How to / DIY > Everything else
Injector preheaters, making your own
rcavictim:
I have problems with my 1.5 liter Rabbit NA IDI diesel engine (now in a DIY power plant) coking up the injectors badly when I try to run on filtered WTF as opposed to clear diesel. It has occured to me over time and reading here and elsewhere that one thing that would be worth my exploration would be providing heat to get the injector bodies up to a goodly warm temperature. As they are now you can hold your hand on them when the engine is hot.
I haven`t yet coked the single injector of my freshly re-ringed 12 HP Petter directly injected air cooled single used only so far on new oil, but have smoking problems that sometimes clear after a good hard run. I cobbled together a simple electric silicone strip heater around the injector last week and gave the plant a 6 hour run at half speed (900 RPM) and very light load (1.7 kW). It ran very nicely and was not emitting more smoky as the run progressed. I had the top part of the injector that I could reach at I`ll guess about 140 F., uncomfortable to hold after a couple of seconds. Originally it ran cold. I was encouraged by what I saw from this first attempt at injector preheat and believe this to be an idea worth persuing.
I would like to come up with a electric heater design that would be inexpensive and easy to apply to the injectors of both the VW and the Petter engines. It would be a bonus if the heater design also lent itself to heating the injector high pressure fuel feed lines as well.
I have an idea that I want to experiment with. I have some teflon insulated wire here, about AWG18 that has silvered, stranded copper inside. I have been stripping short lenngths of this insulation to use as spaghetti insulation on under chassis electronic components like resistors and capacitors in the building I do of custom hi-fi tube amplifiers. I have several colors in stock and the stuff will never melt in the applications where I employ it. The teflon I have appears to have a working temperature range up to about 500 degrees F. I was thinking that if I could somehow pull a good length of the outer teflon sleeve off my wire stock and snake a nichrome wire salvaged from an electrical heater down the center hole I would have a heating element that could simply be wrapped around the body of a fuel injector and associated piping. A step down and isolating power transformer would be used to apply a suitable (lower than full mains voltage) current to the heater(s). They could be safely heated to perhaps 400 F which might be enough to heat the injectors to the desired 200F target range. Thermal insulation of some sort could be placed outside of the lines and injectors if necessary to increase the efficiency/heating capability of this system as needed. Pink fiberglass or better yet, rock wool and self adhesive aluminum heating duct tape could do the job for an example.
I offer this in the spirit of sharing DIY ideas and invite comments and further suggestions from the readership. I will report here when I have anything to add after my experiments begin.
fuddyduddy:
The KISS principle is truly the best.
This has been covered many times, and is found in many forums. Heat, and/or treat, and/or dilute.
Is WTF waste trannsmission fluid? If so, Power Service Diesel Kleen, a little dilution with regular pump gasoline (one gallon in twenty or so), and Diesel 911 from Power Service will go a long way toward helping eliminate the problem.
One forum that has great info on coking, wetstacking, etc, is http://biodiesel.infopop.cc/6/ubb.x?a .
Dana Linscott has a great website to help us understand cures that work, also. http://www.vegoilconversions.netfirms.com/ Yes, some will say those are mainly vegoils, not used lubricating (transmission) oil. However, they are all hydrocarbons, and act similarly, and many of the same "cures" work for problems with using them in diesel engines.
Mr X:
Yes I also have been wanting to make a injector line heater. I understand it is posible ,quite simple. I dont have supplies but have tore a toaster apart for the nicrome wire, maybe too thin. You need woven ceramic fiber 1800 and 2600 degrees f . Silicone tape 500 deg f,, to wrap the wire and insulation to the injector line. Now as to ohms and length and gauge of the wire at 12 v,I found it sugested 20 watts/ injector line. A good sorce is Macmaster Carr but us here north of the 49 th cant assess this source due tio the growing security risk.
X
biobill:
--- Quote from: Mr X on October 19, 2006, 02:30:32 AM --- A good sorce is Macmaster Carr but us here north of the 49 th cant assess this source due tio the growing security risk.
Our administration is well aware of plots to use Lister powered generators and resistance wire to melt the polar ice cap and flood Manhatten
X
--- End quote ---
Geno:
I've been thinking about the same thing and want to use AC as thats what I have easily available. Mcmaster Carr. $3.18 per ft. and it only uses 3 watts per ft. If you want to go to 250°F the other stuff is twice the price.
"You won't need a thermostat for this cable. The colder it gets, the greater the heat output; as the temperature increases, the heat output automatically decreases. A thermostat can be used, however, to turn unit on and off. Use on metal and plastic pipes for freeze protection and low temperature process maintenance.
Cable can be safely overlapped. It's single phase. Not suitable for burying underground. UL listed, CSA certified, and FM approved Class I, Div. 2, Groups B, C, and D.
To Order: Please specify 20-, 30-, 50-, or 100-ft. lengths, or any length up to the maximum operating length.
Standard Heat Cable— Max. continuous heat output is 150° F. Can be exposed to temperatures from -40° to +185° F. Cable with metal braid is approximately 13/32" Wd. x 3/16" Thick. Cable with metal braid and jacket is approximately 29/64" Wd. x 7/32" Thick.
High-Temperature Cable— Max. continuous heat output is 250° F. Can be exposed to temperatures from -40° to +428° F. Cable with metal braid is approximately 3/8" Wd. x 5/32" Thick. Cable with metal braid and jacket is approximately 13/32" Wd. x 13/64" Thick. "
When my engine is up to temp my injector housing shoots at 160°F. Logically, with a 6/1 fuel rate that should be enough to get the temp up but I've heard enough people who've done it say differently.
Thanks, Geno
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