Is it better to just pour the charcoal on top like that or mix it in with the wood.?
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Tom, I have tried adding char only a few times and always on top. It seems most of it will sprinkle down and be consumed first of all anyway. If the dust is not screened out properly it will tighten the charbed after only a couple miles.
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Part of the difference comes from throttle position. Spark ignited engines are most efficient at wide open throttle. So when you are driving a less powerful engine the average throttle position will be greater and average efficiency will be higher.
Another part of the change in efficiency is because of the low flame speed of woodgas. This makes the pressure change in the engine fit the engine’s geometry better. With gasoline/petrol there is a pressure ‘spike’. With woodgas there is a smooth curve.
A third reason for increased efficiency is because woodgas contains water vapor. Water vapor can help both petrol and diesel engines run better and more efficiently. Water injection (engine) - Wikipedia
Rindert
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Hi Rindert, I very much agree with your first statement, which I also tried to illustrate in the above graph, I also took into account the decrease in efficiency on gasoline at full charge of the cylinders (solves the Athinson cycle).
Your second statement that due to the slower combustion of wood gas, more efficient engine operation does not occur to me, because with slow combustion engine parts are exposed to high temperatures for a long time, which means higher heat loss and poorer efficiency, today’s engine manufacturers strive to achieve shorter combustion time and ignition of the mixture even after the upper dead position of the piston, precisely due to heat loss.
I can’t explain the third reason you cite water vapor. In the attached link we talk about water as a liquid or small droplets that gasify at high temperatures and add additional pressure in the working cycle, in some cases with excess carbon, even the process of reduction and re-oxidation takes place.
Rindert, I hope I didn’t offend you, but I’d like to understand the processes of wood-based vehicles with the intent of “knowing where to hit.” 
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Hmm …, 
I protest that with a slow combustion of the fuel mixture there will be large heat losses on the engine parts … I think that everyone who drives on wood gas noticed that it is almost impossible to heat the engine to a boil. In my Opel, when the ambient temperature is below “0⁰С” when driving at a speed of 80-90 km / h and the position of the interior heater is above average, the engine radiator remains completely cold, and when the interior heater is turned on at full power, the engine temperature begins to fall and the arrow of the T indicator falls into the blue zone.
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Joni , you don’t have a high pre-ignition because you don’t need it due to the higher compression ratio and the combustion of the dense mixture goes quickly , but still the engine does not exceed 30% efficiency , so 70% waste heat is generated , part of which is removed by the radiator and part by the exhaust. .
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Joni, I’m sorry but I wasn’t very clear.
What I meant was woodgas is more efficient because of LESS heat loss than running gasoline. Reasons for that described by others.
Edit: Sorry again! Reply not for me 
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Jo, Joni states that the heat losses are lower, he protests to me, I’m guilty 
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All internal combustion engines operate on the principle of the Carnot cycle, according to theoretical calculations, their efficiency cannot be higher than 33% for gasoline engines and 44% for diesel engines. Based on this, I think that at the same speed on the same road, the engine performs the same work, both on gasoline and on generator gas, therefore, if I am driving on gasoline, I will not have problems with the interior heater, but if I food on gas, that is, they are … That is, with the same operation, the engine emits a different amount of heat, respectively, the result of all this is the efficiency of the engine (the efficiency is higher)
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I’m siding with Joni on this. If you watch the Project Farm you-tube channel he has a see through plate over the cylinder and shows on different videos the use of many different fuels in a small one cylinder engine. The flame spread for more powerful fuels, because they ignite very fast, generate more heat in a more confine part of the cylinder. He has demonstrated almost anything that will burn used as IC engine fuel. He has not done wood gas as far as I know but it would have a similar burn pattern to the lower powered fuels, so less generated heat, more spread out across the surface and more easily dissipated through the mass of the castings. Shoot me if I’m wrong.
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I keep poking at home to run woodgas in the see through engine!!! He has said a few times he likes the idea
Tone,
I am not offended. I have a ‘thick skin’, as they say. I love to argue. If you show me I am wrong then I will learn something and I will have a better mind than before. I win. 
