Woodgas vs cng for duel fuel in diesels

First off I’m new on this site. I’m a 33 year old automotive tech located in kelowna BC Canada. I have experience modifying late model fuel injected vehicles from import(mostly Mitsubishi) to GM.
Ok I see all these newbie change the world of woodgas project proposals and it makes me wanna hold my tongue. Lol… But anyways. Here’s mine.
In researching a vehicle candidate worthy of a woodgas conversion I came across cng kits for diesels that supplement a large portion of the diesel required for natural gas. I know that these forums don’t really cater to ci engines but I would still wish to run a small amount of #2 or bio diesel possibly for a pilot.
I’ve been looking at what the cng guys are doing to pull fuel once the natural gas is added into the equation. On the 6.6 duramax from 2001-2007 specifically, the answer is nothing. The stock ECM will automatically pull diesel (the cng kits supplement 45-95percent) from the engine based on throttle position and desired rpm/ load. So if I was supplying the extra fuel with a wk gasifier setup instead of a cng tank the ECM should react the same. Provided the gas composition resists ignition until desired similar to natural gas that is.
Mmmm I have access to a couple of these trucks as I do rebuilder trucks as well. Not scared to pop an engine as I have several;). Oh and there’s an aluminum intake mani on these engines beneath the plastic turbo intake pipe that you see when you pop the hood. I would fab an aluminum intake pipe in place of the factory with the necessary branching for woodgas to enter pre turbo.
Looking at controlling the woodgas entering with either a drive by wire throttle body or a custom butterfly. The controller for the cng system is cheap $200 and would lend itself to control this as well. They just set it to shut off the cng below a rpm set point and let engine idle on diesel. This would be the same as I would do albeit via a butterfly/tb. These controllers will also shutoff the cng at a set egt point in case of abuse. The cng adds hp when used with diesel. So if u were pulling a heavy load up a hill and demand was there u could have full woodgas and full diesel entering the engine which would create a rich condition. This safety shutdown would prove handy I’m sure;). Overall I’ve been critiquing this on myself but I can’t see a big reason that this wouldn’t work. Maybe someone else on here may see something I’m missing. Not an expert on the gasifier end but I know my way around a truck.
I don’t know how much fuel is state side but We are over $5 a gallon. (1.40 a litre). Anyways I know there’s a few guys on here to help and some possibly to discourage me but I welcome any productive comments. Cheers!

The first thing that pops to mind is that the “C” in CNG stands for compressed, which means it needs a valve to hold it back. Woodgas on the other hand goes nowhere unless you’ve got engine vacuum pulling it out of the reactor. CNG just shows up, because the compressor did the hard work before the gas ever went into the tank. Woodgas depends on your engine to do all of the hard work in real time.

Different animal, different set of infrastructure, even though the chemical composition may have some similarities.

Yes you are right. Totally different animals. However I assume that the big ol 6.6will have no problem creating sufficient vacuum pre turbo to pull through a properly designed gassifier system. What interests me is the ability for the factory engine computer to automatically remove diesel from being delivered when supplementing gaseous fuels. I figure as long as the woodgas composition is sufficient in octane to resist preignition then it would run fine. I think natural gas is 116 octane if I remember correct.

Hi Chris
I have run a naturally aspirated diesel tractor on wood gas. It ran but could not increase the revs with out increasing the diesel, I did not run under load.
The rule of thumb with wood gas is you have to have a comp ratio of 13-15 :1 , so most turbo diesels will do !
Having run a Chevy 250 on wood gas I would say build some sort of explosion relief system between the inlet and turbo ! Or you may separate your engine from its inlet manifold with a bang !
But I would love to follow your build I think it has great possibilities !

Yes I would most definitely need some sort of relief/blowoff valve in case of an intake backfire forsure.
I wonder if the lack of throttle body or restriction on the air inlet on your diesel made it not pull hard enough through the gassifier? I know diesels have no vacuum at idle and moderate loads. That is why the brakes are run off the power steering pump on most diesels vs a vacuum booster. I have no worries on vacuum as I won’t be running woodgas until I’m off idle and under load which will cause the turbo to spool and create a large vacuum on the intake pipe where I will introduce the gas.
The lb7 (Pre 04) duramax is 17.5:1 and 04.5-? Are 16.8:1. However these are very efficient modern designed engines. I know a good piston and combustion chamber design go along way in staving off detonation. I could lower it with custom gaskets (cometic mls) but I will cross that bridge if I have to.

you could always try a combination of push/pull on the gasifier using blowers of some kind

Welcome to the DOW ChrisD.
Nice to see another actual working auto tech show up. Ha! I can sit back and more enjoy my typing fingers/brain snoozing retirement.

