Dual feed VE

[bgilbert]

Any benefit to dual fuel feeding the VE? Seems like I heard some guys are doing this Where would the second feed enter the pump? Reason I ask, is my fuel pressure regulator has two outlets, one of which is plugged right now and it might add to the cool factor under the hood .

[wannadiesel]

Some guys have talked about feeding pressure direct to the pump case, but it seems like a recipe for a big fuel leak to me...

[KTA]

Pump case can run as high as 120psi in stock form, not really a problem putting 60psi of fuel pressure to it. If I didnt have my truck apart at the moment I might take some pics of what I rigged up. I'll try to elaborate on it later if there is interest.

[bgilbert]

If I didnt have my truck apart at the moment I might take some pics of what I rigged up.

Probly not something easily rigged up by the average home mechanic eh?

[TOMTOM]

All ctd owners are above average. Guys give all avable info on fuel systems. just added a pump in-line but want a big set up. also did i mention i have a complete P-PUMP. Don't give me a reason to install it.
(just jokeing) i want to play a lot more with the VE before that happens.
TOMTOM

[Cschafer]

I would like to know more about this also.

[JLeonard]

If there is only one inlet port it makes no sense to run two lines into it. Just use one big line to handle the volume. At 500 hp you will need approximately 25 gal per hour of fuel flow. Someone can do the math, but something like 3/8 or 7/16 ID can handle that I would think.
I had 1/2 inch id lines in my boat for the 6bta 270 I had and it was flowing 45 gph (includes return fuel).

[g1625s]

I think problems arise when too much pressure is fed to the inlet on the VE. So, even with 1/2'' line, only so much volume can be pushed into the inlet before the shaft seal starts leaking fuel into the timing case. By adding fuel directly to the pump top which regularly sees 120+psi (as was already stated), ruining the inlet side seal is averted and the ability to keep pump case volume and pressure at desired levels is now possible through an aftermarket pump designed for such a job, rather than the weenie vane-style pump on the inlet side, which seems to be all done by 350 rwhp or so.

[wannadiesel]

My fuel leak comment seems to have been misinterpreted. I meant that you need a high pressure feed pump and lines, and those have to be capable of handling the same pressures as the pump case. Just taking some diesel hose and a couple hose barbs and plumbing a system isn't going to cut it here. You also need a pretty serious pump.

I think the idea has great potential, but I'm not ready to do the R&D myself.

[Begle1]

Wouldn't it be possible to put a pressure regulator on the line going into the injection pump? So you could have two pumps in parallel going up to a regulator set at 15 PSI. On the lift-pump side of the regulator you could see pressures over 30 PSI, but the injection pump would only ever see 15 PSI.

Why hasn't anybody ever done that? If the problem with having big lift pumps (even piston pumps) is that the shaft seal can't take it, why not just regulate the pressure so that the seal never sees above 15 PSI?


I'm very skeptical of putting an auxiliary pump straight into the pump case. Isn't the case pressurized in such a way as to correlate with engine speed? The faster the engine, the faster the vane pump, the higher the case pressure and the more advanced the timing?
If that's true, then not only do you need a pump that can supply over 100 PSI, it also needs to coordinate its pressure output with the vane pump's. Which sounds rather insurmountable.

[Cschafer]

one pump that flows enough that's regulated at 15psi has been done before. There would be no advantage to running two pumps if you get one that has enough. I would like to know more about this dual feed system though.

[Begle1]

one pump that flows enough that's regulated at 15psi has been done before. There would be no advantage to running two pumps if you get one that has enough. I would like to know more about this dual feed system though.

Well, after you install the piston lift pump the next step is to an electric fuel pump. Since it's just as easy to install the electric pump in parallel with the mechanical pump as it would be to remove the mechanical pump, a lot of the higher horsepower guys are running both; some use the mechanical for cruising and flip on the high-flow electric for romping time.


I don't think we've reached a consensus yet about what "dual feed" exactly refers two; either having two lift pumps feeding the vane pump, or having a lift pump feed the vane pump while also having a 100+ PSI pump bypassing the vane pump and shooting fuel straight into the shutdown-solenoid hole. The latter system is more of a thought experiment and I don't think it sounds possible...

And now I've realized that the original poster has a fuel pressure regulator and I managed to go full circle all by my self. Duhhhh, i plaey futballe........

[bgilbert]

I'll probly make myself look stupid here, but here goes....

Ok there Mr Kta , you've got everyone talkin about this at Scheid's event and on the other sites... Is 15psi of fuel pressure, at idle, feeding directly into the fuel return port of the VE enough ? What about all that internal pump case pressure?

I take it with no fuel drain out of the VE, it will always have positive pressure? Or will the case pressure/fuel run right back into the fuel pressure regulator, then back to the tank? I'm trying to understand this, ole Ayers got me thinking.. and confused lol. I already got metric/AN fittings on hand and the Aeromotive regulator so it wouldn't be nothing to plumb another line to the VE.

[jogl]

The guys going for big mileage running VW 1.6's and 1.9's with VE pumps like to monitor the case pressure. If I recall correctly they think that case pressure is used somehow for the governor function in the pump.

Anyhow, there might be some interesting reading about case pressure on some of the VW diesel forums.

JP.

[KTA]

No you need a check valve on the return with a T-fitting so that the dual feed only flows in when the case pressure is less than the supply pressure. Case pressure is normally between 45 and 110psi, and yes it controls the timing in the pump.