The holes should be sized according to the engine displacement - but really charcoal is quite forgiving. In theory smaller holes gives higher air velocity and richer gas, but I dont think anyone has ever posted any results from trying various sizes and comparing the power output of the engine. Obviously if you make it too small, then there is too much restriction, and you starve the engine of enough gas.
The original design of the flute nozzle had multiple holes to try and reduce the height of the reaction to fit into a very compact space. If you do not have that limitation, then a single hole in the middle of the pipe works fine. It will also keep the hot lobe away from the sides of the reactor. I would say if you are running 200-500cc engines, a single hole of about 1/2" to 3/4" in diameter would probably work. If using multiple holes, just make the CSA equivalent. If running bigger engines, you will likely need more area. Maybe look and see if @sbowman made notes on the hole sizes for his corolla.
Thanks. I would say between 2 and 5 hundred cc’s would be about what this thing would be expected to run. I may have to buy a 212 cc Preditor to test this on. I only have right around 400 cc engines right now. Because the nozzle will just slip in and out now, I’ll start with one half in hole as you suggested.
Look very long and hard at the engines on the shelf. I believe that the last three SKU numbers of the 212 predator with the open chamber hemi head is 636.
The reason I say this is because if you remove that head, and swap in a head off any 5.5 hp clone or even a real Honda ( also change push rods ) you will bump up the compression ratio. The 18cc Honda head is fine the 14cc clone head also works, its a question of what you can find and one will not make a significant difference over the other.
While the head is off find and mark TDC on the flywheel and find 25 deg BTDC and mark it. Set timing accurately…
Make your self a decent gas carb throttle body, its not difficult…
Retain the governor though you really want to use that. don;t leave it out and especially never let the governor arm flop around free because there is interference inside the engine with moving parts and you could wreck the engine.
Put a fabricate an exhaust that’s straight out of the head ( parallel to the ground not the exhaust flange ) Large wiener mufflers for 8hp engines are generally good ( 3/4 inch pipe thread ). It would be very nice to get about 6 or 8 inches of length there and some experimentation with length. Not too long however you need to brace this so it does nto Shake and break
Reasons for these modification:
The increased compression will help compensate for some power loss. The small head volume will somewhat compensate the slow burning fuel and reduce the need for timing advance. A well made gas carb thats a straight feed into the intake port lets you see if you are taring up the valve and it makes it easier to spray something in there to clean it. The bigger straight flow muffler will help you get the exhaust out. You can’t do much to increase the flow on the intake side, but the exhaust can help you scavenge better and make more room inside to pull a harder vacuum on the gasifier.
This is all about maximizing the engines ability to pull on the gasifier and then extract what energy it can from the fuel, it will not make a 212 predator much better but its as far as you need to go
“I’m sick of dicking with it and want to move on to something else. This is the last thing I will build no weld. Trying to maintain that and the use of box store components has wasted too much of an old man’s time.”
TomH this is a hard steep climb you’ve set yourself to.
No welds; out of lay about materials, have been done. They are limited usage and very short lived.
Think about it.
What you can do with an angle grinder. Or three. (I just got two more from Harbor Freight to add to my original old Craftsman.) Relatively low wattage AC and then you can do without a gas cutting set; or a plasma cutter. Plasma cutter you need then enough AC wattage to power it PLUS a adequate volume air compressor.
So start with that one angle grinder. Then two, Then three. You’ll only use one at a time. No more wasting time/efforts then cutter-wheel/grinder-disk/flap-sander swapping.
Now for just a few AC 120 watts stepping up, you can HF machine stick weld.
Good enough for all of those hundreds, thousands of water well tanks, air pressure tanks, and propane bottles kicking around out there.
And you learned well that a simple weld joint saves a lot of costs, and weights versus all of those heavy pipe fittings.
Ha! I’ve handed out photo copies of S.E. Werners tanks build woodgas systems.
The Windward folks up here in Washington State proved well that in any Group only 1-2 has to be able to learn to steel metals Fabricate. Their GEK system builder was a very capable woman.
Regards
Steve unruh
One of the best purchases i made recently was my little hot start mini stick welder off of Amazon. Can use 220 or 120V and doesn’t seem to use a lot of power, i can keep my work lights on the same outlet as the thing.
Teeny tiny welder, I call it my Lunch Pail. I’m still practicing at stick welding though.
Carl,
Regarding flue nozzle hole sizes, you are right, that it is not critical–enough velocity for rich gas, but not enough to restrict flow too much. For the 1.6 liter engine Koen calculated 4 half inch holes would be good. I use four holes of different sizes from 3/8 inch to 5/8 inch with the largest hole on the air inlet end. The other end is capped. If I change anything I’ll go to the 4 half inch holes. I’m not sure there is a need to vary the hole sizes and I’d like to try more velocity. It continues to work well though.
I think the reason for varying holes was Kristijan noticed with his one ended flute the air was going out the furthest hole with the most velocity so he tried to equalize it more.
