Lister Engine Forum

How to / DIY => Everything else => Topic started by: rcavictim on October 15, 2006, 01:07:54 PM

Title: Injector preheaters, making your own
Post by: rcavictim on October 15, 2006, 01:07:54 PM
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.
Title: Re: Injector preheaters, making your own
Post by: fuddyduddy on October 15, 2006, 03:12:14 PM
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.



Title: Re: Injector preheaters, making your own
Post by: Mr X on October 19, 2006, 02:30:32 AM
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
Title: Re: Injector preheaters, making your own
Post by: biobill on October 19, 2006, 06:19:54 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
Title: Re: Injector preheaters, making your own
Post by: Geno on October 19, 2006, 03:00:21 PM
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

Title: Re: Injector preheaters, making your own
Post by: Mr X on October 19, 2006, 04:00:56 PM
Geno It depends on what your burning, wvo acording to Fatteywagon site requires hot hot, in the range of 180- 300 f . I think the stuff your looking at is for melting the snow in your roof gutter. Check out wvo site http://www.fattywagons.com/fwlinks.htm.
   Poke around Forrest Gump site and get some ideas. Ive heard its not good to get your dino diesel real hot, but it is for wvo.
Title: Re: Injector preheaters, making your own
Post by: Geno on October 20, 2006, 09:34:01 AM
Mr_X, I agree with what you say, Alternate fuels need to be hot. McMaster had many other options for heat cable.
Heres a copy of the page. Let me know what you think.
http://www.genedevera.com/temp/mcmaster/Mcmaster.htm

I haven't seen it with my own eyes yet (and others who have say differently) but it still *seems* to me that the fuel will be the same temperature as the injector housing. Its a decent size chunk of metal with about a quart of fuel an hour going through it.

Just exploring the possibilities.

Thanks, Geno
Title: Re: Injector preheaters, making your own
Post by: dkwflight on October 29, 2006, 04:32:00 PM
Hi I wanted to use a/c for my injecter heat too.
I ordered part no. 36005k35 from mcmaster-Carr.

http://www.nelsonheaters.com/
This is a self regulating heat tape with a draw of 15 watts per foot. runs on 115v.

I thought this stuff would heat to 250f per mcmasters  description.
What I get is 100- 105 by my infared thermometer.
It does heat up to this level fairly quickly.
It turns out that this is the top limit for exposeing the heat tape to an out side source of heat.

Siince I bought this stuf I will try it out on veggie oil.  I will wrap the heat tape with friction tape to try to keep the heat in and transfer to the injecter line better.
 I will post my results when I have some.
Dennis
Title: Re: Injector preheaters, making your own
Post by: Geno on October 29, 2006, 05:02:03 PM
I thought this stuff would heat to 250f per mcmasters  description.
What I get is 100- 105 by my infared thermometer.
It does heat up to this level fairly quickly.
It turns out that this is the top limit for exposeing the heat tape to an out side source of heat.

Thats good info Dennis. Where does that top temp limit info come from? Also the tape you bought is "self regulating" I wonder what the "constant wattage" tape would do.
Thanks, Geno
Title: Re: Injector preheaters, making your own
Post by: dkwflight on October 29, 2006, 11:25:08 PM
Hi I have an e-mail in to Nelson              http://www.nelsonheaters.com/

For more information.
Nelson says this tape can be exposed to up to 250f from extrenal sources like steam heat. The Mcmaster-car info implies the tape is good for 250f. A completely different thing.
Nelson heaters have several different products that are good for up to 11oo degrees. Most need thermostatic control of some sort.

The constant wattage stuff is good for much longer lengths the heater wire is connected every so often so you can cut it to length.
Dennis
Title: Re: Injector preheaters, making your own
Post by: rcavictim on October 30, 2006, 12:02:19 AM
Well by golly I have it!  What one needs are a whole handfull of tiny ceramic beads with a hole through the middle.  Slip them onto a piece of nichrome wire and wrap that around the injector.  Use a step down isolating power xfmer from the mains voltage to power it safely.  Operate that heater incandescent red if you need to without worry about melting it.  Pack a wad of rock wool and some aluminum HVAC or HVDC tape around that for outside protection and to keep the heat in.