Do you understand octane ratings for all kind of fuels. a standard measure of a fuel’s ability to withstand compression in an internal combustion engine without detonating.The higher the octane number, the more compression the fuel can withstand before detonating.
So, what is this detonation? This is when an engine makes a bad sound, like a diesel, but in a petrol engine. You know your engine is breaking. But why does this happen? Because the air and fuel mixture is burning too fast and creating a pressure spike. This is bad for engines and wastes fuel.
Here is more discussion.
Rindert
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Gentlemen,
Let us simplify.
Internal combustion piston engines are heat engines regardless of their cycle types.
The one that most completely converts that fuels heat made energy into true useable shaft power wins.
Currently that is Atkinson cycle type engines in the small: some Honda’s and some and Toyota’s engine applications. Both now at, and above 40% conversion efficiency.
Some of the very large slow marine piston engines exceed this.
Tone dynamic factors in engines and fuels results are what rules in useages.
You can never fix, or fixate, on one factor.
Gasoline engines have conversion improved by many, many small changes. Like offset crank shafts. Toyota storing the previous engine heated coolant in thermal vacumn bottles for the next useage.
And at times they go too far chasing the rabbit as in direct into cylinder injection. Carboning up to unrunnable in under a thousand hours of useage.
Modern diesel engines have improved by lengthening out the injection into three distinct phases now. Yes. A longer softer piston pushing cycle. Better able to be converted into reciprocating mechanical power.
Conversion efficiency is different from effectiveness of usage.
Mazda’s Miller cycle “Sky Active” is for power with least emissions. Combustion bye-products outputs are the GOD all engine manufacturers must kneel down too for the last 50 years. Very unfair. That GOD makes increasing demands. Never ending demands.
And we only have their produced results to work with as base engine to woodgas fuel with.
Hey! We have it great compared to the 1940’s guys.
Choose wisely.
Steve Unruh
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Hey we have it great compared to the 1940’s guys. They dreamed to have our factory compression ratios.
Always this though in your woodgas fuels maths:
Multiply by a factor of WF.
Wood Freedom.
Can’t grow fossil coal in my back yard.
Can’t grow natural gas, or petroleum crude in my back yard.
Can’t grow propane in my back yard.
Don’t want to grow old dead tires or pounds and cubic meters of consumer plastics in my backyard.
I, and anyone else with just 2 acres/one hectare can grow fuel woods. That’s enough for 1/3 of a house hold total annual energy needs. Many here on the DOW do this now.
My WF’s are always X3 factors.
S.U.
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Rindert, Steve, Joni, Jo and other friends, you gave good information for processing in my brain, so the engine captures through a wide open throttle the full amount of a mixture of air and wood gas, which contains in addition to combustible gases a large proportion of nitrogen and water vapor , all compressed well and ignited, but due to the large proportion of ballast gases, the final temperature does not rise as high as when running on gasoline, but the mass density of the gases effectively does the job to the exhaust stroke and heat loss is less. This is logical and meaningful to me, thank you all for enlightening my mind.
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Allow me one more thought, if the above statements hold, I could easily simulate this by running part of the exhaust back to the intake manifold at my Subaru and this would reduce consumption from the current 9l / 100km to 6l / 100km. It would be interesting to try. ,
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Doesn’t that already happen in the form of EGR emissions control?
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I knew about the diesel engine, but not about the Otto engine. always dripping in the background, Kristjan said well, “we are finding out something that people used many years ago”
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Mounted the new trunk lid the other day and then
wife and I went for a 100 mile roundtrip yesterday. 50 miles one way is perfect for this hopper size.
We did one extra stop though - but only to check the cleanout rubber cap. Reason? The temp leaving the heatex climbed above 250C, but I found no obvious extra heat or leak down there.
So it seems the only reason is - with the trunk lid mounted, the temp-probe is no longer out in the open. I was surprised to discover the true reading is almost 100C higher than what I’m used to. Last pic shows the probe’s position.
Also, I will have to add to the insulation around the gasifier, because the hayfilter bucket picks up some radiation. It gets armpit warm on that side but still cold to the touch on the opposite side.
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Nice job JO, turned out very well with the tailgate.
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