Assume a 2.0 L4 engine, 85mm bore x 88mm stroke, good to very good quench characteristics, high 9s to 10:1 compression, running 91 octane. I'm seeing only about 22* advance at wot from 3500rpm on up. My gut tells me in order to make max torque/power the engine can use quite a bit more advance (based on previous experience with old school carbed engines). But approximately how much would it need?
That might be about right. Heck, modern design 2-valve chambers work best with only 25-26 degrees or so.
Remember the whole point of good chambers is to get the mixture burnt FAST, reduce the amount of ignition lead required so you waste less crankshaft energy/pump less heat into the cooling system from trying to compress an expanding charge. And ignition timing may not be knock limited, either. You might very well be able to advance it up to 30 degrees or beyond without knocking, but it would not gain any more torque.
In reply to Knurled :
Yes! Thanks for reminding me of that tech info. Looks like only spark sweep on a dyno is the only way to get truly optimized, then.
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