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#15
by
the caveman
on 08 Aug, 2008 14:29
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Why are you installing a lift pump for a vehicle that doesn't normally have one? I was doing it on a couple of conversions and only after having complaints that the cars had less power i read on VWdiesel parts forum that Hager and now a couple of engineers have confirmed that using a feed pump will retard the timing which is the opposite of what i would think you would want and in particular for VO applications] by screwing with the internal pressure of the IP. Now i don't want to start any arguements, but 3 indepentant sources and my own experience seem to show that it may just make things worse. I do know there are ways to inprove the systems that Bosch and VW have developed, however i believe that they have had them installed at the factory if they really needed them. I also think that in installations with looped returns , the pump helps to mask problems that wouldn't be there if the overflow is just returned to the tank like every other diesel system in the world.
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#16
by
greg123
on 08 Aug, 2008 16:47
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Well, you are entitled to your opinion.
If you just name the cars that vw produced suitable for running on vegoil, I'll be happy to take your comments on board.
If not - maybe there is a reason we loop return and use a lift pump. The liquid that is being moved from that tank, under suction alone per factory, is much thicker than diesel. There is NO way as OEM that such a system would be commisioned without a lift pump. Did you know that many cars from FACTORY have a lift pump fitted? Technically, it's far superior. Of course it's cheaper to omit it!
What makes you think that timing is altered? It's set electronically - why would it suddenly be retarded because of a low puressre on the lift? Do you think that 200tdi, 300tdi, BMW & Vauxhall 2.5 to name a couple run retarded timing due to their factory lift pumps?
As a vegoil converter, seeing many vehicles and familiar with the many suction and air ingress problems in non-lift pump vehicles, I know why I'd want one.
IMHO of course, we all pays our money and takes the choice!
Greg.
Why are you installing a lift pump for a vehicle that doesn't normally have one? I was doing it on a couple of conversions and only after having complaints that the cars had less power i read on VWdiesel parts forum that Hager and now a couple of engineers have confirmed that using a feed pump will retard the timing which is the opposite of what i would think you would want and in particular for VO applications] by screwing with the internal pressure of the IP. Now i don't want to start any arguements, but 3 indepentant sources and my own experience seem to show that it may just make things worse. I do know there are ways to inprove the systems that Bosch and VW have developed, however i believe that they have had them installed at the factory if they really needed them. I also think that in installations with looped returns , the pump helps to mask problems that wouldn't be there if the overflow is just returned to the tank like every other diesel system in the world.
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#17
by
greg123
on 08 Aug, 2008 16:48
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Anyhow buddy, you were asking about the PD originally, which does have a lift pump.
Cheers, Greg.
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#18
by
the caveman
on 08 Aug, 2008 19:13
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Yah after some arguing with a couple of people, all VW PD's have a lift pump. And yes on any PD conversion i will be installing a pump.
As for older VW"s i've now done about 18 , mostly older , but about 1/3 TDI's. None have had a premature failure, and a couple have covered over 100,000 kms. One Eurovan i have done has done close to 150,000, kms and just last week his IP kicked the bucket. However the truck has 388,000 kms and even though the pump was rebuilt once, it was at least 6 years ago, and before the conversion was done.
As for the timing i should have made it clear that i was talking about non TDi IP's . The full mechanical IP's should not use a lift pump. It screws with the timing. As for pulling thick VO, thats why all the heat exchangers possible should be used,tank,filter and i use vegetherms which heat it up to 100 o C . Of course there is a school of thought which says we could heat it up to 300 o C but then you're going to have other issues. Only if the oil is heated that much will the VO come close to diesel viscosity. In most applications the VO is still 2-3 times thicker. So matter what you do, there are comprimises to be had when using VO.
I appreciate your opinion, and am always trying to make conversions better for my customers.
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#19
by
greg123
on 08 Aug, 2008 19:42
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Your tank is at the back of the car. How does a heat exchanger help with pulling it from the tank???
