PD Pump Lift Rate?

[PakProtector]

What is the PD pump lift per crank degree? BEW engine( if it matters ) is of interest, but if there are several, I'd not mind hearing. Or if an aftermarket cam has a different rate, that would be welcome info as well.

Douglas

 

[oilhammer]

You mean the lobes that drive the pump-jet injectors themselves?

I know all three of the 8v PD engines sold here (BEW, BHW, BRM) use different camshafts... but they also all three use different injectors. I'm not sure specifically what the difference is, but I do know someone who was putting BEW cams in BHWs that I had to fix, because they had low power. A new proper BHW cam install fixed them perfectly. So something was clearly different there.

 

[PakProtector]

I am not sure what the pump rocker ratio is, so the question is directed 'at the pump itself'. Interesting that the BHW might have a more rapid injector lobe... I know of the half mm smaller pump dia of the BRM vs BEW/BHW. The BHW pumps I have seen all had 1043 nozzles...which is decidedly *Not Bosio DLC1043...but I thought the BHW and BEW pump bodies were otherwise the same, and not the ARL/PD150 style with a more convoluted fuel path...

Douglas

 

[oilhammer]

The rocker ratio is the same for all of them, as they all use the same rockers and shafts. The ratio is determined by the location of the rocker pivot and the ends of the rocker (think back to those old pushrod air-cooled dubs, if you have any experience with such a thing).

The PDs, while having plenty of overhead fueling capability, are still tied to old fashioned mechanicals, so the "dwell" of the injector cam lobes is probably just as important as the lift.

 

[PakProtector]

Lift rate and overall lift are the important bits. Dwell a secondary for filling. Assuming we don't leak much, the 8mm pumps will run ~40mg of fuel per mm of lift. It is a matter of rate to determine how many crank degrees per mm of lift. This lift rate will likely be less than linear at the ends, but in the meat of its travel it should be linear( actual, 1st order line of degrees and lift ). So to say, pump is on the lobe and then it gets fired by the ecu where it is moving relatively consistently.

Douglas

 

[oilhammer]

What is the base of your question here?

 

[PakProtector]

other answers. most likely, other questions too. for now, something simple will have to do.

Douglas

 

[oilhammer]

Well if you have a better framed question, with some end goal in mind, someone that perhaps knows the ins and outs of PD cams could give better answers. No context here, so I'm not exactly sure what you are asking, let alone why. The PDs were kind of a dead-end stop-gap thing as it was.

 

[PakProtector]

It is the piece of information I need. How fast w.r.t crank degrees do they act on the pumps. It will be a distance over degree of rotation. Why is unimportant, either the answer is out there or it is not... That the BHW might have different lobes is interesting for sure...

Douglas

 

[03Golfer]

Time to break out a degree wheel and dial indicator I suppose?

 

[PakProtector]

Time to break out a degree wheel and dial indicator I suppose?

That is about what I figured. And wonder of wonders, I happen to have a BHW head assembly( disassembly actually ) that I can check also...

Douglas

 

[oilhammer]

Gosh, if only someone here had access to a computerized X-Y-Z plotting cam profiler.... hmmm.... Darn.

 

[PakProtector]

Print a degree wheel, bend up a pointer and chuck the cam in my lathe should be adequate...

Douglas