Rack cooler for shortbed trucks

I have a shortbed pickup that is too short to haul much more than 8 foot lumber. This is common with quad cab and small to intermediate size light trucks, so I was thinking about making a cooling rack that would cool a gasifier and allow me to haul longer lumber or some 4x8 plywood, etc even after I fill the shortbed with gasifier tanks, etc…

Here is a snapshot of the routing that I worked out, and found it amusing, like a puzzle to try to trace out the flow from one corner of the truck bed to the other without doubling up a tube… I could add down pipes and more cross pipes at the rear window, but not sure if they would be needed for cooling, since this one will have a lot of pipe in the wind…

How much surface area is “typical” or required for a gas cooler ? How thick on the tubing, 1/16 or 1/8th ? etc…


Interesting problem. I don’t know that you need the part over the cab, it won’t get much flow unless you “force” air through it. All Wayne’s racks are open jointed, i.e. the gas can take the path of least resistance at any intersection. This way a plugged line will not stop the system. Design for longevity at every step…

I think if you are happy building full “sideboards” like that then just put a full rack in there, it will be about enough. Basically just skipping the stepdown that Wayne does. If you want to carry lumber then extend the rack over the cab like you suggested, just not carrying gas, only to support the lumber.

Hi GaryG
I once moved a whole 16 x 20 foot cabins worth of onsite milled 1 x 12 and 2 x 6-8" fir lumber all cut as 20 footers from one offgrid location to another 60 miles away. Trick was this was all on my 1994 F150 2wd Ford pickup with a 5.0L, 18 MPG little mouse engine.
So do not discount the sloping rack arraignment. Tail gate was pulled off and my 12V screw gun and 12V chainsaw site built (from the lumber) sloping tray rack allowed me 4 feet down and back from the edge of the actual bed then angle up and over the cab half way across the hood length. This put good weight over the front axle, yet kept half the load weight low closer to the rear axle below the top of the box line. Worked good. Actual 2000 pounds every hunting trip moved that season. Room for deer and gear (or gasifier equipment) under the front section. Handled good and no tickets on the County, state and forest roads. Pretty truck camper boys liked me for clearing out the low hangers.
High load racks only good for wide 1 ton dualies or a few hunderd pounds of ladders and long stuff before she roll steers on you with the narrow low GVWR vehicles.

Steve Unruh

It has been my experience to use a small light trailer to haul with. You will need to get around the bed of the pickup to do the things you need to do to run the truck on wood and to maintain the system. I had also thought to build my gasifier on a trailer and leave the bed of the truck open.

Hmmm. there’s always more to it when the practical experience speaks.

Good points CS on eliminating single passage lanes that could cause a water blockage (like going around corners or during braking) and SU on hauling those 20 footers… I will need to haul some length when I go get metal to build the cooler with (still have not figured that one out yet, other than use shorter pieces). Woody, use of a trailer came up as a suggestion for my other vehicle as well (rack not feasible on 41 Ford coupe).

Thanks for the replies and considerations !

Can anybody tell me what the minimum amount of cooling pipes we can get by with and still do a decent job of cooling. I see Chris Saenz truck with what looks like 6 8 footers on each side plus some by the cab and then Mike Larosa’s trailer has what looks like a 4x5 radiator. Is there any formula to use? The reason I ask is I have been researching using an Astro van for my vehicle. I would move the up swinging tailgate to just behind the second row seats and fill in under it I like that the fuel tank is behind the drivers seat underneath and the spare tire sink hole behind the rear axle can be cut out to drop the gasifier down through between the frame to reduce the height on top. I like the side swinging half tailgate that can hide the bottom of the gasifier and filters and fuel bags and stuff. The doghouse engine cover might present a problem running pipes but control knobs would be handy with short linkage. This is still in the planning stage but I think it might work. I played with some pictures from Craigslist to see how it would look.
Don M

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Looks similar to what John Stout has done: http://youtu.be/f3wpoCOC1us

Hello Don.

I don’t have a lot of cooling on my V-10 because of needing to pull goose neck trailers. But the gas needs to reach the dew point before it gets to the condensate tank.

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It all depends on the total cooling surface. You can expand that by parallelling many 3/4" vertical pipes, connected by two horizontal square tubes. Bolt on top of the upper square a lid made of metal sheet for access to flush the vertical ones. Same lid on the low horizontal one makes welding of the tubes a piece of cake. Inside welding is easier.

