Max said don’t go too small, they’re less sensitive. He says DJ’s truck mixer is much too small, the Volvo is just right, although it’s dual diaphragms and I’m not sure how that compares to a single.
I can’t see the harm in a great big one, so this one is 9.5" across.
While I’m posting here, might as well put up some pictures of the one successful automixer in existence. This is the one from Dutch John’s Volvo. He says it did as good a job as anyone could by hand.
I don’t think I have seen this video before. When I saw those pictures before, I would’ve figured there would have been more movement on the rods. So what if your diaphragm plate was more like 4"?
No idea…? It’d probably still work OK. I’ll ask Max again Friday, but I think bigger diameter is better, limiting factor being the hood has to close.
EDIT: you said diaphragm plate, meaning overall diameter? Or something else?
I think that would be better.
Yeah, I should have been more clear. Instead of the 2" washers. I was just thinking of the picture Marvin put up. The plate of the diaphragm is just short of the total diameter of the diaphragm itself.
Gotcha. Yeah, that makes sense. Bigger diaphragm plate… yep. Can do.
http://www.ebay.com/itm/280988358420?_trksid=p2057872.m2749.l2649&var=580143305865&ssPageName=STRK%3AMEBIDX%3AIT
I ordered one of these too. It’ll be a couple of weeks before stuff gets here on the slow boat. You might look for something like this in a printer or something?
Ooh fancy!
My bushing right now is the inside of a plumbing fitting welded to the top of the tank… not the smoothest.
I’m thinking about going for a lighter weight rod on the diaphragm. Right now I’m using a 5/16 x 8" steel bolt. Less moving mass should mean more energy available to the job at hand…
Ok I’m getting a head ache!! I have read this thread from top to bottom 4 times and it might be seeping in a little. DJ uses 2 diaphragms because he has the hose from the gas side going to one diaphragm and the hose from the air going to the other diaphragm. The action of the diaphragms appose each other. You are putting the gas hose on one side of your diaphragm and the air hose on the other side.TomC
Sorry But still studying. In the 2nd picture of DJ’s that you posted; there are 4 openings. One for air, one for gas, and one for the air/gas mix. Is the 4th one for one of those heated wire sensors and if so he has air flowing in that opening also. ( if that is the case, I don’t think American cars have used that sensor )
What is the gizmo in the 4th picture. It is attached to the throttle but it appears to move horizontally by pulling a cable. ??? It also has another pull cable attached — a throttle control pull cable??? TomC (again)
What is this thing actually doing?
Are you simply assuming that a higher intake manifold “vacuum” reading means that you need more woodgas and, if so, close the “choke” more?
Or just the opposite?
Or something completely different from the above?
Not sure if Chris is still on here so I’ll stick my nose in. This takes the place of the pull cable that we set the balance of “air” to “gas” ratio. When that meter that is hooked to the exhaust pipe says we are running rich, we move the cable to allow more air in to get the infamous stoeometric ration. Usually in driving we don’t have to move that very often. This thing is going to always give you an optimal air fuel ratio.(?)
Seeings I don’t adjust my air/fuel mix after I get it rolling, I’m not sure what the benefit is. TomC
I do know it will help my Dakota. Sometimes after a cruise and I come to a 4 way stop or a light, my mix will be really lean and stall out. (embarrassing)
Nice idea once the bugs are ironed out,and adjustment could be made,a throtle stop switch and stepper motor might be another way too go for idle air mixture control for stop light’s or coasting.Then again the auto mixer might fix that Too.
Max has always said a bigger vac pot is better, I think your 9 inch is on the money chris. I too think a larger diaphragm stiffener is in order. Keep it up Chris can’t wait to see it work for ya.
I really like this! Way better for me than the electronic auto mixers that I don’t understand. Now if the diaphragm is flat sheet as it seems, It would have to stretch in order to move off center position. Have you left some slack in it to allow movement? is the stretch enough?
So if I’m thinking correctly, this will give you perfect 1:1 ratio. Would you not still have to have a manual control too, say for example if you wanted to richen up for a hard pull, or for starting?
With regard to size of the diaphragm, the larger diameter will give you more force on the rod, but will respond a little slower.
Hi! I think setting the gasmixing functions in 3 stages will bring a bit more clarity in what is happening where, and what the aim is at each stage…
Stage 1.
You were on the right track, wrong fabric, cotton doesn’t have elasticity.
it looks like the diaphragm actuators use silicon on polyester, or nitrile on nylon.
I would think the -shape- of the membrane is important like it seems you could get away with a much smaller size if it had like an indented ring built into it. Like a diaphragm pump… breast pump replacements are the most common,but look like they are made of silicon. You can buy nitrile sheets fairly cheap but I don’t know if you can heat and mold it.
scroll down and you will see the replacement diaphragms, which looks a LOT more like what you want, and they are 10-20 dollars.
Max, glad to see you found this thread.
We’re not measuring intake manifold vacuum. We are comparing gasifier vacuum at the engine to the vacuum behind the air valve. If these vacuums are the same, you have equal pressure of woodgas and air, thus a 50/50 mixture.
Here’s my best explanation:
The valve position will change depending on the measured vacuum of the gasifier. It will automatically open the valve if the gasifier is producing more pressure like at a stop sign. Then it will close again when you whack the throttle and that gas pressure goes away. Under hard acceleration the gasifier presents more restriction, so the valve should close slightly. Those of you with woodgas trucks will note that closing the air valves on a hard pull will often give you a bit more power, this is the same thing.
