What is the "Default" advance? Is that checked with a timing light? Easy starting can be up to 15 degrees of advance. For full power use up to 27 degrees of advance is good up to 10,500 RPM. Boosted engines require less advance as boost increases. Because the effective compression ratio as well as charge temperature is going up. Very high boost my have advance closer to zero. Advance is used to allow full combustion
of the charge before the exhaust port opens. At higher pressure and temps the flame front speeds are increasing. So, less time is needed. Thus less advance is needed. Lowering intake air temps with an inter-cooler and adding water spray can allow higher boost.
Boosting to maintain sea level performance would probably not shorten engine life. Boosting for additional performance does shorten engine life. The kids get over 600 HP with boosted drag racing engines. This is fine if you only need the engine for 9 seconds. You have to know what the actual advance is to make any decision. Mark the flex plate or flywheel teeth with paint so you can check actual advance during any RPM.
It is difficult to detonate an NA engine. It is not difficult detonate a boosted engine.
Lynn E. Hanover
Steve,
I’m running default timing or maybe 1 degree advanced. Early on I experimented with 1-2 degrees advance for many flight hours and did not detect any noticeable change in engine performance. I did push the engine to what I believe was detonation during a ground tuning session. I was tuning under boost (44” MP) , 7000 rpm with a wideband O2 on each runner and adjusting Mode 9 and Mode 4. With F/A balanced between each rotor and EGT’s under 1600F I was trying to see if increasing timing would lower EGT’s. F/A was in the 11’s. This was at the end of the session and the engine and supercharger were already hot. I think I had added 4-5 degrees advance with no noticeable EGT decrease when I encountered a mild bang or misfire. This condition was well above my 38” MP limit I sometimes use for takeoff.
I’m curious about the dwell time setting difference between LS1 and LS2 coils. I switched to LS2 coils sometime back with no failures to date. I remember seeing an option setting in some of the code you or Finn posted. Internet research indicates LS2 coils require less dwell time than LS1. Possibly 0.5-1 ms less.
Bobby
Sent from my iPad
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> Hi there Guys
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> Of the guys with Renesis engines using EC2/3 can you comment on your timing settings.
> I’ve to date left the timing at the default setting figuring its set by the location of the CAS.
> Not sure if the various coil options have different trigger timing latency.
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> Thanks
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> Steve Izett
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