That's great Dave now lets get back to 2012 and what has been learned since.Pete, I am not saying that there will be NO torque and pressure fluctuations. But you have a long history of hyperbole on things that fall rather short of being cataclysmic.
Source: Richard van Basshuysen and Fred Schäfer (ed.). Internal Combustion Engine Handbook - Basics, Components, Systems, and Perspectives. SAE International 2004.
In the above, the drive torque and pressure fluctuations are plotted. In the worst case, the torque fluctuation is about 15Nm peak-to-peak. All intermittent pumps and reciprocating devices are going to exhibit this behavior, and there is a simple solution for this: You put an inertial weight, like a flywheel sprocket.
With regard to pressure fluctuations, the worst case amounts to about +/- 0.01 kbar or 10 bar. With the mean at 1500 bar, that's 0.67%. Not the magnitude that will make a lick of discernable difference (especially when we're not only talking about one injection event but rather more commonly now up to 7 per cylinder per cycle over a wide span of crank angle).
And this data is on FIE that's at least 8 years old, based on the date of the book. There have been improvements made in succeeding generations.
Like I said, Pete, you have a long history of spouting out your opinion rather than well-established and accepted fact. So, I kindly challenge and invite you to post written proof from a credible third party (e.g. Bosch Automotive Handbook or similar, not some unknown, non-cited website or "expert individual") that unambiguously confirms your assertions. I've done my part.
Even if you timed the 3 plunger pump to an 8 cylinder engine via a 1/1.333 pulley, how do you account for the pump deactivating one plunger?
eff who knows. Maybe it has to be synchronized with moon phases to make sure it doesn't blow up. Great pumps they have turned out to be, eh. But *** do I know? Later!
Interesting graphs. Shows how pressure fluctuations are worse at lower fueling rates, which is kinda anti-intuitive to me--but explains why HPFP's hate trailing throttle. Since it has been mentioned to get a five-port rail and cap off the fifth, I wonder if a spring-loaded plug could be machined or sourced to assist with maintaining consistent rail pressure. Plenty of choices in the required strength range needed to maintain 22,000 psi.Pete, I am not saying that there will be NO torque and pressure fluctuations. But you have a long history of hyperbole on things that fall rather short of being cataclysmic.
Source: Richard van Basshuysen and Fred Schäfer (ed.). Internal Combustion Engine Handbook - Basics, Components, Systems, and Perspectives. SAE International 2004.
In the above, the drive torque and pressure fluctuations are plotted. In the worst case, the torque fluctuation is about 15Nm peak-to-peak. All intermittent pumps and reciprocating devices are going to exhibit this behavior, and there is a simple solution for this: You put an inertial weight, like a flywheel sprocket.
With regard to pressure fluctuations, the worst case amounts to about +/- 0.01 kbar or 10 bar. With the mean at 1500 bar, that's 0.67%. Not the magnitude that will make a lick of discernable difference (especially when we're not only talking about one injection event but rather more commonly now up to 7 per cylinder per cycle over a wide span of crank angle).
And this data is on FIE that's at least 8 years old, based on the date of the book. There have been improvements made in succeeding generations.
I'll grant that Pete is a master at twisting and spinning facts. You'd make a good politician Pete! What he said is not technically wrong. Inside the pumping element there are large pressure fluctuations from the bottom of the stroke to the top; that's the nature of how they work! There's absolutely nothing abnormal about this. The inline, VE and PD systems work on the same principle. However, this is not what happens in the rail, where there are ball check valves in the high-pressure outlet of the HPFP and the relatively large volume acts as an accumulator and damps out fluctuations. The graphs show pressure in the rail and it has already been shown that the variation amounts to less than 1% in the worst case.1800 bar pressure variations?
Cold starting and emissions.....
and volunteer his Jetta as a test mule. Ryan if you have parts in your warehouse to just match up this might be a worthwhile opportunity for you.
Hydraulic accumulators have been doing this for the better part of a century, except instead of a spring use an inert gas at rail pressure as the spring.
Inert gas with a bladder, as I recall...
Niclochard said:
The rail in the VW can't store very much volume at available pressure. There is no dampening medium and the fuel is the only compressive force in the system.
Per the factory manual the HPFP sprocket can be mistimed by cam/crank by several millimeters (I'll verify the actual amount later) which on such a small pulley should equate to quite a few degrees.
Thank you ranger1. When I asked for substantiating an argument, this is what i meant. I'll take a closer look at that paper. Right to the heart of the issue! Not I said the little red hen.Thanks `tooef!
Who wants to bankroll a project?
