Bob,
Thanks for playing with the pipe grate idea. Hopefully Kristijan will also weigh in on the idea and give Tom some build specs. I don’t see the need for the angled restrictions in your sketch. Can you explain?
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This is not worth a separate topic so I guess this is as good a place as any to stick it. This is a video of a truck with a propane conversion.
There are many others on-line of course. I am thinking that for a dual fuel set-up this may be a good fit with wood gas. One regulator on the propane set up is fed hot water from the heater core piping because propane needs to be warmed to work well. Wood gas needs to be cooled but the carb adapter should dispense either gas the same once it reaches there. Then its just two simple switched solenoids to go back and forth from fuel supplies.
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Funny, just yesterday i asked if Kristijan would mind giving me some idea of dimensions for a downdraft and here we are now working on it ! 
This a terrible sketch of what i had in mind , i think it just needs to have the distance from air in to gas outlet sized correctly or maybe as Bob has done and do away with a grate and use another flute type nozzle for the gas out .
This sized drum is what i use at the moment for my updraft system with a vertical nozzle at the bottom attached to bottom of the drum and then the drum sits on a platform to allow lighting from below .
Dave
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Hi Bruce, in any good down draft gasifer needs a restriction zone where the gases and air speeds up. This is where the real transformation takes place the oxygen is stripped away from the CO2 and H2O, making them CO and H2, it continues down into the reduction to the grate. It needs to be completed before it leaves the charcoal. If not then the good gas starts to burn up. This what we call over pulling on the gasifer or going into a heater mode. Not good, you are now burning up the good gas you have just made.
After looking at my drawing I think there needs to be more space and distance to the grate pipe. I will make a revision to my drawing.
Above the nozzles flutes have 2 plates above them. This closes up the area to help keep the heat from moving upwards into the hopper and also helps the charcoal to move down to the nozzles more smoothly the pieces should be made out of stainless steel.
Here is the new drawing
With the grate pipe it needed protection on top and the out sides of the restriction zone too.
I also made the reduction zone longer so the ash could settle and move to the ash drop area below.
Now the finish product of gas will move upwards and into the grate pipe and out to the cooling rails and filter.
Bob
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@KristijanL, I just realized I have this charcoal flute gasifer on the wrong thread. Sorry for hijacking your thread on the Skoda pickup on wood.
I have moved my design drawing to the new topic "Double Flute Charcoal Gasifer.
Bob
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Tom,
If you are still interested, there are now details and dimensions in the new topic: The double flute charcoal gasifer - #41 by TomC
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Always interested Bruce. Haven’t quite grasped what everyone is talking about but I am very interested in the idea of a downdraft charcoal unit. Kristijan seems a lot like me. I can’t really believe he would want someone else building his design but he says it’s a simple build. I’m a simple man. Seems like a good fit. I’ll take a crack at it when the plan gets a little more firmed up.
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Ok guys here is whats happened the other day. My trusty Škoda, who served me dayly for the last year, was wrecked by falling out of gear and handbrake while standing parked on a slope with a 800 pound bale on the bed. Later l investigated and found the cause for both failiures was most likely a small 2" stump l run over and must of torn or pinched the cable. The handbrake did seem stiff when l parked…
Anyway, hit a tree at around 20mph and it wrecked it. I was miserable. Looked for a suitible priced pickup for 3 years and l wrecked it in an instant.
Anyway, by a miracle, wife found a same Škoda the other day its actualy younger (1995) and in a better shape. The wrecked Škoda luckly only has its distributer crushed, everything else is great for spare parts!
Same 1.3l motor. But! Its not carbourated but mono injected above the TB. This is the reason l got super excited woodgasing it.
Reason being, l think this way wuld fit woodgas real good. Apart from hybriding being possible, probably, l like the fact the jet is over the tb. No high manifold vacuum sucking on the jet, and runing the engine on dino shuld flush any tar if it ever gets made off the tb. Problem is just l belive it has a separate idle jet that has to somehow be cut off.
If possible, l wuld ask someone German speaking like @Til to take a look at this. Hint a bit how this could be make usefull for woodgas…
If l get this right the whole thing has a controle module. It might be possible to just cut the power to it? The rest of the car is so primitive it probably wuldnt notice thods?
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Hello Kristijan,
I am watching this in CC, auto translate English. Slovenian is just farther down in the selection listings.
Very clear translation into English.
At 3-4 minutes describes that the idle is determined by an electrical pusher holding open the throttle plate for idle air.
The idle gasoline fuel introduced above the throttle plate by the central injector.
Fellows woodgasing throttle body systems COULD dual fuel with gasoline but found they had to positively fuel shut off gasoline external to the injector feed.
Low pressure from the then sucking wood-gas/air would suck gasoline out of the injector even de-energized
S.U.
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Interesting, wondering if there is no similar system on my Suzuki, does Don not have such a system as well?
By the way, how far have you come on your carburetor Steve, a little curious.
Jan
edit. simular?
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Hi Kristijan,
hope that I can find some time this evening or tomorrow to help you with this video.
Til
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My 1995 Geo Tracker has multiport injectors instead of single throttle body.
