Quote:
Originally posted by dpeete
True. My race car runs 4 additional degrees of advance in all conditions (110 degree days at Thunderhill Raceway aren't uncommon) and has no problems. But I have tested the car in various conditions to see what I could get away with.
The thing to remember about modern motronics is that it is far more costly on performance to advance timing until you hit a ping then it is to just run a little more conservative. On BMW's I see the ECU pull out 6-8 degress of advance as soon as it senses a knock. So if you advanced the default timing by an extra 4 degrees at a given RPM point and get a ping you will wind up netting negative 2-3 degrees of timing. If you had just played it conservative at 3 degrees of extra advance you would always be ahead of the game.
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That has proved to be quite a problem with the GM LT1/LS1/LS6 small-blocks -- they are hypersensitive to ping and sometimes confused by resonation of engine accessories (gear drives, blowers, etc.). Some guys are constantly fighting to keep the ECU from pulling out their advance.
Luckily, both the stock 460 ecu and the earlier 5.0L Mustang ECUs lack knock sensors, so this is not an issue with those. On the Tundra, it's a different matter, although it seems more tolerant than most. Obviously, one will have to excercise care in modifying the iForce's advance curve -- sometimes less is more.