Johan’s Volvo 850 2.5

This is my project for wood gasifying:

I have ripped out some stuff that was in the way, the air filterbox + some plastic ducts and the interiour in the trunk + spare wheel.

My thoughts: the gasifier and heatexchanger in the trunk, have not decided if there will be a cyclone or a dropbox yet, cooling rails on the roofrack, hay/woolfilter in the trunk also. Plus the hopper condense/tar tank and the cooling rail condense tank too.

I am a little concerned about the fuel tank, the hearth will be in the spare tire bin insulated with 75mm superwool (the white insulation) and as you can see the fuel pump is under that white lid next to where the spare tire was. Is it better with siporex or insulation in this case?

And this is my drawing of the hearth:

Inputs is very welcome, both good and bad but the bad is better so I can change stuff towards a working gasifier :smile:

Oh yes, the puffer lid contraption is not yet decided so that is why it is not drawn
Also thoughts about dropbox or cyclone is welcome.


I will make a blown up picture of the nozzle part now, it needs explaining.


This will be interesting to follow, i cant wait :smiley:
As a car mechanic im not a big fan of volvo 850, but your’s seems to be in excellent shape :+1:
As for fuel tank i believe metal-insulation-metal sandwich should work fine. One thing thought, if your car-inspector uses the old rules, it says: atleast 1 meter between fuel tank, and all parts of gasifier, before gas cooler. (Smaller fuel tank, 5 liter, are allowed closer to gasifier).
Keep pic’s coming :smiley:


This is my thoughts for nozzles and serviceable hearth, with this it is the hopper flange and the nozzles that hold the firetube, just take away the nozzles and hopper then the whole firetube with grate can be lifted out completly and the nozzles are completly changeable.

Hopefully this is understandable


Yes, this concerns me a bit too, I would like to get it checked but I am not so sure. The old rules also says that the distance can be shorted if a metal radition screen and insulation is used. I think the shortest distance allowed was 400mm, have to check that out more though. Or if it was older than the -70’s regulations perhaps, this is from memory only so it can be completly off.


Man, I suck at getting all info in the first post… A concern is the bigger bolt in the welded nut on the gas/air tube, could that be gas tight with just molycote (graphite paste)?
Or if other things are more appropriate perhaps.


Yes, 400mm seems familiar, i’ve read that too (somewhere) and a radiation shield, preferably sheet metal- insulation (asbestos :grimacing:)-sheet metal.
Your nozzles seems interesting, i can recomend Biltema’s stainless steel fully threaded rod, was available in m24 when i built my nozzles.
It has hold up surprizingly well, and is very affordable.
Best is though to drill them out on a lathe, slow speed, and a cobolt drill-bit (Swedol)
Edit: some things to try for sealing threads: pure graphite dissolved i oil, if you know anyone working at Sapa, Gränges, Outokumpu, they use it for extruders.
Or: lead-based anti-seize compound (vitsmörja) extremely forbidden today because of it’s containing lead, but still nothing better to hold up in heat.


I do think that it needs to be a bolt to be able to use the head as a seal, I could of course weld the nut onto the threaded rod to get it gas tight.
But the main concern is the nut/thread on the incoming air side if that can be gas tight somehow, otherwise I think this can be scrapped as air will then go in to the gas stream and probably cause a bomb and make me look for the puffer lid a mile away


I did some inventory check, there is Wolfrakote top and Gleitmo 165 on the shelf as extreme high temp anti-seize
The Gleitmo 165 is oilbased and dries out over 200c and is still a dry lubricant till 1200c and it seems that the wolfrakote top is about the same
These could hopefully be used


Johan, I agree with Goran, it will be interesting to follow this project. This Volvo has a very interesting engine, 4 valves per cylinder, CR 1: 10.5, piston stroke 90mm, piston diameter 83mm,… the data is very good for the use of wood gas. Allowing me some thoughts on your gasifier sketch: - the gas that leaves the hot zone travels from one side along the torn surface of the hot zone, and on the other side with fresh air, I don’t think the best results are achieved, the gas will come out very hot as it steals some of the high temperature in the oxidation area, while the air it will not heat up to a very high temperature - The WK fire hose is a very good solution, just insert the heat exchanger in the space around it


My thoughts on that was to keep the firetube as hot as possible to not steal any heat from there and to steal as much as possible afterwards or is it a zero- sum to heat the air into the firetube with the firetube heat so ’no’ temperature is lost in the firetube?

Not sure what that means


You did ask about cyclones versus drop-box (settlement chambers).
Just like J.O. on his Volvo vertical distance space for a raw wood system is you hard numbers enemy.
When I asked him why-how he did as he did; it was to shorten the height vertically of his system why he went initially grateless with all gasses flow swept out for offset cyclone separation. He had to make the foot fit the shoe.
You too for this vehicle I think.
Steve Unruh who hates cyclones


Yes, I know the shoesize but the foot has not yet shown itself completly.
I was always thinking of a dropbox but I havent seen any sizing data on them or is it perhaps just a matter of winging it, the gasspeed has to come down to let the particles settle calmly, there is probably a number out there and my senses tell me that it should be at least a five gallon void but I have nothing that I have seen to back this up


WK - Wayne Keith… The gas leaving the reduction zone is probably around 500-700°C, and the hot zone at the height of the nozzles - the oxidation area - is heated to a higher temperature, you do not want to cool this area with gases that are then sent to the refrigerator and the energy is wasted.


Figure at least 10X to 15X the flow space area of your main hot gas tubing. Bigger will be better. Slowed over a distance of say one meter. Vertically. Or horizontal. Helps with laminar flow disrupters like in the vertical WK. Tone’s jacketed internal fins proposed system.
Be tough for you with that small shoe.


So then I should switch the outer gaspipe and the airpipe around which would also make it a lot easier with the nozzle thread problem I had on the drawing (post 4), no more problem with that then

Yes, that will be a tough one to fit in the trunk with the gasifier in the middle, it needs some more thinking. Thank you for the experience and numbers :slightly_smiling_face:

Yes, but it remains to be seen :smile:


Huh, if what Tone says about the engine is true this shuld be fantastic on woodgas!

Whats the plan with trunk arrangement? Will you cut the floor? Trunk lid?

Wery interesting project, good luck!


Johan if you don’t mind my two cents, I’m working with a similar issue for my Cavalier. The trunk opening can’t even fit a 12" diameter tank vertically.

I’m working on a truck bed to come out of the trunk, but the gasifier I’m building a platform using a receiver hitch.

Don Mannes gave this drawing to show how the truck bed could be. He did something similar with his Geo.

The gasifier will also be supported by the truck bed, going up through it and bolted to the bed frame. This will help relieve the weight limitations of an adapted square hitch(my limit with a Class 2 hitch is a 200lb tongue weight).

It will make your car longer but will solve your fuel tank worries, and any carbon monoxide worries. JO’s Volvo appears to have a more wide generous trunk.

Maybe I’m dead wrong, hard to tell just from pictures. See how big of a tank you can rest in vertically through the trunk’s opening.


The plan is to go J-O style and have the monorator hopper sticking out of the trunk lid to cool it, it will be a bit low to cut out the floor because of speedbumps and such.
The hopper also will have to be a bit offset according to my measurements


Lurking in the background… :innocent: