Injector temperature

For discussing the modifications needed for diesel vehicles to run with 2 tank veggie oil conversions.

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Re: Injector temperature

Postby SunWizard » Mon Apr 09, 2012 1:44 pm

othello wrote:And I assume you would add the FPHE before the filter to give the filter the maximum benefit of already hotter oil?

No, I put it after the filter, as close to the IP as possible to minimize heat loss. The WVO before the filter is heated with TiH line. The WVO only needs to be >40-50F to pass the filter, so no need for max. temp there.
othello wrote:And do you then top this off with eletcric line heaters for the steel lines leading to the injectors? In my Mercedes the steel lines are apt to loose a lot of heat from the IP to the injector.

No, insulation works to prevent that for a lot less money. And I block a portion of the radiator, up to 90% depending on temps, and it makes a huge difference, more than any other item. A 176F thermostat should be fine, thats all I have used for 6 years on 3 different vehicles, and my WVO is always >160F at the IP.
YVORMV - Your veg. oil results may vary.
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Re: Injector temperature

Postby othello » Fri Apr 20, 2012 3:45 pm

Well, I changed my thermostat, that increased the coolant temperature by nearly 10 C, it was low before.
I also blocked part of the radiator and installed a FPHE.

So now the temperature of the VO is higher up to where it exits on its way to the IP and then onward to the motor.
Leaving the FPHE it is around 75C and it looses around 10C on the rest of the way.

My injection pump is just not that hot and it also is quite a chunk of metal which would first need to warm up, but the wind probably cools most of that off again.
Do others experience the same temp drop going thru the IP and beyond??
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Re: Injector temperature

Postby John Galt » Fri Apr 20, 2012 10:59 pm

And I assume you would add the FPHE before the filter to give the filter the maximum benefit of already hotter oil?
No, I put it after the filter, as close to the IP as possible to minimize heat loss.
That has caused problems when poly formed in FPHE's and 'trashed' the IP and injectors. It's always good practice to leave the OEM filter and IP unaltered and introduce alternative fuels and heaters upstream of that OEM filter. Insulating the filter, IP and lines will help retain heat.
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Re: Injector temperature

Postby othello » Sat Apr 21, 2012 4:02 am

So I guess now I am caught between John's and SunWizard's opinion where to put the FPHE.
And I guess when John speaks about the unaltered OEM filter you do mean the heated WVO filter!?!

What I like about John's approach, if I understand it correctly, is that the last thing before the injection pump is a filter, the heated WVO filter.
And the heat losses I am concerned with should be dealt with by insulation.
Is that right?

That leaves the question of how to best insulate the IP and the steel lines going to the injectors, there is not much space there.
A picture, preferably for a Mercedes 300 series, would indeed be worth a thousand words.
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Re: Injector temperature

Postby othello » Sat Apr 21, 2012 6:59 am

Another thing.

I noticed that the temperature of the FPHE fluctuates, I can only explain this with uneven flow of my coolant.

And is it not correct, that every narrowing of my heater loop which goes to my veggie tank in back, that every unevenness in resistance of the various loops of coolant, creates uneven flow, or, under certain circumstances, flow could come to a stop.

If this were correct than an addition of an extra coolant boost pump would not only be a good idea, but nearly a necessity, or not?
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Re: Injector temperature

Postby John Galt » Sat Apr 21, 2012 8:14 pm

othello wrote:And I guess when John speaks about the unaltered OEM filter you do mean the heated WVO filter!?!


Original Equipment Manufacturer, ie. the filter that came with the engine.

What I like about John's approach, if I understand it correctly, is that the last thing before the injection pump is a filter, the heated WVO filter.


Yes, that would accomplish the same thing.

the last thing before the injection pump is a filter
Yes, that's the important factor, regardless if it's the OEM filter or an added filter.

And the heat losses I am concerned with should be dealt with by insulation.
Is that right?


I agree.
That leaves the question of how to best insulate the IP and the steel lines going to the injectors, there is not much space there.

