Woodgas Fuel Characteristics Inside an Internal Combustion Piston Engine

Hi All,
TomH., BruceJ. and I were developing a great exchange on this recently inside of a fellows topic.
I was searching for an already set topic to ask to request having those transferred into.
Nothing fit.
“Small Engines to Woodgas” . . . NO. Not just for small engines.
"Fuel Injection Engines to Woodgas Run . . . NO. Not just those, carbureted and gas mixer engines then get left out.
“LS Engines to Woodgas” Run . . . NO. Obviously too limited
Many other pre-exiting topics. None fit.

So why is this so damn important SteveU???

Engine selection. Practical. Available to be worked, engine selection. Not woo-woo, some-day, only-if, engines.

In BruceJ’s case he can select from Ford FE’s 360’s or 390 V’s. Which would be better to pursue? He can now selelect between a GM/Chevrolet 366 or 454 V-8. Which would be better, eh?
In my case recently I had to select to buy either GM 6.0L V-8, or a Ford 6.8L V-10 to buy for real needed working. With later the best results woodgasing potential.
The topic were on the fellow had a whole passel of already owned possibilities. Which to have the best end-result usefulness to him?
Tom H want to support off-grid power generating using trees his buddies already have.
Better to get rare bird now opposed flat head Onan generator, and convert set up? A Chinese new clone but thoroally modern overhead valve, many-branded names, new gen-set?

I know. i know a lot of you international fellows now rolling your eyes at us lands-of-many engines American and Canadians spoiled with our choices.
“Must use and not destroy the engines I do have and can get here.”
Some engines have worked out ok. Some have not.
Easy to just blame the gasifier. Blame the wood. Blame the operator. Sure. Sure. But what about the actual IC engines design factors in these successes, and failures, eh?

So this narrowed, focused new topic.
Steve Unruh


This is a great new topic that has been talk on other threads occasionally. This thread can be dedicated to this alone. Much needed with the new and older members. Thanks Steve.


Thanks BobMac

O.K. I’ll start.
My experiences and readings, and over-the shoulder studying’s say in this order of importance: big-bore; short-stoke; LONG connecting rod engines. Overhead valve engines. Engine with already engineered for best torque at off idle to ~2800 rpm torque.

I have developed into the strong belief that “The replacement for displacement using woodgas is higher compression ratios.”

There are two other prevailing beliefs about what should be favored on engine design factors to favor when on woodgas fuel.
Ha! Let these fellows speak up for themselves.
Steve Unruh


The big 8.0 liter V-10 Dodge 3/4 ton (proven) or Ford V-10 engine with no need to adjust timing manually are good choices for wood gasification work trucks in my opinion. In my area it is hard to find one that is not all beat up and wore out and still with a high price tag on it. With higher gas prices this will change. Not that I wishing for higher fuel prices, but if it happens and gas goes sky high in price and sets new records highs. People will sale the older gas hogs and look for more fuel efficient ones like diesels.


I’ll respond with a couple of foods-for-thought BobMac.
Washington State the price of pump diesel is now carrying a $1.00 premum over pump 87 R/M gasoline.
Those diesel driving guys are getting hammered with a 25% higher cost in WA, Oregon and California. This offsets their more fuel efficient diesels. Zero-net. Worse. Pay for V-10 or big block gasoline oil, and fuel filter changes versus the diesel guys. Ohh. I forgot about my diesel families owning now higher costs in DEF.

2nd thing. The Ford still in production V-10 is not at all comparable to the Dodge V-10 in life cycles costs of ownership. The Dodges can and do last out to 300,000 miles.
The Fords lucky with the best of oils and changes to make it to 150,000. Nearly all die before 200,000. miles.
I pocket carried a needles bearings worn out Ford V-10 cam follows finger just to remind myself no matter what Ford boxvan I found. No matter what the price or circumstances, just do not buy it. There are thirty of these follower buggers in a Ford V-10. Two wearing camshaft phaser assemblies. Two clogging phaser oil control valves. Three timing chains. Three oil pressure dependent chain tensioners. Five? Seven? plastic lined chain contact guides.
$5.000-$7,000 for an upgraded remanufactured Ford V-10 engine. Not including R&R.