Brilliant or what!?  ;D
Title: Re: Injector preheaters, making your own
Post by: Mr X on October 30, 2006, 01:32:02 AM
There is some tape I think it is silicone tape it has no adesive on it but bonds to itself  good for 250 or maybe 500 f not sure its in my shop and aint running out ther.Try wrapping with that. This stuff is easily avalible seen it in the building supply and Canadian tire. And Macmaster Carr.
Title: Re: Injector preheaters, making your own
Post by: Guy_Incognito on October 30, 2006, 02:26:48 AM
How about a 12V 100W H1 or H3 halogen bulb in close proximity to the injector, wrapped in rockwool or whatever you've got to insulate it? There's a hundred watts of heat in a package that's pretty small as opposed to 15W per ft of tape or nichrome wire.

Easy to put in, gets plenty hot, safe voltages, relatively small, a couple can be added around the injector as needed.

Main issue is that you'd probably want a small air gap around the globe - it's quartz envelope is designed to run at a high temp to allow the internal halogen cycle to work properly. But still - all the heat's got to go somewhere and if the metal body of the injector is the only thing near it that will transfer the heat away, it'll go there.
Title: Re: Injector preheaters, making your own
Post by: rcavictim on October 30, 2006, 02:56:55 AM
How about a 12V 100W H1 or H3 halogen bulb in close proximity to the injector, wrapped in rockwool or whatever you've got to insulate it? There's a hundred watts of heat in a package that's pretty small as opposed to 15W per ft of tape or nichrome wire.

Easy to put in, gets plenty hot, safe voltages, relatively small, a couple can be added around the injector as needed.

Main issue is that you'd probably want a small air gap around the globe - it's quartz envelope is designed to run at a high temp to allow the internal halogen cycle to work properly. But still - all the heat's got to go somewhere and if the metal body of the injector is the only thing near it that will transfer the heat away, it'll go there.

I don`t think the filament will take the engine vibration for long which can be very severe on some of the singles like my Petter, and full wattage rating would likely melt the bulb if the heat was not allowed to escape through the design open air radiation process.  Less than proper operating temp and the halogen cycle wouldn`t work, leading to filament evaporation.  Too sum up, I don`t think that will work.
Title: Re: Injector preheaters, making your own
Post by: Guy_Incognito on October 30, 2006, 03:58:42 AM
Quote
Too sum up, I don`t think that will work.

You'd be suprised. Allow me to let a little bit of experience with underground mining equipment slip through:

- Low voltage filaments are rather thick. I use 24V dichroic halogen bulbs on mining equipment in solid metal frames that gets shaken enough to break any loose wiring on the brackets in a day or two and hot enough in the tiny metal frames that it will eventually burn the connecting wiring off the pins. In those conditions they run about 400-800 hours before bulb failure.

- I've run 24V bulbs at 12V for hundreds of hours without deposits forming on the envelope (used as low intensity tail lights). In a confined space next to an injector, envelope temp should be high enough to allow the halogen cycle to work ok at 12V.

Anyway, it's cheap enough to experiment a little with it.

Otherwise, as you mentioned, there's beaded ceramic heating wire you can use. I didn't recall it until you mentioned it, but I used to use it for large solder pots that ramped up to 500 deg C.
Title: Re: Injector preheaters, making your own
Post by: rcavictim on October 30, 2006, 04:58:31 AM
I guess my challenge now is to find a source of suitable ceramic beads.  Anyone have any ideas?
Title: Re: Injector preheaters, making your own
Post by: buickanddeere on October 30, 2006, 05:17:54 AM
  How about a heat exchanger using exhaust thermnal energy? It would even be possible to send some heated fuel back via a return line to the supply tank. This would improve filtration and col/cold weather flow from storage.
Title: Re: Injector preheaters, making your own
Post by: Guy_Incognito on October 30, 2006, 05:24:37 AM
Try :

http://www.saxonburgceramics.com/ceramic-insulators/ball-socket.html

or

http://www.du-co.com/standard/ball.php

Hmmm. In the same city? Makes me wonder if they're in cahoots.