I used multiple layers of recycled aluminum foil, cheap, easy, effective

an addition of an extra coolant boost pump would not only be a good idea, but nearly a necessity, or not?


You could do that, or simply give the FPHE it's own separate parallel coolant loop. That's the best design that gives the most heat to the FPHE.

The most reliable systems have the engine coolant circuit connected like this:

╔=coolant pump====╗
╠=cab heater======╣
╠=FPHE ==========╣
╚=HOH+filter+etc===╝
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Re: Injector temperature

Postby SunWizard » Mon Apr 23, 2012 2:54 pm

othello wrote:What I like about John's approach, if I understand it correctly, is that the last thing before the injection pump is a filter, the heated WVO filter.
And the heat losses I am concerned with should be dealt with by insulation.
Is that right?

Its not good to put a large filter after the FPHE, since it will contain a large amount of cool WVO (even the best heated filters make very little heat) which gets burned poorly since its cold in the critical first 10 miles after switchover. Much better to put a tiny clear inline filter after it if you are worried about your FPHE spitting chunks. If your WVO is so bad and full of poly that its making buildup in your FPHE (which I have never seen in 6 years) there is likely buildup in all your lines and inside your IP so you have a much bigger trouble to watch for.
YVORMV - Your veg. oil results may vary.
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Re: Injector temperature

Postby John Galt » Mon Apr 23, 2012 3:18 pm

poly that its making buildup in your FPHE
There have been numerous reported incidents of poly forming in the FPHE, which they attributed to the FPHE being continuously heated while full of UVO not circulating.
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Re: Injector temperature

Postby othello » Mon Apr 23, 2012 3:22 pm

SunWizard wrote:Its not good to put a large filter after the FPHE, since it will contain a large amount of cool WVO (even the best heated filters make very little heat) which gets burned poorly since its cold in the critical first 10 miles after switchover. Much better to put a tiny clear inline filter after it if you are worried about your FPHE spitting chunks. If your WVO is so bad and full of poly that its making buildup in your FPHE (which I have never seen in 6 years) there is likely buildup in all your lines and inside your IP so you have a much bigger trouble to watch for.


Well, I can't say that I am worried my FPHE might be spitting chunks, I do have little experience with all of this and at this point listen to the experience of others. And without first hand experience many of the arguments brought forth here seem plausible to me.

But you brought up now the not often mentioned first few miles after switchover which dump varying amounts of rather cool WVO into my IP.
What is the effect of that?
Is this offset/made good/cleaned away by a large amount of hopefully very hot WVO which follows?
Or would not an electric injection line heater help much in this critical phase, it could be switched of after some time?
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Re: Injector temperature

Postby SunWizard » Mon Apr 23, 2012 3:33 pm

othello wrote:But you brought up now the not often mentioned first few miles after switchover which dump varying amounts of rather cool WVO into my IP.
What is the effect of that?

The effect is a bad spray pattern in the injectors which can lead to smoke, deposits on the rings, and a rebuild after a long but unknown mileage.
Is this offset/made good/cleaned away by a large amount of hopefully very hot WVO which follows?

Not ever made good, ring deposits can require a rebuild as the only fix. The hot WVO only gets there after 10 miles if its your 1 quart size stock filter full of cold WVO, and this is why a tiny filter is better.
Or would not an electric injection line heater help much in this critical phase, it could be switched of after some time?

They help but are a very small amount of heat and not enough if you are pumping cold WVO into the lines for those 1st 10 miles. A tiny filter solves any worry about the uncommon problem of chunks from FPHE for a lot less money. And it gets the hot WVO to the injectors quicker.
YVORMV - Your veg. oil results may vary.
95 Dodge Cummins 4x4 SVO WVO conversion.
81 Mercedes 300D- stock and happy on V80/D20 blend.
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Re: Injector temperature

Postby SunWizard » Mon Apr 23, 2012 3:37 pm

John Galt wrote:There have been numerous reported incidents of poly forming in the FPHE, which they attributed to the FPHE being continuously heated while full of UVO not circulating.

