Peter, I was about to buy a piece of pipe today. 18" long, 12"D to run a 460 Ford. Who are the guys I should talk to about fire tube length?
Your welding is unbelievable!
John Stout
Thanks Steve.
That is an interesting question. Whereas most of our projects are one - off, I do not have much experience in the production - manufacturing field. By nature of construction, this is a time consuming project. I think utilizing new tube – saw cut, upgraded fixture & rotary head stand would be a time saver.
I would have to build another one with production in mind to answer your question.
Peter
Thanks Peter.
Thanks John,
Wayne, Chris, Sean French would be the guys to ask. As it happened, Sean explained to me in great detail of what & why i needed certain dimensions for my particular application.
Peter
For the bigger trucks or high-performance applications we are currently recommending the 22" firetube. It provides more of a reserve. For small trucks like the Dakotas or Rangers the 18" is plenty. Definitely talk to Sean, he’s got some suggestions in this department.
I take it a 7.4L 454 would be a candidate for the 22" firetube?
Is it just the length or also the diameter that increases?
What size opening would be recommended for the choke/restrictor plate?
Henry,
Many factors need to be considered, vehicle weight, CID, final drive ratio, expected performance etc. I would recommend talking to Sean.
Peter
Hello Wayne Keith,Chris Saenz,Wayne B,Steve Unruh,John S, Henry A and Everyone Else
First off Peter awesome job that tube looks great!!!
To lightly answer all of your questions about proper sizing of the gasifier to the load (truck). Both Peter and I looked at all the components making up this build 1. vehicle weight 2. average driving speed 3. at the required speed what are the rpms 4. how many miles per gallon are we looking at if it is guzzling gasoline it’s going to guzzle wood 5. general size of the engine in liters. All of the above information can be plugged into an equation that I have come up with to aid in proper sizing of gasification equipment. More too come very soon I am neck deep right now in r&d for my generator project and writing the book as I go. BBB Sean
P.S. I am currently running a 16"dia. firetube 25" long on my 5500lbs. f-150 V6 pulling trailers,running 70kw generators and driving highway speeds.It takes 1,3000 miles to fill up the char bin. With no tarr Dimensions are only part of the woodgas challenge. Details on plans for custom performance work coming soon.
Nice work on the tube and all Peter C.
Tube experts and metal finishers…
I have a 12"x22" tube for my 460, but it is really rusty - it actually has an interesting texture different than surface rust… it has small pits like craters all over it, inside and out (like it was used for saltwater or steam or something? ) It is thicker than 1/4" on one side and a bit thinner on the other, really weird.
I am considering the time and patience required with rusty, dusy metal flying all over the place to grind it smooth inside and out.
Any chance of further erosion using it as-is ?
Grind it smooth on the inside ?
or just keep looking ?
Here is a link to the photos of the funky fire tube: http://www.driveonwood.com/comment/3198#comment-3198
Henry
Yes use the 22" tube and start with a 6" restriction. As well as John with the 460 ford. With experience you can make provisions to go with a bigger restriction 7 1/4" later. Regards Sean
Gary,
No need to clean up the tube, rust and pitting is OK, the main concern is that its thick enough. Check the depth of the pitting. 1/4 is the minimum, how thin is it in the thinnest spots? If a significant part is thinner than 1/4" then you should look for another tube. If its a few deep pits then you could fill them with weld. Sorry to be picky but you’re going to put a lot of work into the firetube and what follows, let’s make it a solid foundation that won’t burn out.
Chris Saenz,
We started building our fire tube 12’’ dia. and 18’’ long for a 1 ton Chevy with the 350 engine. We thought this is the universal dimension. Do we need to change to a 22"?
HI Gary,
Can you post some pics. of this fire tube erosion? Then we can get a better idea on how to proceed.
Sean
Thanks Sean, 22" it is.
I was with Rick, thinking that the 12" x 18" tube was a universal firetube with whatever restrictor is needed. I wonder if anyone else has begun work on their firetube making this same assumption?
We really more info regarding firetube sizing! Sean, any chance your formula can be put into an excel spreadsheet with drop down lists or cells for the necessary values? It sounds like the real numbers of concern are liters of displacement and rpm’s?