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Bom napisal v slovenščini:
-motorna elektronika nadzira delovanje črpalke, ko daš kontakt se črpalka vklopi in če ne vžgeš motorja se za par sekund ugasne, prav tako se ugasne če motor crkne med vožnjo. Najdeš kabel , ki jo napaja , ga prerežeš (obvezno samo + žico) in to vežeš preko sikala, če montiraš plin, ta signal preusmeriš na magnetni ventil.
-šoba za gorivo je prav tako krmiljena iz motorne elektronike, dejansko je to magnetni ventil, tudi tu prekineš samo eno žico , kar prav tako vežeš preko stikala. Pri tem postopku je šoba pred dušilno loputo , to pomeni , da ob majhni obremenitvi ni posebnega podtlaka na šobi , tako tudi ob odprti šobi , ni izhajanja goriva , če pa motor deluje z večjimi obremenitvami , se podtlak na šobi poveča kar rezultira doziranje goriva,… dobro za neke primere
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Tone per: Google Translate:
I will write in Slovene:
-motor electronics monitor the operation of the pump, when you make contact the pump is switched on and if you do not start the engine it shuts off for a few seconds, it also shuts off if the engine dies while driving. You find the cable that powers it, you cut it (obligatory only + wire) and you connect it via a switch, if you install gas, you redirect this signal to the solenoid valve.
-the fuel nozzle is also controlled from the motor electronics, in fact it is a solenoid valve, here too you break only one wire, which you also connect via a switch. In this procedure, the nozzle is in front of the throttle, which means that at low load there is no special vacuum on the nozzle, so even when the nozzle is open, there is no fuel leakage, but if the engine runs at higher loads, the nozzle pressure increases resulting in fuel dosing. … Good for some examples
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Hi Kristijan,
I watched the video. In short, I think Tone described what to do.
Now what I picked up from the video, but I’m no expert in fuel injection systems. So take this with caution.
This system records some engine parameters with sensors:
- Position of the throttle with a potentiometer
- Revolutions of the engine
With this two values the control unit calculates the duration of the injection for a basic air-fuel/mixture with a characteristic diagram. - Coolant temperature
- Intake air temperature
This two parameters are used to correct the mixture (cold vs hot engine) - Lambda-sond as a last check if the exhaust values are ok.
This is also used to correct the mixture.
With this values the control unit regulates the pulses of the injector. As I understand, the injector only has the states open or closed, so the amount of fuel is controlled by pulses.
The control unit also keeps the idle on a constant level by closing or opening the throttle a bit.
At last, the control unit regulates the fuel pump.
So as Tone wrote, the best ways are to go in between control unit and injector and/or fuel pump.
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Tone and Til,
Correct, correct, correct, correct.
Let me add from the video and real working experiences:
Other calulating imputs needed are the manifold pressure and the outside air pressure.
MAP and Baro. (manifold absolute pressure and barometric pressure)
The video shows these as outside measured at a remote mounted sensor.
SOME systems mount these in above the throttle plate air horn.
If so on your these would be terribly skewed by woodgas sucking.
The injector on-off time will be varied on all systems. Called the pulse width. But on some system the frequency of the on-off cycles will be varied too. Listen for this.
Fuel pressure is varied by the in-upper assembly mounted pressure regulator. Allows for greater pressure cranking no-manifold vacuum for cold starting enrichment. Allows for reduced pressure at high speed little throttle high manifold vacuum fuel leaning out.
This will be affected by woodgas sucking.
And the allowed injector pulse width and maybe frequency is determined by prerecorded look-up values. The represented three dimensional map the videos show.
Two reasons to understand this.
Only pre-recorded values will be allowed. System cannot allow outside these ranges. Even will trip codes and trouble light if outside these ranges requested.
Second reason:
some ignition timing delivered spark will be computor controlled too off of sensors inputs and controller maps look-ups too.
Is yours?
No mechanical weights or vacuum advance pot on your ignition distributor then it IS computer timing controlled.
Steve Unruh
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Ok. So the way l look at this is this has a lot of potential to work great for woodgas, but also to then run not so great on petrol…
Thank you guys for now!
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Kristijan you will have much less problems going back to gasoline on this TB system than any carburetor system.
Yet still get the benefits of gasoline intake washing down.
Just find the air side source for the fuel pressure regulator and re-route that to outside if the throttle body assembly.
Put in your own string/beaded chain-wire throttle pull for a woodgas idle. That will open up past the range of the computer controlled one. Let it hunt as it will.
If the electronically controlled spark distributor gives a problem. Switch it out for the earlier one.
I have so little experiences working on TB injections because they never needed it. One injector feeding all four cylinders and they almost never clog. Simple filter then too. With wide range of gasoline quality using then possible.
Great systems.
Only dog-chase-it’s-tail into tighter circles with more and more restrictive emissions requirements force changing to individual cylinder injector systems.
S.U.
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Likewise Steve, only issue I have ever scene with over the top tbi injectors is the occasional burn injector harness from a back fire since the wires are exsposed in the throttle body. Usually on the early tbi Chevys. No trouble at all, as long as they had a consistent 45psi feeding them they were dead reliable
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