TDI-M pump pressure question

[Blades]

Ok, we all know the 1.9TD pump ain't cabable of giving a TDI injector enough fuel pressure.

The Question is ... Is there any way to increase the 1.9TD pump pressure output to get near a TDI required pressure or is it a lost cause.

Would a 10mm mecanical pump be enough ?

1.9 TDI (mk4) + 1.9TD pump + 1.9 intake and exhaust manifold + KKK K24 turbo.

That's the general idea in my head right now.

[QuickTD]

Installing the TDI camplate head and rotor in the TD pump will increase the rate of injection and therefore, the pressure. The next hurdle to overcome is keeping the driveshaft together. The TDI (or any direct inject) driveshaft is 20mm as opposed to 17mm in the TD. The smaller driveshaft will break after prolonged use with the TDI camplate and head. The TDI pump body is also reinforced quite a bit compared to the TD housing. I haven't heard of any housing failures yet though. The best approach would be to use a direct injection pump body from something else (peugeot cummins etc.) and the camplate, head and rotor from the TDI.

[RedRotors]

I'm with Bruce on this, the IDI shaft won't probably be able to hold the extra stress. According to Bosch, IDI pump throw around 400bar and TDI around 800-900bar. I included a picture to show you the difference between the two shaft and the camplate. As you can see, the TDI camplate has much more lift and a more agressive step..






Marc/

[fspGTD]

Great pictures Marc!  That is interesting to see side by side those different camplate profiles.

[Blades]

Time to see if a Jeep Cherokee Diesel (2.4L 4-cylinder) is going to work.

[caddy]

some  1.9 idi pump have a 20mm.
on my passat 1.9td i have a 20mm. but no lda!

for the pump of the cherokee, i think it will turn on the wrong side.

[RedRotors]

I think you'r right.. the late 1.9IDI pump got the same housing than the A4 TDI pump, with a slotted pulley and the shaft seems bigger then our 1.6.. The pump number is NR 0 460 494 473.

Marc/

[Otis2]

I thought you non-Vanagon guys might be interested in Karl Mullendore's reported experiments with a mechanical pump mounted on a 1.9 TDI AHU engine.  Notwithstanding Blades' earlier comment in this forum that "we all know the 1.9TD pump ain't cabable of giving a TDI injector enough fuel pressure", Karl is giving it a shot.  You can find the original post up here on the Yahoo group: http://autos.groups.yahoo.com/group/TDI-conversion/message/5005

Here's the text for those who aren't members of the TDi conversion group.  It will be interesting to see how long this thing lives, with the narrower IDI shaft and stock AAZ pump mounted on it.  Comments from the mad diesel hackers on this site encouraged.  You know who you are.

From:  "Westyman" <syncrowestytd@m...>
Date:  Thu Jan 13, 2005  7:49 pm
Subject:  Update: mechanical TDI AHU: it runs!

I'll start by saying that sometimes just because something looks like it should work perfectly, that doesn't mean it really will. Case in point, the
hybrid pump I built, using first a 1.6TD pump and then a 1.9TD pump as the basis. I swapped the pump head and camplate from the TDI injection pump into each of these, in several combinations, and it just doesn't work as perfectly as I had anticipated. The TDI pump is fairly simple, just an
electronic speed controller and an electronic timing adjuster, so the swap 'should' work. The head and camplate measure and appear perfect for a swap into the TD pumps, in theory it would work fine. But it worked horribly in the 1.6 pump, with smoking and throttle control very minimal. The 1.9 pump combo worked better, but the max fueling screw had to be turned all the way in before the boost would really begin to develop, and then the idle was at 2000 with the adjuster backed all the way out! Just couldn't get enough fuel. Power output wasn't that great either. Meanwhile, I contacted someone at Overland regarding the 'TDD' they use to sell, he stated that all they did was install an un-modified 1.9TD pump and then readjusted things until it ran well. So, I pulled the TDI parts from the pump and reinstalled the original camplate and head. The camplate does have the same lift, but a smoother peak to it; the head however has a smaller pump piston. In any event, the stock 1.9 pump works fine. I still have a little more tuning to do, but it pulls quite well and sounds more 'refined' than the old TD I pulled out. Other side benefits are the coolant and oil temps are WAY lower than with the TD, and it starts instantly without glows. Even the EGT is lower, which shows how much more efficient the burn is in the cylinders. I guess I'll stick with this setup until the Fiat pump arrives and I can play a bit more...

Karl

[VWRacer]

Good stuff, Otis!

He must be very confident of its potential, since I notice that Karl's leaving on a month-long trip across the country and back.

