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I was wondering if anybody scales the MBT timing tables to reach anything over 225kpa Manifold Absolute Pressure, or around 18psi of boost. I want to hit at least 20psi at about 11* of timing. Ive read that these cars can take 20* of timing well over 20psi of boost, is that a safe area to be in?
IMHO , it's good practice to rescale all tables once you rescale one.
If I rescale PT spark I rescale everything in the tune that uses those RPM and MAP values , and adjust the P-ratio values to their new corresponding adjusted MAP value.
I've seen a few SRT4s hit 20lbs of boost and boost levels as high as 22-24lbs....I don't know how long they lasted and I've never tuned one, and I have never built one.
I agree with PurpleRam...
I like rescaling all the tables as well. This way it is "less work" to the PCM or TCM... it becomes more smooth and harmonic throughout all the tables.
I'm not going to suggest you need to do it one way or the other. I just popped in to point out a few examples of it being done both ways by Mopar calibration engineers.
For example, the 2004 calibration 05029415AH only has the MBT timing tables mapped out to around 100 kPa (can't remember if it's 100 or 105 off the top of my head).
The 2005 calibration 05029832AE is the only factory stock calibration that has the MBT timing table mapped out to 225 kPa that I've seen.
Furthermore (and this is a bit more fuzzy in my memory), I seem to recall the Mopar s2 and Mopar S3 calibrations (which are calibrated with a 3 BAR MAP sensor) are definitely not scaled out to 300 kPa in the MBT timing table. If memory serves, they are also only scaled out to 100 kPa, like the 04 stock calibration.
Take that to mean whatever you want. Like I mentioned earlier, I'm not suggesting one way is right and the other wrong. I suspect one way is a bit more ideal (the expanded scaling), but I don't imagine it's going to have a profound impact. Especially if you haven't done any legitimate calibration trials to determine what MBT truly is for your combination within the load and RPM ranges you're extrapolating into.