Hey guys! What’s a safe but not overly rich AFR on a boosted application? I’m currently running 93octane and around 7 lbs of Boost on a supercharged 6.2. I would like to throw some more boost at it, while maintaining its ability to be a daily driver. I am pretty sure my current tune is pretty fat, so was curious what you guys are running. Thanks!
for reference, my current tune is putting me at 9.3 under Boost...

 

Leaner than 12s on a port injected motor is asking for trouble. 11.8-12.0 is a safe place to hang

9.3 is faaaaat. Leaving some power on the table for that

 

If your computer allows you to tune AFR by MAP KPA, then start it leaner and add the fuel in as boost rises.

Like you don't need 11.0 afr at 2 psi of boost type of thing. Slope the fuel in. Start at maybe 12.2 for 0-2psi and slope down to 11.7 by 6+psi.

Running E85 would let that be different because you could run even leaner on more boost and not need all of it until probably past 10psi.

 

lean it up some before adding more boost.You may pick up enough power to change your mind about adding boost
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Thank you guys for your input. I will lean it out and see what how it performs. I Do think will still want to add boost, but if I am overfueling currently, maybe my fuel pump (factory flex) and the 850 injectors will support more boost ?

 

I think those numbers sound more in the range I need. It’s progressively setup currently, but I think it’s like 10.4 at 2psi and down to low 9 at 6lbs.

I have someone helping me tune (I’m an HPtuners rookie), So I’ll try and get it backed off.

that being said, does the computer need a different tune to run E85? I know I would gain a good bit of power, but don’t know if I need to do a separate tune for that. The truck is Flex fuel By default.

 

If it was E85 all the time, you'd want different values in the commanded fueling. It can be leaner. Some computer have a gas EQ Ratio and an Alcohol EQ Ratio that you can set the fueling on.


This is also an important thing to note. The EQ Ratio is a commanded value, once you set that value you do not want to change it again to get your desired outcome. So if you request 11.5 AFR but the wideband is showing 10.8, DO NOT change the EQ Ratio to 12.2 so that it reaches 11.5.

Once PE is set you leave and only adjust the actual airflow tables to bring fueling in line. If it was really .7 richer then you'd need to remove fueling from the MAF/VE tables to bring the actual air fuel ratio leaner to match the commanded.