AlexT is correct. To deliver on demand amounts of woodgas from producer systems requires woodgas to be power dragged out kicking and screaming through a flow restrictive glowing hot bed of woodchar; and then flow restrictive cooling and filtering steps.
Your CI Izuzu DuraMax wants the least restriction pre-turbo air flow as possible for the greatest amount of air as possible to the air-fuel for the hydrocarbons. Operates un-trottled with only the restriction of the air filter and on some modern diesels a air to air turbo inter-cooler.
To make a woodgas system power/pulling intake vacumn you have to air restrict throttle the intake even further on an already air throttled Otto engine. Intake vacuum making throttling your CI diesel and then there will go your “as much air molecules as you want” Rudolph efficiency advantage.
You can easily simulate this by clothing fabric layering your current air filter until you create a 5" to 16" hg pre-turbo vacuum. This is about what an engine drawn woodgasifer system would do to you. Don’t do this long as most turbo’s are not bearing sealed to see much continuos inlet side vacuum. Start sucking turbo bearing oil and you could create and oil fueled engine runaway.
You are correct your PCM should readjust your diesel fuel delivery somewhat to the less intake drawn in actual air.
Happy with your engine power nowthat you’ve air chiked it down?? That, at best, is what you would have to live with once woodgased.
THIS engine lost air and the produced actual shaft power used up to flows suck the gasifier system IS the greatest source of woodgassed fueled “lost” power.
Ain’t so much about the octane/centane or hydrogen/carbon balances!

Yeah. Yeah. Other ways to flow “deliver” the woodgas to the engine like precompressed pressure delivery (comperssor enrgy gobbler and very low energy stored density); and variable blower pushing/pulling on the gasifier system.
Ha! Try engine external power delivering woodgas will give you bitter lessons on the actual drive system wattage needed in 5 to 20 horsepower gasses flow blower systems. Race engines 40 housepower to drive the blower to make 100 more hoursepower is a gain. YOU buying and supplying the energy “fuel” for the blower system is pocket/work expensive!! Small engine trialing this shows the need for about 175 blwer watts per every 3 horsepower of engine shaft power woodfuel made. So loaded 70 mph/113 kpm needing, say 50 engine horse power produced you would have to supply your gasifier push/pull blower system with 1750 air-watts. With efficiency conversion factors that roughly 5 housepower. Cut you into any fuel savings by at least 10%.
And you will need lots of technologist working, sweating on the control side of things then for the widely variable woodgas delivery flows engine needs whether done analogue or digital. Realize woodgas, unlike diesel fuel has to be maintained in a air to fuel in cylinder ratio range to burn or you will mis-fire.
Alligators added layered systems details will eat up your time and $$'s and you will spend much, much to then learn just how much work you have created to now have to chunk up; chip up; grind up and densify pellet/puck compress fuel deliver for the fuelwood side of the system.
Figure at least 25 to 35 dry pounds of fuelwood system needed for each and every gallon (US) of diesel saved. Yes. Save 100 USD gallons of diesel saved will cost you 3500 POUNDS of sourced, sized proceesed, dried down and deliverd wood fuel. 1000 gallons of diesel “saved” ( like a small offgrid home generator power system would use annually) will be at least 35,000 POUNDS OF woodfuel. Most of a log truck load.
Most personal diesel pick-up users I know haul and drive a lot so go through ~ 2500 US gallons a year. So . . .a whole BIG log truck of wood to have to process.

