10mm to 11mm pump rebuild questions/ thoughts for performanc

[shortysclimbin]

Gents,

Finally got my hands on a few spare pumps. One is a perfectly good 10mm tdi pump and the other is a 11mm pump that has been crispyfried due to a car fire. Needless to say I just started pulling the 11mm apart to get ready in install the parts into the 10mm pump. I do have a few questions for someone who has done this.

1) if I am swapping out the camplates-right through the pump head do I need to worry about any of the feed pump rotations internals behind the spring gear?  What possition should I lock the pump at before pulling it apart?

2) REading through the documents in the facts area..."Fuel is metered by the movement of the control sleeve in relation to the plunger cutoff port, Figure 12. Moving the control sleeve changes the effective stroke. The effective stroke is the period at which fuel is pressurized at injection pressure. The longer fuel is pressurized at injection pressure, the longer the effective stroke. So, the longer the control sleeve covers the cutoff port, the longer the effective stroke, and more fuel is injected. At idle the control sleeve is more to the left, providing a short, effective stroke. As more fuel is needed to meet demand, the control sleeve will move further up the plunger, increasing the effective stroke. Note that the mechanical stroke of the plunger remains the same." Has anyone tried to increase the control sleeves size? Was it effective?

3)"At the bottom of the injection pump is the automatic-advance timing device. As fuel-supply pump pressure increases, the piston moves the roller ring opposite to drive shaft rotation, advancing injection timing, Figure 22. As engine speed increases, fuel pressure from the ve pump also increases. This allows the timer piston to overcome thetimer spring, causing the roller housing to move opposite cam-plate rotation. The rollers then engage the cam-plate high points earlier, advancing injection timing."

I know there is such a thing as the kerma timing mod, but all I see it doing is spacing the timing advanced in comparision to stock. Now with this mod we still have 27.5 degrees of advance max? Is there anyway to open up the case and cut the advance area larger and allow more motion of the piston that allows advancement? How is this electronically controlled?

4) Many of us use lift pumps in line with the ve style injection pump to help keep the main pump lubricated and supplied with fuel. General rule of thumb has state that 8psi is the limit of the system. Why was this stated? Looking at the drawings all I can see is that the main pump case relief valve would be the only thing effected right away. Past that your internal pump pressures would be higher and your control sleeve, and delivery valves would operate sooner.  

What I am wondering is why dont we increase the case relief spring pressure, open up the high pressure chamber area, and use higher pressure delivery valves? (which BTW the 10mm and 11mm pump uses two different valves!) I would think by doing this it would allow us to pump higher pressure and volumes of fuel into the pump increasing pump case pressures.

Any info would be great. I would love to be able to see this 11mm pump push more fuel pressure and higher timing advances...

[Tintin]

1: Dont understand exactly what you mean........  but you only have to enligne the camplate pin with the woodruff key on the main shaft

2: you are right, exept that It's impossible to increase the control sleeve size, and anyway it does not change nothing.

3: You are right, and you can cut the timing piston shorter or grind a little inside the timing piston cover, but you have to allow 1mm for a gain of 1 - 1.2 degre timing.

Mechanically the pump allow to 26-27 degre of timing, but in a real world you get a max of 22-23 deg. depending of the initial timing setting.

Pump housing pressure is higher than what is needed to move the tming piston, there is a bleed valve under the pump wich control the pressure to keep the timing in the right area.

4: Pump housing pressure has nothing to do with injected fuel, even if you supply the pump with 100psi, you cannot get more injected fuel, anyway the internal pressure are higher than that,  around 50 psi at idle and close to 130-140 psi at higher RPM.

8 to 15 psi is enough to supply the pump in fuel, more than that is a waste of time.

Increasing the case pressure is necessary if there is a high chip tuning, to successfully get the timing on that request, and especially with a bigger head rotor.