[QuickTD]

The lack of throttle control Karl experienced sounds like the result of improperly shimming the installed height of the plunger. There is a small "button" that needs to be changed to set the initial plunger height. Without the proper plunger height the effective range of the control ring/governor would be out of whack. Symptoms would be possible low pump output, improper "start of injection" in relation to the camplate profile and lack of throttle range. He also should investigate the use of the advance piston and cover from the tdi (or some other DI engine). Due to the slower burn speed DI, engines tend to need more timing advance than IDI engines.

[westyman]

The lack of throttle control when I tried the 1.6 TD pump with the TDI camplate and head weren't a result of improper shimming, but the fact that something is definitely wrong with the pump. It's a 'new looking' one I got on ebay last year with no guarantee. I found the aneroid totally gummed up and the control ring is frozen on the plunger as well, but the main thing is that no matter what I do or where I adjust the lever, it never moves the rocker to move the ring. It's a weird one, I looked at it for a few hours to try to figure out what was amiss. I tried a top from another 1.6 pump and that one gave great control but way over-fueled eeven when the max fuel was screwed way out. I guess tops aren't interchangeable between slightly different pumps. Anyway, the second pump and top were leakers. The TDI camplate has exactly the same lift as the 1.9 TD camplate, just a slightly different profile, as you can see in photos I posted on the TDI conversion site, I doubt it woould break the shaft all that easily. Maybe the solution would be to try shimming the TDI head in the 1.9 pump, but I'm not sure at this point how to figure the proper shimming, anyone? In any event, the stock 1.9 pump setup on the TDI is doing well, torque in the bottom is better than the TD it replaced, but seems lacking about 3000. I am running a slightly larger turbo than the TDI came with, it will make 20-21 psi easily [I will adjust before the trip!]. One mod I may try is to modify the aneroid shaft, on the 1.9 it is flat instead of cone-shaped like the 1.6, I'm going to machine the opposite side of the shaft to more of a similar taper and see if that boosts fueling in the higher rpms. Seems to be getting plenty of air, EGT's won't go over 850 at 30-40 ambient no matter how hard I run it.  Re: the TDI advance, the TDI pump has an electro-hydraulic solenoid to control advance and is totally different from the 1.9 TD pump advance. My feeling currently is the Fiat Chroma pump the German tuners use, plus larger nozzles, will wake it up sufficiently. Anyway...outside of tinkering with the aneroid, we're taking off Wed. for the southwest US, no more time to dilly dally! Wish me luck!

[westyman]

BTW, the IDI camplate you show above has less lift than the 1.9 IDI, which has the same lift as the TDI but a rounder profile like the one pictured. According to the Bosch Diesel FI manual, the 1.9 pump makes plenty of pressure for the TDI injectors.

[RedRotors]

BTW, the IDI camplate you show above has less lift than the 1.9 IDI, which has the same lift as the TDI but a rounder profile like the one pictured. According to the Bosch Diesel FI manual, the 1.9 pump makes plenty of pressure for the TDI injectors.

The IDI pump will give you a max pressure around 450bar instead of 800-900bar in the TDI pump..

Marc/

[westyman]

More reading makes me think the TDI camplate and head should work fine, if not better than the TD ones. When they were installed in the same pump, fuel quantity was way low. From my understanding of the inner workings so far, the plunger then must need to be shimmed to deliver more fuel. I'm not clear on whether to change the button size (smaller or larger?) or the shims between the plunger and cross brace. Marc? Thanks for the advice.

[QuickTD]

If quantity was very low you would need a thicker shim to increase it. The higher the initial plunger position, the later in the stroke the injection ends for a given control collar position. The initial plunger height spec. varies depending on the pump. I'm not sure if Marc has access to this info or not... On the EDC TDI pump it is of less relevance because the pump cover holes are slotted and the quantity adjuster can be moved a considerable distance. On a conventional pump the control ring position is not quite as easily adjusted.

 The TDI's timing system is controlled partly by the electronics. The advance piston spring and housing pressure are set up to insure that the pump timing is always slightly advanced at any given engine speed. The timing control solenoid is then pulse width modulated to bypass some of the pressure around the advance piston, retarding the timing to match the preset map. Feedback for this process comes from the crank position sensor and the pintle lift sensor located in the #3 injector. I would think that fitting the advance piston and cover from the TDI to the IDI pump would get you something resembling the TDI advance curve, but slightly advanced at all speeds. You could compensate for this by lowering the housing pressure or fitting a stronger advance spring or additional shims to the existing spring.