These advanced idealized systems become Rube Goldburg never continuous operating failures showboats even with Gov’mint and University pig-outs support.
The actual, used working woodgas systems just simply engine oversize, keep-it-sucking-pulled-simple & carbon monoxide people safe, and than real world worked.
“I think” CI woodgassing supplementing would be made possible on stationary power and pumping plants with very even, steady loads.
Modern Sweedish, Finnish and India expersinces found on CI woodgas supplementing variable loaded CI trucks, tractors the hard ways it was just more operator usage practical to engine oversize, and spark and air trottle convert for woodgas fueling. Then NO bought out and taxed diesel dependency at all.
Their problems were not pinging but some types of diesel pumps and injectors at low fuel flows overheating and premature wear failures. Expensive. Work-a-rounds possible, yes. Another, system type, by system type specific alligator challenge.
And ALL CI supplementing works had a problem with still flowing woodgas arriving at sudden accelerator/load lifts offs then over-rich exhaust flowing causing severe back firing. Destructive.
The free hydrogen gas componet in woodgas is leaky, sneeky, slippery past rings and valves. And H2 is very, very fast flame front stuff. Hot diesel systems soot glows was the woodgas hydrogen unwanted lite-off problem.
Far, far different combustion speed curves in always variable mixtures pulled out woodgasses that rigid spec spray misted/injected diesel and spec CH4 hydrogen bound methane.
These woodgas system factors are far more important then simplistic fuels BTU’s and octane comparisons.

Lots of info already been put up on the DOW with links on all of this if you search it out.

Wow now thats a reply Steve! Lol. I now see the many hidden issues including the gas composition itself. I might have to just do the tried and true big cu inch mpi. Anyone done a gm 5.3 or 6.0 gasser? The tow button changes the timing to a diff map in the ecu. I can change those values to whatever I want with available software. This would make the timing issue easy. Just advance it and watch for excessive knock counts. The intake manifold is plastic but I could get an aftermarket aluminum one.

I for one am waiting for someone to figure out how to get a GM obdll on wood gas.

I recall somewhere in the distant past that SteveU commented about the GM 6.0 being a potentially good candidate, but you would be a pioneer if you try it. WesK has pioneered the Dakota 4.7, and there are a gazillion GM 5.3’s out there to try. Chris, you may help lead the way into the next generation.

Beyond the purely technical challenges, though, lurks the shadow of government regulation. If your area requires emissions testing and check engine purity, it may all be a waste of time, unless you’re building a truck strictly for the deer lease.

Yeah I would like to stick to a gm truck. Im a big fan of their reliability and build quality. I wouldnt touch a ford 5.4. I have lots of parts for these trucks, including a couple of these trucks with 4.8 and 5.3 engines. 2000 and up. 00-02 have a conventional throttle cable. 03 + have drive by wire tb’s. Might be advantageous to just keep it simple and try a conventional throttle body model. I could swap in a 6.0 to a 1/2 ton model as the 6.0 only came in heavy 3/4+ ton trucks or in the awd Denali trucks. Well u can get em in a 1500hd but that is basically a 2500hd with less spring.
There is decent room under the hood as well as underneath the truck. Not sure on height of bed to cab roof. Those Dakota’s are hard to beat that way.
Took a look online to see who makes aluminum intake manifolds. There’s a ton avail. I will dig into this further as I need.
Thanks for all the warm welcomes and support! -Chris Doye.

Hello Chris and welcome to the site .

You now understand why we say when Steve U speaks everyone listens !! Wow. Thanks Steve

Morning guys
Well 24 hours later after the brain aching from two days worth memory meds in one day to get those ideas legibly out I am able to talk again. Be short now un-medded in real-time Steve brain fog. Expect very bad word/spellling mistakes. SteveU’s accent anymore.
Yes was me expressing that i though that the GM LSII? 6.0L SI engine would be the next go-to woodgas break-out set up.
Matt Ryder is working some with theses now. 2-3 other guys talking about it if you LH top side bar search out GM LS engines. I expect at least two of these to show up by next years Argos get togather.
What is nneded is someone able to really dig into the software/sensors operating systems to proof these out for woodgas adapabilty in road worthy vehicles.
WayneK has proven the Chrysler/Dodge distibutorless 8.0L V-10’s.
WesK now doing a Chysler/Dodge/Jeep 4.7L SOHC V-8 wIth at least two others building to run.
Combo’s of guys back to J.Spreadboro (sp), Martin and ChrisSeymour and SeanF. been wringing out the different Ford electronics capabilities. Been a hatful of non-electronic natural gas Ford V-10 SOHC gen-sets now woodgassed operated.

