Need clarification on using a 4BT Injection Pump for a MTDI

[mullenba]

I've been searching the forums till my eyes bleed trying to come up with a plan for my project.  I'm swapping an ALH engine into a Vanagon Syncro that will generally be very heavily loaded. 

Reading the thread http://www.vwdiesel.net/forum/index.php?topic=5990.msg47083#msg47083 it's mentioned "The cummins pump in stock form with the gov. assembly, etc. will not work properly...however, if you were going to use the pump on a vanagon, there have been some that have found that the "loaded" gov. setup, like what is used on the bread vans, etc. the 4bt pump came from works well for pulling the weight of the vanagon..."

So does this really mean that I could use an unmodified 4bt pump?  If I prefer the 4bt governor, then changing the rest of the parts would be unnecessary?

[westyventures]

I've been searching the forums till my eyes bleed trying to come up with a plan for my project.  I'm swapping an ALH engine into a Vanagon Syncro that will generally be very heavily loaded. 

Reading the thread http://www.vwdiesel.net/forum/index.php?topic=5990.msg47083#msg47083 it's mentioned "The cummins pump in stock form with the gov. assembly, etc. will not work properly...however, if you were going to use the pump on a vanagon, there have been some that have found that the "loaded" gov. setup, like what is used on the bread vans, etc. the 4bt pump came from works well for pulling the weight of the vanagon..."

So does this really mean that I could use an unmodified 4bt pump?  If I prefer the 4bt governor, then changing the rest of the parts would be unnecessary?

It depends on which '4BT' pump you have. Some come closer to working than others. That's why I bought 35 identical pumps for my production. The basics are: you'll need a stronger throttle / governor spring to achieve rpms over 2800, which is what most 4BTs were set at. Also, you'll need the timing piston, spring, and cover from the TDI. The tricky part: the internal pressure control valve, which affects the timing curve - a lot. Too much pressure and too much advance and it will be very noisy, crack pistons, and make poor power above 3000. Too little and it will smoke. Also to consider is the 4BT pump normally doesn't have a DI-specific cam plate shape, so the pressure might be a bit off. Also, the 12mm head size is too much for injectors under .230 in size. I usually install a 10- or 11-mm head for most users, and TDI cam plate. The most powerful mTDIs don't smoke or make much 'diesel noise'.

[dodger21]

It depends on which '4BT' pump you have. Some come closer to working than others. That's why I bought 35 identical pumps for my production. The basics are: you'll need a stronger throttle / governor spring to achieve rpms over 2800, which is what most 4BTs were set at. Also, you'll need the timing piston, spring, and cover from the TDI. The tricky part: the internal pressure control valve, which affects the timing curve - a lot. Too much pressure and too much advance and it will be very noisy, crack pistons, and make poor power above 3000. Too little and it will smoke. Also to consider is the 4BT pump normally doesn't have a DI-specific cam plate shape, so the pressure might be a bit off. Also, the 12mm head size is too much for injectors under .230 in size. I usually install a 10- or 11-mm head for most users, and TDI cam plate. The most powerful mTDIs don't smoke or make much 'diesel noise'.

$20 at a Bosch shop. You can do it yourself in about an hour if it is off the engine. Bosch Number: #1-464-650-366 Make sure it ends in 366! 386 is the stock one.

There is no internal pressure valve. The only 2 pressure valves are for the KSB (affects timing. Power to it advances it a few degrees) and the return orifice which is 2 small holes. Pressure goes up when RPM's goes up. I forget the technical name but it limits flow back, not pressure. You also want MORE timing at faster RPM's to carry the power...

If you mean DI as in direct injection then you are smoking something. All Cummins B series engines are direct injection. IIRC, 245 bar is the pressure needed for injectors on a VE engine.

[westyventures]

$20 at a Bosch shop. You can do it yourself in about an hour if it is off the engine. Bosch Number: #1-464-650-366 Make sure it ends in 366! 386 is the stock one.

There is no internal pressure valve. The only 2 pressure valves are for the KSB (affects timing. Power to it advances it a few degrees) and the return orifice which is 2 small holes. Pressure goes up when RPM's goes up. I forget the technical name but it limits flow back, not pressure. You also want MORE timing at faster RPM's to carry the power...

If you mean DI as in direct injection then you are smoking something. All Cummins B series engines are direct injection. IIRC, 245 bar is the pressure needed for injectors on a VE engine.

