mTDI / TDI-M Injection Pump FAQ:
This objective of this FAQ is to compile a a list of commonly asked questions and answers to what is needed to convert the electronically controlled injection of the Volkswagen 1.9L TDI engine over to mechanically controlled injection in an easy to read mostly complete format. the FAQ is perhaps not going to answer all of your questions but, is more intended to get someone new to mechanical TDIs up to speed and assist in one better understanding the posts they see here and elsewhere. In otherwords to answer the "How do I make a mTDI or TDI-M pump?
" It's a jumping off point more or less.
Sources and Credit where Credit is due:
Most of the information here is a collection of information found in postings on the GTD Forums, TDI Club, and elsewhere on the Internet. Most has been gleaned from posts by RabbitGTDguy, hillfolk'r, Named Tintin, and others. If I used something here of yours and didn't specifically mention you, my apologies, let me know and I'll add you to the list. It has been written by me (Ziptar) as part my educating myself and getting a better understanding of how to build a TDI-M myself. I haven't actually done it, yet, so if I have missed something or completely gotten it wrong let me know. I have reworded and/or changed some stuff around a bit to help organize things and to better flow together info, quotes, etc from different sources.What Injection Pump can I use to build a TDI-M?
The non Pump Dusse TDI uses an electronic version of the Bosch VE "Verteiler" Rotary style Injection pump. The Bosch VE Injection Pumps is available in a mechanical version as well. Mechanical pumps were used by many vehicle manufacturers, to name a few Volkswagen, Fiat, Cummins, Peugeot, and Ford (Europe).Okay, so I can just get any Bosch VE mechanical Pump and strap it on a TDI then?
Well no, not exactly. Bosch produced VE pump in two shaft sizes...17mm and larger 20mm mainshaft pumps. The shaft sizes differ mainly in relation to the size of the pump head, 17mm shaft for up to 9mm head and 20mm shaft for 10mm head and over. The theory is that the larger the mainshaft of the pump, the more pressure the pumps can handle (i.e. All DI engines require higher injection pressures) Usually 20mm shaft drive pumps also have a certain amount of reinforcment improvements to the pump housing as well to support the extra pressures they require. The VW TDI came with a 20MM shaft VE pump in two basic versions a 10MM head for standard transmission cars and a 11MM head for automatic transmission cars. What that means then is any mechanically injected VE pump you use should at the very least approach the head size of a stock TDI pump, too small a head will not deliver enough fuel to the TDI injectors. The reverse of this then is that just about any Bosch VE pump can be made to work on a TDI, it depends on what you plan to do woth the engine overall.How do I know what Bosch VE Pump I have or am looking at buying?
The Bosch part number on the Bosch VEs pumps are fairly standard i.e. 0-460-4XX-XXX VE , what are important to note are the 6th and 7th digits of the Bosch Number. The 6th digit indicates the plunger size, 9 for 9mm, 0-10mm, 1-11mm, 2 for12mm. The 7th digit the is the application, 4 for 4cyl., 6 for 6cyl., etc. The specific manufacturers part number may also be on the pump and completly different, for example, the Cummins 4BT injection pump numbers do not indicate plunger size, everyone I have seen to date has been 12mm. Since the 4BT is a 4 Cylinder engine we can assume that part.
3917530 1986-90 VE Series Rotary, CPL 858, 105 HP
3908191 1986-90 VE Series Rotary, CPL 767, 105 HP
3917535 1986-90 VE Series Rotary, CPL 857, 120 HP
3906631 1986-90 VE Series Rotary, CPL 593, 105 HP
3919716 1991-93 VE Series Rotary, CPL 1260, 105 HP
3926831 1991-93 VE Series Rotary, CPL 986 & 1848, 120 HP
The only way to know for sure is with the Bosch part Number.So which pump should I use then??
There is not a single best answer to this question, it is a combination of what you have available, what kind of horsepower and boost you are shooting for, etc.
The options are basically:
- The "Hybrid" or "Franken" Pump
The Hybrid pump consists of a 1.6 TD pump (or 1.6NA pump with the LDA aneroid from a TD pump), swapping in the pump head, plunger and camplate from a TDI pump. The pump base could also be from a Peugeot but, the Peugeot pump has a very short nose and a gear on the end of it that does not allow proper alignment of the pump to the cam, etc... using this as a base would require the swap of the entire mainshaft assembly from another pump with the VW style mainshaft.
Usually all hybrids are of the smaller shaft diameter, which is 17mm. For those using or looking to use a large, 11mm or 12mm head, this is thought by some to not be the best choice as the smaller diameter shaft could possibly snap under the higher stress.
That being said, Hybrid pumps can exist in a variety of other forms as well, for instance; a 1.6 TD or NA base pump with a VW IDI TD LDA assembly coupled with their choice of camplate (Peugeot, Cummins 4bt, Mitzu, Fiat Croma, etc) and their choice of hydraulic heads... IDI 10mm from Peugeots, Ford Escorts, or VW TDI stock pumps.... 11mm heads from VW TDI (automatic only) or 12mm heads from Cummins 4bt's, etc.
- DI specific mechanical pump from the Cummins 4BT
The Cummins pump can be set up to run a TDI-M. This setup is usually favored by those looking for more fuel or performance since most stock 4bt pumps come with 12mm heads and 20MM shafts, some came with 11mm and 10mm heads. For that matter you could swap the 10mm or 11mm TDI head onto a Cummins pump as well.
