Forced induction A/F ratios?

[97 Jimmy]

Could I get some feedback on what others are idling at with centrifugal applications? Mine idles @ 14.7, 12" manifold vacuum (about .5 psi leaving the S/C). Thanks in advance, Les.

[Lextech]

Mine idles at 14 inches and 14.7 Stock 305 w/twin T-3 turbos.

[rat]

At idle you should have vacuum, and run 14.7:1 afr, should also be in closed loop, with the fuel trims trying to keep it at the 14.7afr.

Only when your manifold is in boost should you really start to richen up the mix.

[97 Jimmy]

Originally Posted by rat

At idle you should have vacuum, and run 14.7:1 afr, should also be in closed loop, with the fuel trims trying to keep it at the 14.7afr.

Only when your manifold is in boost should you really start to richen up the mix.

I do idle in a vacuum, just not 18-20", 12" in fact, I am into boost shortly there after. Was wondering if idling a little richer would smooth the transition from CL to OL. Looking to see if anyone has a similar issue?

[rat]

Mine did that when i swapped manifolds. It was a tune issue. Watching my wideband i could easily see it was spiking lean.

I ended up adding fuel in the high map/low rpm area of my ve table. 70+kpa, 2000rpm and under.

[97 Jimmy]

Thats great and what I need to hear! We are going back out with a clean slate to get a log and try again. Les>>>