ChrisD you could be the guy woodgas proving the adapabilty of the later GM LS injection/senesors/electrinics packages.

Ha! Not me. I am twice your age, with old, old GM arrogance hating 50’s, 60’s prejuduces that I still stuggle with. My last full year working as the used car tech at a combo Buick/Saturn/Nissan dealership I had to change out far too many 40-60K coolant leainkig into the oil V-6 plastic intake gaskets failures to wash away my GM arrogance prejudice. Did learn to admire the production LS V-8’s though.
Why I’d gone last intensively with the Chrysler/Dodge route to say as clear as possible out of the friends and families Ford/Chevy warring. (plus more repairs needed with billable hours to earn on the #3 domestics)
And now family/friends all mostly converted to Honda &Toyotas. And even the Wife now pulled away from Chrysler to Hyundai. Thank you dear. I love so much for the third time working on your microprocessor controlled Automatic Temperature Controled heater/AC system! Darn good thing I have that Cad/Buick/highline Chysler AC’s experiences.

Again AlexT is correct. Past the basic engine system nuts and bolts is the characteristics of the diffenrt tattle-tail OBDII systems versions.
Making it snesors/elecrinics/timing work with woodgas is one issue.
I will remind in the mandatory inpected areas that the PURPOSE of the whole OBDII mandated protocol guidelines was to make systems that would tattle-tail report ANY modification on a factory certified and registered engine/vehicle emission control systems.
Only true way to beat that is to NOT be inspected. Or be exempted from inspections.
Here in WA that means not licensing in one of the four urban core counties. Oregon in one of the three urban core counties. Or having a base chassis manufactured before the rolling 20 year (OR) or 25? (WA) no longwer inspected cut-off dates. California you are so screwed. They go back inspected to 1967 I think. ID and MT are “free” states.
US PNW we can do the old without vehicle killing road salts so far.
British Columbia uses a lot of road salts!!
So . . . their emissions inspection requirements are??
None? Or just the Vancouver/Victoria areas?


I will have to do some searching on here. I haven’t had much time lately. Looking at trucks in the yard. I have a 2000 chev 1500 reg cab long box. It was cheap and it’s kinda beat body wise but it may suit the purpose. Only a 5.3. Dime a dozen at least. Auto wreckers got so many on shelf because they don’t sell em. $500 around here. Lots of hot rodders throwing carb intakes on em and swapping cams for an easy 400hp for $1500.
Yeah Steve those plastic “gaskets” were a dumb idea. I’ve done a few head gaskets and engines in those gm fwd v6 garbage.
I think they’ve all had so many bad ideas it’s best to wait a few years and buy used. Look at everyone who bought those 6.0 diesel fords or even the 6.4 2008-2010 were just headaches. Auto wreckers can’t keep em on the shelf at 7k a pop. Be mighty pissed to spend 60k on a truck and have to do a motor in 160,000 miles. A diesel at that.
The best thing to happen to engine tuners in regards to software was obd2 ironically. Seems to hae made it easier for the aftermarket tuning software companies to break the code or some manufacturers are open with the companies. There’s acouple programs hp tuners and efi live that allow you to change virtually all the operating parameters with data logging capabilities as well as wide band 02 switchable maps for timing and fuel. You can also turn off inputs of certain sensors. Disable egr, o2 sensors, change knock count/timing retard, basically you have full acess to the brain. You can change map sensors for boosted applications, modify anything from line pressures to shift points in automatic models too. I’ve used hp tuners on a few gm 6.0, 5.3’s. Not sure if the mass air sensor will prove to be a hurdle. I think I can disable mass and just run on the map off the VE table. Have to look into that…

It’s my understanding you would want to keep the engine a slow speed(rpm) one? So big cubes and run on low rpm torque. Most driving under 3k rpm I’d imagine.

No emissions testing around here. Just the Vancouver area and possibly Victoria but I’m not sure.
As for road salt it is used a bit but not near like in the eastern Provinces. Our cars around here actually do pretty well for rust. Northern BC is worse. Longer winters and more snow. I’m only a hour and a half from the border town of oroville wa. So we don’t get long winters.
Have a good one!

