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#15
by
theman53
on 25 Jul, 2015 09:58
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EGT and fuel would be the benefit to the more aggressive cam plate. You should probably time it to what works, I would start with what most of the pump was built with.
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#16
by
TylerDurden
on 25 Jul, 2015 20:11
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Thanks!
Please help me understand the advantage of the more aggressive cam then?
And any clue as to where I would set my pump timing on this thing if I stayed with the 2.55mm plate? Would it be the same as the aaz if I am using the long delivery valves and 2 stage injectors?
Generally, for a given plunger diameter, a taller camplate makes a longer stroke and thus can deliver more fuel.
The devil is in the details though: starting when, and for how long... That's a combination of camplate slope, timing, injector pop pressure and control collar.
e.g.
The MF engine (US turbo):
9mm IP
2.19 camplate
135 * 155 bar injectors
1mm timing
boost enrichment
The 1V engine (US eco):
8mm IP
2.55 camplate
155 bar injectors
1mm timing
no boost enrichment
So, while the US eco has a longer stroke, it also has a smaller diameter, so fuel load is about the same... the cam slope is steeper to
compensate and not let the injection lag deliver fuel faster. *
But the eco also has no boost enrichment, so the fuel load on-boost is comparatively less due to the control collar opening earlier.
The result: higher combustion temperatures, less soot and more NOx, so a catalytic convertor was added.
Corrected
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#17
by
libbydiesel
on 25 Jul, 2015 21:45
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MF and 1V injectors were both 155 bar.
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#18
by
TylerDurden
on 26 Jul, 2015 04:41
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Corrected.
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#19
by
BoostedOne
on 26 Jul, 2015 06:18
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I won't lie. I am so confused and trying to process all of this.
Let me see if I can try to put this together..
So even though the smaller cam plate can deliver the same amount of total fuel as the larger cam plate by adjustment of the fuel screw, the difference is the larger cam plate will shoot the fuel in much faster. This decrease in total injection time will allow more time for the fuel to burn, and that's what leads to a decrease in chamber and exhaust temperature?
Thanks for all the help in attempting to get me up to speed. And I hope I do not come across as someone who is just sitting here asking questions and wanting others to figure it all out for me. Every response has me looking up more information I am just trying to make heads or tails of it all.
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#20
by
BoostedOne
on 26 Jul, 2015 06:19
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Also, did you make that graph or pull it from somewhere else?
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#21
by
TylerDurden
on 26 Jul, 2015 08:28
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#22
by
TylerDurden
on 26 Jul, 2015 08:37
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Good reading:
BOSCH Diesel-engine management 2nd edition.
ISBN 0-7680-0509-4
Google search for "BoschDistPump.pdf" gets some interesting hits.
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#23
by
BoostedOne
on 26 Jul, 2015 09:18
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Cool thanks for the links. I will check them out more in depth when I go back in the house this evening.
I get the longer stroke obviously allows for more injected fuel, but am I on the right track with what I said above in the last message? Because on one hand in this thread I am told even the 2.1mm cam can provide the fuel I need with the tradeoffs being the additional heat which obviously is not wanted.
I will likely order a copy of the book, thanks for that info as well!
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#24
by
TylerDurden
on 26 Jul, 2015 09:53
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You can probably get all the fuel you want. There are caveats.
It seems VW and Bosch were playing with injection duration by using the 2-stage injectors and higher pop pressures, trying to balance increased fuel quantity with combustion quality.
If it were as simple as just dumping more fuel, it would be a cakewalk, but clatter adds stress and heat. And even with 2-stage injectors and/or higher break pressures to extend the injection duration, the fact remains that more power requires more combustion that generates more heat.
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#25
by
wolf_walker
on 26 Jul, 2015 10:11
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You can probably get all the fuel you want. There are caveats.
It seems VW and Bosch were playing with injection duration by using the 2-stage injectors and higher pop pressures, trying to balance increased fuel quantity with combustion quality.
If it were as simple as just dumping more fuel, it would be a cakewalk, but clatter adds stress and heat. And even with 2-stage injectors and/or higher break pressures to extend the injection duration, the fact remains that more power requires more combustion that generates more heat.
I always wondered what of the changes vw made as time went on was related to performance, if any, and what was for emissions?
My inclination is always to go with the latest (best?) iteration of a thing like this, but I was never convinced the dual stage injectors and such
were actually an enthusiasts definition of "better".
One of these days I want to build or buy a pump for my NA 1.9L that is basically a 1Y code motor, they apparently did not use
two stage injectors at all in those throughout it's lifetime even though they were available and used in some other motors,
begging the question, why?
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#26
by
vanbcguy
on 26 Jul, 2015 19:48
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Emissions are definitely a factor. As mentioned earlier any of the cam plates you've got your hands on should work fine, I wouldn't go out looking for an AAZ one until you're at the limits of what you have.
The dual stage injectors are largely for noise reduction. The pilot spray gets the burn going so pressure doesn't rise as sharply when the main spray happens. I believe there's an emissions component to that too, wouldn't surprise me that it reduces the particulate and unburned hydrocarbon levels. Absolutely everything in the passenger diesel market uses multiple injection events these days; it started with the 2 stage mechanical injectors and has continued through to modern common rail stuff where there can be several injection events happening for noise, performance and emissions reasons. Anyhow I don't think you'll see any real performance difference in terms of raw horsepower but a camplate with the right shape to run dual stage injectors and the dual stage injectors themselves will yield a quieter running engine, which isn't really a bad thing.
I think the questions are great personally. This is "advanced diesel combustion theory" at this point.
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#27
by
BoostedOne
on 08 Aug, 2015 09:32
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Thanks for the help in figuring this out guys!
I hadn't abandoned this. In fact I have done just the opposite. I tracked down a copy of the Bosch Diesel Management book and ordered that, as well as ordered a pump rebuild video off eBay.
I was out of town all week for a work event which prevented me from reviewing any of the material.
I did buy some two stage injectors. Not for the stated benefits, but I can say with a 1.9 currently running on short delivery valves and single stage injectors I am fed up with leaky injector pipes. The seller I bought the injectors from only had 3 though, so if anyone has a 4th 028130201B injector they will part with, please let me know.
OK I will settle for the cam plate I have now. I can aways upgrade it later.
My plan is to make the time to go through these pumps and combine them into one, and do the governor mod. Get the injectors cleaned and popped at my local shop, and get them on the engine.
Do the delivery valves get pop tested as well? I saw they have shims in there.
Then I will start building the turbo stuff.
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