But I'd probably get some from RS components, as they're pretty good on supply/delivery times.
http://rswww.com/cgi-bin/bv/rswww/searchBrowseAction.do?obs=sObs&name=SiteStandard&No=0&N=0&Ntk=I18NAll&Ntt=fishspine
(If that URL's mangled, search for 'fishspine' on the RS components site.)
Title: Re: Injector preheaters, making your own
Post by: rcavictim on October 30, 2006, 05:29:29 AM

     Re: Injector preheaters, making your own
« Reply #16 on: October 29, 2006, 09:17:54 pm »
   Reply with quote
  How about a heat exchanger using exhaust thermnal energy? It would even be possible to send some heated fuel back via a return line to the supply tank. This would improve filtration and col/cold weather flow from storage.


Buick,

If you can successfully wrap a section of exhaust pipe around the fuel injector that allows the injector to be serviced when required please do so and send us pictures of how you did it.

For me a injector heater that is practical, effective and easy to service is more important than the 25-50 watts of electrricity it will rob from the output of the plant.
Title: Re: Injector preheaters, making your own
Post by: dkwflight on October 30, 2006, 11:16:31 PM
here is their reply

Dennis,

 

There are many factors that will affect the amount of heat you will see in this type of application.  The cable’s output is directly affected by its environment.  To estimate the heat, you will need the following information:

 

Insulation type and thickness- friction tape is not a traditional insulation, would need K Factor and thickness

Line size, outer diameter

Minimum ambient temperature

Wind speed

Is product flowing or non-flowing- if flowing, you will need additional information such as flow rate, specific heat, mass, incoming temps, etc.

 

To evaluate this yourself, you can download our design software from the website and input your variables.

 

Best regards,

 

Nelson Heat Trace

 


Dennis
Title: Re: Injector preheaters, making your own
Post by: dkwflight on October 30, 2006, 11:20:12 PM
Hi
The ceramic bead idea has merit. I was thinking a light dimmer, with enough capacity, would control the temps OK.
Dennis
Title: Re: Injector preheaters, making your own
Post by: rcavictim on October 30, 2006, 11:56:52 PM
Hi
The ceramic bead idea has merit. I was thinking a light dimmer, with enough capacity, would control the temps OK.
Dennis

The light dimmer will work to adjust the heat OK but I wouldn`t operate such a heater in intimate contact with a grounded engine block without some form of transformer mains isolation for shock and fire protection.  You could use the dimmer with a 120 volt to 120 volt line isolation xfmer that was rated at the wattage required.  The dimmer would go after the xfmer on the heater element side of the xfmer.  When I suggested a DIY ceramic bead heater element in the earlier post you will note I suggested ther use of an isolating xfmer.  With a step down xfmer of the appropriate voltage for the application the dimmer or variac, etc. could be eliminated entirely.
Title: Re: Injector preheaters, making your own
Post by: Andre Blanchard on October 31, 2006, 12:13:57 AM
With a step down xfmer of the appropriate voltage for the application the dimmer or variac, etc. could be eliminated entirely.

With the appropriate voltage out of the transformer you could also just use the steel injector line as the heater element.
Title: Re: Injector preheaters, making your own
Post by: rcavictim on October 31, 2006, 12:25:21 AM
With a step down xfmer of the appropriate voltage for the application the dimmer or variac, etc. could be eliminated entirely.

With the appropriate voltage out of the transformer you could also just use the steel injector line as the heater element.


