Quote:
Originally Posted by towndrunk
We are running lean burn in first gen Chevy Volts with good results, but does require a custom tune and open loop.
We run leanest (~20:1) at 1400 rpm (idle speed) and normal AFR above 2200 rpm. Running lean requires a lot more cam advance and a lot more spark due to the loss of power and slower burning mixture when lean. You also don't want to run lean with a cold engine, which created a lot of hurdles, but I think we handled it quite well. With the addition of a alcohol sensor ($45 in parts), the mixture is accurate with either premium fuel or ethanol blends of E30 (due to higher octane) to E85. Since the first gen Volt is high compression, we decided to stick with premium fuel to take advantage of it. Our tune is highly optimized even with E85.
It may not sound so impressive running max lean at 1400, but we're able to maintain 1400 rpm at highway speeds of up to 59 mph for an extended period of time.
More info on HPTuner's forum. forum.hptuners.com/showthread.php?63020-First-Gen-Volt-Tune-(Volterado)
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I'm interested in how you changed the cam timing for your lean burn tune. I'm running a lean burn tune on my Subaru WRX (up to 17.5:1 with up to 7.5 degrees ignition advance.) with some success, which
I posted about here.
I haven't changed cam timing at all as I'm not really sure how it affects the tune. Is it recommended to advance both intake and exhaust timing in tandem or adjust valve overlap as well? My DIT engine is knock limited even at highway cruising loads, so tuning cam timing may be tricky, as it will affect knock, and therefore ignition timing.