[Diy_efi] Ignition Timing

[Jim Butterfield]

Hi Damon
Glad to see your looking into all aspects of making big HP, its a bigger concern today with these new power plants... ive a 3800 SC engine and we really have to watch the knock as we drop in pulley size.... our engines have knock sensors. What we do is just drop a pulley size and scan the engine computer.. we can then look at the log and find out how much knock retard we get.. two choices there... get the exhaust to flow better or lower the boost... If you have a newer car and it has a knock sensor as yousay, get a scanner  for your pcm and drive and check the logs... 
 
whats the MBT you talk of???
 
jim

"Becker, Damon (Damon)" <damonb at avaya.com> wrote:

I have a turbocharged 4-banger making around 350 crank hp.  Knock is clearly a concern in this setup as I map my EMS.  This discussion is for the knock-limited range, not the off-boost cruise range.  Since I'm knock-limited, I won't hit MBT timing before I hit knock, right???

I have read many books that advocate reading the plugs as a great way to set the ignition timing.  I have read other places that using a stethoscope against the block and listening for knock under heavy loads while doing the dyno runs is the best way.  I have yet others say it's best to use the stock knock sensor (unmodified internals, stock knock sensor still valid) to listen for knock.  

What's your best way?  

Thanks for your time, 
Damon 
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