right place to kill the tar. Wayne’s design takes care of this and will run any size engine once it gets up to operating temperature. I run Onan generators off my truck unit all the time. I just go for a ride to warm it up. To get a better understanding of the process of gasification go to this link and download the free book http://driveonwood.com/resources/pdf-articles/handbook-biomass-downdraft-gasifier-engine-systems. Everything you need to know is in there.
Greetings all, The last 2 times I was cutting grass, I couldn’t pull that much
water(about 4"). Well, on shut down yesterday I see that one of my filters
collapsed. Since spring I’ve noticed slight rust droplets about 8" down from the
top. I figured it’s about time to replace the thin ductwork.
Upon opening them up I find my media has rotted away to half volume and my
screen on the bottom has corroded away. So I ended up with media in my supply
tube. Mike L mentioned years ago to stay away from aluminum screen. Well it took
2 seasons, but it did let go. Also it was such a warm winter I got a lot more
corrosion in my system than usual. I plan on emptying my filters during the
winter from now on.
Terry
hi terry
yea it’s funny how that stuff sneaks up on you
we had a big power outage so i was really working the gasifier until the restricter burned out i guess i hadn’t pulled it that hard for 24/7
How much vacum do you normaly pull?
thanks
Tom
(copied from yahoo)
Gang,
I’ve had a wisp of smoke coming off the block of the lawnmower the last 2 times
running it. Turning off 2days ago I noticed it stopped quickly when the key was
turned off. Checking the oil I see it’s in bad shape. So I changed oil yesterday
but when I went to start it, it was locked up. Pulling the heads show what looks
like iron oxide on the left side.
Pounding the pistons with a wooden drift barely moves the engine. I guess I have
to yank the dang thing.
Discoloration on a connecting rod tells me where the problem is. Yup, gauling on
the rod bearing.
My guess is that with the corrosion from my media, screen and throttle
butterflythis past winter, all this crap made it into the oil. Making enough
heat to smoke the oil in the crank case.
I found a local place where I can order a new connecting rod. I hope I can emery
off the gauling on the crank good enough to last.
There is always something to keep you busy on a gasifier.
Terry
Hey TerryG
Well sorry to hear the bad news. If as you suspect it died from hard iron particle contamination out of the gasifier system then you will also have wear and scoring on the other connecting rod crank throw, the cylinder bore and piston faces, and the camshaft surfaces. Then you’d know. If only this one rod big end then was a Sheet Happens. Lost lube to it; bearing crush grip in the rod loosened allowing the bearing to spin, etc. The localized friction heat would cook the oil quickly.
In forty plus years with hundred thousand engines worked on and operated I finally had a sheet happens to me too. Fresh oil change on a Chev Suburban with a 350 V-8 in it crank siezed and locked up out on my test drive. Burnt cooked the new oil good.
So open it up a little more and see if just a sheet happens or truely an “I killed it!”
Nice picture on the piston crown and valve heads. Very little carbon build up.
Steve,
I popped both pistons out. The rod on the good side had slight marring. I’ll guess from the cooked oil. The second compression ring on the bad side was stuck.
The directions that came with the rod I ordered showed that #1 cyl has the oil hole down and #2 has it up. When I took it apart both were down! I’m surprised it lasted as long as it did!
Hello all,
Sad day yesterday. I’m afraid I’m throwing in the towel on this old girl. Since the rebuild she has made a whirring noise from the valves and now it sounds like a rod nock. This motor is discontinued now so I can’t get a new one. It’s served me well for twenty years now and has allowed me to burn unthinkable things through her.
I’m not sure if I’m going with new or used but I’d like to get a zero turn mower. I wonder if a producer mount would upset the balance on it. Yes, charcoal is a possibility, but I would like to try to stay with wood. I feel obligated to continue the gassing tradition and awful thinking about burning gasoline for my lawn maintenance.
T
R.I.P. good old mower we will miss you , it was a classic,I hope you are able to convert your next mower to woodgas it would be interesting to see one running on charcoal.
So sad yes TerryG.
All good things end much later rather than sooner - but do end.
You could repower this much cheaper than any new zero turn machine with a new horizontal shaft V-twin Briggs, Kohler or Kawasaki engine. Depends on the balance of condition of the trans, steering and mower deck on this old HD machine. Sentimental value counts too.
Cheapest by far is a used running newer non-zero turn standard LD rider. I paid $300 for a running used clone as a parts donor for our 7 year old $1600 when new Scotts/JD medium duty Hydro rider.
Either way you would be upgrading to much better overhead valves with better gases in and out flowing.
These the good engines to look for: Briggs Intek and Vangards; Kohler Commands and Command Pro’s; any Kawasaki.
Avoid the very inexpensive Kohler COURAGES and Honda’s IMHO. The first are self-destructive, the second very power overrated with expensive parts.
Terry,
Can you post some photos of the intake mods that you did ? I could see the combination ejector/air valve in the video, but did not see a carburator or how the motor is fed from the air cleaner(?)… is there a carb on the engine ? I have a Craftsman 42" cut with a 13HP I/C Gold Briggs (no chains) and it did not look very easy to mod the intake for dual fuel because of limited space.
I also studied some of the conversions by Francois Pal and may be able to use his method on my older hydrostatic Montgomery Wards tractor with a 15HP Briggs. Any details on the intake tract are appreciated as I turn the corner to make my gasser do some work.
Steve, as always, thanks for your advice. I’m still doing research.
It’s a shock to me, for some reason I thought I would always have that mower. I still might find a way to reserect her but then the transaxle might go. I’ve stressed it with tire chains and gearing it up. When running strong I can carry the front wheels about 6ft. It’s had a leak for about 9 yrs now and I’ve been putting knuckle grease in her to slow it up.
Gary, I never ran dual fuel in her. Once you have the woodgas bug I don’t think you will want to run petrol anyways. The first year after the conversion I got rid of the carb all togeather. Just run WG right into a mixing chamber before the intake. The flare/ejector does make a fine air intake.
Hi Terry
Is your old engine an opossed twin?
If so i have some old engines
I have an old koler twin i think it runs good just don’t have a use for it
I also have a 14hp koller off a bolens that i have on a 25 KW gen LOOKS LIKE A FLY ON AN ELEPHANT LOL I will be putting a nissan engine on it soon
If one of those would help and we can get it to you your welcome to have it
Let me know about shaft sizes and stuff i can send you a pic if needed
Good luck
Tom
Thomas, Thanks so much for the offer. I feel it’s at a point that will start breaking down at every turn.
I decided to get a whole new mower. I’ve got a lot of warranty on it so I’m weary of gasifing it. Doesn’t mean I won’t be thinking about it.
Terry
