Some help from me - T4 ori file at
http://www.ecuedit.com/vw-transporter-t4-2-5-tdi-vp-151hp-t564

Thanks a lot! Yes, I am blind, I admit it... :geek:

Now to work out a new pump voltage map. Am I right in thinking these values need to be scaled to 5/4, per cylinder? So 50mg/stroke in the T4 map will be 62.5mg/stroke in the 4-cylinder map or do they scale 1:1?

Regards

The scale is 1:1. The pump voltage map is "per injector" no mater the number of injectors.

Thanks again, that helps a lot!

Looking at the T4 map, I can see that I used the wrong values to interpolate from (some graphics/spreadsheets posted in other forums, not from original dumps). The part number (BOSCH Nr: 0 460 415 985 / VW-Nr: 074 130 109 R B00) for the T4 pump I found tells me it is a 10mm pump.

Taking into account the 11mm plunger installed on my pump, it has 21% more area than the 10mm one. Due to the higher pressure, there will be higher leakage losses, so I'm calculating 15-18% more volume over the 10mm plunger, but still researching whether I can calculate this more correctly. I'll have to look at maps with 10mm/11mm plungers again and see whether they scale about as proportionately and by how much and adjust the factor.

From what I've read, with a 10mm plunger piston a VP37 can push a max of 70 mm³/~58mg per stroke (depending on temperature), with an 11mm plunger 100mm³ or ~83mg/stroke. Depending on injector size, internal pump pressure and leakage losses differ, but the absolute limit is set by the plunger. So with 100mm³, if I just do linear interpolation (multiplying the map by 15-18%), the map goes up to between 71 and 74mg/stroke @ 4500 RPM at max safe quantity adjuster voltage (4,85V).

Remains to be seen whether this can be used or not - SOI will have to be moved forward a little bit, definitely, and EGT and smoke tested.

My long term plan says about 68mg/stroke @ 4000 and about 73-75 @ 2300-2500 - both of these limits should be doable, from what I've calculated.

First step still will be to get the pump voltage map as right as possible, and then scale up to the short term goal of around 150hp/320Nm smoke-free and go on from there.

Regards

Hi,

hybrid turbo is installed and running fine :) Now let's get this show on the road!

However, I'm not so sure about my 15-18% factor or the 21% area increase being a realistic scaling factor - since the max fuel rate per stroke for the 11mm plunger vs. the 10mm one differs by almost 43% instead. So I guess there's nothing else to do but buy a wideband AFR sensor and do logging runs with 10/20/30/40/50mg etc to calculate better values...

The pressure and associated leakage losses do increase, as well, but probably not by as much - they are ~6mg/stroke for a 10mm pump with .184 injectors, 51mg/max vs. 57mg theoretical (70mm³), and almost nil with .216 injectors and 10mm pump (about the 57-58mg/stroke the 10mm plunger can offer can actually be injected).

The values I have estimated (with the 15-18% factor) would work out if there were ~10-12mg/stroke in leakage losses, which is probably higher than real-world.

So I'll start out with a little lower voltages than previously calculated (higher IQ gain by plunger change) somewhere between 21 and 43% in the pump voltage map for the same IQ and measuring AFR, probably smarter to approach optimum from the low IQ side than from the high one.

Regards

Okay, did some more research and found out some of the numbers I used to calculate from previously were bogus. Helps to think about them and not just blindly copy.

Namely, the plunger piston displacement volumes - the values I found were not for 10/11/12mm but for 10/12/14 (14mm exist, although not OEM AFAIK) and scale proportionately to the area increase. I was getting a headache trying to figure out why 10% diameter increase should produce 42% more displacement anyway...

i.e. theoretical limits for a VP37 in good working order are about 57mg/stroke using a 10mm plunger, 69 for the 11mm and about 83 for 12mm, all @4000-4500 RPM.

So the 15-18% values I was using to start out with weren't so far off the mark after all ;) Area increase is ~21%.

Taking this into account, my long term goal still is doable, but it's at the outside of the envelope - may have to use larger injectors or live with a few HP less, we will see what log runs, EGT and smoke say.

Regards

Keep up the good work :thumbup:

Thanks :mrgreen:

Also, I've compared my IQ values for projected torque with values I got from other VEP cars and logs in stock configuration - seems the IQ I was using from a PD file is a bit off.

From my new data, I'm projecting 5,6Nm per mg/stroke @ 1900 (torque max) from the stock file - 210Nm (37.5mg/stroke from logs). This will be falling as RPM increase because volumetric efficiency decreases, so I'm going to investigate more in the stock file and see what the pump voltage map tells me to estimate VE and resulting necessary IQ at higher RPM.

So new values (without VE so far) would be -

Torque max
350 Nm @ 2300-2500 -> 62,5mg/stroke

HP max
315Nm @ 4000 = 180 HP -> 56,25mg/stroke

That takes the remap out of the danger zone into safer territory, at least as far as calculations go. The IQ @ 4000 will probably have to be adjusted up a bit due to VE decrease.

Also, looks like I won't have to extend maps to 75mg/stroke just yet, 70 should be enough ;)

Regards

Its not actually the VE that is changing the fuel requirement IQ.
Its the BSFC IMHO.
Mine is 0.34 lb.hp hr @ 2000
That drops to 0.38 lb.hp hr around 4000rpm

This is not unexpected as its cam design too.
Best idea is normally to map stock IQ vs power vs RPM.
Build a BSFC chart from that.

Thanks a lot for the hint!

Okay, that looks doable - will work on a BSFC table. All I need now is a stock torque curve with some more data than just max HP/torque ;) Off to research!

Regards