That one is easily solved by putting a ball valve on your coolant loop(s) so that if you are not running WVO for a long period, you shut off heat to the WVO side. A ball valve on the coolant flow is also very handy to balance the flow between the cab heater versus the WVO side. I run on WVO all the time after the coolant is warm, so I have never had to use that valve even though I installed one just in case I was on a trip where I couldn't find any WVO.
YVORMV - Your veg. oil results may vary.
95 Dodge Cummins 4x4 SVO WVO conversion.
81 Mercedes 300D- stock and happy on V80/D20 blend.
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Re: Injector temperature

Postby othello » Sun May 06, 2012 7:54 pm

The way I routed my FPHE right now is after the switching valve, so it is heating both diesel and WVO.

The reasoning is that when I start on diesel and the diesel gets warmed up it will already pre-warm the pump and the injectors a bit, so the transition period when I switch to veggie oil will be reduced.

Sofar that seems to work. And I haven't blown up my car yet.
Which would be hard to do with diesel at 60 C.

Or am I missing something??
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Re: Injector temperature

Postby coachgeo » Wed May 09, 2012 11:25 am

othello wrote:...And do you then top this off with eletcric line heaters for the steel lines leading to the injectors? In my Mercedes the steel lines are apt to loose a lot of heat from the IP to the injector.

Esp. with the MB 617A motor Very few use elec. line heaters. Few even use inj. line insulation. Fuel's Time spent inside the steel injector lines is very small in the over all scheme of things. Not much time spent there for temp of the oil to drop. You should see marked improvment in all area temps once you got her worked out to be getting better heat transfered into the oil from the coolant system.

Typically the 617 engine loves veg. fuels. It is the least problematic engine to convert to veg. and tends to be the engine that most easily combust fuels outside of diesel.
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Re: Injector temperature

Postby SunWizard » Wed May 09, 2012 12:13 pm

othello wrote:The reasoning is that when I start on diesel and the diesel gets warmed up it will already pre-warm the pump and the injectors a bit, so the transition period when I switch to veggie oil will be reduced.

Or am I missing something??

A large % of the diesel is returned to the tank, so you are transferring the limited heat during warmup from the coolant to the diesel tank. This would make warm up of the coolant take longer. Since the switch should be after the coolant is warm, this means you would have slower time to switchover. The opposite of what you think.

If you loop the diesel to avoid this, then you would get the same time to switchover as if you didn't heat the diesel at all. But your WVO will be cooler at switchover and for the first few minutes, since its not sitting still in the hot FPHE during the warmup time. And this option would add the problem of any air that gets in the loop would never have a chance to get out, and could build up to cause trouble.
YVORMV - Your veg. oil results may vary.
95 Dodge Cummins 4x4 SVO WVO conversion.
81 Mercedes 300D- stock and happy on V80/D20 blend.
Low fossil net zero house- 100% solar power and heat.
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Re: Injector temperature

Postby othello » Fri May 11, 2012 5:00 am

SunWizard wrote:If you loop the diesel to avoid this, then you would get the same time to switchover as if you didn't heat the diesel at all. But your WVO will be cooler at switchover and for the first few minutes, since its not sitting still in the hot FPHE during the warmup time. And this option would add the problem of any air that gets in the loop would never have a chance to get out, and could build up to cause trouble.

Oh, I need to understand that last sentence better.
Why would I possibly "accumulate" air in the system if I pre-heat both diesel and WVO, meaning the FPHE is installed after the last electrical switch valve??
If you could please elaborate on this point.

During this work my injector temperature has slowly been improved and now is up to 70C.
But hesitation still troubles me at times. I don't know the cause but trapped air could be one of them.
The other could be a clogged filter.
Since I try and clean my oil very diligently (with a centrifuge) I think the heated WVO oil filter should last longer than the 500 to 1500 miles I get. Unless it runs to cool and glyzerin or whatever else is in this oil clogs it, and not dirt.
At what temperature should the WVO typically pass thru the filter?
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