How to set a AFR Target Table for Endurance Race

I'm wondering how People set a AFR Target Map for Endurance Races like 24h.

We did it on a Stock ECU before several times and used fuel like nothing else. Now going to a PNP solution with a MS3.

It highly depends on octane rating of fuel in use- the higher it is the leaner you can go. But in order to find out exactly you need a Dyno to play with the numbers. For instance you might loose a few hp by reatarding ignition timing and leaning out the fuel map to some extend - it's an act of balance. 4G63 makes best power at 10.8-10.9 and it would loose a little bit of power at 11.3-11.4 but save some fuel.

georg1970

It highly depends on octane rating of fuel in use- the higher it is the leaner you can go. But in order to find out exactly you need a Dyno to play with the numbers. For instance you might loose a few hp by reatarding ignition timing and leaning out the fuel map to some extend - it's an act of balance. 4G63 makes best power at 10.8-10.9 and it would loose a little bit of power at 11.3-11.4 but save some fuel.

When you say the 4G63 makes best power at those AFR values, are those for absolute best power or best power and also with ultimate safety?

At the beginning of my Evo 8 journey i very quickly realised that they tend to run single digit timing amounts and richer than most engines! Even at moderate boost pressures its common to see less than 10 degrees

Find places you can safely pull fuel - WOT is not one of those places to try and skimp once you've found what the engine wants for the power level you're targeting - it ends up being an aggregate of small changes not just one big sweeping change:

Partial throttle - many race (na) setups run 13:1/.89ish lambda everywhere because its easy and makes for not really having to play with accel enrichment to keep throttle response crisp. There's no reason if you're keeping EGTs in check that you cant run closer to stoich so long as accel enrichment is dialed. Obviously run whatever the car wants under boost if its not NA.

Decel - if your engine doesn't need the fuel for lubrication or cooling (rotaries and others) you can generally do without the pops, bangs, snorts, and fireballs on decel for the most part. Turn on fuel cut, or at the very least dial back how much fuel you're dumping at 'high' vacuum and decel.

Accel enrichment - while having them dialed in well is fantastic, it's also easy to be extremely lazy and go overboard.

The list goes on, and there's no magic bullet but you'll find gains here and there. Add them up and it's measurable.