Another woodgas vehicle choice question

So, I really want to use a Chev Avalanche. There are two basic choices, the 1500, and the 2500. The 1500 got a 5.3 with about 285 hp and 325 ft lbs. The 2500 got an 8.1 with 330 hp and 450 ft-lbs.

I figured the 8.1 was a no brainer, but as it turns out, it weighs 1000 lbs more than the 5.3 version, and is actually touch slower 0-6 and in the quarter mile as well.

So it looks like the 5.3 could be the one to go with?

There is also a rarer 5.3 Z66 option which deletes 4x4 and shaves even more weight off the truck compared to the 5.3 4X4 0-60 numbers listed above.

So is power to weight ratio the ultimate deciding factor here? Looks to me that apples to apples, the big block truck would still be slower getting up to speed on wood gas compared to the 5.3 truck?

The 5.3 4x4 truck weighs 5734 lbs, so that’s 20.1 lbs per hp. The 496 truck weighs 6793 lbs so that’s 20.6 lbs. per hp. The 5.3 2WD weighs 5487 lbs so that’s 19.25

Compared to Wayne’s V10, he should be around 6000 lbs and 300 hp, so again, around 20 lbs per hp on gasoline.

I need to be able to go at least 120 km/hr (75 mph) only occasionally, but for 2-3 hours at a time when I do.

Am I pushing my luck here?

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You’re right, it’s all about power to weight ratio. A lighter truck with a slightly smaller engine will do better. However, if you’re about maximum towing capacity, as Wayne is with his V10, then bigger is better regardless of the top speed.

From everything I know, the 5.3 is an excellent engine and should do quite well on woodgas. However, no woodgas truck that I know of will maintain 75 for multiple hours. You will need to run at least hybrid with gasoline, if not straight gasoline.

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Thanks, power to weight seemed to be the best metric. I won’t be doing much towing. I could see all that low rpm torque would be beneficial for low speed towing and work duty in general though :slightly_smiling_face:!

I’ll think a little more on vehicle choice. I need to run on the 401 highway which is a fast moving 4 lane. 120 is what the semi’s do, and the left lane regularly runs 130 (80+ MPH) for hours. Last summer, I went over an hour running with the flow of traffic at 140 (87+ MPH).

I’d love to be able to at least run the right lane at 110-120 with out guzzling gasoline to do it, but I realize it is probably not going to happen :disappointed_relieved:.

I think Wayne has gotten his V 10 up to those speeds with wood. My mechanic is a dodge guy I have always had chevy trucks myself not for any good reason. Anyway my mechanic told me the dodge makes good since for a wood conversion because they have longer stroke motors with higher compression. I don’t know how much difference there is as I have not don’t a conversion yet but if your looking to push the speed Wayne has had good luck there.

Yeah, I remember Wayne saying there is more to be had speed-wise if it weren’t for gasifier temps scaring his foot off the throttle :slight_smile: !

If all goes according to plan, I will build with stainless and ceramic to handle the temperatures. I don’t think Wayne really knows how fast the V10 will go as he’s never held his foot down for long once past his comfort zone temp wise to save it from a melt down. I’d bet it would go quite a bit faster if everything was made from stainless and he felt comfy holding the loud pedal down :slight_smile:

I may go charcoal, and I think using Don M’s nozzle design, + all the latest tricks learned here + good quality materials that can take corrosion and temperature may allow for some pretty good speeds.

If still not fast enough, and hybriding is required too often, one could look at turbocharging or other tricks for more power.

I remember reading in some old writing there is power to gain by increasing the compression only if your engine is below 10:1. If you’re already at 10:1 or higher it’s not worth the trouble. It seems the power curve flatens off fast above 10. I think most modern engines are already close to that number (maybe with the exception of low octane parts of the world.)

Good morning Will,

I think I could build a gasifier than would run the trucks the speeds you have mentioned , The big problem is they would be little use to me because they couldn’t function at lower speeds . Just not enough turn down ratio and would run too cold and tar the motors at the lower speeds .

With a gasoline vehicle horse power usually means speed and torque because the fuel is always there to feed the horses .

With a gasified vehicle there is another issue to consider . You can have plenty of horses under the hood but they do you no good if you can’t fed them properly .

There are times when the gasifier is at it’s prime running 40-50 mph and then go to WOT to pass a vehicle or pull a steep grade . I am making plenty of fuel ( feed ) and the more horses under the hood the better . Within a short distance I could do with half the horses because I can’t make enough feed to keep them happy .