Ha! Go out and kiss your motorhome’s 440 (7.2L) and say; sweety, you are mine forever more.
Steve Unruh


My current V10 is sitting at 256,000 runs like a top. The new to me woodgasser build has 300,000+, NO BLOWBY! For many other manufacturers that is wildly unheard of. The 318/360 and V10 I believe are all of the same family of engines with similar upgrades through the years. My time in shops I rarely did much to the 318, just services and replacement transmissions. 360 service and transmission, valve cover gasket( don’t know why, the magnum motors will loosen off the valve cover bolts) and occasional valley pan gasket. Very little work done on V10 but alternators/pcm which controls the alternator and was problematic, but can be fixed. The V6 Dakota no bueno, head gasket failures sub 150,000. In my opinion the Dodge biggest fall is faulty electrical systems, and weak front end components. Ball joints, steering box, tie rod ends, unit bearings. The rest of the truck seems to hold up well to age. Often found beaten mercilessly and still operating, the old faithful work truck or garbage hauler. That speaks volumes to the trucks longevity, which of course we should factor in a woodgas truck choice. To my limited knowledge I believe the 360 was a bored and stroked 318 from the factory with different heads and pushrod location at the valve train point, where in early days a 318 would get custom milled 360 heads and stroked to 383? Been a while since I dug into that build recipe. Now what is the length of rod for each and it’s rod ratio I wonder :thinking: all seem to take to the woodgas well, producing adequate power and torque. Without digging into aftermarket goodies these seem very suitable for anyone to pickup and build with. But other then the fuel injection benefit what makes it take to the woodgas so well? Displacement can’t hurt, high flow heads from the factory of good cast iron quality mixed with good old pushrods for simplicity, but what is inside that makes it work so well. Manifold design? Compression ratio? Connecting rod length and or ratio? Piston shape and design? I don’t think anything downstream of a exhaust valve would be very beneficial, even though my auto shop teacher drilled it into my head there are 3 rules to making power and torque: let it breath, let it breath, let it breath. A engine is a big air pump, the more you feed it,the more it pumps. First step being high flow air breath IN. Performance air filters, high flow carb/ throttle body, intake manifold. Second step high flow exhale. Headers, larger exhaust pipe less restrictive muffler. Third step breath capacity. Valve job, port heads and intake, decked heads, camshaft lift and duration, valve rocker ratio, compression ratio, piston type, bore and stroke. That’s the recipe for power, oddly enough a very similar recipe for efficiency. Which of these are implemented from the factory into a motor that makes it the ideal candidate for wood or char gas? And do each of these benefit woodgas the same as it does gasoline and diesel? Or do some shine out where others do not? We know compression ratio is a helper. High flow breath in is pretty much regulated by what your gassifier can produce and feed the motor. The motor can only eat what it can breath, so cam style changing vacuum demands of the engine would tend to flow more stable and maybe more of the gaseous fuel we use. Is there a benefit to the exhale on woodgas? I can’t really think there would be, as long as it is somewhat free flowing.

My brain just spat all that out, I didn’t think of anything just what I have been thinking lately


Thanks Steve that is why I said (proven) after the Dodge V-10 and not for the Ford V-10. All good to now to stay away from the Ford V-10.
Yes my 1976 Dodge 440 is a great engine. I treat it with TLC only 86,000 plus miles on it. Lots of power to move my 25’ motor home down the road.


Wow. Don’t turn on the computer for a few hours and barely able to keep up.
The main thing I know about engines is if you put them in race cars/drag race cars dropping five tenths of a second elapsed time will probably cost you a grand. That is a base line for every half second your going to gain. And I’m talking 40 year ago dollars there. No clue what it would take now. Oh yeah, I should amend that to Before Nitrous oxide. IC engines are just as complex as they are simple, but we are not talking about race engines. I believe most of us are mainly interested in engines that produce torquey grunt, load hauling power. My work trucks have never seen 5000 rpm. They have spent all their long lives between 2 K and 4500 and the high end only because somethings must be done in first gear low range for about a minute. My wifes grocery getting Nissan Rouge is perfectly happy running our 55mph roads under 3000 rpm unless having to downshift for some of our long hills. So WG or not I have no use for anything but mid-range torque out of any engine. I wish I knew something about Dodge v-10’s. zero experience. Having watched almost countless dyno runs of different engines in different configurations maybe the most surprising thing is seeing the torque curve for a mostly stock Chrysler 440 wedge engine. 600 foot pounds on a mostly flat line from 2000 to 4000 rpm. Blew a crate hemi out of the water by comparison. The high dollar hemi makes horsepower. That is the rpm range virtually all of us will be doing most of our work in. So that is the first gas fueled engine I’m nominating.


