Made some new drawings, this is based on some common principles used in engine tuning, especially two-strokes. The “simple” one is the only that needs to be calculated “exactly”.
The others can be tested along. The expansion chamber along with the suddenly change from negative to positive pressure should do the work.
This “principles” can probably be incorporated, “built in” the gasmixer instead of building separately?
My manifold is made of EMT conduit and weighs less than air filter assembly have had this manifold on this engine for about 10 years without any issues…if it was any further away…I would support it some way. with my setup I could use my engine to pull the gas to carb by running on Gasoline and closing the air butterfly and when engine started running rich…use my toggle switch and shut fuel off at carb…and adjust my air and gas butterflies until I got the sweet spot. Just worked for me…
Hey Goran,
I did something very similar (or I thought I did) by using the filter box as the expansion chamber. Not enough volume I guess. If a larger air box volume would fix it that would be nice. Having the mixer valve near the engine controls makes sense to me.
Reminds me of the Tesla one way valve;
https://en.wikipedia.org/wiki/Tesla_valve
I’m talking more of people that add to the existing airboxes with PVC valves unsupported. I work with a lot of conduit and I agree your setup is definitely light enough.
Wow, that screams for a 3d printed part! How easy is that?
I would try putting a piece of corrugated plastic shop-vac hose in the system. It sure smoothed out air and gas flows for me.
Rindert
I thought I have seen a non-spring flapper type plumbing backflow preventer used in a video I saw a couple or three years ago? Seems like the pipe for the air mixing valve turned horizontal. It was several inches long, then the back flow preventer and then the mixing valve open to atmosphere
Is your air mixer located directly at the carb? If so you may want to set it up remotely, ever since I started doing this that issue went away.
Another thing is check your valve lash you may need to tighten it up.
Hey Matt,
I saw your setup and others have recommended it. Do you have any startup issues with the air valve so far from the engine?
Good tip on the intake valve. I had actually loosened it up and might have left it a bit too loose. Everything is so floppy in that valve train it’s a little hard to measure.
No not really. I just pull start to prime the gas with the valve closed. Then with the valve still closed I hit the electric start and they fire right up.
Actually if the valve lash is loose then the valve is closing plus some delay. So that should alleviate the pulsing.
An ecellant topic and good exhanges going on here on this problem.
Yep. I sucked a lot of single cylinder intake woodgas CO in the Victory Gasworks Shops 2009-2012.
My many reverse flow ideas did not work out so well. Internal reversal edge ledges and l-o-n-g intake pulse tuning piping led to RPM biasing. Means only works in a single narrow RPM range. And make the problem worse outside those ranges.
Long distance remote mixer mounting helps, yes. But then have slow response times. Can lead to extended long cranking engine starting up. Gives a lot of fuel-air volume for a significant intake valve ignited pop-boom.
All leading to my advice since: to just get 3-4 cylinder engines to not have the pulsating intakes.
And that will pull load your woodgasfier systems up hotter to perform better anyway.
Even two cylinder, and V-twin generator engines have pulsating intakes.
But now with my newest near 500cc single cylinder Inverter-Generator and back at the intake pulsating on woodgas.
This time I am approaching differently.
A loaded single cylinder engine has THREE pulsating sources.
Intake.
Crankcase.
Exhaust.
How are the different liquid gasoline carburetors systems using these for benefits?
Three of my seven fourstroke small engines use crankcase pulsator gasoline fuel pumps.
And some of these are using crankcase pulsations into the carb side of the air cleaner box to even out intake gasoline spitback.
And ALL of my current all-position 2-stike engines use crankcase pulsations in their carburetors to pump liquid mix into the carburetor.
You can see these three pulsations in slow motion on the Project Farm YouTube channel.
You can see very detailed engine pulsations for gasoline carburation benefits on the very detailed educational TheRepairSpecialist YouTube channel.