Just a thought…
Hi Henry,
The 12"x18" tube is a good size for a dodge dakota or a truck close to that size and weight. My little ford ranger 4cyl. runs this same tube size because the truck weight is close to the dakota the engine is smaller but requires the same amount of woodgas because the rpms are twice as high. For example the dakota turns 1,500rpms to go 70mph the ranger turns 3,000rpms for 70mph half the engine double the rpms same speed same size on the gasifier. For now the best thing everyone can do is post there project before starting we will do the sizing together and will be able to tell you what speed you will be able to travel,how much wood it will burn etc. I had to
tarr a lot of engines to get this to the point where it doesn’t make tarr anymore. Sean
Hello all,
Sorry about the slow response posting. I had a flat on the tractor yesterday (rear) and had to fix it in the 103-105 temps and was beat at the end of the day and passed out last night.
Some of the factors in selecting the dimensions of the gasifier as Chris and Sean have already touched on are.
Fuel size, weight and size of the vehicle, motor size, intended speed and use of the vehicle.
On the Dakota trucks that are intended for mostly hy way driving 50-70 mph I try to keep the profile low so as to keep the air drag to a minimum.
The restriction area of the gasifier can be adjusted simply by raising or lowering the choke plate and /or increasing or decreasing the inside dimension of it.
On the Dakotas that the construction videos are based on( 4,ooo-5,000 pound) a 12 inch x 18 inch burn tube seems to works well. With the wood size I am using and the speeds I am driving I think a six inch restriction is best. On my last Dakota I have a 7.25 restriction and a distance to the nozzles of about 12 inches. The truck is a little slow to worm up at highway speeds and at the next opportunity I think I will reduce the restriction down to 6 or 6-1/2 inches.
On my ¾ ton truck I us a 22 inch burn tube, 8 inch restriction and a distance to the nozzles of 17 inches.
The truck is working well for most that I am using it for. This is on farm use and driving moderate highway speeds. It is short on power pulling a loaded trailer and I wouldn’t want to try to keep up with interstate highway traffic even empty , for a long period of time (70-80 mph) I have over 5k miles on the truck now and have a chance to experience climate changes of the winter and rain, also the last few days triple digit temperatures.
Because it can set and idle long lengths of time , use smaller fuel, and makes clean gas I think I will increase the restriction size to about 9 inches the next opportunity I have and test it for a while.
Ideally I would like to have a larger diameter burn tube but on my units I keep the internal parts small enough to fit inside the 55 gal drums.
I think the weight, size, profile and speeds are more of a requirement for gasifier sizing that motor size.
To experiment with the adjusting of the restriction diameter and depth one can use bigger or smaller fuel or judge the performance at light work vs. heavy work.
If the gasifier is trying to plug and not purging the ash and small char one can bring the restriction closer to the nozzles. If the gasifier is flowing well but running high temps one should lengthen the distance from the nozzles to the restriction.
It will be hard for anyone to size their gasifier for all the different conditions it will face .( weather, terrain, fuel size, moisture content ,shape of fuel, size of vehicle ,motor size ,speeds)
About the best we can do is suggesting a base line to start the experiments.
Even the best gasifier will not perform well in the wide rage of work it is asked to do. I think it is best to design for the moderate condition rather than the heaviest work it will be doing.
I think it is better to have to add a little gasoline to pull a steep mountain than to have the gasifier designed to pull the mountain easily. If designed to handle the heaviest loads easily this same gasifier will have to be shut down and the vehicle run 100% on gasoline for idle and light work.
A gasifier just can’t be designed to handle 100% of the range compared to gasoline, maybe 75-80%
Keep in mind operating 100% wood gas among gasoline cars and not being noticed is very difficult. Operating 95% wood gas and blending in traffic is easy.
Great post Wayne, I will add that to the page I am making on the topic.
Here’s something to consider. A gasifier makes a certain amount of horsepower. How much do you need?
Here’s a great calculator to figure out how much HP you need at any given speed. It’s very accurate!
Check out this page. I did my best to explain the way sizing works. http://driveonwood.com/premium/firetube-sizing
Hey Chris,
Thanks for the post.
I think we said about the same thing. The differences are you having the ability to say it where people can understand it.
Wayne Chris, Sean: This is good. Many thanks. And thanks to Peter for posting the pic of the tube extension. It got us thinking.
John