If you just wanted to heat the line that would work very well.  In my case I wish to concentrate heat on the injector itself.
Title: Re: Injector preheaters, making your own
Post by: SCOTT on October 31, 2006, 02:07:22 AM
Here is what I use for preheating vo:
Item #3641k23 page 473 at Mcmaster.

I wrapped the 3ft section of wire around ¼” copper tubing that I used to replace the stock steel line.  As you can see from the picture below I added a temp probe using a brass “T” close to the of injection coupling.  I was able to get temps as high as 250f and probably could have gone higher if I had not unplugged the heater

(http://thumb17.webshots.net/t/53/553/4/67/41/2345467410098736957vmHuQU_th.jpg) (http://good-times.webshots.com/photo/2345467410098736957vmHuQU)

That is all fine and good, but I don’t want to baby-sit this thing, so I am going to add a bimetal thermal switch which will be configured as normally closed open on rise at 250f.  The switch should arrive by next week. 

High pressure line:
I am not sure what kind of pressure the pump creates, and I only used copper because it was easy to work with for this initial test.  I had intended on using brake line as the injector line, it has pretty good flex and can withstand higher pressures than the copper.   I have tested the copper arrangement for a few weeks and one drawback is the amount of time it takes to purge the system of Veg oil after switching back to diesel.  As you can see in the picture below the ID of the copper is much greater than the original steel line, the steel is <2mm and the copper is around 5mm.

(http://thumb17.webshots.net/t/59/59/8/44/72/2380844720098736957AYRnvY_th.jpg) (http://good-times.webshots.com/photo/2380844720098736957AYRnvY)

The wire above is with the shielding pulled back.


The copper conducts better but the steel is stronger and allows for a quicker changeover, I will use the steel.  Another advantage of the steel is that the thickness of the walls allows for some degree of heat storage, it is like a mini heat sink.  This becomes important when the load increases, the temp will not drop as quickly as with the thin walled copper.  Going along with the heat sink theme the new version I am building will have an area of increased mass to allow for more heat storage. It is in some ways analogous to the flywheel on the lister itself, they store kinetic energy, the increased mass will store the heat, helping to lessen internal veg oil temp swings.  See below

(http://thumb17.webshots.net/t/34/34/4/99/96/2284499960098736957ZKApIn_th.jpg) (http://good-times.webshots.com/photo/2284499960098736957ZKApIn)

That piece of steel is 1 ¼” thick x 1 ¼” wide and about 2” long it weighs about 1lb.  The hole in the picture will be taped ¼” NPT to accept the temp switch; there is another hole on the side for the temp probe, which is just an automotive temp gage.  The heat rope will be countersunk into the block and the edges will be rounded, I may add conductive putty but I don’t think it will be needed.  The entire line and steel piece will be insulated with ceramic insulation from Mcmaster

One last note, it is important to cover the line from the pump on up to the injector, the flywheels create a lot of air movement, simply holding a piece of cardboard under the line allowed the fluid temp to rise at a faster rate. 

When the next version is done I will post some pics and some performance data.

Scott
Title: Re: Injector preheaters, making your own
Post by: Geno on October 31, 2006, 12:46:17 PM
Here is what I use for preheating vo:
Item #3641k23 page 473 at Mcmaster.
I wrapped the 3ft section of wire around ¼” copper tubing that I used to replace the stock steel line.
Scott

Good info. Thats the stuff I was thinking about trying after reading Dennis's experiment. 3' of that stuff equals 125 watts. No wonder it got so hot. Based on your findings I'll probably try 6" (25w) or a foot (50w) wrapped directly around the injector and wrapped in some high temp tape. When up to temp my injector housing shoots at 160-170°F I don't think I'll need more than a few watts to get it up to 250°F
Thanks, Geno
Title: Re: Injector preheaters, making your own
Post by: buickanddeere on October 31, 2006, 04:33:35 PM
  "If you can successfully wrap a section of exhaust pipe around the fuel injector that allows the injector to be serviced when required please do so and send us pictures of how you did it."

