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  1. Replies
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    Well you are regurgitating an internet myth from...

    Well you are regurgitating an internet myth from the days when people removed the emissions equipment on carbureted 305s. Of course they had issues running carbs and HEIs calibrated to work with EGR...
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    Absolutely zero of that is true on a L30 Vortec....

    Absolutely zero of that is true on a L30 Vortec.

    The factory L30 heads flow better than the Mexican L31 Vortecs GM has been selling for the past 20 years. The L30 heads make max power around...
  3. I have not downloaded or looked at the HPT file,...

    I have not downloaded or looked at the HPT file, since I am responding from my phone, but figured that was the case. He needs to look at the vacuum modulator and adjust it for the new vacuum levels...
  4. I also want to say those Kodiak 8.1Ls were...

    I also want to say those Kodiak 8.1Ls were detuned for 250-280 hp and ~4,000 rpm maximum engine speed. It is the same engine, GM just limited the throttle body opening and engine speed...
  5. If it has an Allison AT545 in it, I recall those...

    If it has an Allison AT545 in it, I recall those somewhat relying on the engines rpm governor to help upshifts. When the rpm governor activates, the increased vacuum draws on the modulator helping it...
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    458

    Just toggle the switch in the flip down window to...

    Just toggle the switch in the flip down window to non-computerized automatic. It works despite what some claim.
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    1,055

    Scott, I am also going off first hand...

    Scott,

    I am also going off first hand experience tuning that engine in everything from a 26K motor home to a friends 99 K3500 dually towing a large travel trailer. If you are ever towing with it,...
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    1,055

    The 2nd issue if datalogs were not made, it is...

    The 2nd issue if datalogs were not made, it is impossible to know where your engine is operating at a given point in the spark timing map. A stock engine may see a cylinder load of 0.64 gm/cyl at...
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    Scott, I would say at 8 in/hg vacuum, maybe...

    Scott,

    I would say at 8 in/hg vacuum, maybe 20-24* if it is over 3,000 rpm, like part throttle kickdown, running uphill kind of scenario. If its lower rpm, like 2,000 maybe as little as 16* ...
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    I still feel like 28 is too much even on 91+...

    I still feel like 28 is too much even on 91+ octane. 24-26 is about as much as I would dare on 91. No more than 22 on 87. Curve can be a little quicker at lower rpm and the negative values brought...
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    Guess you have not done much tuning on a 454 with...

    Guess you have not done much tuning on a 454 with those heads or an 8.1L for that matter. 24-26 is pushing the limits on 91 much less 87 octane. My personal 8.1L in my 99 Tahoe made peak power on...
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    1,186

    His PCV and timing driven crank oscillation...

    His PCV and timing driven crank oscillation theorys were out there. He claimed many times a cold air intake would cause an engine to fail because it would not allow 2 in/hg of crankcase vacuum at...
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    These all spark knock on 87. Best to run 91 and...

    These all spark knock on 87. Best to run 91 and give it the timing it wants to run well.
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    373

    I am fairly certain I have a stock 2004 or 2005...

    I am fairly certain I have a stock 2004 or 2005 DBC 4.8L as well.
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    985

    If he put a stock L31 van tune in it, runs...

    If he put a stock L31 van tune in it, runs flawlessly like a stock L31 van does on an 0411 or a GMT800 L31 truck runs on a P59.
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    1,075

    I am 100 miles from my tuning laptop at the...

    I am 100 miles from my tuning laptop at the moment, but I will add it up on here when I am back in town. Might be a week or so.
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    I have a 2005 Mexican L31 file that goes into a...

    I have a 2005 Mexican L31 file that goes into a DBC Green/Blue. Was a factory L31/5spd manual.
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    The fuel gauge was not wired through the PCM in...

    The fuel gauge was not wired through the PCM in 96 or 97. Starting in 98 it was. My 97 van has a fuel level buffer module to the left of the column under the dash that the sending unit feeds a signal...
  19. I have never had much luck keeping the GM vans...

    I have never had much luck keeping the GM vans cool using electric fans. My 87 G20 had far better cooling using the clutch fan and OE shroud. I had my 6.0L in the van using mounts that put the 6.0...
  20. You absolutely can change the TPS on a DBW...

    You absolutely can change the TPS on a DBW throttle body. The TPS is a fraction of the cost of a replacement throttle body. I have changed many of them. It is an easy, quick procedure.
  21. The 4.8L and 5.3Ls I have tuned with 706/862...

    The 4.8L and 5.3Ls I have tuned with 706/862 heads and stock cams hit MBT around 26*. 24* will not sacrifice much output. I also only run 26* at 5,200+ RPM. I have tuned multiple examples on the...
  22. It might take up to 28-29*, that being said leave...

    It might take up to 28-29*, that being said leave it at 26, work on the timing curve a bit and the fueling. The engine may like a bit more timing in the low-midrange. Hard to say for sure without...
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    10:1 is still a safe WOT air/fuel ratio. The...

    10:1 is still a safe WOT air/fuel ratio. The factory tune runs that rich when it is in catalytic converter overheat protection mode. Not saying you need to run that rich, but GM adds fuel fairly...
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    For boost, best to re-pin for a P01 or P59 and go...

    For boost, best to re-pin for a P01 or P59 and go to a custom operating system. I prefer the P59 since it has a 3-bar OS available. Not hard to do since the last 4.3L S10s and Astro vans had the P59...
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    Not all tuning software has the MAF fail...

    Not all tuning software has the MAF fail frequency option for all operating systems. I have tuned all black boxes from 96+ so I forget which ones have the fail and which ones do not. I typically tune...
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