Hello guys...

I was wondering one thing regarded boosted tuning.. when is it a good idea to have 14.7 SToich afr...

if you look at it from the N/A standpoint.. anythign above 80kpa is most of the times WOT since you will probably hit that over 66% or more TPS...

In a boosted car you can see boost even at 1/2 throttle.. should the AFR still be at 14.7 even if you see 1-3psi boost or should the PCM calc for lower afrs to avoid detonation??

Or is it really a matter of TPS where the car feels the push?

Thanks

 

14.7 AFR is way too lean for even a stock motor. 12.5 AFR is about as lean as you want to get in a blown motor...12 would probably be safer. Do a search to get more info.

 

You misunderstood... i was talking about PART throttle...

Thanks

 

If you have boost at part throttle, you are essentially putting more air in that the engine can flow.

This is equivalent to "more than full throttle" on a normally aspirated engine regardless of the throttle position.

Closed loop will try to maintain 14.7:1. The LT1 computer has a setting where you can force open loop operation above a certain throttle opening. I think stock is approx 80%. I would drop this lower to around 50-60% with a big charger. Final drivability will dictate what this number should be.

I would try about 12.6-12.8 as you just get into boost (1-2#)
Gradually add fuel nearing 11:1 at high boost (around 12#).
Rich is safe. Lean it out to increase power watching for excess cylinder temps & detonation.

Remember it will generally make the most power where it is closest to engine damage. Don't let greed override your budget or you will have a sick empty feeling in both your stomach & pockets as well.