06-01-2012, 07:00 PM
Officially Welcomed to the 'Fest
Join Date: Sep 2010
Mein Auto: 4 diesels
Caution: Do not read this if you are impulsive and lack self control.
Originally Posted by TDIwyse
I'd love to have access to someone's car who has a BT and the Evolve or RENNtech tunes to compare the rail pressures, injector timing/openings, EGT's, etc.
Any ideas on what limits the remap's pwr levels? Is it also rail pressure related due to flowing more fuel than the HPFP can feed?
Based on the things I saw from this (http://introductions.www.bimmerfest....&postcount=101) it appeared the limit to the present HP situation was not due to the HPFP.
So, the local vehicle above recently got an Evolve tune. This was somewhat of a gamble as they were not forthcoming on specific questions regarding what parameters they were manipulating to get the gains. Since the presently available “box” options mainly fool rail pressure it was hoped that the tunes were behaving in similar fashions to options from the other common rail vehicles that have been remapped and left the rail pressure alone …
Turns out that is indeed the case. A lot of the day was spent playing and collecting data. Lots of interesting data.
The Evolve tune appears to be making power by increasing the start of injection and increasing the length of time the injectors are open, as well as increasing boost. It is not increasing rail pressure above the stock 1600 bar. This is exactly what was hoped for.
Because the remap leaves the rail pressure alone, this opens the door for something the common rail truck crowd has done for a long time, which is stacking a pressure box with a timing/duration approach.
And the data shows the JBD plays with the remap. CAUTION: There’s now enough low rpm fueling in some circumstances that you could likely break things. This likely eliminates most/all margin in the system. You are your own warranty station. It is not BMW or anyone else’s fault if you doing something that breaks things . . .
Now, if one was so inclined to continue down this path here’s what you might expect.
The testing ground changed from the above Gtech data to a more isolated place with flatter, smoother roads and mature forests on each side of the road (great wind blocks). On this new location the recorded baseline JBD #’s are a bit lower than above. There was some previously recorded data from a similar day (where initial low level methanol/water injection was being examined) as today that will be used as the pre-remap baseline and labeled as JBD 85%. Also the previous JBD alone data was with a freshly regenerated DPF and today‘s data is with a DPF approaching a new regen cycle. However, since it’s a different day with different fuel in the tank and a different DPF situation a 1:1 comparison is impossible. However, it was within ~6 F temps and very similar wind conditions. Since the Gtech utilizes a Serial port interface and none of my home PC’s have one (they’re all USB and the serial to USB device I bought doesn’t work) it will have to wait until after Monday (when I return to work to use my PC there which has a serial port) for the graphs.
But here’s the summation of the hp/tq #’s. The JBD @ ~85% produced similar TQ #’s as the remap, but a bit better HP. Now it might be that the tank of Illinois fuel in the vehicle has lower cetane or BTU’s than what was in the vehicle for the previous tests. Don’t have a way to test that.
After analyzing the BT data and seeing how the remap worked the owner decided to try the JBD with the remap. This is were things got interesting. On the same day, with the same fuel, with the same temps, with the same testing procedure, the data shows the JBD produced similar delta-HP number increases above the remap as the above data for comparisons of stock vs. JBD. For this test the full fueling was specifically held off at low rpm’s to minimize strain on the tranny. This was tested at JBD 0% and with one switch thrown so the JBD was at 65%. 85% was not tested as the BT data needed to be analyzed to see how EGT’s and DPF pressures were doing. The 65% JBD setting produced ~30hp on top of the remap and more torque even with careful low rpm fueling. CAUTION: Full fueling with this combo with a locked up torque converter at low rpm’s could be detrimental to the health of your vehicle.
So, here’s some of the interesting BT data (the hp/tq curves will need to wait ’til I get to work and download the data on the serial port). Note: the JBD only at ~85% were taken with a slightly slower sample rate so it’s a bit “compressed” compared to the other data, and also with a freshly regenerated DPF. I tried to cut the data samples for the comparison at the same time the dyno plots (should show up after Monday).
Comments: The remap increases the boost over stock and JBD (which doesn‘t do anything for boost as the manufacturer states). This appears to help the EGTs (post turbo) #’s. Also, interestingly, the Intake Air Temps for more power a slightly lower with the remap and stacked vs JBD alone.
The JBD at high settings does appear to increase the main injection pulse width and increases the injection timing slightly. But not as much as the remap.
Stacking the JBD with the remap, in my opinion, is showing that it works quite well for these initial tests. The IAT’s are lower for more hp (due perhaps to the extra boost). The EGT’s are (537C is under 1000F) still in a reasonable area, especially for short durations (see this thread for one of hundreds of example discussions: http://forums.tdiclub.com/showthread.php?t=206994). However, if one were to to be at cruising situation at low rpm’s with the torque converter locked up and you applied full fuel then this combination could cause negative consequences. Please be cautious with the information and don’t do anything stupid.
Having the JBD respond with an additional input from the engine rpm would be ideal. That way it could be held off at low rpm and given some leash at high rpm to make more of a flat torque curve across the rpm range.
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