That was interesting, I imagine I have around 4-5" resistance through the unit and the cyclone now, must check this, sounds strange.
After all, we have almost the same size units, the only major difference I see is the grate, I haven’t thought about the fact that I have a hersistant on mine.
Strange also with the outgoing temperature, mine is up to 400f after about 1-2 miles, and almost immediately I let off the gas it drops in temperature.
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How I start the car most of the time, 47c = 110f approx, 270c = 500f approx.
It’s Thursday, so I should have cleaned the soot hatch and the cyclone today, but forgot about it.
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Are all time zones measured from GMT? I am 5 hours West of GMT. Trying to figure out what time your post was made, Jan. Just about 8 Am here now with daylight savings in effect.
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Thanks for the start up and ride video Jan. Did I understand that you switched off the petrol once you got on the main road? I have to keep my rpm’s higher at first to get the gasifier going better. It sounds like you were idling until the main road and had to use the starter a couple times.
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Yes, I tested once before the main road, and then once on the main road, usually starts at 140f on outgoing gas from the unit, it is sensitive on the secondary air I have a pretty big throttle there.
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I made the video this morning, 6.30am, but posted it when I got home at 11.00am
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Good video of every day woodburning, Jan.
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Jo, I checked the vacuum between the hopper and after the cyclone, it is at about 8" both before and after I took out the ash.
about 1.6 on the hopper, and 9.4 on the radiator pipe after the cyclone, all at 2000rpm on a smooth road.
Tried closing the air into the unit a bit, to see if I could produce a hesitation, but noticed nothing.
Have you tried driving on spruce, it reacts faster than birch?
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9.4 : 1.6 = 6:1. That’s where I’m at sometimes too, but I consider it a little tight and usually give the grate a tap or two (if I need the extra power). I like to see 4:1 for best performance. If I get down to 3:1, which Wayne recommends, the rail temp starts climbing slightly.
Vacuum ratio does affect my hesitation sympthomes some, but even a really loose charbed doesn’t eliminate them compleetly.
I think my main problem is my nozzles are too small. I use 8mm nozzles - 10 of them. At a sudden accelleration the air blast is so violent, that for a short while I produce more CO and steam than the charbed below can handle. Not enough accumulated heat down there to handle it.
Also, the air blast shatters the coals more than necessary, creating even more surface area. With bigger nozzles, at an idle the air would gently pour down the ash slope and reach closer to the restriction, consuming char and keep the temp up down low. I think that’s one of the reasons a WK works better than Mr Imbert could ever dream of.
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Ok, maybe I should do it so I can shake the grate, mine is fixed.
I have 5 x 10mm nozzles in my car, should that also be too little?
But didn’t you make a WK, for Volvo?
Edit: you have 12-15 on the rails, and in the hopper?
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It seems so, yes. Depends on what hight from the restriction of course.
It’s a matter of defenition. The Volvo-gasifier’s only similarity to a WK is the depth of the charbed.
That particular rail vacuum would equal 3-4" in the hopper.
Ideally the rail vacuum is 4 times the hopper vacuum at all times. Doesn’t matter if I sit idling or if I’m pulling a trailer full throttle at 3000rpm up a hill. The ratio is still 4:1, wether I pull very little vacuum vacuum or peg the rail guage.
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Sorry if I interfere, I don’t think the size of the air nozzles will solve the problem, think about what the condition is for the air to enter through the nozzles. This is the difference in pressure between the outside air and the pressure in the nozzle area. What is the difference when you stop the car after driving, when the interior of the gasifier is heated and there is a large expansion of pyrolysis gases and water vapor? It is likely that the pressure inside exceeds the ambient pressure, which prevents air from entering the interior, regardless of the size of the nozzles, and these gases flood and cool the hot zone. WK has a large heat accumulation and a well-cooled condensation zone, which reduces these symptoms, but probably does not completely eliminate them… 
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Ok, so I learned something today too (I hope), so if the lid on my hopper is leaking, will the difference increase?
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Tone, the problem is I experience hesitation even after I see to that a fair amount of negative pressure is maintained throughout a short low demand period. Hitting open road and accellerating after maintaining 50 km/h through a residential area is enough to feel some short lived hesitation sympthomes. Coasting down a 10 second decline and climbing again - same thing.
BUT - you have a point there. The condensing ability in the hopper is one important factor.
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Yes, that’s right. If you’re running with the lid open you won’t get any hopper vacuum at all, but still have a normal rail vacuum 
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Yes, can test why the vacuum is like that, tested yesterday when I went home (the road was almost free of ice) and the car did at least 60mph, before I had to let go.
Shouldn’t go like that if I have twice as high a vacuum as I should have.
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Hey I love it when you guys talk-dirty . . . .in working observed negative and positive pressures and derived ratios. Your draw conclusions, then re-try, proof them. In real world using conditions. The six and eight channel LAB data’s are never openly published up. And out in true field usages require then needing much modifications. Aristotelian blindsided.
I am here to learn the true woodgas using gaps in my own understandings.
Thanks much for sharing this.
Best Regards
Steve Unruh
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Strange, I blew with compressed air the hoses to the hopper and the cooling pipes (vacuum) yesterday.
Tested this morning and had 11-15" difference between them.
Revved the car to about 3000rpm, and then had 7.7" on the radiator and 3" on the hopper.
I experience the bed during restriction as very loose when I try with the iron.
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Yes, I’ve noticed some condensation sometimes form in low spots in the vacuum hoses and the reading will not be accurate. When it freezes I don’t get a reading at all.
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Do you know why they have long and short nozzles, is it for penetration or what?
My pipe is 300mm and I have about 2-3 cm long nozzles, but according to the book I would have about 6 cm long.
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