A/F ratio under Decel?

[JustinL]

In terms of performance on a turbo car, what is the ideal air fuel ratio on decel overrun?

Lean- more heat... maybe more turbo spool between shifts (popping exhaust)
rich- more fuel to cool the turbo (flames out exhaust)
cut- fuel economy

I'm all ears and willing to learn

Justin

[ae1969]

In terms of performance on a turbo car, what is the ideal air fuel ratio on decel overrun?

Lean- more heat... maybe more turbo spool between shifts (popping exhaust)
rich- more fuel to cool the turbo (flames out exhaust)
cut- fuel economy

I'm all ears and willing to learn

Justin

Great question. I don't have the answer as you know.....

BUT I ran the car with 14.7 at those low KPA cells...... and it was enough to make it POP POP POP POP.......sounded like an f1 car....

BUT I ended up richening up those med/high rpm / low kpa cells ........ I did not notice much on the butt dyno. Except no popping.

What I did notice is that it is a fine balance of too much fuel not enough timing....... your egts climb pretty fast if this is out of balance. I have set up mine to not climb past 1600F.

The dilemna is that those higher rpm/low kpa cells are also at play in highway driving. Thats when I noticed my EGTS really climb if the mix was wrong. (AFR to Timing)......... I tried to keep adding more timing to counter act the climbing egts but my knock light started going on when I would DECEL at high rpm.

SO its a balancing act for me. Where it should ideally be......... pfffft. Don't have a clue but I am going by what my guages say.

High egts/ knock light on. Not good.........adjust until those are gone.