It’s common knowledge that woodgas is less powerful than gasoline. There are several reasons for this; mainly, the gases have far less BTUs than gasoline does. One of the often stated reasons is that, since we’re using air, the woodgas contains nitrogen, a dead gas. Obviously gasoline has no nitrogen in it, so the woodgas must be less powerful because of all the extra inert gases.
Let’s look at some percentages. You might be surprised.
78% Nitrogen, 21% Oxygen. [Ignoring trace gases.]
Woodgas as measured from Wayne’s gasifier:
20% Hydrogen, 20% CO, 10% CO2, 2% Methane. The remainder is 48% Nitrogen.
A gasoline engine runs on gas and air, mixed about 12:1 (it varies). 92% Air and 8% gasoline.
So the Air/Fuel mix on gasoline looks like this.
71% Nitrogen, 19% Oxygen, 8% gasoline.
Woodgas is pretty much 50/50. So the Air/Fuel mix on woodgas looks like this:
63% Nitrogen, 10% Oxygen, 10% Hydrogen, 10% CO, 5% CO2, 1% Methane.
So we have LESS nitrogen on woodgas. If we count the CO2 and Nitrogen together as inert gases, there’s basically the same as on gasoline.
Do you see something different though? How about oxygen? Only half as much! Should we experiment with adding some? [Please remember, oxygen is dangerous and expensive.] Supplementing 10% O2 at 2,000 RPM, a 318 would run through about 16 cubic feet per minute (largest bottle is 330cuft). Yow! Far from practical.
Now let’s think about Nitrogen for a minute. You might assume that removing nitrogen is always a good thing - after all, it takes up space and doesn’t contribute to combustion.
But you might be forgetting a basic fact about engines - they are air pumps. Heated nitrogen has a good expansion rate - without any in the cylinder, where would all the heat go? Much less work could be accomplished, because there wouldn’t be enough inert gases to absorb the heat and expand outwards. Without it, your engine would generate lots of excess heat, and accomplish less work overall.
I don’t have any proposed solutions for increasing the potency of woodgas. But it’s good to be aware of what’s happening, and not to blame everything on nitrogen.