![]() ![]() ![]() On a more speculative note, it would be interesting to see other people with various tunes to see how their tunes compensate for high IAT situations, which we know are very common on these cars? I am personally not sure if the ECU scales back timing on a linear scale, or of it is target based - in other words. The ECU has plenty of room to pull back timing a few degrees (which is all it needs to pull back from those levels) to compensate for the high IATs. Something VERY important is to see that at initial WOT, before the IATs hit temps to cause the ECU to pull back, I hit -15deg. Now if you look at that log (it is posted in the dataloggers thread - I know it's a bit difficult to read), the last "jaunt" (when my MAP sensor reaches it highest reading in the log), you can see my timing running in the single digits AND you can see my IATs hitting 185F (it was very cold outside). My most recent log, from February, which is also with my most recent tune, shows roughly -15 to 0 timing at 100% load. As you may or may not know, the ECU will pull back timing when it sees high IATs. Unfortunately I have an IAT issue with my car which can cloud my numbers somewhat. BTW, you have one of the sweetest looking SL65's I have laid my eyes on, seriously, I love that picture.David, Marcus, what is your timing under load, if you know it off hand? I don't see that you have listed whether or not you have a tune, do tell if you don't mind. You know I love this forum! Such a wealth of information and experience readily shared. Tuning could have changed a lot over the last few vering my A.blah blah blah If someone is honestly showing -24 to 25 on a tune, according to what I have learned and ONLY talking about our E55's, it's a ticking time bomb. Upon talking to some other tuners I was told that is on the edge of safety and to be careful around that range. Then tuners seemed to get a tick more aggresive and I had a couple slip and tell me they were running in the 20-22 range. I have had tuners change the subject on me when just asking what they run.Īnyway, it's my understand that under load like Marcus said, average numbers were running in the upper teens on most tunes. Seems like that timing number is the most coveted secret in tuning. Gotta be over a half dozen so far over the years. I wonder if I hold the record for most tunes put on one car from different tuners. I am by NOOOOO means a tuning guy (know intricate details) but I am just repeating over the years of hearing numbers come from tuners. ![]() I'll pull my old charts out and post the numbers, but it was only like 1% power for each degree of timing. On a side note, B&M saw on their dyno that you only loose a little bit of power for each degree of timing pulled. Now, with all the ECU's, you really need a dyno or a GOOD knock sensor to see what is going on. In the old days, it was easy with a MSDS boost retard box, you simply turned the knob down to you heard some rattle, and then backed it off a tad. The BEST tool for this is the DYNO.ĪKA tweak the timing as high as you can, and once you reach detonation, back it off a tad. Hence there is NO magical number you can use, as EVERY engine will be slightly different. Yes gentlemen there are tolerances in EVERY engine made. Hence 31 may work for one without detonation, and another may only take 28. The problem is that ALL engines, even built by hand, have differences in them. However, MOST engines can not take this much with our lovely gas sold these days, hence they turn it down. It DIDN'T matter who made the engine as BM, Weiand, and several others tested their blowers on ALOT of engines and ALL of them came up with this magical number Old school logic from the 80-90's is/was ALL FI motors like timing and that MAGIC number is 35 degrees advance for MAX power. ![]()
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