The Glow plug heater IS a proven WVO heater. YOU must use the right amperage glow plug though. The Mercedes Glow plug heats to about 1100/1200degs!! Theres no way the WVO is going cool a red hot glow plug tip down around 100degs or so.

well MAttSD300, your question was going south. many posters said it is not the best design and there might be something else you can do. pawoSD made a suggestion about a better way, and that idea is what i was trying to improve upon.

with comments like that you might as well just answer your own questions...

You wanna reduce the voltage to a glow plug?
Wire a 2nd glow plug in series with it. Now you have 1/2 the voltage and 1/4 the wattage in each plug, they should last forever and convert half as much electricity into heat as a single plug.

Thats what I would suggest as well. Twice the surface area of two GPs would make for a much better heater.
You would have to electrically insulate the pipe fitting from ground. Two insulated tees plumbed together, connect +12volts to one gp terminal ground wire to the other gp terminal. Added bonus is the current requirement drops too.

That sounds like a plan....
As discussed...run 2 of these orignial t fittings together, with 1 mercedes gp in each unit. If each heats to about 1,200 degrees, with the reduction in voltage each would now heat to 600...or 300 degrees...(Dan says 1/4 the wattage...would be 300 degrees each.) AND with 2 in unison the fuel is being heated longer , and would get to the temp you're looking for ......

ANy comments?

Mitch & WhiskyDan,

Thanks so much!... Thats a great idea!:D

I'd make a controller circuit using a large MOSFET and a variable duty-cycle pulse controller, to get the right temperature. The temperature can be measured indirectly by the resistance of the heater, which can be determined by the voltage across a low-value high-wattage resistor in series with the ground. More voltage (during the on cycle) means more current, lower resistance, and thus lower temperature.

Translation please for the rest of us...

I understand him......:D







But then I have a background in electronics...








Its basicly building a self regulating heater...........

I was thinking the same thing. Your not necessarily limited to MB glow plugs. Look around till you find one that suits your needs.

Danny

Partial translation: A MOSFET (Metal Oxide Semiconductor Field-Effect Transistor) is a type of transistor which takes no input control current (that's a fudge - there is capacitance at the junction) and, if run in so-called saturation mode, has extremely high or extremely low conductivity, which means that in reality, it takes almost no power from the circuit even if switching a high current (which you will have). "Normal" transistors are called bipolar, and they always have a voltage drop on the controlled current, thus they always take power from the circuit. Taking power isn't the problem; the problem is getting rid of the heat generated to avoid destroying the transistor. With a 1 volt drop and a 15 amp current, you need a 15 watt transistor. That's a lot of heat. While it can be achieved, I'd just go with a MOSFET.

Duty-cycle is the ratio of on-time to total-time for a square-wave signal. A duty cycle of 1 (100%) means always on, 0 means always off. In between gives you variable power, even though it's always either full or none at any given instant. Varying the duty cycle can give you variable power, as needed.

As for measuring the temperature, this is how it's done in a MAF sensor. Controlling the duty cycle from this is really not very complex, although the circuit design is complicated by the fact that you can only reference the temperature when the MOSFET is conducting.

You are overthinking this one. All glowplugs, not just MB plugs, get really hot like 1100-1200*F hot. A glowplug is designed to heat the air in a prechamber and provide a localized hot spot for the fuel to ignite on. When you use them to heat WVO or any other liquid they stay MUCH cooler if there is significant flow past the element. This should be obvious as you are now asking the glowplug to heat a much more than it was designed to and also using a far better conductor of heat than air, WVO. Chrisboyer has already pointed out that a single glowplug heater was not enough for a VW Rabbit diesel. Glowplug "heaters" installed in WVO systems are generally used to boost the WVO temp after it has already gone through the coolant heat exchangers right before the WVO enters the IP. They also work well installed in a fuel filter head to keep the filter from plugging. They are not enough to heat the WVO significantly on their own. On domestic pickup truck diesels that have been converted to a two tank WVO system is isn't uncommon to see 3 or 4 glowplugs used at full power to heat WVO. Another way to regulate the WVO temp is to install a temp gauge in the fuel line right before the IP. If the WVO temp gets to high, turn the heater off. RT

Porcocane!
 

:eek: Note to self: Never buy a used diesel from a WVO'er.:eek:

LOL :P

But think of all the interesting engineering that may be onboard the vehicle! :D :D ;)