As for the timing on the EPVE - can you give me some more info, I'm interested. In my single tank conversions I haven't noticed a change in engine note and mpg and economy were both better when running closed loop with lift pump, the engine noticably struggling more on full throttle when pulling thick veg from the tank just on the minimal EPVE interal lift pump 10 foot away under the bonnet. That was on an XUD I played with, after that I just lift pump as a matter of course. Again, how to you explain how the LR 200/300tdi's run? They have lift pump, and a EPVE from factory. Others too.
What kind of feedstock are you using? Std liquid vegoil at 70-80c is well in the margin of diesel viscosity. Have you done any viscosity testing with your fuel?
As for the therm kits... I don't touch them. Reason being, are you using more than 3kw of electric? Because that's what the small, compact, all alloy heat exchanger will give. All from coolant heat, no electricity and hence drag on the alternator. Yes a therm would warm it up a bit quicker if you use enough glow plugs, however as it's a bad idea to inject oil till the combustion chamber is hot (and hence coolant) what's the point. A heavy duty version on a single tank conversion, maybe I can see the merit in that.
I am not aware of any school of thought that would have oil at 300c, that temperature crude breaks down and distills off, so I can only guess what it would do to vegoil? Further, what it would do to pump seals and electrics/rubber/plastic I can take a good guess!
It's great you have had successful conversions, however I try to look from the technical standpoint. I know of many EPVE engines that have lasted many k unconverted. It doesn't mean they are running right though. I know of many people who had been running engines for years with retarded injection timing. Again, doesn't mean they were performing as they should. I know a guy who never changed his oil and never had a problem. But I think we would agree that technically, that's not a good idea.
Great to talk to you and I agree, always good to improve things. Let me know more about that pump advance with lift pump issue thing - I'm keen to check that out.
Greg.
Yah after some arguing with a couple of people, all VW PD's have a lift pump. And yes on any PD conversion i will be installing a pump.
As for older VW"s i've now done about 18 , mostly older , but about 1/3 TDI's. None have had a premature failure, and a couple have covered over 100,000 kms. One Eurovan i have done has done close to 150,000, kms and just last week his IP kicked the bucket. However the truck has 388,000 kms and even though the pump was rebuilt once, it was at least 6 years ago, and before the conversion was done.
As for the timing i should have made it clear that i was talking about non TDi IP's . The full mechanical IP's should not use a lift pump. It screws with the timing. As for pulling thick VO, thats why all the heat exchangers possible should be used,tank,filter and i use vegetherms which heat it up to 100 o C . Of course there is a school of thought which says we could heat it up to 300 o C but then you're going to have other issues. Only if the oil is heated that much will the VO come close to diesel viscosity. In most applications the VO is still 2-3 times thicker. So matter what you do, there are comprimises to be had when using VO.
I appreciate your opinion, and am always trying to make conversions better for my customers.
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#20
by
the caveman
on 09 Aug, 2008 18:30
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Hey greg123
will make this short as i'm going on vacation tomorrow [i love being able to drive 2000 kms for free and causing 40 % vless pollution] and am wrapping up all my emails etc and i won't get back to any for a week.
The heat exchanger i'm talking about is a Hotfox or other tank heater. I also use The triple bypass hose that golden Fuel systems sell as i like that the 3 hoses are wrapped together and so keeping the VO warm as it runs to the front.
Any time i'm talking about not using an extra pump is on mechanical IP vehicles that don't have a lift pump from stock. I will concede that perhaps a TDI or any other electronic control pump may benifit, however my 98 TDI jetta [now sold to a very good friend] has now been running for almost 2 years and about 38,000 kms without one without any running issues.
I will get some data on VO viscosity [ i just hired a new guy who has had many years of running VO diesels in Bulgaria and is writing a university paper on VO and diesels] and pump timing with modified systems. this will interesting for all of us i'm sure.
The Vegetherms use only 240 -390 watts and once warm pull a very easily low current. Very simple design, low possibilty of failure and cross comtamination of fluids.