  I was talking about pre-heating the fuel just prior to the injection pump. It's not too difficuilt to make a double wall hx for the exhaust stack. Or even just loop the line in a coil in close proximity to the exhaust stack. My Deere tractor has a couple of loops from each of the injector return lines between each leg of the exhaust manifold. The fuel line returning to the tank is plenty warm to hang onto.
  Exhaust heat system is easier to control with a return line to the fuel tank. Keeping the alternate fuel warm in the tank and through the filter never hurt either. Waxed up or jellyed fuel never flows very well through a tank/line/pump/filter or what ever. Alternate fuel more so than #2 diesel oil. 
  Starting on diesel and swapping to atlernate fuel once temps have been achieved is the usual method. Insulating the line between the injection pump and the injector will keep the fuel hot. On a 210F coolant temp engine the injector should be hot enough  it's at least not cooling down the fuel.   
  Of course with the hotter, less dense and light viscosity fuel. Injection delievery will have to be increased slightly to maintain full HP.
  This system also keeps the clutter away from the high pressure pipe work.
Title: Re: Injector preheaters, making your own
Post by: gpkull on November 01, 2006, 01:18:17 AM
heaters for your injector lines can be purchased pretty much dirt cheap. 12volt 12bucks each have not priced 120volt but dont need to. yes preheat the golden or black gold to the ip but the line heater after the ip heats to way higher than the ip can stand and the inj loves it . can heat till your juice cooks or cokes in the line the hotter the more viscuos = the better atomization = the cleaner burn less carbon . i would not waste my time with beads and such. thats me and for what its worth thats my two pennys
Title: Re: Injector preheaters, making your own
Post by: Geno on November 01, 2006, 11:37:40 AM
Here is what I use for preheating vo:
Item #3641k23 page 473 at Mcmaster.

Hi Scott, can that heat tape be cut shorter to give less wattage? I'd like to buy a couple one foot pieces, one for the injector and one for the IP and would like to customize the output for each application. The price is about the same and I don't want to come up short with 6" pieces.

Thanks, Geno
Title: Re: Injector preheaters, making your own
Post by: SCOTT on November 01, 2006, 01:43:39 PM
Geno
There is nothing specific in the description that says they can be shortened, but then again there is nothing that says they cant.  In practice they can be cut to shorter lengths.  I know this only because I was a bit to aggressive unwrapping the wire from the injector line.  The wire lead separated from the thin coiled heating element, I just cut some of the core material away and re crimped the lead wire back on.  The element works fine, using a Kill-o-watt meter, my 36” wire draws about 100watts, so based on the mcmaster numbers I cut off 25watts worth of element.

You may consider adding a thermal temp switch, they can be had for about $30 and they will do a good job regulating the temp.  I should have one operational in about a week, mine is a probe that will be in contact with the actual fuel.  I think that a surface mounted thermal temp switch would also do a pretty good job; you would just have to raise the set point a little because you are not measuring the actual fuel temp.  The surface mounted switch has the advantage of allowing you to keep the fuel line intact, and makes for a less complicated install.

Scott
Title: Re: Injector preheaters, making your own
Post by: SCOTT on November 09, 2006, 02:02:50 AM
Below is a picture of the current version of my injection line heater,

I am using the Mcmaster heat rope mentioned in an earlier post, along with some automotive break line tubing and a few “T” pipe fittings.  The bottom “T” fitting houses the thermal switch, which is set: normally closed (on) open (turn off) on rise set point 120c or 248f.  I had to use black pipe vs. brass because the brass was a little too short for the probe.
The upper “T” houses the automotive temp probe I took my temp readings from.  In the background you can see another thermal switch for a radiator fan.  This one was to be set normally open, close on rise set pt 105c or 221f.  They sent the wrong set point, (150c or 302f) so I have not tested the radiator switch yet.