The best than I have been able to do is design the truck to run clean at the low end needs ( stop and go traffic , idling around the farm ) and let the top end speed fall where they will . With the light small profile truck I find this is about 60-70 mph flat roads . With the heavy truck and high profile 50 -60 mph empty and level roads. I can go faster for short periods but only until the gasifier begins to over heat .

If you have work to do you have to have a truck big enough do do the job. The big truck will use a lot of fuel working or just driving . If you just need transportation I would suggest a small profile vehicle .

With ether of my trucks I can run your 87 mph all day long BUT must add in or hybrid with gasoline .


Hello Will

Along with rising temps there may be another issue to consider pulling hard on the gasifier . For the gasifier to make gas the oxygen is pulled in at the nozzles and while moving through the char bed toward the grate the oxygen will be consumed and converted to gas . If the flow / velocity of oxygen gets great enough there may not be enough time or distance for the conversion of gas to take place going through the char . If this oxygen makes it past the grate it is like turning the switch off in the truck . Any oxygen that making past the char will be consumed by the gasifier . ( heater mode )

In short even if the temps can be tolerated I’m not sure that you can get too much more turn down ratio ?


Hi Wayne, thanks for your valuable input. I never considered pulling so hard that you end up burning the fuel up in the gasifier - but now that you bring it up, that pretty much puts another hard limit on how hard you can push the gasifier aside from temperature alone.

I guess the ultimate solution would be an engine swap. A huge engine swapped into a light vehicle would probably do the trick. But In my driving area, I have certain authorities to consider that are essentially beyond reproach in their judgment. What they say goes, and I have no option to argue in court. So I always have to keep this problem in the back of my head.

All of that problem goes away if I use a stock OEM vehicle.

Decisions decisions…

Will those “certain authorities” let you drive on wood where you live?

Hi Don, uncertain.

It is my opinion that laying low will produce the best result: 99.5% chance of not being pulled over. This would mean driving a regular looking post 1998 OBD2 vehicle with no mods visible from a casual look over the vehicle. If I did this, I’d have no worries and I would be totally comfortable.

However, if I wanted to overcome the speed limitations on wood gas by putting a 540ci BBC into an old 1/2 ton 2WD pick up truck - then I’d have some issues. Emissions testing issues, Insurance issues, old trucks get pulled over by two agencies and inspected for fitness and emissions compliance. Now I’d really have to be careful to hide/disguise the equipment and plumbing just to be safe.

Who knows, I may be pulled over, have to reveal I’m running on wood gas, and the officer may just shrug and say “Cool!”. But he could just as soon give me trouble - I won’t ever know for sure till it happens, and could well depend on the officer himself than any rules that may exist.

That’s another reason I’m considering charcoal - easier to hide. I’m doing it regardless of the legality, so I’m going to play it safe and deal with the downside of that decision (like having to hybrid).

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If or when I do a woodgas truck again it would be a Chevy 5.3 vortec 1/2 ton 2wheel drive. Pre-06 because I would want to avoid the variable cam timing that started then. I would add 50-75 hp from the start. There’s a lot of cheap add on hp for that motor. For wood gas you have to be able to advance the ignition timing by either installing an aftermarket distributor or electronically advancing the timing by a piggyback computer. Some OBD2 systems wont allow timing manipulation (dodge 4.7L) and you’ll be stuck at 50-55 mph if the road is flat with no cross wind. I would go 2WD for the extra real estate under the truck which would make the plumbing easier. I don’t know if anyone has done a 5.3 OBD2 wood gas truck yet. Just my 2 cents worth.

Wes Kuehl


Listen to this man. He speaks from experience…

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Thanks for the input Wes. I would want to avoid the Variable cam timing, and variable displacement engines too! I know the LS motors have a lot to offer, if the OBD2 became problematic, I would run the coils with one of the MegaSquirt products.

I have to pass an E test on vehicles newer than 1987 every two years. 1988-1998 vehicles get a pipe sniffer, 1999+ vehicles get an OBD2 port scan for readiness and codes. I am also subject to roadside emissions equipment enforcement via the Ontario Smog Patrol, these guys target older and modified looking/sounding vehicles. The Police and MTO (Transportation authority) can also nail me with equipment infractions with near impunity.

It doesn’t pay to get pulled over here as the officials can essentially do whatever they want, and you don’t have any recourse. If you end up with a guy who’s having a bad day, you’re screwed.

I go back and forth all the time weighing my options, but I’m sure not going to start work on it until I find a way to get going without getting yanked off the road. But I sure don’t want to be stuck at 50mph either.

I’m really going to have to think out of the box on this one…