Thanks for the real seen inputs TomH.

Ha! Ha! You left out your biker days experiences man. Harley Davidsons in many different states of tune and modifications.
They started as flat heads (valves-in-block) and stayed that for decades. Then improved to push rod overhead valves. Don’t want to sound knowing and use in-the-know nicknames of the different factory mods to those systems.
I do know they never jumped up to overhead camshaft systems. No need. No benefits. Just costs and maintenances downsides.
On a previous now-defunct stationary engines for DIY electricty making forum was a suburban Londoner working engineer. Called himself “Guy Faulks” (an Englishman’s culture joke took us not-English years to figure out!) He like the British bikes as once ground breaking traditional. Said he could appreciate the engineering in the Italian and Japanese OHC rpm screamers. But vacations Euro-touring he’d use his Harley any day. Just hours touring more relaxing. He liked the Harley for touring even over his previous BMW’s. The very best working Toyota Master Tech I ever met; home relaxed; mod and tuning his Harley.

I figure you know more than you giving yourself credit for.
Steve Unruh


And this one is for you Bruce Jackson. One of my research proofs for my woodgas in engines beliefs:
If this does not work open up the top bar DOW Library.
Scroll down to the CGPL/Indian Institute of Science.
Open that up, and scroll down the many, to:
“Zero-dimensional modeling of a producer gas based reciprocating engine”
Download the PDF
published number page 925 shows great detailing of the two engines they used.
Bottom of that page shows the squish area; combustions chamber shaping; spark plugs locations; bore&strokes; bump clearances, etc., etc.
farther down on pages 927, 928, 929 are the in-cyclinder pressure rises by crankshaft degrees; ignition timings tried; and compression ratios tried. Text on last page gives their conclusions.
Date of these found results versus later engines researches like the “Performance analysis of an internal combustion engine operating on producer gas” says they settled on a 12:1 compression ratio as the best loaded engines working compromise.

Hmm. Maybe this will work:
A studious fellow can get lost in all of the papers there. THANKS, Chris Seanz!
Best, tell your son and wife where you dove in and to come drag you out.
Steve Unruh


Ahem! From 1903 to 1926 Harley Davidson built and sold “F” head and OHV engines. There is a world war I Harley riding around Calumet in the summer with an oil soaked leather clad rider. Do not tail gate him, or you will never get the oil off your windshield.


Built a few Triumph’s in my time Steve. A couple of Nortons. Never A BSA but I would have liked to. Always thought they were the best looking English bike. All those engines are just alike. If you have the book with the clearances and torque specs They come apart and go back together like butter. Harleys, even easier. Of course no one I knew would even swing a leg over a BWM but I risked cat-calls once. Maybe those jugs sticking out the side looked foolish but it was the smoothest ride I ever took. Perfect old man bike I say. Better than a Gold wing. It was the 750 Kawasaki’s that really got my attention. I knew then that Japanese bikes were the future. This was of course long after Honda but I never saw anyone make any real power out of a honda. I never cared for the Ninja or any of those RPM screamers regardless of how fast they were. The BMW sounded like riding a Singer sewing machine so big thumbs down there. A Harley just thumped along putting you into a semi-trance, like riding blues music. If you focus on the rhythm section of a band the bass has the same sound as a cam in a big V twin. I see you are a Suzuki Hayabusa.


Ahh, total loss oil systems in a 4 stroke. Just the way God intended spraying dollops on the road so the guy behind you meets his demise!


Reading the zero dimensional paper…and btw, that’s a fluid dynamics tool to take the units out of a complex process in order to try to equate two different things. Like brake specific fuel consumption equates a Wartsila with a lawnmower engine.
So I learned something kinda obvious if I would have spent my life building engines…the two engines in the test both open their exhaust valves a long way before bottom dead center…the three cylinder @66° and the [email protected] 41° Wow! Everything really is happening between TDC and half a stroke down! For some reason I always visualized an engine getting power from a full stroke. It’s just not something you learn from indicator/ Pressure/Volume diagrams.

You better explain your belief in short stroke long connecting rod. I wanna make sure I get it. Thks DF


Long rods. The most comprehensive one-place explanation I’ve seen/read here:

His explaination is the WHY. (I follow him with the CC enable and the volume off. His voice/cadnece . . .)
The What is on a many Q&A forums of if you do overbuild your small block Chevy/Ford/Dodge by stoking out to mondo the bore side pressure wear will make for short lived engines. Factory 400 small block Fords and others.