(http://thumb17.webshots.net/t/59/559/1/35/32/2763135320098736957ATMMnY_th.jpg) (http://good-times.webshots.com/photo/2763135320098736957ATMMnY)

I ran the engine for about an hour and the temp gage registered a high reading of about 240f and a low reading of just above 200f.  I don’t remember what the dead band was rated as,  and am not sure of the accuracy of the temp gage, it is a sunpro from JC whitney.  The probe has a contact MTBF rating of 100,000 cycles @6 amps 120Vac.  I expect the temp range will tighten once the line is insulated and shielded from the “wind” of the flywheel.

More results to follow.

Scott

Title: Re: Injector preheaters, making your own
Post by: rcavictim on November 09, 2006, 04:16:11 AM
Anyone else find it impossible to view Scott`s picture on webshotz?  That site is a real waste of time if you have dialup. 
Title: Re: Injector preheaters, making your own
Post by: Guy_Incognito on November 09, 2006, 05:45:56 AM
I'm curious - anyone know what the injection pressure is on that engine?
Just wondering how well your temp sensor and thermal switch will handle pulses of "x" hundred (er, thousand?) PSI long term.
Title: Re: Injector preheaters, making your own
Post by: SCOTT on November 09, 2006, 02:02:19 PM
Rcavictim,
I posted the same pic in coppermine, at a much more compressed level, link below
 
http://listerengine.com/coppermine/displayimage.php?album=lastup&cat=10064&pos=0

Guy_Incognito
The temp switch is rated at 7000psi so I have no doubt it will be fine, the temp sensor is not of the same quality, I do not know what the psi rating on that is.  The pressure of the pump is the main reason I switched from copper tube to break line.  I would rather use the stock steel lines, but I did not have a good way to secure it to the block of steel that I had drilled and taped to accept the thermal switch and the temp probe.  I think the pipe is too small to weld and I never tried to braze or silver solder anything. 
Any suggestions?

Scott
Title: Re: Injector preheaters, making your own
Post by: Guy_Incognito on November 10, 2006, 01:35:55 AM
Never thought the temp switch would be good for 7000PSI  :D

What's the I.D. of the steel line? Perhaps you could flare (or double-flare) it and use standard brake-style flared fittings in your steel block? Don't know how standard steel compression fittings and olives would hold up.
Title: Re: Injector preheaters, making your own
Post by: SCOTT on November 10, 2006, 02:35:39 AM
Guy_incog..
As you can see in the picture below the ID of the copper is much greater than the original steel line, the steel is <2mm and the copper is around 5mm.  The break line is about the same ID.

(http://thumb17.webshots.net/t/59/59/8/44/72/2380844720098736957AYRnvY_th.jpg) (http://good-times.webshots.com/photo/2380844720098736957AYRnvY)

Flaring is unfortunately not an option.  I think the only way to do this is by brazing or silver soldering.  I may try that on the next version.  The downside to using the break line is that the switch from VO to diesel takes longer
Title: Re: Injector preheaters, making your own
Post by: Guy_Incognito on November 10, 2006, 03:06:03 AM
I thought that would be the case  :-\ It's kind of indicative of the pressures they're under as to the amount of steel in that pipe. I know that contained volume in injection lines is a factor as well, but still... Makes me worry a little bit about the thin-walled pipe you're using as a replacement.....

But silver soldering should do the trick. If you drill a reasonably snug recess for the pipe (3/8" deep should do), use a goodly amount of flux, and sweat the silver solder + pipe into it.
Title: Re: Injector preheaters, making your own
Post by: Geno on November 16, 2006, 12:44:15 PM
Got my heat rope. 1', 50 watt, high temp. The same stuff Scott used just shorter. The rope shoots at 300-400°F Its diffucult to get an accurate reading where the housing enters the block but the housing on top shoots at 210°F with the power on and around 160°F with it off. Its to early to be sure but this amount of heat seems about right. Thanks Scott for breaking trail. I'll put another piece on the pump soon to thin the WVO in it.

