Well, I guess I'll post this up for everyone's benefit (if it really is a benefit). I was contemplating the problem of not being able to rev the LBZ past the 3500ish area under load. I came up with a somewhat unorthodox way of getting some more RPMs out of these motors. I can't say how well it pulls in the higher RPMs or how it shifts. I have never actually tested these theories on my truck. It isn't because I am afraid to; it is due to the fact that I am a loooooong way away from my truck right now. Okay, now on to my method.
The first thing I did was went into table B1102 and raise the torque based fuel numbers from 3400 and 221 Ft-Lbs and higher to 120. I did the same thing with 4800 RPM except I started at 74 Ft-Lbs. I thought this alone would cure the defuel problem, but there is another table somewhere that drops commanded fuel independantly of this table.
In order to work around the unseen table I went first to table B0720. What I did there was modify it so that my max fuel in the 180 and 190 MPa columns extended all the way down to 30 mm3. I then went to table B1001. What I did there was make the any block in the 3600+ RPM range and 35+ mm3 range be 190 MPa. This would ensure that above 3600 RPM I would have 180 MPa of rail pressure and should keep my injector duration at my highest desired level all the way down to a commanded 35 mm3 of fuel. I also dropped anything at 3400 RPM or less and 95 mm3 or less to 170 MPa. This should push the duration to the 170 MPa column and allow the truck to defuel if it is at 3300 RPMs or less so the transmission should be able to shift. Like I said, I've never been able to try this out so I can't say for sure if it works or not.
The next things I addressed were boost and timing. Since the truck thought it was getting less fuel it was dropping boost and timing. To fix this I just went into the timing tables and extended my max timing at 3400 RPM and 4800 RPM all the way down to 35 mm3. To fix the boost I did the same thing I did to the timing.
You will also need to go into table B1118 and B1119 and make the corresponding block for whatever you want to be your max RPM, and anything higher than that, "0".
Just as a final disclaimer, I have personally never tried this and cannot vouch for how well it pulls, shifts, smokes, revs or anything. The only thing I have is a log that shows it going 70 mph in 3rd gear at 4300 RPM.
If you try any of these mods and get a satisfactory result I would love to see a log of it. I would also be interested to hear if you try this during a sled pull to see if it allows you to get some good RPMs while you are under a heavy load since that was my main motivation for trying to get more RPMs in the first place.
Attached are some screen shots of the tables I modded. Good luck.
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The first thing I did was went into table B1102 and raise the torque based fuel numbers from 3400 and 221 Ft-Lbs and higher to 120. I did the same thing with 4800 RPM except I started at 74 Ft-Lbs. I thought this alone would cure the defuel problem, but there is another table somewhere that drops commanded fuel independantly of this table.
In order to work around the unseen table I went first to table B0720. What I did there was modify it so that my max fuel in the 180 and 190 MPa columns extended all the way down to 30 mm3. I then went to table B1001. What I did there was make the any block in the 3600+ RPM range and 35+ mm3 range be 190 MPa. This would ensure that above 3600 RPM I would have 180 MPa of rail pressure and should keep my injector duration at my highest desired level all the way down to a commanded 35 mm3 of fuel. I also dropped anything at 3400 RPM or less and 95 mm3 or less to 170 MPa. This should push the duration to the 170 MPa column and allow the truck to defuel if it is at 3300 RPMs or less so the transmission should be able to shift. Like I said, I've never been able to try this out so I can't say for sure if it works or not.
The next things I addressed were boost and timing. Since the truck thought it was getting less fuel it was dropping boost and timing. To fix this I just went into the timing tables and extended my max timing at 3400 RPM and 4800 RPM all the way down to 35 mm3. To fix the boost I did the same thing I did to the timing.
You will also need to go into table B1118 and B1119 and make the corresponding block for whatever you want to be your max RPM, and anything higher than that, "0".
Just as a final disclaimer, I have personally never tried this and cannot vouch for how well it pulls, shifts, smokes, revs or anything. The only thing I have is a log that shows it going 70 mph in 3rd gear at 4300 RPM.
If you try any of these mods and get a satisfactory result I would love to see a log of it. I would also be interested to hear if you try this during a sled pull to see if it allows you to get some good RPMs while you are under a heavy load since that was my main motivation for trying to get more RPMs in the first place.
Attached are some screen shots of the tables I modded. Good luck.