Yes ChrisD you are reading it correct.
Woodgas WILL power up into 4000 RPM; but much better efficiency down in the 2000 RPM loaded ranges. Much better torque fuel that HP fuel.
Fits in will most all modern fuel effiency gearing better than the older winding, screaming out, small engine carburated stuff.

I am really not any one brand loving. Spent more tech working years in work-on-all independent shops than at dealerships.
Very, very clear relationship across ALL brands that first year in production models have the most problems. Those “oop’s” sorted through then in the 2nd and 3rd years of production. Then 4th and 5th year production, cheapened and de-contented, profit farmed, waiting for the “new”, “improved” model change to come on line. Always then with new system “better ideas” set of of new problems. Hey! just like Goliath Microsofts every 3-4 year operating systems churning for consumer bucks, eh?
Been very hard enforcing to family and friends to pick your brand as you please: but then wait for only 3rd year production released models.
Of course some models, in all brands never, ever, do get any better.

With you on the better, leveler playing field actually with the OBDII’s.
I was extremely impressed my GM dealership used car tech year in 2007 seeing just how high milage reliable that the Chevy/GM Suburban/Youcon /1500/2500 chassis 2000-2007 were proving out to be. Only ever needing light bulbs, drivers power window switches and rear brake jobs and that was it.
Beat out comparable Chrysler/Dodges hands down - tranny’s tranny’s and more tranny’s!!. AC work, and more AC work especially on the Jeeps. Near 100% Jeeps rear diffenrtial’s needing overhauls for bearings/gearing noise.
Ford equivalents versus GM’s needed more work and that work always costing twice as much and twice the PITA to do. Lots and lots of Ford 4x4 front bearing hubs work - not so bad. Near 100% DPEF’s work needed on the gasoline’s - OK? Which part? The DPFE sensor? The exhaust tube restrictor? Or just a exhaust gasses aged, cracked hose? Thread pulled spark plugs on the Triton V SOHC’s. Long, deep down one-time-only fix m-a-y-b-e possible on that before needing new cylinder heads. And Every Navistar V-8 I inspected past ~150K miles had an external rear LH cylinder head coolant leak across the engines size range. These also always seemed to need work on the turbo controls to keep the codes cleared for re-licensing inspection.

So street rodding these GM chassises means in your area you are NOT mandatory emmisions inspected. Good. Opens up then the whole range of EFI/woodgas fueling possibilites without having to toady to Big Brother always breathing down your neck. Ha! Just those pesky Canadian mandatory chassis safety inspections. Thank you road salt.

Ford MAF’s default nicely to speed-density. Just wierds the tranny shift point some.
You’ll be the one to proof out the GM’s. Woodgas is sooty and mildly corrosive. Some having suscess with engine inlet air side isolating the hot-wire MAF. Really needs a system gastight isolation valve for the MAF. Hot gasifier at shut down will self pressurize and try to flow out anywhere that it can.

Steve Unruh (the emissions bootlegger scofflaw)

The only guys that have mandatory inspections as in safety checks, are the commercial trucks. Over a certain gvw. Maybe they used to do something here with passenger cars but that was before my driving days;)
So essentially we are good to go with modifications here.
As for the mass air. I’m

As for mass air sensor. I would either isolate with a anti shutter type valve that closes the wood gas pipe entering the engine or just run it on the map. I mean why are both needed anyway. Most fuel injected vehicles run one or the other. I guess there must be a reason but I hate mass air sensors. Always a wildcard in diagnosis finicky things. Here’s sa link to some of the features of the program I use. One is running on map sensor only. This could prove handy if the mass pisses me off. GM > Operating System
Torque is king for drivability anyways so I will base my build around that. Maybe swap the cam for a custom high lift, low duration one to enhance torque production and low rpm power. Guys put a 4" stroke crank in these 6.0 engines to make a 408 cu inche and with a mild street cam are pulling 550 lb ft at 2500 rpm. 600hp when revved out to 5800. This is with the larger l92 cylinder heads from the 6.2’s. I think with the big cubes and the smaller port 6.0 heads that you could make similar torque even lower in the curve.
That would be rev. 2 though. Start with a factory 5.3 and see how she behaves. The old kiss rule applies to everything I find. One thing at a time.