XD3T / AAZ Hybrid Bosch VE pump project

[Bean]

As discussed in my 505 TD wagon build thread, I had played around with various ideas to extract more performance from the 2.5L XD3T engine, and after reading the VWdiesel.net forums I decided the AAZ hybrid injection pump and 2-stage injector idea needed to get pursued. (I blame Automotive ADD).

I contacted a one of the users on VWdiesel.net as I noticed he was in Saskatchewan and we chatted via e-mail for a bit. (Great guy.) A few weeks later he sent me a link to a post selling some used XD3T pumps on the IDI forums. After some negotiation - I bought one of the pumps he had for sale. (Condition was unknown since it was off a car in a pick and pull yard.)

The seller of those pumps told me about the special registration process for the site - so I joined after finally getting my request approved. With a core XD3T pump found, the first task was to put an advert up for AAZ injection pumps as well as some AAZ 2 stage injectors. Now that I was on the forums I could actually contact people, and make more inquiries.

After reading about the governor mod the VW guys do, I noticed the author of the article (8V-of-fury) was also doing pump reseals. I contacted him to see if he'd be willing to work on Peugeot Bosch VE pumps, and that's where the project took off. Jeremy was beyond helpful, and is a true diesel enthusiast. Not only was he up for doing the reseal work - but he was also keen on the AAZ hybrid idea and happened to have a donor AAZ pump available for the project! Not only that - but he agreed to document the build with pictures and comments so that I could document the project here on 505turbo.com

I've basically edited our correspondence back and forth to build the article - so hopefully it flows well enough to follow:

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These are the pictures upon removal from the shipping box. Seller dismantled the throttle linkage so it would fit in a medium shipping box, so all external settings will need to be set up based on the pump currently on your car.

You can see the max fuel screw looks tampered with, but it will be one of the things you will adjust once you get it on the engine.. so it does not really matter.

These are pictures of the internals, and they look alright. Varnished from being sat full of fuel, but so far so good.

This picture in between the lines shows a hairline "Crack" so to speak on the governor assembly cage. I have broken them before with improperly taking the lids off and getting the throttle arm twisted and jammed. This one was like this when I took ti apart, so it has been opened before. It doesn't look compromised too badly, but I just wanted to note it to you.

The stock Peugeot governor assembly is on the bottom, with a 1.9 AAZ assembly on the top. As you can see the Peugeot has a bigger spring with more coils, therefore making it a softer spring rate. As well the Peugeot cam plate first and then a 1.6 TD cam plate second. As you can see it is basically the same as a VW 1.6TD cam plate.

Peugeot pump is now fully dissembled and just starting to be cleaned up now. As can be seen the insides are in great physical condition. They are a little varnished as though the pump sat full of fuel for a long time, but it will not affect anything. The important parts look good. The head and rotor look good, as well as the lift pump and its rotor. The throttle sensor that was the plastic thing you wanted pictures of earlier, appears to be broken. So I do not know if it will function for you or not.

I was looking at the difference between the Peugeot advance piston and the VW AAZ one. They are different offsets to interact with a different depth cover and what not. So I will need to look at that further to see if we can even use the AAZ spring and piston or not. The springs are physically the same un-sprung length so it seems as though it will work without issue.

Peugeot pin and respective spring

1.6TD pin and respective spring

1.9 AAZ pin (nothing to be had here...) and respective spring

And the same three again, Peugeot left, 1.6 TD middle and AAZ right.

Jeremy’s thoughts:

“I am thinking we will use the stock Peugeot advance piston so that interaction with the front cover will remain the same, and I will use the AAZ two piece spring in place of the stock spring. They have the same free length, but the VW spring is much softer, so advance will come on a lot sooner which is generally more desirable with performance tuning in mind.”

**Edited correspondence with Jeremy to create the article above

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After finding out how big the cam plate lift difference was, I am confident the decision to pursue the AAZ hybrid idea is going to pay off in a big way when it comes to improving output of the XD3T.

Rabin

[JunktionFET]

FYI, that is unmistakably an early ('81-'83) XD2S pump. The vacuum EGR modulator and lack of a cold start advance device are giveaways.

I believe the injection advance curves are the same between the XD2S and XD3T, however the fuel delivery settings and especially the Boost LDA are quite different. Since you're going for a custom tune anyway, this may not be a big deal. However the XD3T's LDA pin would give you a greater range to play with than the XD2S's.

[Bean]

Thanks very much for the info Joe! Pretty sure I should be able to install what I need / transfer parts including the LDA from the pump on my car.