Wow, thanks for the attitude. Maybe I won't bother next time.  
1) I don't need or use 'Bosch' springs. There are tons of choices from precision spring makers that give more options for desired max rpm.
2) More internal pressure = more advance - the internal pressure does relate directly on the movement of the advance piston. We can argue about it, but there is a pressure control valve, directly opposite the fuel inlet, on every VE pump including the eTDI pump. This does quite certainly control the internal pressure, add a gauge to the pump case and see for yourself.  
3) Agree that the 4BT is in fact DI. BUT - the cam plate shape (ramp) is not correct for a proper mTDI. The later 144 pump did have a more suitable camplate, as did the 138 'LT' pumps.
Go smoke something and stop accusing others with experience, maybe they'll be less likely to no longer contribute factual experience.  

[westyventures]

http://issuu.com/rswords/docs/bosch_ve_manual

Page 15.

 

[dodger21]

$20 at a Bosch shop. You can do it yourself in about an hour if it is off the engine. Bosch Number: #1-464-650-366 Make sure it ends in 366! 386 is the stock one.

There is no internal pressure valve. The only 2 pressure valves are for the KSB (affects timing. Power to it advances it a few degrees) and the return orifice which is 2 small holes. Pressure goes up when RPM's goes up. I forget the technical name but it limits flow back, not pressure. You also want MORE timing at faster RPM's to carry the power...

If you mean DI as in direct injection then you are smoking something. All Cummins B series engines are direct injection. IIRC, 245 bar is the pressure needed for injectors on a VE engine.

Wow, thanks for the attitude. Maybe I won't bother next time.  
1) I don't need or use 'Bosch' springs. There are tons of choices from precision spring makers that give more options for desired max rpm.
2) More internal pressure = more advance - the internal pressure does relate directly on the movement of the advance piston. We can argue about it, but there is a pressure control valve, directly opposite the fuel inlet, on every VE pump including the eTDI pump. This does quite certainly control the internal pressure, add a gauge to the pump case and see for yourself.  
3) Agree that the 4BT is in fact DI. BUT - the cam plate shape (ramp) is not correct for a proper mTDI. The later 144 pump did have a more suitable camplate, as did the 138 'LT' pumps.
Go smoke something and stop accusing others with experience, maybe they'll be less likely to no longer contribute factual experience.  

1) I have added and helped over a dozen Cummins pumps. The Bosch springs have 4 different max defuel points. 2800, 3600, 3800, 4000. All it does is move the defuel point. No power is added. The VE makes all of its power sub 2k rpms. I looked at a VW setup but it looks riveted to the throttle shaft...
2) The VW may have a pressure control Valve but I have a Cummins pump pulled apart in my house. It does NOT have one. In fact, it is used for the KSB solenoid. More RPM's or more fuel pumped into the inlet means more pressure. Only so much fuel can be pushed through the hole slightly bigger than this period.
3) AFAIK, the cam plate has 2.8" of lift. According to Cummins, the ideal pop off pressure for a VE is 245-259bar. Anymore and you shorten the life of the pump by adding undue stress and timing would be too far advanced.

No attitude. I realize now it does sound snarky but I did not mean it. Just trying to help.

[westyventures]

1) I have added and helped over a dozen Cummins pumps. The Bosch springs have 4 different max defuel points. 2800, 3600, 3800, 4000. All it does is move the defuel point. No power is added. The VE makes all of its power sub 2k rpms. I looked at a VW setup but it looks riveted to the throttle shaft...
2) The VW may have a pressure control Valve but I have a Cummins pump pulled apart in my house. It does NOT have one. In fact, it is used for the KSB solenoid. More RPM's or more fuel pumped into the inlet means more pressure. Only so much fuel can be pushed through the hole slightly bigger than this period.
3) AFAIK, the cam plate has 2.8" of lift. According to Cummins, the ideal pop off pressure for a VE is 245-259bar. Anymore and you shorten the life of the pump by adding undue stress and timing would be too far advanced.

No attitude. I realize now it does sound snarky but I did not mean it. Just trying to help.

The springs I use can take the rpm even further, depending on what my customer wants. I can accurately measure the spring rates and choose the correct one. Never said it added more power - more rpms. 

All VE pumps have the pressure control valve - otherwise there would be no advance. The internal pressure rising pushes against the advance piston, all VE pumps have it, even 6-cyl pumps. Just opposite the fuel inlet bolt is a small 2-sided part screwed into the pump - this is the pressure control valve. Tapping down in the center of it will increase pressure in the pump as rpm increases. A stuck valve will blow the top off, ask me how I know that. 

I've built a ton of mTDI pumps since 2005, it's been quite a learning curve. The correct cam plate must be used for the head size. The one that is supplied with most4BT pumps is too mild - later pumps had a more aggressive profile similar to the TDI camplate. The 'LT' pump uses a camplate very much the same as the later 4BT - that one definitely supplies all the fuel needed for the largest injectors up into the 'Race' series. The smaller, milder early 4BT camplate might allow one to use the 12mm head with smaller nozzles than .230.

[dodger21]

On the cam plate, I learned something new!