Veggiestroke/valveless RTT/loop switching.

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

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Postby hheynow » Mon Mar 24, 2008 9:55 pm

I like the idea of putting a tee and switch on the B99 return line. When driving on B99 it returns to rear tank and when purging you switch it to return to the front tank. When I converted my truck my vegoil tank return port was capped off. There is no reason why it can't be used again. My vegoil has a looped return and my rear tank still is prone to cross contamination. Seems to be the easiest solution for me.
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Re: RTT

Postby Welder » Tue Mar 25, 2008 3:28 am

sanderlings wrote:Hi Welder,

I hope your pump project is on track. I don't know what kind of connections are on your return, but on the 6.2L there is a daisy chain of push-on tubes that connect all the injectors with the return line. I have run a looped return before without problems, but I got cold feet about the push-ons being in the loop with the IP and return to tank on my revised "valveless" system.


Yeah, the Frankenpump project is moving along slowly. I've got the DC motor and fuel regulator and I've ordered the pump head. They've shipped it, but it hasn't arrived yet. A custom machined direct drive system is planned.

Anyway, getting back on topic, what do you mean by cold feet? I understand the expression, but I don't know how you've applied it to your coment on your return plumbing mods.
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Cold Feet

Postby sanderlings » Tue Mar 25, 2008 6:05 am

I just got worried about all those loose (On the 6.2 anyway) connections being put into service in the fuel delivery loop. They are designed to just handle the return to tank under slight pressure. In a looped system they might come under a vacuum and I was worried about air getting into the lines. I guess I could wiggle in there and put sixteen little spring clamps on those tiny lines but I opted for RTT.
todd
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Postby roverhybrids » Sun Mar 30, 2008 9:27 pm

SunWizard wrote:
Welder wrote: I'm wondering if constantly bleeding veg flow off of the veg line wouldn't decrease the pressure availabe at the IP intake.

.......
A full loop is the simplest since you save another pipe run and tank fitting, and I have never had air problems. A full return is less simple since you need to run another pipe all the way back to the VO tank (same with limited loop.) And you then are pumping, heating and filtering about 5x as much fuel as you would if looped. Which means you will get slower switchover times since you are consuming your coolant heat much faster and having to heat much more volume. And you will have to change your VO filter more often since it needs to be cleaner to flow 5x as much.


Wouldn't the switchover time still be the same since the VO is not yet flowing to consume the coolant heat?
Or are you refering to the fact that you need more coolant heat exchange for the higher flow rate of RTT, so the system design for RTT would take longer to switchover?
Are you not using TIH and a 30 FHE?
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Postby SunWizard » Sun Mar 30, 2008 9:42 pm

I am using TiH and a 26 FPHE. Its mostly that you need much more heat available for RTT, and when its cold, even turning on my cab heat can use all the available heat and then the coolant doesn't hit 180F for miles more. So with that plus the heat that RTT would consume, I could switch at 150F and then have the coolant and VO get cooler, and take a long time to get to the usual 180F. So I would need to wait longer before I switched to avoid that. These are things I have learned by having a VO temp guage before the IP, and watching that and the coolant temp closely when its cold.

Often when its cold I can tell that my thermostat never opens for 30 miles. Which tells me I am using all the spare heat the engine is producing to heat my cab and my VO, with none to spare into the radiator. This is with a full loop, and a full RTT would make that balance worse. Having a winter front blocking 90% of the radiator helps more than anything I have tried, including the block heater. Since it lowers the airflow over the entire engine, IP, and lines.
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Postby tommc56 » Sun May 04, 2008 7:30 pm

"I am using TiH and a 26 FPHE. Its mostly that you need much more heat available for RTT, and when its cold, even turning on my cab heat can use all the available heat and then the coolant doesn't hit 180F for miles more. So with that plus the heat that RTT would consume, I could switch at 150F and then have the coolant and VO get cooler, and take a long time to get to the usual 180F. So I would need to wait longer before I switched to avoid that. These are things I have learned by having a VO temp guage before the IP, and watching that and the coolant temp closely when its cold.

Often when its cold I can tell that my thermostat never opens for 30 miles. Which tells me I am using all the spare heat the engine is producing to heat my cab and my VO, with none to spare into the radiator. This is with a full loop, and a full RTT would make that balance worse. Having a winter front blocking 90% of the radiator helps more than anything I have tried, including the block heater. Since it lowers the airflow over the entire engine, IP, and lines."




It would be nice to have a way to monitor the temp at the injector line as well , such as a clamp on aquastat or mechanical gauge to get a feel for IP heat consumption and purge time . Additionally , a remote or thermostatically controlled , full radiator shutter might be the most effective insulation available .

Tom
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