Dodge Cummins tuners sell a couple trick parts including a new custom LDA pin, so I'll mostly be playing around when tuning for best results. Local shop might even have a diesel pump dyno so checking into that as well.

BTW - is that plastic piece the EGR modulator? I had no idea what it was and suspected it might have been a TPS of some sort.

Rabin

[andrethx]

this is a very interesting topic, even though i don't have a diesel (and have never owned one). i did a bit of research on this topic and saw that some of the VW guys use late-model peugeot internals to modify their pumps, so turnabout (your project, rabin) is certainly fair play...

i also got sidetracked on the topic of mechanical VNT control...also very interesting...

andré

[Peugeottogo]

this is a very interesting topic, even though i don't have a diesel (and have never owned one). i did a bit of research on this topic and saw that some of the VW guys use late-model peugeot internals to modify their pumps, so turnabout (your project, rabin) is certainly fair play...

i also got sidetracked on the topic of mechanical VNT control...also very interesting...

andré

I too find this topic Rabin very interesting and I have a diesel! No plans to make any modifications but great info

[Bean]

After seeing how much power VW guys are getting out of their old 1.6L and 1.9L engines I thought the 2.5L XD3T should have a TON of untapped potential. Since the VW IDI diesels share so much with our engines (Injection pump and injectors being the major items) I started to think that the mods they do should work on our engines.

Jeremy was really curious about my questions regarding the AAZ pump being a possible upgrade path, and when he was enthusiastic about seeing what could be done - I had no choice but to follow through! There's no hurry on my part for the pump and I've told Jeremy to work on it at his leisure as I will only really need it this Spring / Summer.

I also just received a set of VW AAZ 2-stage injectors that will be rebuilt with Monark nozzles with both stages of pop pressures re calibrated. If all goes well the engine should run much quieter and have a lot more power. Jeremy is also going to do the governor mod which allows the pump fuel all the way to redline, so power increase should be substantial indeed. Since the car is an auto - I'm not worried about over-revving - but tuning will be critical.

Rebuilt stock turbo is also on the list - so once it all goes in and tuned - my goal is to be as soot free as possible while having as good or better performance as a Turbo gas wagon. Steady state cruising should still return the TD economy I want - but highway passing should be a lot less eventful with some power on tap.

Rabin

[JunktionFET]

The turbocharger chokes the exhaust on the XD2S and XD3T more than it does the N9Txx because the wastegate "canal" starts deeper in the "scroll" of the housing, if that makes sense. Barring replacing the turbocharger with a larger unit (increasing lag) or a VNT unit (complex control system), I think the XD2S/XD3T might benefit greatly from an external wastegate. If you're deleting the EGR system, that might be a good place to tap into the exhaust stream.

[Bean]

I've already got a set of EGR-less intake and exhaust from a UK market car, and I had noticed the turbo exhaust scroll being hugely restrictive as well with the divided entry to the WG port eating up a good chunk of the scroll and just a tiny opening into the wheel.

The flange is a standard T3 flange, so there are options - but I may have more options if I modify it to a T25 flange like I'm doing for the N9TE manifold.

Plan for now is to just rebuild the stock turbo as it's the cheap and easy option, and if the car runs as nice as I hope it does with the IP and injector mods - then I'll then look at turbo upgrades that would allow it to breath. VNT is my top choice, and there are some neat manual set ups that look like they'd work decent - but ideally a stand alone controller with a nice VNT turbo will be what I go with if I get it running the way I want.

A smaller gas engine externally wastegated turbo might be an option as well - but we'll see how it runs first, and where the VNT stuff is at for nice retrofit options.

Rabin

[JunktionFET]

I stumbled across something in one of my Bosch PDFs (for distributor injection pumps). A "Soft running device". There's a page devoted to it; It looks like they are describing a special kind of plunger assembly. The idea is that injection speed is decreased at light throttle in order to reduce noise and harshness. At larger throttle openings, it seems as though it would go back to normal. Also, I assume this works with standard injectors?

Have anyone ever seen or heard of this, or know what cars might use it?

[Bean]

Interesting concept, but I'm curious how much the decreased flow rate would affect running as it would still have to overcome the injector pop pressure, and combustion would still be a single event.

Seeing how the 2 stage injector works, this makes much more sense to me as there are two injections for each combustion event - the first small one starts the event / burn, and the second larger injection is the power shot if you will.

Modern direct injection uses a similar idea - but it can do 7-9 injections per event which is why the new high pressure direct injection diesels are so good.

