shared filter performance veggie system

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

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shared filter performance veggie system

Postby mike_belben » Tue Feb 23, 2010 5:00 am

i like sunwizard's system very much, but my 12v p7100-pumped cummins is modded and nearing the stock lift pump limitation. my fuel lines are also in need of an update from weather and age, so im looking to do a complete fuel system overhaul in conjunction with my veggie conversion all at once.

-remove OEM lines, lift pump, fuel heater and filter
-install single electric fuel pump, 90 gph@45 psi or so
-all new fuel lines
-filter & heat exchanger pressurized rather than vaccuum.

this is what i had in mind.
Image

mind you, this would also run diesel through a flat plate heat exchanger and likely heat it to 160+F. i felt like this was dangerous at first but recently found out the truck has a fuel heater on it stock. also, liquid fuel in sealed lines cant combust without air, right? hot diesel should atomize very quickly, reducing smoke and improving economy as well.


id prefer to have one one selector valve running through the floor and to leave the system with a looped return all the time. the 3 way valve for the return line would be under the cab, only for filter changes or repairs.

other than the obvious "forgot to purge before shutdown and now the veggie is gelled" scenario, what do you expect i would run into with this arrangement?
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Postby coachgeo » Tue Feb 23, 2010 11:51 am

how/when does the stock fuel heater work? As in is it thermostatically controlled?

Does your engine's IP design use the cooler temps of the diesel to help drop the temps of your IP?

Does your IP use your fuel as a lubricant and will your IP lube well enough with heated thinned out diesel? If not... you might should consider running with a bit of veg in your diesel to up the lube qualities of the fuel.
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Postby John Galt » Tue Feb 23, 2010 1:45 pm

you might should consider running with a bit of veg in your diesel to up the lube qualities of the fuel.

That's the simplest solution to the problem some people have with heating diesel fuel, 5% VO is adequate.
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Postby mike_belben » Tue Feb 23, 2010 2:37 pm

boy those are good questions i hadnt considered. to the best of my knowledge the bosch p7100 pump is engine oil lubed and the fuel heater is just a coolant loop through a small exchanger, often deleted on performance trucks. though i dont know whether thats due to the restriction or the need for fuel cooling effect.

on the flip side, id certainly expect to run well with SVO in the grease tank as well as a hearty veg blend in the D2 tank during warm months for even further fuel savings by using the heated setup for both tanks.


im also unsure about fuel return issue on large electric transfer pumps at idle. wondering if the return line diameter will need to be increased to accomodate the extra fuel being pushed to the IP at idle. a bigger return should let the pump freewheel against a small resistance and hopefully extend its life.

your thoughts?
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Postby SunWizard » Tue Feb 23, 2010 4:35 pm

The stock fuel heater is on a thermostat so its only on below 40F which is a good useful design. I wouldn't heat my D2 since its got poor to marginal lubricity and its easy to avoid heating it.

I wouldn't add an electric fuel pump, there is nothing stronger than the stock piston lift pump for VO. Electric pumps including the $600 ones don't even come close for life and performance. And the stock ones are cheap and available at almost every auto parts store nationwide.

The stock pump is good for fuel volume for huge amounts of mods. If you are modded at all, you should be careful of lube oil polymerization. Anytime your mods blow any smoke, thats unburned fuel which gets scraped off by piston rings and into the crankcase.

Sharing a filter for D2 and VO is a bad idea. It makes purges take way too long since its hard to clean out all the VO from the pleats of the filter. It eliminates the very useful feature of 2 filters, so if either one gets plugged you can switch to the other filter and not have to be changing a filter in the dark, snowing, 10F below, etc.
YVORMV - Your veg. oil results may vary.
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81 Mercedes 300D- stock and happy on V80/D20 blend.
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Postby mike_belben » Tue Feb 23, 2010 5:11 pm

no offense intended at all, but im having a hard time understanding how a gear rotor pump could have difficulty with veggie vs diesel? whats the failure mode? i use a gear rotor to pump unfiltered veggie with large particles at cold temps with no trouble whatsoever.

i'll do a little more research on the stock pump's power limits, seems everyone's first recommendation is to just get a FASS. my truck isnt ever going to roll coal, its got 90hp injectors, a number ten plate, air-raide intake and 4" straight back. only smokes on cold startup and very lightly at WOT. a little more boost and tranny mods are where it will probably end up. i dont rev past 2200.

thanks for the info
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Postby mike_belben » Tue Feb 23, 2010 5:19 pm

SunWizard wrote:
Sharing a filter for D2 and VO is a bad idea. It makes purges take way too long since its hard to clean out all the VO from the pleats of the filter.


whether running shared filter or separate, im not following how it would be any longer. are you saying that a two tank system switches back to diesel after a purge cycle that does not completely flush all veggie out of the filter? with a two filter, youre still waiting just as long to purge diesel through the veg right? are the filters of vastly different composition?

i do agree about the failsafe beauty of two filters for certain.
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Postby SunWizard » Tue Feb 23, 2010 6:29 pm

When you have 2 filters, one of them always is totally full of VO. Purge takes <1 minute instead of 5.