Using a Cummins 4BT Pump on a TDI engine requires swapping a VW IDI LDA top, VW IDI TD Governor / Pump Control Lever Assembly, VW Governor Assembly, and VW IDI TD Boost Pin. Swap the caged governor spring assembly from the VW TD pump to the Cummins pump, you must also swap the control level assembly that is in the pump itself. It is held in by the two "odd", almost 13mm bolts on either side of the pump. The governor flyweights should be the same. The ENTIRE VW LDA needs to used so that the hooks correctly to the VW IDI control level in the pump. The cummins LDA can be used but, takes more doing to hookup properly. The boost pin is actually a matter of choice and what performace goals are, there are ways to use the nice steep stock Boost Pin of the Cummins pump) . If you have a KSB device on your pump, you may wish to change this out, It involves removal of the pressure relief valve and the front timing cover, etc. You'll want to do this anyways and also at the same time if you have a TDI donor pump, swap in the TDI advance piston, shims and cover which is MUCH deeper than an IDI pumps advance mechanism. You could "cut down" a IDI VW assembly but it kinda voids out the timing mechanism. Swapping the entire TDI style timing mechaism into the bottom of the Cummins pump and using the TDI pump timing cover, will also allow for easier and better internal timing. In order to use VW timing tools in the Cummins pump you will need to swap the central portion of the hydraulic head at the rear of the pump from a donor TDI pump into the Cummins pump or use an adaptor as the Cummins hole is too large. For heavier applications, such as truck, vanagon, etc... the stock cummins Govenor setup is kinda nice for "loaded" applications.
Using the Cummins Pump also takes some fabrication of the pulley. See "What about the Pump Sprocket / Pulley?" for more info.
- 1.9L IDI TD Pump with Larger 10mm TDI Head, Cam Plate, and Plunger
The simplest option would be to use a 1.9L TD IDI (AAZ engine code) Injection Pump and Pulley. The AAZ pump has a 17mm mainshaft*, 9mm head, a very mild, if not "straight" boost pin which limits the extra fuel supplied under boost (some swap in a different boost pin 1.6 TD for example, Peugeot, etc... with a more aggressive ramp). Because of the 17mm shaft it's probably best not to exceed 10mm on the head and risk snapping a shaft and it taking rest of the engine along with it
"What about the Pump Sprocket / Pulley?"
It depends on the pump you use;
- If you use a VW IDI Pump with the 17mm shaft, just use the original Sprocket an you are done.
- If you use the Cummins VE Pump, You will need to get the pump sprocket to align to the cam sprocket on the TDI because the nose on the cummins pump is shorter than a TDI. This is somewhat critical and if not aligned exactly the timing belt could slide off, once again wrecking your engine.
- You can use an IDI sprocket and have it cut to the size of the Cummins mainshaft and aligning it that way with the woodruff key. this can be tricky and tough to get exactly right.
- You could make spacers to align it to the cam sprocket and engine and an adapter to convert the VW IDI pulley as as Named Tintin did in this thread.
- Use the two piece MKIV style "press on" hub and adjustable sprocket. You'll need to find a core pump with the "hub" that is pressed onto the IP shaft from an ALH pump as well as the sprocket, or buy these new at the dealer (part #'s anyone??). You'll need to have "hump" on what is normally the front of the sprocket machined down to be flush with the hub and then actually mount the sprocket turned backwards onto the hub. DO NOT take any material off the hub or off the sprocket itself once you remove the "hump" from the front side. This setup should line right up, the advantage of this method is it retains the original TDI timing setup and, the adjustable sprocket makes tuning the injection timing easier because you don't have to loosen and move the pump, just the sprocket. This is the method used by and detailed in RabbitGTDguy's The GTD RETURNS! Thread[/list:o]
- Other VE Pumps Peugeot, Ford, etc.
I was unable to find much info, if you have some I will add it here.[/list:o]Figured I might as well add the "Factory VW 12mm mechanical pump" info here as well.
Info courtesy Tintin:
2.8TDI=158HP for the common-rail version, year 2003, code engine AUH, BCQ, but the older version 1996.... have 125HP code engine AGK.What are these sprocket, spring, LDA, governor, thingies you are yammering on about?
Call a bosch shop and ask for the 0 460 424 138
Part number is: VE4/12F1900R693 (0 460 424 138) for a 2.8TDI VW pump.
Parts of the Bosch VE Pump obviously :D
The Diagram Below is for a non turbo VE pump so there is no LDA on top but, it's enough to give you an Idea.
And the LDA Itself
Also see the Robert Bosch type VE Diesel injection pump by Martin Jägersand
(source of the first diagram) for a really good overview of the pump.Great! but, I want to know more detailed meat and potatoes information about the Bosch VE Pumps?
Then you should read the Bosch VE Injection Pump Manual
and The Complete Pump Assembly Tutorial with Pictures (Now English) Thread on the vwdieselparts.com forum
. Kind of funny that it's a translation of a tutorial posted here on the GTD forum :P Thanks for all info but, this seems kinda complicated. Can't I just buy a pump prebuilt and setup for a TDI-M?
Yes, You can I hear. Don't ask me where, I have no idea. The point of this FAQ and the forums is for the DIY'er to turn their own wrenches and put something together. Another answer to this is since the setup and timing of TDI-M pump is kinda of an art and science unto itself, many wind up tuning by ear ultimatley. The service guys will more than likely look at you crossways if you brought a mTDI into service at a VW dealer. You will be the mechanic ultimatley so best you understand whats going on. If you really don't think you can tear into and modify a pump, gather your parts, take them down to your local pump shop and tell them what you want done, at least then you'll have a hand in it.