2 stage injection used in the AAZ was the most advanced IDI tech available prior to TDI/HDI which is why I pursued the hybrid AAZ pump idea.

More details on this soft feature would be cool though as I'm curious how the reduced flow rate worked with injection pop pressures, and how that affected idle quality. This is the first I've read of it and I spent a lot of time researching these pumps.

Rabin

[JunktionFET]

I'm with you there. I think that multiple injections are clearly the way to go to quiet the diesels down, and more importantly, reduce the sharp rise in temperature that produces NOx emissions.

Slowing down the injection makes sense to me, and I can see how it was probably an earlier attempt at the aforementioned noise and NOx abatement. This style of plunger is probably rare. My google searches haven't turned up any concrete information, aside from that blurb in the Bosch manual. Weird.

[Joe Ernest]

You appear to be working on several avenues of upgrading your XD3T, turbocharger, VNT, AAZ pump and 2 stage injectors.
Any progress on your projects?
 

Can you recommend a turbo upgrade?
And any other upgrades I might make as component replacements become necessary?

Thanks....................JoE

[Bean]

Hi Joe!

Good Lord this is shameful - I can not believe how time flies by...

Part of me wanted to stop posting until I could post REAL progress, and that's pretty much exactly what's happened on its own.

I now have the custom built AAZ injection pump, and the Monark nozzles,  but I still need to have the AAZ injectors rebuilt.  

I've also picked up an amazing 5sp td donor sedan that should fix the wiring nightmare as well as all manner of other issues since it's the same colour.

As for your turbo advice - it's a standard T3 flange, so there are options,  the problem is most options are quite large gas turbos.  Volvo's use the same bolt pattern as the T3, and use some very quick responding TD04HL-13G Mitsubishi turbos that might be a good option on a budget.

Spending more money opens up other options, but without fueling mods it would be moot.

I'll need to find some time to revisit VNT stand alone controllers as that really would be the ideal turbo for the diesel since they have such small rev range.

Initial plan was to just rebuild the stock T3 to start, but I'll play mix'n match with the stock turbo from the N9te to see if I can upgrade the compressor side for a bit more flow.  

Rabin

[SRDT]

You an use a VNT without electronic, the first diesel with VNT where like that: Croma TDID, Renault Espace 2.1 dTv...

This guy is using a Croma turbo on his P4:

http://forum.clubmbf.com/viewtopic.php?t=4491

[Joe Ernest]

Hi Rabin,

Thanks for the response. I too would prefer to wait till I have tried and tested results to report, but, sometimes inquiring minds want to know what you've figured out so far. Thank you for sharing.

If I understand correctly:

On the fuel side - you've had Jeremy build you a hybrid AAZ - XD3T pump, and you will have AAZ injectors rebuilt with Monark nozzles, recalibrated to AAZ pop pressures.  Could you send me Jeremy's contact info (to [email protected])?  (yes, I have a 1967 Land Rover 109 diesel Carawagon. - loaded! Freewheeling hubs, Fairey OD, Capstan winch. A/C? Yes, the pop out vents below the windshields are screened to exclude hayseeds.)

On the air i.e. turbo side - the XD3T turbo's standard T3 flange allows for some substitutions, a suitable turbo has yet to be identified. A turbo with a VNT controller may be the preferred option.

My near term need is for a turbocharger. And I might as well upgrade rather than just replace. For my Vanagon TDI I installed a K03/K04 hybrid - 03 exhaust side, 04 compressor side - awesome with a 11mm IP head, Bosio 520 injectors/nozzles and Stage 4 tune. I haven't come across a similar beast for the XD3T.

JoE

[Bean]

Joe:  Jeremy moved and as far as I know he stopped rebuilding injection pumps on the side.  I contacted Giles at Performance Diesel out East but he refused to dyno the injection pump and do any tuning unless he did the rebuild and the modifications.  Sucks - but understandable.  Now that I have two engines to play with, I'll use Jeremy's IP build as the proof of concept, and if it runs anywhere near as well as I hope, I'll get the spare IP redone by Giles and tuned specifically for whatever turbo I end up with.

SRDT:  I know I could run a VNT with a manual controller, but to get the most out of the VNT and the widest power and torque curves, as well as the fastest spool - a stand alone controller running the VNT is likely the best bet.  Failing that - I'll play around with the stock turbo, as well as trying the stock 505 Turbo gas turbo out using a normal T3 exhaust housing...  The .36 AR is pretty small so I'm curious how it would spool with the 2.5L diesel...

Rabin