(http://www.genedevera.com/listeroid/engineroom/P1010059.jpg)

(http://www.genedevera.com/listeroid/engineroom/P1010060.jpg)

http://www.warrensburgvendors.com/geno/listeroid/#engineroom

Thanks, Geno
Title: Re: Injector preheaters, making your own
Post by: SCOTT on November 16, 2006, 02:03:51 PM
Geno
Be careful with that heat rope.  The rope really needs to be in contact with metal over the whole length that is braided. If it is not in contact with metal it may get too hot and burn out, it needs to be able to sink the heat it is generating.  You may want to try wrapping the rope around the injector line vs. running it parallel, you will have a larger contact area between the rope and injector.

Or you could shorten the rope.

I like the clean simple install.

Scott
Title: Re: Injector preheaters, making your own
Post by: Geno on November 16, 2006, 03:03:46 PM
The exposed leads are the pigtails that do not get hot. The thicker, braided, hot portion is under the tape, in contact with the injector housing and not crossing over itself. I'm often wrong but I reasoned that getting the heat as close as possible to the injector tip will reduce losses. This is the first time I've tried it but I just can't get it out of my head that the large injector housing at 165 F will cool off the WVO. 165F or so is where it runs without any outside heat source. It would be easy to put the heat rope on the injector line, let it get hot and shoot the housing though.

Thanks, Geno
Title: Re: Injector preheaters, making your own
Post by: SCOTT on November 16, 2006, 03:36:32 PM
AHH

I can see in the second pic that the part of the rope with the heating element is in contact with the housing, my mistake.

I tend to agree with you that the fuel will take on the temp of whatever it is in contact with.  In my setup It takes on the temp of the heated injector line, but then most likely cools down once it reaches the housing which has no active heating.  I like the idea of heating close to the point of injection.  The only drawback is that I can't think of a good way to accurately measure the fuel temp and regulate the heating element.

It may be possible to add a surface mounted thermal switch to the injection housing as long as ther is a good flat surface big enough.  But then again regulation may not be needed if you can size the rope properly as you seem to have done.  I am interested in your wvo test results, keep the good info comming

Scott
Title: Re: Injector preheaters, making your own
Post by: Geno on November 16, 2006, 07:23:06 PM
The only drawback is that I can't think of a good way to accurately measure the fuel temp and regulate the heating element.
Scott

Agreed. I'll probobly peel back some tape near the bottom and shoot it after things have had time to warm up. Not perfect but should be pretty close.

It may be possible to add a surface mounted thermal switch to the injection housing as long as ther is a good flat surface big enough.  But then again regulation may not be needed if you can size the rope properly as you seem to have done.  I am interested in your wvo test results, keep the good info comming
Scott

I want to size the heat rope properly. Partially for simplicity and partially because I'm tired of getting nickel and dimed.

I should have time for some better testing this weekend

Thanks, Geno

Title: Re: Injector preheaters, making your own
Post by: Joe on November 17, 2006, 01:58:13 PM
Geno,
   I have to say I really enjoy your website…well organized…great pictures …easy to navigate…lots of facts and excellent detail in many different areas…it really makes for some nice reading….

Joe
Title: Re: Injector preheaters, making your own
Post by: listerdiesel on November 18, 2006, 08:03:06 AM
Well by golly I have it!  What one needs are a whole handfull of tiny ceramic beads with a hole through the middle.  Slip them onto a piece of nichrome wire and wrap that around the injector.  Use a step down isolating power xfmer from the mains voltage to power it safely.  Operate that heater incandescent red if you need to without worry about melting it.  Pack a wad of rock wool and some aluminum HVAC or HVDC tape around that for outside protection and to keep the heat in.

Brilliant or what!?  ;D

http://www.oldengine.org/members/diesel/Ebay/Beads2.jpg

Peter