Delica Canada | Mitsubishi Van Club

Ok guys just an update. I am finally running on veggie so I have done some more testing. Keep in mind that my temp sensor is on the fuel RETURN line. On diesel, so no heating at all, fuel return temps sit around 132 f. I switch the vegtherm off and just relied on the hotfox and vegmax. After about 10 minutes or so of driving it didnt really change much at all, couple of degrees maybe. The disappointing part is I then turned on vegtherm and it took another 10 minutes or so of driving to get to 143 F and that is where it hovered from 142-143. At idle, I can get up to 170 (looped return) but haven't yet tried driving it after getting it that warm to see what happens.
So basically, either the fuel is moving so fast through the system when you are driving that it wont get as hot as I would like, OR, the injection pump is sucking alot of the heat out (I believe that both are equal culprits). I am going to move the temp sensor to the supply line I think and see what temps I get then. That way I can say for sure that it is the fuel making it too cold or the injection pump sucking out the heat. I am also going to make a small surge tank and put hotfox in that so it can have a smaller area of fuel to warm up.

Thanks for that info Eric. I have everything installed on my set up, just deciding how to heat the fuel in the tank. I may end up getting a HotFox in the end, I can't find a good source of aluminum or stainless tubing here. In the end I will probably heat my supply line, just not sure if I'll use a Vegtherm or Racor heated line.

James

If you have the ability, make a small surge tank and stick the hotfox in there. I think that way you will only have to heat a small amount of veggie oil up so that hotfox will have a better chance of actually doing anything. If it is in the main tank, it has to heat up so much more volume that it will take too long and the stuff that passes through hotfox I dont believe spends enough time in there to actually take on much heat. I am going to cut my front tank shorter and make one this week to see if it is better. I think a 4"x4" square tube just long enough to fit hotfox will do. Then just weld the ends shut, cut your holes, thread in some fittings and mount it. If you have the ability to do this then you also have the ability to make your own hotfox. It is nothing special, the only reason for its cost is the fact it is stainless steel and someone spent alot of time tig welding it.

The surge tank is a really good idea, could put a little pump like Adam's in between to move the colder oil in. Also, after reading a report this morning on polymerization, oxidation and other nasties, it sounds like it is better to minimize the heat in the main tank as it speeds up reactions. I think I even have some spare aluminum kicking around, if I use thicker material then I can MIG it here.

I would like to see a cross-section of the inside of the HotFox. I need an idea of how much material is required. I would rather make my own, just for the satisfaction of it, and my system is cobbled together anyways.

James

I'll make you a 3d cad drawing tonight of the basic design and post it as a jpg. It is just a tube with a bigger tube over top. After driving it today I am convinced it is the fuel that is the main cause of cooling everything down. Around town, I can get temps to 170 but get on the highway with sustained hi rpms, fuel temp drops a degree every 5-10 seconds and rests around 134 or so. Vegtherm will heat it up from there but it is slow. I went and bought the same pump (only about $60 and came with a filter) as Adam too (thanks for the research man) and I am going to build the surge tank today. There is a nice little spot for it to sit underneath between the rear heater box and the wheel arch.

Ok, this is rough but it was quick.

The three parts, skinny tube is the one that the fuel goes through, thread the hole to 1/4" NPT, (hotfox uses a large 1/2" pipe) on the top so you can attach a fitting. The fat tube is the one that the coolant flows through. The bottom of the fat tube needs a plate welded to it, then a hole drilled in the center to allow the skinny tube to pass through, then weld that together. The big circle is the mounting flange. The same hole that is in the bottom needs to be in the top for the same reason, the fuel tube passes through. Weld it on. Then you need 2 holes on either side of the fuel tube that are threaded to 1/4" NPT also so you can stick in your fittings. Just make sure that the holes feed into the void of the large tube that will be filled with coolant. Then drill the mounting holes along the outside of the flange. There you go that is it. Sorry if I dont make any sense, not feeling well, that is the best I can explain it at this time. Feel free to ask me to clarify. I am going to buy the parts tomorrow so I can make one, just because.

Thanks Eric, that makes perfect sense. I'll try to make one on the weekend.

James

Ok, built one, had a bit of a design change though. There is not enough room to fit all 3 fittings across the top so I raised it all and put the coolant holes through the side. If I had planned for this I would have bought longer tubes so that the top plate wouldnt interfere with the 90 degree fitting. Instead I just threaded the fitting on first then welded the plate. The little plastic thing in there is an old brake fluid cap with a level sensor float. I am using it to trigger the low fuel warning for my VO controller to shut off the veggie.
All assembled like that it fits perfectly between the wheel well and the rear heater box.