Now the Enginnering Expained Guys video “What Makes More Power: Bore or Stroke?” seems to say stroke. Yes. On Longer burning duration gasoline. Not short duration burning woodgas. Whose simple fuel gas molecules get converted easier, needing less time.

Long complex cross linked many carbons chained fuels simply need more time-in-burn And Forced in Oxygen in the case of diesel and heavy oil fuels to fully burn convert.

Why VW/Audi with gasoline felt that they could use their diesel experiences get better gasoline fuel usage economy, with less carbons emissions by going back to undersquare smaller bore, longer stoke engines.
Problem! How to get enough air in forced to have smaller valve to fit the smaller area of those smaller bores. Thier solution was their five valve engines. Three intake. Two exhaust. More complicated. Higher manufacturing costs. More to wear. More to failures.
They gave up that. Reverted back to four valves.
This is Net searchable by: Why five valves? Why did VW/Audi change back to four valves?

Again, as I stated on the other topic . . . you must design around the intended fuel and it’s actual characteristics in-engines. Methanol engines make racing power. Why methanol? Crash Fire safety. CART rules. F-1? Let 'em burn.

Woodgases “slow” burn rate is made faster with compression ratio. IISc papers.
Joni proved re-discover this by jacking up his compression on his four cylinder Euro-GM.
He no longer had to jack up his ignition timing.

More if anyone askes.
Steve Unruh


BruceJ some of these youtube explainer guys do cover a lot in-cylinder detonation.
I like a lot on the other topic where you said, “Woodgas. Detonation? What is that?”
Not having to fight gasolines detonations open up a lot of possibilities, yes.


I belive Max would have argued there’s nothing new under the sun :smile: I remember Johan Linell shaved down the head on his old Volvo B20 back in 2007. Ended up with something like 12:1 with a significant increase in power.
I’ve read on another Swedish site there’s usually very little extra power to gain and not worth the effort to further increase compression, if you’re already at 10:1 stock. This was one of the things that helped me make my mind up when choosing the Volvo I’m running right now - 9.8:1 stock.


I thought you would question why I called you a Hayabusa SteveU. It’s because as far as I can tell you are the only one that could put one together. Complexity, complexity complexity and all for only one purpose. Going faster than anyone really needs to. Hah. I can’t believe I said that. Four valve combustion chambers. In my mind just added complexity for getting you from one stop light to the next.

Regular old cast iron block and head engines are just the right amount of complexity for my current state of mind, but even there, from top to bottom, there is no wild card to play. Every component only functions in relation to every other component. When Bruce notes that everything is really happening between TDC and half a stroke down you start dealing with something I never understood until just a few years ago. Lobe separation angle. People buy a aftermarket cam. Invariably they spec it by lift and duration. Most cam manufacturers understand that and for most grinds they sell, they set the LSA mid-range. Usually between 108 and 112 degrees. Grinds above and below these number are usually custom order grinds. See how much farther you can reach into your pockets. Why do we care in the context of this discussion? All timing isn’t just a matter of distributor rotation or ECM programming.



Haha Tom, I started filling out the competition cam help form…to get a wood gas recommendation…then I remembered where I was at…lol. You have given me some ideas for what to research. These days, my driving is all done at 1500 rpm (which btw Steve, that was a little fast, 1500rpm, in those indian tests), so I could really use all my torque at that rpm. I suppose they make a cam for that. How to find it through? Tom?


So…not to cut a fart in the elevator with youse, but…
In the 20 years that I have been making fuel for various engines there has been one golden rule. Engines love consistent fuel chemistry. Gasoline is not a consistent chemistry it’s a mix. Biodiesel is a consistent chemistry, methyl esters. Charcoal is a consistent chemistry, carbon monoxide. Vegetable oil and wood are not consistent chemistries, your proportions of different molecules can vary. In the case of vegetable oil, the molecules can be bigger or hydrogenated, and their gel Point gets raised into the 50° range. Wood contains various amounts of water, and that water will make hydrogen.
Hydrogen is going to cause you problems if your compression ratio is too high. This is why I was talking about making the engine a better air pump first before doing any high compression stuff. Because if you’re making gas that’s mostly monoxide you don’t care about detonation, but if you have a spike in hydrogen, you are going to have pinging or detonation.
I suppose I am being a ninny about it.