So . . . how do single cylinder propane mixers conversion kits meter and control low pressure suppled propane, eh? I only have worked with multi-cylinder propane mixers. Steady intake Flow volume metering. Some with exhaust O2 sensor feedback duty cycling solenoids.
I am just going to have to buy different single cylinder propane dispensers; open them up. and see. Diameter says they are using intake pulsations to meter propane gas…
Then how to upsize for a low pressure delivered woodgas?
Accommodate the soots in woodgas.
The corrosion of woodgas. Bronze. SS. Some plastics.
For now I only have unproven ideas.
For now . . . for me . . .for you-all; a simple in air cleaner housing mixer works good-enough.
Regards
Steve Unruh
Anyone tried reed valves on fourstrokes? Probably not the best with sooty woodgas, but would be interesting to try, mounted in a “box” acting as a form of plenum.
I have to look up my books on gasifying of big, single cylinder hot-bulb’s, some good info about that in the book: gengas.
For the ones interested to try reed’s there are kevlar/carbon fiber material for making own reeds available, easy to cut with a dremel, and fairly cheap, and best of all: stays in shape, don’t slightly bend over time as steel-reed’s.
Goran, you only take halve of the pulse away. At max.
The no moving parts way to handle pulsing like this is to connect a long skinny pipe to a volume (like a propane tank) between the source (gasifier) and the pulsing drain (engine). The long pipe is probably already there. It’s the buffering tank that would need to be added.
The tank volume absorbs most of the pulse like a spring and then the momentum of the flowing gas in the long pipe prevents the remaining back pressure pulses from reaching the gasifier. It’s like your classic mass and spring mechanical engineering or a snubber in electronics but handles gas pulses.
The problem here is that you don’t want to have lingering mixed air and fuel. I guess you could have two tanks and two pipes… one for fuel and one for air.
Hmmm now that I have a 3D printer, I bet I could print a Tesla valve. No moving parts
You’d only need a tesla valve on the air intake to avoid losing fuel gas. The intake air is guaranteed low temp and plastic friendly. Great idea Matt! That is definitely worth a try.
I still think a small buffer tank just ahead of the mixing valve is still relevant. (1-3x engine displacement). Any reduction in the pulsing from the fuel side will reduce the performance requirements for the valve on the air intake side.
The basic problem here is that the intake stroke pulls fuel gas down a long hose, getting all that mass moving pretty fast. Then the intake valve slams shut with no other cylinders ready to pull in turn (single cylinder). The fuel gas is already moving and wants to keep moving so it spills out of the air intake. So… give it a place to go before the intake valve opens next?
Weirdly you’d want the “tank” to be more like a plastic (silicone?) bag that would deflate rather than fall below atmospheric pressure. A fixed volume tank could come into partial vacuum, sucking in air and risking pre-ignition but I’m getting ahead of myself again.
As usual, out of my pay grade. I think I understand that you are looking for ways to re-establish a more continuous flow from that which is chopped up by the blockage of the intake valve whereas in a multi cylinder engine the gas flow maintains velocity by transferring to an different cylinder. I had never heard of a Tesla valve before. For you other dummies like me, here is a video.
I don’t really grasp how this much restriction in the gas stream is a benefit.
Me too Tom. But great invention.
On the other hand, the pulses are used to increase cylinder fillings. Taking pulses away and restrict breathing further more result in less filling and less power.
Maybe bether adapt the gasifier somehow.
The Tesla Valve is a one way valve for high flow gas streams and it is esoteric. Few commercial products use them. A one way valve is useful here to prevent fuel gas from getting pushed out of the air intake… and a tesla valve might do that.
Unlike a check valve, tesla valves do not block pressure, just flow, and even then it is imperfect, though in its best use cases a tesla valve performs well. A traditional check valve blocks both flow and pressure more or less completely in the one direction but it has a moving part. In an engine that is cycling dozens of times a second traditional check valves may struggle to toggle quickly enough and may not survive long run times.
Matt’s instinct here is a good one. Tesla valves are very appropriate to the task.
