Cody's 2011 GMC Sierra 4.3L

I’ve been talking about it for a hot minute but because the Mazda will take a while to be road worthy again I’m going to go ahead and get the Sierra ready. The fuel prices are killing me with this gas guzzler, and the Buick keeps leaking coolant for which I have next to no time to diagnose and repair.

The Sierra is a 2011 WT(Work Truck) 4.3L.
I have never seen a 4.3 that looked like this. Most 4.3L engines have the throttle body closer to the radiator pointed forwards, but this one is closer to the firewall and pointed up. The air box has a stock “snorkel” that leads to just behind the passenger side headlamp.

I have already wired the injector and fuel pump shutoff switches, what I’m going to do next is plan out my air adjustment and gas plumbing. I can cut the long air cleaner snorkel and splice in my butterfly somewhere behind the MAF sensor. MAF is right after the air cleaner and I have about 2 feet of 3" plastic pipe before it reaches the throttle body.

I intend to get a reece hitch mounted luggage rack to place the gasifier and hopefully also the filter, making it easy to remove for inspections. I’ll have some modest cooling pipes before filtration just because it’s a bigger engine pulling on an updraft gasifier.

I am going to add a thermometer at the gas exit so I can gauge how much I have in the hopper.

My main idea is to make the gasifier sit on the luggage rack so I can have bed space to hold fuel. I plan to get a rigid bed cover to keep fuel dry. The reason why I’m going for charcoal is for the shorter startup times and because it’s what I know the best.

The real challenge will be making the reactor short enough that it doesn’t make too much drag. I have originally planned to use a sideways 55 gallon drum as my hopper but I think I will opt for a shortened upright 55 gallon drum instead. I’ll have shorter distances I can go on a hopper but I will have an 8 foot bed to be able to store bags and bags of fuel.

I’ll upload some images shortly of the engine compartment.

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Here’s the air intake hose. Maybe it’s situated like this because this is the WT body so it could also fit the bigger V8s?

Where I have my hand is where I could splice in the air adjustment and gengas in.

I’m going to worry about plumbing first. I can test if it will take gengas well by using the Mazda’s old updraft. Then I’ll go about getting the reece adapter and luggage rack.


Cody; Don’t know if this will help, I don’t have air conditioning so more room. This is a 94 WT . TomC


It must be a WT trim thing. I find it so odd that they’d make a totally different intake for a truck.


Wow that is super simple and clean, little black spray paint and would be camouflage to the unknowing eye makes my engine bay look like crap haha

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I do have one other way I could mount this gasifier. A 55 gallon drum sits below the top of the cab, so I could just mount it similar to how I did on the Mazda. I need to think of a more rigid way to hold it down than with ratchet straps however. Probably just weld some plates to the base and bolt it down.

For fuel storage I guess I would just make some dry boxes to hold the bags. This method would be cheaper and give me longer distance per refill.

Cables, hooks, and turnbuckles might work.

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My super top secret weapon for getting the Sierra to run on chargas. I’m finally trying out the hexoloy silicon carbide fancy tubes for my nozzle tip. It’s .1 shy of 25mm which according to Koen’s spreadsheet is adequate for my 4.3L.

I’m going to make the air entrance come in through the side and elbow up. That way there is a place for water drip to be introduced like a Flute. Gives it dwell time to flash to steam.

The guys that have used these say to just drop it into a plumbing fitting so that’s what I’ll do. I may do a sealing bead of muffler sealant silica just so it won’t bounce out of the fitting but it won’t be glued all the way, to allow for thermal expansion.


I had to turn a 3/4" black pipe nipple in the lathe in order to make it slip in.


I need to think of a more automatic way to add water drip. I think I’ll finally attempt to make a wide open carburetor for adding water. I can cast it out of aluminum and use a stainless steel straw or hypodermic needle as the jet. Only hard part for me will be figuring out what the throat size should be to make it a real carburetor. Maybe make the smallest part of the internal hourglass the same size as the nozzle ID(25mm).

I already have a simple drip mechanism so I always have something I can fall back to.

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For a different project I was working on, I bought a 24 VDC solenoid valve for a home irrigation system. I was going to use it for low pressure compressed air. You could put something like it on a switch, maybe dribble water on a foam pad in the intake like a whole-house humidifier… Obviously, a spray from a carburetor would be a more elegant solution! :slightly_smiling_face:


I will have to test my theory out.

I’m thinking to take the pipe that will hold the nozzle and sleeving the opposite end down with the next size down, chamfering just a bit so it isn’t a sudden step, and then drilling a hole for a basketball inflating needle as my jet. Since the jet uses regular threads I can attach a hose for a tank.

I’m hoping to have a tank sitting on the floor of the bed and the vacuum at the air entrance is enough to feed itself like a Briggs and Stratton style carburetor on push mowers.

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Here are two images showing and describing Kurt Johnannsen’s water drip device. He built a couple of gasifiers some years ago in Australia:


I just did some research on Kurt. It turns out he was quite an industrious person. Here is some interesting reading on his life:


Great summary article of a true DOer, Steve Bowman.
The most complete I so far read.
Never have been able to find a copy of his book, “Son of the Red Centre”.
Best Regards
Steve Unruh