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#21
by
jtanguay
on 09 Aug, 2008 23:23
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i think using exhaust heat to heat the veg oil would be far superior... doesn't take long for the exhaust to get warm :wink:
i find it hard to believe that adding a lift pump (4 psi or so??) would interfere much with the timing. extra pressure is bled off by the pressure relieve valve is it not? (older diesels) but at the same time, it can only bleed off so much pressure...
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#22
by
Tintin
on 09 Aug, 2008 23:31
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around 30-50 psi at idle and up to 100-150 psi at high RPM for a VE pump, I really dont think that the 4-10 psi lift pump can affect the timing.
If its really affect, Its a little help in high rpm, not the inverse, but with a good pump adjustment, no need a lift pump on VE TDI.
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#23
by
jtanguay
on 09 Aug, 2008 23:56
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around 30-50 psi at idle and up to 100-150 psi at high RPM for a VE pump, I really dont think that the 4-10 psi lift pump can affect the timing.
If its really affect, Its a little help in high rpm, not the inverse, but with a good pump adjustment, no need a lift pump on VE TDI.
by adjustment you mean the pressure bleed valve or even replacing the feed pump if its worn too much?
i've been thinking that the little solid state fuel pumps might not be able to flow enough fuel for high rpm if the pump is set up to deliver lots of fuel... they have anti siphon valves etc so if the pump were to lose power, the injection pump would be starved... a set of lines with check valves could take care of that though
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#24
by
jimfoo
on 09 Aug, 2008 23:59
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i've been thinking that the little solid state fuel pumps might not be able to flow enough fuel for high rpm if the pump is set up to deliver lots of fuel... they have anti siphon valves etc so if the pump were to lose power, the injection pump would be starved... a set of lines with check valves could take care of that though
That's what I have and fuel can be sucked through mine.
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#25
by
Tintin
on 10 Aug, 2008 00:05
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i've been thinking that the little solid state fuel pumps might not be able to flow enough fuel for high rpm if the pump is set up to deliver lots of fuel... they have anti siphon valves etc so if the pump were to lose power, the injection pump would be starved... a set of lines with check valves could take care of that though
That's what I have and fuel can be sucked through mine.
Exactly.
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#26
by
G60ING
on 14 Aug, 2008 19:06
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I've added list pumps to an AHU and ALH. Both responded well to 6-10PSI.
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#27
by
the caveman
on 25 Aug, 2008 13:41
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Last week my customer came back because we decided that his PD probably should use a lift pump, because the OG system has one. So i go and wire it all in so that the og one runs on diesel and shuts off while the extra one runs on VO. Well while figuring everything out and reading some of the PD course lit again i see that the OG lift only works to circulate the fuel through the cooler when it hits a certain temp. So all to say that this is all bull*** because the OG pump isn't even there to push fuel to the front. BTW he drove his car for 3500 kms before i did install the second pump with no running issues.
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#28
by
jtanguay
on 25 Aug, 2008 13:45
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Last week my customer came back because we decided that his PD probably should use a lift pump, because the OG system has one. So i go and wire it all in so that the og one runs on diesel and shuts off while the extra one runs on VO. Well while figuring everything out and reading some of the PD course lit again i see that the OG lift only works to circulate the fuel through the cooler when it hits a certain temp. So all to say that this is all bull*** because the OG pump isn't even there to push fuel to the front. BTW he drove his car for 3500 kms before i did install the second pump with no running issues.
very interesting... thanks caveman! i'll stick with my little solid state fuel pump though. they're great for fuel filter changes
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#29
by
the caveman
on 25 Aug, 2008 16:15
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I would like to keep this thread going as to really understand all this. The info about IDI IP pump pressures and VO viscosity is still coming. I'm still trying to get into work mode since my vacation. BTW we drove to the south coast of New Brunswick from Montreal -2400 kms and it cost me 40 bucks of diesel.