Filters can be many compositions, makes no difference to purging.
Last edited by SunWizard on Tue Feb 23, 2010 6:44 pm, edited 2 times in total.
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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Postby SunWizard » Tue Feb 23, 2010 6:33 pm

If you aren't blowing big clouds of smoke on hard acceleration, then you aren't even close to the limits of the stock piston pump.
Last edited by SunWizard on Tue Feb 23, 2010 6:48 pm, edited 1 time in total.
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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Postby SunWizard » Tue Feb 23, 2010 6:35 pm

mike_belben wrote:whats the failure mode?

Many failure modes, brushes that go out, shaft seals to leak, bearings, motors windings wear out. The piston pump is run off the cam, no motor to wear out. And it adjusts its flow to the engine RPM nicely.
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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Postby mike_belben » Wed Feb 24, 2010 1:14 am

alright, points taken on the E-motor failures, and big fueling on veggie being a no-no. thanks.




question about your system, and this may be miniscule:

<img src="http://www.xyzworks.com/voconversion.jpg">

the return valve either sends diesel back to the diesel tank, or sends WVO back into the WVO line just before the tank selector valve. if the return loop were tapped back in just upstream/after the tank selector (between tank valve and lift pump) couldnt you leave it looped regardless of which tank you were drawing from? or does an excess of return volume cause problems?






When you have 2 filters, one of them always is totally full of VO. Purge takes <1 minute instead of 5.



??

whether using a shared filter or separates, the veggie filter and heat exchanger -whose volumes are fixed- must be flushed of veggie in their entirety, correct? how can devices of fixed volume have varrying flush times if the pressure and flow of diesel to flush them remains constant? what am i missing?


thanks again for the help
mike
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Postby John Galt » Wed Feb 24, 2010 2:28 am

Use a separate coolant loop for the FPHE, and another parallel loop for all the other VO heating devices.

Avoid the problematic tube in hose. Bundle the lines together and cover with foam pipe insulation.

Avoid heating the whole tank, use a heated fuel pick-up instead.
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Postby mike_belben » Wed Feb 24, 2010 6:51 am

thanks for the tips john

my smokestack is going to be tucked up against the side of the veggie tank with a sheetmetal heatshield to heat the pickup tube area. might not need to run coolant into it at all but i will be incorporating the option when i fab it up.

ill see about drawing up a schematic for the coolant lines to be sure i get what you're saying
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Postby SunWizard » Wed Feb 24, 2010 10:14 am

mike_belben wrote:the return valve either sends diesel back to the diesel tank, or sends WVO back into the WVO line just before the tank selector valve. if the return loop were tapped back in just upstream/after the tank selector (between tank valve and lift pump) couldnt you leave it looped regardless of which tank you were drawing from?

Yes you could do that, but purge would take far longer since you would be slowly diluting the VO in the loop with D2, instead of quickly (1 gpm) emptying the lines and IP of VO and sending it all back to the VO tank.
There are no advantages to looping on D2, only drawbacks.

whether using a shared filter or separates, the veggie filter and heat exchanger -whose volumes are fixed- must be flushed of veggie in their entirety, correct? what am i missing?

The VO filter and FPHE don't ever have to be flushed of VO with 2 filters.
Last edited by SunWizard on Wed Feb 24, 2010 10:24 am, edited 1 time in total.
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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Postby SunWizard » Wed Feb 24, 2010 10:21 am

John Galt wrote:Use a separate coolant loop for the FPHE, and another parallel loop for all the other VO heating devices.

This extra complexity isn't needed with this vehicle since it has a strong coolant flow. Mine heats up the VO to within 10F of coolant temps without a special loop for the FPHE.
Avoid the problematic tube in hose. Bundle the lines together and cover with foam pipe insulation.

There are 1000s of systems using TiH, and few reports of problems. The only problems I have heard were from kinking the tube during installation, which is also a problem with bundles. If you don't do TiH, you will need to put the FPHE before the filter, which creates a whole new set of problems.
Avoid heating the whole tank, use a heated fuel pick-up instead.

Agreed.
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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