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A/F ratio under Decel?
Posted: Mon Sep 11, 2006 1:52 pm
by 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
Re: A/F ratio under Decel?
Posted: Tue Sep 12, 2006 10:36 am
by ae1969
JustinL wrote: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.