There is not such thing as too much cooling, because we should not talk about cooling, but about condensing. Condensation starts at about 60 degrees C. Cooling back to, say, 40 degrees at 20 degrees ambient temperature leaves a lot of humidity in the gas. Condensing gas also helps to catch unfiltered dust. Since it takes time for carbon dust to stick to water, a long, but wide enough cooler is benificial.


Hi DonM
Your Astro concept looks reasonable. Maybe stack the non hearth componets fore or aft of it on the same side to allow for tool and wood fuel space opposite beside the gasifer.

If not prying will you be using in the bed, or on top of the bed walls vertical cooler tubes with horizontal upper and lower trunks as you have suggested on your current pickup build up?

Steve Unruh


Haven’t a pic yet, but the precooler (between cyclones and wet filter) will come on top of the front bed wall. So behind the cab. Not a windy place, but the delta T will be enough to get condensation. Cyclones do help a lot to cool, they are the most compact coolers one can imagine. The cooler after the filter will start on top of the filter and end on a side wall of the bed. Compact, but a lot of cooling surface.

I like vertical or sloped tubes, because these are self cleaning. But if keeping a low profile is important, a rack-like cooler like Wayne’s design can be done too when wide tubes are used.


Hello DJ, I’m 100 percent Dutch down the line from the 1840’s, when my great,great grandparents left Holland because the goverment started taxing individual livestock, so they hid livestock in their house when the tax accessor was spotted down the line. Would you explain the “Delta T” for condensation?

Thanks DJ
I Can see this in my minds eye. Ha! Ha! Unlike another mutual friend I am now conversing with on his hearth design concepts.

Hi DougD.
“Delta” means a difference change in some energy measurable. DJ’s DeltaT means a measurable usable changeable temperature difference from before and after. in his case a heat energy bleeding off cyclone or metal tube cooler.
If you watch a lot of aviation of areospace movies set in the late 40’s or later you will hear the characters saying dramatically, “The Delta V (velocity change) is going to tear us as apart if we don’t burn up first from trying to bleed off that much speed so quickly!!”
You or a family/friend own dam# near any Ford domestic product '96 through 2007? Look under the hood. Find the VehicleEmmisionsContolsInstalled (VECI) sticker. Somewhere it will show a little device called a DPEF. Means Delta Pressure Exhuast recirculation control valve Flow sensor. Measures the exhaust pressure drop differential created by flowing the to the EGR valve Inert exhaust gasses through a calibrated washer built inside the metal cooling metal supply tube. Tells the engine control computer if the EGR system IS actually effectively flowing and and then able to calculate how much actual exhaust flow IS occurring up into the intake manifold. Lets the computer compensate for clogging tubing, valve and intake passages. Lets the computer system diagnose 10-12 different reason for a system malfunction.

Ha! Ha! See. Fly on any American made Boeing flying airline. Drive a domestic Ford vehicle and you DO live with American engineer specified Delta differential energy measurements keeping you safe and sound every time.

Steve Unruh

Just thought I would add that between my cyclone, relatively small cooler and then the filter housing that I still see water in the rubber hose running through the bed. This rubber hose thanks to Ted Carbone also does quite a bit of cooling with it’s ribs. I have a water trap under the truck as well. I have a neodyne magnet in the gas stream in it. Some of this water is residual. I made the mistake of flooding and washing my filter out last fall and that hay is in bad shape and held way too much water. I drilled a hole in the base of the filter but nothing drains out of it. The screw already rusted out and I’ve replaced it twice. I was going to jump in on the drum discussion but held back. They rot too fast here for me to use anymore. My truck now has rot holes in the bed around the wheel wells. I guess this explains why it no longer fills up with water after a big rain like it used to. Oh well … Back to cooling, I just pull the rubber hose off from time to time and drain the water out … I haven’t seen any more rotten hay in the hose so I think my stainless steel screen (thanks Chuck C) is still in place.
I will probably cut it open in Indiana to stay busy and see what the insides look like. As it is working and is not causing a restriction I don’t plan to do it now. It is just sealed with a wrap of duct tape and then aluminum tape over that to keep the sun off the duct tape. It has seen many sneezes with no issues. Water tanks are real easy to get here. Just have to take time to braze up the holes that caused them to fail. Mike

Just thought I’d post a current tax day picture. It’s raining … Been dryer than a popcorn fart around here … Mike

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