Cody,
The reason I question that is because I am getting more velocity out of the first hole which I don’t think is due to the larger hole size. I thought of reversing ends on my next cleanout to see what effect that has.
This project was started as a survivalists fuel making devise that could not only be built out of box store parts, but could also be built by someone from the debris of decimated structures. I doubt anyone I am involved with other places will ever make one anyway. Right now I’ve got it to where other than the bilge blower, that would be possible. Not that hard to come up with an air sucker of some kind anyway. The one thing I’ve found that I consider to be a big plus is packing the sand/clay cob mix around the reactor and the outside bucket. I have done three different bases like that while messing with this thing and all of them baked into something like a clay flue pipe like they used to use in fire places. I will be doing variations on this theme for future builds. I am weary of dealing with people who talk the talk but don’t walk the walk. I spend very little time with my old cyber companions for that reason and much more time here among people that actually do things I do. In defense of the others I grant that they are mostly agriculturalists and focused primarily on that and I have learned a lot from them in that area but I am sure that anybody can buy a cheap welder and learn to run simple beads, at least enough to stitch some metal together. Pretty sure even a monkey could master it.
I’ve been messing around with this thing again. This is the one with the hexaloy nozzle end. I have it hooked to my Generac which has a 400 cc engine. On gas the engine puts out a steady 123 volts. Off the gasifier it runs between 112 and 114 volts. On gas it runs pretty steady but shakes quite a bit on char gas. Also I can run this gasifier for hours with the blower but it will start to overheat after about 15-20 minutes on char gas. I’m guess the engine is overpulling the unit. The first ammo box is reading over 200f and the second around 180 and the vacuum cleaner hose I’m using to feed the engine hit 150 before I shut it down. Seems to be making a far amount of gas. I have fiddled a lot with the gate valve I’m using for air-fuel mixing and there is still extra gas coming out of the air intake tube even while it’s running. Needs some of the brain trust now.
Hi Tom , the inverter generator i run on a daily basis also has a 400cc engine with the Hexaloy 1 inch nozzle , i am guessing that if it is over pulling then its down to the size of your reactor not being large enough to cool down the gasses , maybe you could try your other gasifier see how that goes .
No problem with the big gasifier Dave. Temp out of the cyclone on that has never been more than 100f. The simple fire has an 8 inch reactor with 30 inches of 6" hopper into it. I could fill the first ammo can with char to increase the volume and just use the second one as a filter, but I don’t think that would solve the problem. I’m wondering how others with these or smaller vertical tube units deal with the heat. Or the ones on lawn mowers and such with just a five gallon bucket full of char. I’m starting to think that wood or char gas is only viable for people dedicated to it’s use and not for a power source for the regular folks. I’ll try and take some video of it running and maybe you can spot something I’m not doing right. I also have the second unit that I slapped together but have never run. It has the vertical pipe cap nozzle. I will try and make some time to hook that up and see if it has similar problems. I’m thinking that even the PVC is at risk at the temps the first one is running.
Hi Tom , on smaller units over heating will always be a problem once you are 1/3rd down on your charcoal fuel in the hopper , you need that full amount to keep the gas nice and cool , it may just be that the 400cc engine starts off running ok and as your fuel level drops so will the output of your engine .
Just a though .
Dave
Opened the hopper today and the char was gone all the way to the nozzle. I guess that explains the heat issue. I think that was from running about half an hour on the blower and not more than 20 to the generator. I have run that blower with the flare for over an hour before and didn’t use more than a half gallon of fuel. That was about 6 gallons I used yesterday. I guess I’m going to have to run it for about 10 minutes and then measure the fuel amount to determine what’s the maximum run time without refilling. I’ll also have to see if opening the hopper to refill will cause a problem. It’s an ammo can. I can open it with a stick from a couple feet back.
Hi Tom , for refilling just stop engine /fan and wait a few seconds and then open up the lid without looking in and then refill , sometimes you get a gentle flame thrown up other times nothing , never had any sort of wild explosion or flames when filling on the run .
Dave
Tom,
In the old days, I understand they would toss in a lighted match upon opening the reactor lid, in order to safely refill. I have been doing that, too with the Toyota.
It runs fine. I have not been driving enough lately, though. I am finding that the more experience I have driving it, the better performance I am getting out of it. I guess that’s what is meant by the 75%.
I am contemplating incorporating the blower and flare burner into a permanent installation mostly under the hood, so that by using check valves and a toggle switch, I can engage and cut out the blower startup system with just the flick of a switch without opening the hood.
Went to run this thing again today but it wouldn’t make much gas. I have buckets of fuel sitting around and I think I grabbed the wrong one that had not had the dust sifted out yet. Sucked it back out with the shop vac. Looked down the pipe. Hexaloy and the pipe fitting it is nested in look pristine, Dave. Thanks for steering me into that.